JP6505833B2 - Polarizing element in which a film having high retardation and a layer containing a dichroic dye are laminated, and a display device provided with the same - Google Patents

Description

  The present invention relates to a polarizing element in which a film having high retardation and a layer containing a dichroic dye are laminated. The present invention also relates to a display device provided with the polarizing element.

  In general, a polarizing element used in a liquid crystal display device, sunglasses, goggles, etc. is made to adsorb a dichroic dye such as iodine or a dichroic dye to a film made of a polymer substance such as polyvinyl alcohol Then, the film obtained is uniaxially stretched to orient the dichroic dye molecules in a certain direction, or the polymer film is uniaxially stretched and then manufactured by a method of adsorbing the dichroic dye. However, since the polarization axis and absorption axis of the polarizing element obtained by these methods are perpendicular to each other, the shape of the polarizing element is usually limited to a flat plate. Furthermore, in the production of such a polarizing element, a film obtained by swelling and dyeing a polyvinyl alcohol film, and subsequently stretching it in a boric acid aqueous solution, and further performing water washing and drying The complicated process of bonding a protective film using an adhesive agent was needed. In addition, it has been required to provide a polarizing element in a desired portion more simply.

  In view of the problems of the conventional polarizing element as described above, Non-Patent Document 1 discloses a method of producing a polarizer by orienting dichroic dye molecules in a certain direction by rubbing treatment. However, the coatability of the dye solution on the substrate is reduced by scratches and dust on the substrate caused by the rubbing process in the rubbing process, and further by electrical scratches and the like generated due to static electricity. Therefore, there is a portion (coating failure) which is not coated on the obtained dye film, and as a result, in the polarizing element having the dye film, the quality of polarization performance is not satisfactory.

  Patent Document 1 discloses a technique for obtaining a polarizer having high polarization performance by orienting dichroic dye molecules in contact with the photoalignment film in an arbitrary direction using the photoalignment film. However, when the surface of the dye film of the polarizing element is observed with an atomic force microscope (AFM), a portion in which the dichroic dye is uniformly oriented and a portion in which the dichroic dye is hardly present and are not oriented There is a (crater). Therefore, the polarization performance of the obtained polarizing element has not been sufficiently satisfied as a practical level in a polarizing element for a display element.

  In Patent Document 2, in order to further improve the uniformity of the orientation of dichroic dye molecules and the polarization performance of the obtained polarizing element, the occurrence of craters is reduced as much as possible, and the orientation of the dichroic dye compound is generally enhanced. There is disclosed a method of manufacturing a polarizing element at a practical level for display elements. The polarizing element uses a liquid crystalline polymer thin film having a photoactive group as an alignment film, irradiates the thin film with linearly polarized light, aligns the molecular axis of the photoactive group of the polarized light irradiation portion in a certain direction, and then another micropattern Applying linearly polarized light having different polarization axes through a mask, and applying a dichroic dye solution with a roll coater so that a specific range of pressure is applied vertically to the substrate on the thin film. Manufacturing method. However, in the production of the polarizing element, a certain pressure needs to be applied between the roll and the substrate, and the pressing pressure must be strictly controlled. Therefore, development of a polarizing element excellent in polarization performance that can be more easily manufactured without requiring such strict pressure control is desired.

JP-A-7-261024 Patent No. 4175455 gazette

Transactions of the Institute of Electronics, Information and Communication Engineers, 1988, JJ 71-C, p. 1188

  A polarizing element having a dye film obtained by applying a conventional composition containing a dichroic dye has not obtained sufficiently satisfactory polarizing performance due to the influence of rubbing treatment and the like. Therefore, it is necessary to further improve the polarization performance. In addition, it is also desired to more simply manufacture a polarizing element excellent in such polarization performance.

  Therefore, an object of the present invention is to provide a polarizing element excellent in polarization performance which can be easily manufactured, and a display device provided with the same.

  As a result of intensive studies to solve the above problems, the inventor of the present invention has laminated a stretched film having a retardation of 3000 to 50000 nm and a layer containing a dichroic dye, and the stretched film has a thickness of 20 to 500 μm. It has been newly found that by using a polarizing element of the present invention, it is possible to obtain a polarizing element excellent in polarization performance which can be easily manufactured.

（式（１）中、
Ｘ_１は、１つ若しくは２つのスルホン酸基と、水酸基若しくは１乃至３の炭素数を有するアルコキシ基とを有するフェニル基又はナフチル基を表し、
Ｘ_２及びＸ_３は、それぞれ独立して、フェニレン基又はナフチレン基を表し、該フェニレン基又はナフチレン基は、１乃至３の炭素数を有するアルキル基、１乃至３の炭素数を有するアルコキシ基、水酸基及びスルホン酸基からなる群から選択される１種又は２種の置換基を１つ又は２つ有しており、
Ｒ_１は、水素原子、１乃至３の炭素数を有するアルキル基、アセチル基、ベンゾイル基、或いは、非置換のフェニル基又は１乃至４の炭素数を有するアルキル基、１乃至４の炭素数を有するアルコキシル基、アミノ基若しくはスルホ基で置換されたフェニル基を表し、
ｍは、０又は１であり、かつ
ｎは、１又は２である）
（７）Ｘ_１が、置換基として下記式（３）で表される化合物又はその塩であることを特徴とする（６）に記載の偏光素子。

（式（３）中、ｊは１又は２である）
（８）前記二色性色素を含有する層は、ポリオキシエチレンポリオキシプロピレンアルキルエーテル又はポリオキシエチレンポリオキシプロピレンブロックポリマーをさらに含有することを特徴とする（１）乃至（７）のいずれか１つに記載の偏光素子。
（９）（１）乃至（８）のいずれか１つに記載の偏光素子を設けた表示装置。That is, the gist configuration of the present invention is as follows.
(1) A polarizing element characterized in that a stretched film having a retardation of 3000 to 50000 nm and a layer containing one or more dichroic dyes are laminated, and the thickness of the stretched film is 20 to 500 μm. .
(2) The polarizing element according to (1), wherein the stretched film is made of polyethylene terephthalate.
(3) The polarizing element according to (1) or (2), wherein the dichroic ratio is 5 or more.
(4) A molecular anisotropy larger than the molecular anisotropy imparted to the surface of the stretched film is further imparted in the same direction as the stretching axis of the stretched film. The polarizing element as described in any one of (3).
(5) The stretched film is further characterized by further including a retardation film having a slow axis or a fast axis of retardation at an angle of 10 ° to 100 ° with respect to the long axis direction of the film ( The polarizing element as described in any one of 1) to (4).
(6) The polarizing element according to any one of (1) to (5), wherein at least one of the dichroic dyes is a compound represented by the following formula (1) or a salt thereof .

(In the formula (1),
X ₁ represents a phenyl group or a naphthyl group having one or two sulfonic acid groups and a hydroxyl group or an alkoxy group having 1 to 3 carbon atoms,
X ₂ and X ₃ each independently represent a phenylene group or a naphthylene group, and the phenylene group or the naphthylene group is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, It has one or two types of one or two types of substituents selected from the group consisting of a hydroxyl group and a sulfonic acid group,
R ₁ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an acetyl group, a benzoyl group, an unsubstituted phenyl group or an alkyl group having 1 to 4 carbon atoms, 1 to 4 carbon atoms A phenyl group substituted by an alkoxyl group, an amino group or a sulfo group,
m is 0 or 1 and n is 1 or 2)
(7) The polarizing element according to (6), wherein X ₁ is a compound represented by the following formula (3) as a substituent or a salt thereof.

(In the formula (3), j is 1 or 2)
(8) The layer containing the dichroic dye further contains polyoxyethylene polyoxypropylene alkyl ether or polyoxyethylene polyoxypropylene block polymer, any one of (1) to (7) The polarizing element as described in one.
The display apparatus which provided the polarizing element as described in any one of (9) (1) thru | or (8).

  The polarizing element of the present invention, characterized in that a film having a retardation of 3000 to 50000 nm and a layer containing a dichroic dye are laminated, has a high retardation of 20 to 500 μm in thickness as a substrate. It uses a stretched film. The polarizing element of the present invention using such a specific stretched film exhibits a high degree of polarization, particularly a degree of polarization of 85% or more, a high dichroism, particularly 5 or more dichroism. Therefore, the polarizing element excellent in polarization performance can be obtained by using the specific stretched film in this invention as a base material. Moreover, the polarizing element of this invention laminates | stacks a specific base material and the layer containing a dichroic dye. Therefore, according to the configuration of the present invention, it is possible to obtain a high-performance polarizing element which is excellent in polarization performance and which can be easily manufactured.

  Hereinafter, the present invention will be described in detail. In the following, the numerical range represented using “to” means a range including the numerical values described before and after “to” as the lower limit value and the upper limit value. Further, unless otherwise stated, the compounds (substituents) represented by the formulas (1) to (3) are represented in the form of a free acid, and the salt of the free acid is, for example, a sulfonic acid group or a hydroxy group I mean salt. Also, in the following description, unless otherwise stated, "compound represented by Formula (1) or a salt thereof", "compound represented by Formula (2) or a salt thereof", "substitution to avoid complexity. The “compound represented by Formula (3) or a salt thereof” as a group is a “compound represented by Formula (1)”, “a compound represented by Formula (2)”, and “a compound represented by Formula (3) as a substituent”. It describes for convenience as a compound represented by this.

  First, the polarizing element which comprises this invention is demonstrated. The polarizing element of the present invention is a polarizing element in which a stretched film having a retardation of 3000 to 50000 nm and a layer containing a dichroic dye are laminated, and the thickness of the stretched film is 20 to 500 μm.

(Stretch film)
The polarizing element of the present invention uses a stretched film having a retardation of 3000 to 50000 nm as a substrate. The material of the stretched film is not particularly limited, and examples thereof include polyesters such as polyethylene terephthalate and polyethylene naphthalate, and resins such as polycarbonate, polystyrene, polyetheretherketone, polyphenylene sulfide, and cycloolefin polymer. Among them, polycarbonate or polyester is particularly preferable. These resins are excellent in transparency and also excellent in thermal and mechanical properties, and the retardation of the film can be easily controlled by drawing, and the degree of crystallization after drawing is high. The dimensional change such as heat shrinkage after stretching is smaller than the polyvinyl alcohol-based film used in the polarizing element of the present invention. Therefore, the dimensional change is extremely reduced compared to the polarizing element using the conventional polyvinyl alcohol-based film be able to. Moreover, the stretched film used by this invention has the above high retardation, even if it is comparatively thin thickness of 20-500 micrometers. As a material of such an oriented film, particularly polyester represented by polyethylene terephthalate is most preferable because high intrinsic birefringence is obtained and high retardation can be obtained relatively easily even if the thickness of the oriented film is relatively thin. It is a good material.

  The higher the molecular orientation in the stretched film, that is, the higher the retardation, the better the orientation of the dichroic dye molecules coated on the stretched film. Therefore, in order to obtain a polarizing element having a high degree of polarization, it is preferable to use a stretched film having a high retardation. As mentioned above, the range of the retardation which the stretched film used with the polarizing element of this invention has is 3000-50000 nm. A polymer film having a retardation of more than 50000 nm is not preferable because it is easy to be fixed and the thickness of the film is correspondingly increased, as a result of which the handleability as an industrial material is reduced. On the other hand, from the viewpoint of visibility, it is preferable to use a stretched film having a retardation range of 3000 to 30000 nm. It is known that viewing a display screen through a polarizing plate such as polarizing sunglasses has a particularly good performance exhibiting a strong interference color. On the other hand, if the retardation is in the range of 3000 to 30000 nm, such interference does not appear and good visibility can be ensured. However, when the retardation is less than 3000 nm, when the display screen is observed through a polarizing plate such as polarized sunglasses, since the display screen exhibits a strong interference color, the envelope shape is different from the light emission spectrum of the light source, and as a result, good visibility is ensured. And the performance of the polarizing element is degraded. Therefore, the range of retardation of the stretched film used in the polarizing element of the present invention is 3000 to 50000 nm, the lower limit of preferable retardation is 4500 nm, more preferable lower limit is 6000 nm, more preferable lower limit is 8000 nm, more preferable lower limit The value is 10000 nm, and the preferred upper limit of retardation is 30000 nm.

  The method for producing a stretched film used for the polarizing element of the present invention is not particularly limited as long as the stretched film characteristics defined in the present invention are satisfied. Moreover, as a stretched film to be used, for example, a film described in JP-A-2012-230390, JP-A-2012-256014, or Cosmo Shine (super-birefringence) which is a polyethylene terephthalate film manufactured by Toyobo Co., Ltd. Type films (SRF films) can be mentioned, and the use of such a stretched film makes it possible to develop molecular anisotropy on the film surface and to orient dichroic dye molecules. The state in which the film is stretched means that the anisotropy is expressed with respect to the orientation of the dichroic dye molecule on the film surface, and the retardation is expressed. The development of this anisotropy can be measured by diffraction measurement by X-ray measurement, retardation measurement, anisotropic IR absorption analysis or the like. In particular, “Alexxander, L. E. Diffraction Methods in polymer Science New York”, 1969, Chapter 4, p. In the orientation coefficient obtained by the calculation method of fc described in 241-252, fc may be 0.3 or more, preferably 0.5 or more, more preferably 0.7 or more, and 0.9 or more. Particularly preferred. The method for stretching the film is not particularly limited as long as anisotropy is developed, but in particular, by using a uniaxially stretched film, dichroism can be obtained in the subsequent application of a solution containing a dichroic dye. Dye molecules exhibit high orientation in the stretching direction, and as a result, it is possible to obtain a polarizing element exhibiting a high degree of polarization.

  In the present invention, the retardation (retardation value) is a parameter defined by the product of the anisotropy of the biaxial refractive index on the film and the thickness of the film, and the optical isotropy and the anisotropy are It is a scale to show. Therefore, this retardation can be determined by measuring the refractive index and thickness in the biaxial direction, for example, using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (manufactured by Oji Scientific Instruments). It can be asked.

By subjecting the stretched film as a substrate to corona discharge treatment or irradiation with ultraviolet light, it is possible to improve the dichroism of the polarizing element to be described later, and to improve the polarizing property of the obtained polarizing element. Corona discharge treatment can be applied by using various commercially available corona discharge treatment machines as an apparatus which performs corona discharge treatment, and in particular, use of a corona treatment machine having an aluminum head is preferable. The conditions of the corona discharge treatment are, as the energy density, 20 to 400 W · min / m ² , preferably 50 to 300 W · min / m ² or so, at the time of corona discharge treatment per time. If one corona discharge treatment is insufficient, the corona discharge treatment may be performed twice or more. Ultraviolet irradiation is similarly applicable by using various commercially available ultraviolet irradiation devices. The wavelength of ultraviolet light to be used is not particularly limited, but, for example, deep ultraviolet light of 300 nm or less is preferable. The ultraviolet irradiation is preferably performed under an oxygen stream, and the irradiation time of the ultraviolet light may be several minutes at most.

(Dichroic dye)
The polarizing element of the present invention has a layer containing a dichroic dye in order to form a dye film as an element exhibiting a polarizing function. A dichroic dye is used as a material for forming a layer containing a dichroic dye, and the dichroic dye is a compound which exhibits polarization by arranging in a certain direction by itself or in an aggregate. . Examples of such dichroic dyes include dye-based compounds such as azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes, anthraquinone dyes and the like. Etc. The dichroic dye used in the present invention is a compound that exhibits lyotropic liquid crystallinity under a certain solvent composition, dye concentration, and temperature conditions. For example, Masahiro Irie ed., "Application of functional dye", First printing issue Version, CMC, Inc., June 2002, pp. 102-104. In addition, it is preferable to use a water-soluble azo dye as the dichroic dye, and among them, a compound having an aromatic ring structure is more preferable. As the aromatic ring structure, for example, in addition to benzene, naphthalene, anthracene and phenanthrene, heterocyclic rings such as thiazoles, pyridines, pyrimidines, pyridazines, pyrazines and quinolines or quaternary salts thereof, and further, benzene, naphthalene and the like And aromatic rings such as sulfonic acid groups, carboxylic acid groups, amino groups, hydrophilic substituents such as hydroxyl groups, or salts of sulfonic acid groups or carboxylic acid groups. Is preferred.

  As specific examples of such dichroic dyes, for example, C.I. I. Direct Orange 39, C.I. I. Direct Orange 41, C.I. I. Direct Orange 49, C.I. I. Direct Orange 72, C.I. I. Direct Red 2, C.I. I. Direct Red 28, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Direct Violet 9, C.I. I. Direct Violet 35, C.I. I. Direct Violet 48, C.I. I. Direct Violet 57, C.I. I. Direct Blue 1, C.I. I. Direct Blue 15, C.I. I. Direct Blue 67, C.I. I. Direct Blue 78, C.I. I. Direct Blue 83, C.I. I. Direct Blue 90, C.I. I. Direct Blue 98, C.I. I. Direct Blue 151, C.I. I. Direct Blue 168, C.I. I. Direct Blue 202, C.I. I. Direct Green 42, C.I. I. Direct Green 51, C.I. I. Direct Green 59, C.I. I. Direct Green 85, C.I. I. Direct Yellow 4, C.I. I. Direct Yellow 12, C.I. I. Direct Yellow 26, C.I. I. Direct Yellow 44, C.I. I. Direct Yellow 50, mordant yellow 26, C.I. I. No. 27865, C.I. I. No. 27915, C.I. I. No. 27920, C.I. I. No. 29058, C.I. I. No. No. 29060, etc., and further JP-A-1-161202, JP-A-1-172906, JP-A-1-172907, JP-A-1-183602, JP-A-1-248105, JP-A-1 The dichroic dye described in each publication of JP-A-265205 and JP-A-9-230142 can be mentioned.

  Among the dichroic dyes shown in the above specific examples, compounds represented by the following formula (1) or formula (2) are particularly preferable, and in particular, compounds represented by the formula (1) are preferable. The compounds represented by Formula (1) and Formula (2) exist as free acids or salts thereof. The salt of the free acid is not particularly limited, and may be, for example, an alkali metal salt such as Li, Na or K, or any salt such as a quaternary ammonium salt. By using such a dichroic dye, the polarization performance of the resulting polarizing element can be improved.

（式（１）中、
Ｘ_１は、１つ若しくは２つのスルホン酸基と、水酸基若しくは１乃至３の炭素数を有するアルコキシ基を有するフェニル基またはナフチル基を表し、
Ｘ_２及びＸ_３は、それぞれ独立して、フェニレン基又はナフチレン基を表し、当該フェニレン基又はナフチレン基は、１乃至３の炭素数を有するアルキル基、１乃至３の炭素数を有するアルコキシ基、水酸基及びスルホン酸基からなる群から選択される１種又は２種の置換基を１つ又は２つ有しており、
Ｒ_１は、水素原子、１乃至３の炭素数を有するアルキル基、アセチル基、ベンゾイル基、或いは、非置換のフェニル基又は１乃至４の炭素数を有するアルキル基、１乃至４の炭素数を有するアルコキシル基、アミノ基若しくはスルホ基で置換されたフェニル基を表し、
ｍは、０又は１であり、
ｎは、１又は２である。）

(In the formula (1),
X ₁ represents a phenyl group or a naphthyl group having one or two sulfonic acid groups and a hydroxyl group or an alkoxy group having 1 to 3 carbon atoms,
X ₂ and X ₃ each independently represent a phenylene group or a naphthylene group, and the phenylene group or the naphthylene group is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, It has one or two types of one or two types of substituents selected from the group consisting of a hydroxyl group and a sulfonic acid group,
R ₁ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an acetyl group, a benzoyl group, an unsubstituted phenyl group or an alkyl group having 1 to 4 carbon atoms, 1 to 4 carbon atoms A phenyl group substituted by an alkoxyl group, an amino group or a sulfo group,
m is 0 or 1;
n is 1 or 2; )

（式（２）中、
Ｙ_１は、スルホン酸基を１つ又は２つ有し、さらに水酸基又は１乃至３の炭素数を有するアルコキシ基を有していてもよいナフチル基を表し、
Ｙ_２及びＹ_３は、それぞれ独立して、フェニレン基又はナフチレン基を表し、当該フェニレン基又はナフチレン基は、１乃至３の炭素数を有するアルキル基、１乃至３の炭素数を有するアルコキシ基、水酸基及びスルホン酸基からなる群から選択される１種又は２種の置換基を１つ又は２つ有しており、
Ｒ_２は、水素原子、１乃至３の炭素数を有するアルキル基、アセチル基、ベンゾイル基、或いは、非置換のフェニル基又は１乃至４の炭素数を有するアルキル基、１乃至４の炭素数を有するアルコキシル基、アミノ基若しくはスルホ基で置換されたフェニル基を表し、
フェニルアゾ基としての

は、末端ナフチル基の５位、６位、７位又は８位のいずれかに置換されており、
Ｒ_３及びＲ_４は、それぞれ独立して、水素原子、水酸基、スルホン酸基、１乃至３の炭素数を有するアルキル基又は１乃至３の炭素数を有するアルコキシ基を表し、
ｑは、０又は１であり、
ｐは、１又は２である。）

(In the formula (2),
Y ₁ represents a naphthyl group which may have one or two sulfonic acid groups and may further have a hydroxyl group or an alkoxy group having 1 to 3 carbon atoms,
Y ₂ and Y ₃ each independently represent a phenylene group or a naphthylene group, and the phenylene group or the naphthylene group is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, It has one or two types of one or two types of substituents selected from the group consisting of a hydroxyl group and a sulfonic acid group,
R ₂ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an acetyl group, a benzoyl group, an unsubstituted phenyl group or an alkyl group having 1 to 4 carbon atoms, 1 to 4 carbon atoms A phenyl group substituted by an alkoxyl group, an amino group or a sulfo group,
As a phenylazo group

Is substituted at any of position 5, 6, 7 or 8 of the terminal naphthyl group,
R ₃ and R ₄ each independently represent a hydrogen atom, a hydroxyl group, a sulfonic acid group, an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms,
q is 0 or 1;
p is 1 or 2; )

等が挙げられる。Specific examples of the compound represented by the above formula (1) include, for example,

Etc.

等が挙げられる。Moreover, as specific examples of the compound represented by the formula (2), for example,

Etc.

Among the compounds represented by Formula (1) or Formula (2), X ₁ in Formula (1) or Y ₁ in Formula (2) is a compound represented by the following Formula (3) as a substituent By having it, the polarization performance can be further improved, and in particular, it is represented by the formula (1) having a compound represented by the following formula (3) as a substituent at a point having a high dichroic ratio alone. The use of compounds is preferred. The said substituent is also present as a free acid or its salt similarly to the compound represented by Formula (1) and Formula (2). The salt of the free acid is not particularly limited, and may be, for example, an alkali metal salt such as Li, Na or K, or any salt such as a quaternary ammonium salt.

（式（３）中、ｊは１又は２である。）

(In the formula (3), j is 1 or 2)

  The above dichroic dyes used in the present invention may be used alone or in combination of two or more. There is no particular limitation on the combined use of such two or more dichroic dyes, but it is possible to further improve the dichroic ratio of the dichroic dyes by using an additional dichroic dye. it can.

  Next, a method of producing the polarizing element of the present invention will be described. In the polarizing element of the present invention, a solution containing the above dichroic dye is applied to the stretched film as the substrate described above and then dried to form a layer containing the dichroic dye on the stretched film. It is produced by Since the layer containing the formed dichroic dye exhibits a polarizing function, a laminate comprising a substrate and a layer containing the dichroic dye may be used as a polarizing element, and the dichroic dye You may use the laminated body by which the protective layer etc. were further laminated | stacked on the surface of the layer to contain as a polarizing element.

  In order to orient the dichroic dye molecules in a stretched film as a substrate, a solution (coating solution) containing the dichroic dye is prepared. The solvent as the coating solution is not particularly limited as long as it can dissolve the dichroic dye to be used, and, for example, water, alcohols, ethers, pyridine, dimethylformamide (DMF), dimethyl sulfoxide (DMSO) And N-methyl pyrrolidinone (NMP), dimethyl acetamide (DMAC), dimethyl imidazoline (DMI), etc., and among these, only one solvent may be contained, or a plurality of solvents may be contained. It may be In particular, when a water-soluble dichroic dye is used, a mixed solvent with water or the above organic solvent mainly containing water is preferable as the solvent. Although the mixing amount to the water of the organic solvent with respect to water is arbitrary, 0-50 mass% with respect to water, especially 0-20 mass% is preferable. The concentration of the dichroic dye in the coating solution is preferably 0.1 to 25% by mass, more preferably 0.3 to 10% by mass, and still more preferably 0.5 to 5% by mass.

  In addition, the polarizing element of the present invention has a layer containing a dichroic dye formed using a coating solution further containing a polyoxyethylene polyoxypropylene alkyl ether or a compound of polyoxyethylene polyoxypropylene block polymer. By this, the polarization performance can be further improved. When the layer containing the dichroic dye further contains such a compound, it is possible to improve the coating failure which has conventionally occurred at the time of coating in the preparation of the dye film on the substrate. These compounds may be used alone or in combination of two or more. The concentration of these compounds in the coating solution is preferably 0.001% by mass to 5% by mass, more preferably 0.01% by mass to 2% by mass, and still more preferably 0.05% by mass to 1.0%. It is mass%.

  Next, a solution containing this dichroic dye is dropped onto the surface of the stretched film of the present invention as a substrate, and the dichroic dye having a uniform thickness on the stretched film is contained by a coater or a spin coating method. To form a coating layer. The method for providing the coating film is not particularly limited as long as the solution containing the dichroic dye can be coated, and for example, the stretched film of the present invention in a solution containing the dichroic dye A method of immersing the solution, a method of applying the solution by a bar coder, a method of applying a coating method of an inkjet printer such as a piezo method, a thermal method or a bubble jet (registered trademark) method used for household or commercial use, a spin coater Methods of spin coating, roll coater coating, flexographic printing, screen printing, gravure printing, curtain coater coating, spray coater coating, etc., but in particular, roll coater coating, curtain coater coating, spray coating using a spray coater The method is preferred.

  Further, the substrate coated with the solution of the dichroic dye is dried to form a solid dichroic dye layer, whereby a layer containing the dichroic dye of the present invention is obtained. Although the drying conditions differ depending on the type of solvent, the type of dichroic dye, the amount of the solution containing the applied dichroic dye, the concentration of the dichroic dye, etc., the drying temperature is preferably 5 to 100 ° C. The humidity is about 20 to 95% RH, preferably about 30 to 90% RH.

  The thickness of the layer containing the dichroic dye of the present invention is preferably thin from the viewpoint of improving the polarization characteristics, and for example, it is preferably 0.001 to 10 μm, particularly preferably 0.05 to 2 μm. Moreover, in order to form the layer containing the dichroic dye of the present invention in such a thickness range, the thickness of the coating film to which the solution containing the dichroic dye is applied is 2 to 10 μm. Is preferable, and 3 to 5 μm is more preferable.

  In addition, the stretched film of the present invention coated with a solution containing a dichroic dye may be further subjected to heat treatment and / or humidification treatment. The adhesion of the layer containing the dichroic dye to the stretched film of the present invention, and the polarization performance, dichroic ratio and durability of the obtained polarizing element can be improved by heat treatment and / or humidification treatment. it can. The temperature of the heat treatment is room temperature to 110 ° C., preferably 60 to 90 ° C., and the humidity of the humidification treatment is 40 to 95% RH, preferably about 50 to 90% RH.

  The polarizing element of the present invention thus obtained has a dichroic ratio (Rd). The dichroic ratio is generally defined as the ratio of absorbance along the absorption axis to absorbance along the transmission axis. The dichroic ratio of the polarizing element of the present invention is calculated by the following formula (4), and if the dichroic ratio is 5 or more, it means that the polarizing function is exhibited. The dichroic ratio of the polarizing element of the present invention is 5 or more, preferably 10 or more, more preferably 15 or more, and still more preferably 20 or more. When the dichroic ratio is less than 5, the degree of polarization is less than 65%, and the function as a polarizing element is not sufficient. The polarization degree of the polarizing element is usually 65% or more, preferably 70% or more, and more preferably 80% or more. The degree of polarization is the ratio of the light intensity of the polarized component to the total light intensity, and the higher the degree of polarization, the higher the polarization performance. In the following formula (4), Ky is the transmittance of the axis that most transmits light when polarized light is incident, and Kz is the transmission of the axis that most absorbs light when polarized light is incident It is a rate.

  As a method of further improving the dichroic ratio of the polarizing element of the present invention, the molecular anisotropy given to the surface of the stretched film in the same direction as the stretching axis of the stretched film with respect to the surface of the stretched film in the present invention The dichroic ratio can be further improved by further imparting molecular anisotropy larger than the property. As a method of expressing larger molecular anisotropy than the stretched film, for example, a method of rubbing the stretched film may be mentioned. Such rubbing is exemplified, for example, in Japanese Patent Application Laid-Open Nos. 06-110059 and 2002-90743. Although the measurement of the molecular anisotropy of the surface of a stretched film is not specifically limited, For example, it measures by the measuring method used for the anchoring measurement of the alignment film for liquid crystal. Further, a device for measuring such molecular anisotropy is not particularly limited, and, for example, Lay Scan manufactured by MARITEX SCOTT can be used.

  On the stretched film of the present invention, the molecular anisotropy in the long axis direction on the surface of the film having a slow axis or a fast axis of retardation different from the long axis direction of the film, preferably 10 ° to 100 °. It is also possible to produce a polarizing element in which a retardation film showing the properties is further laminated. Such a retardation film is obtained by imparting molecular anisotropy in the major axis direction by rubbing or the like to the surface of the retardation film having a slow axis or a fast axis of retardation at an arbitrary angle, Thereby, the polarization axis or absorption axis of the polarizing element can be arbitrarily controlled. That is, a further retardation film having a slow axis or a fast axis of retardation at an angle different from that of the long axis direction of the film and exhibiting molecular anisotropy on the surface in the long axis direction, By using the stretched film of the present invention, it is possible to produce a polarizing element having an absorption axis or a polarization axis at an angle different from that of the slow axis or the fast axis as the retardation axis and the retardation axis. Become. The angle between the retardation axis of the retardation film and the absorption axis or polarization axis of the polarizing element is most preferably 15 °, 45 °, 75 ° or 90 °. The reason why such an angle is preferable is that, in general, when it is desired to control linearly polarized light to circularly polarized light, a film having a retardation of 1⁄4 with respect to the length of the wavelength to be controlled is It is known to set at 45 ° to. Also, as a method of reversing the polarization axis of linearly polarized light, it is known to set a film having a retardation of 1⁄2 to 90 ° with respect to the length of the wavelength to be controlled. The reason for placing the film at 15 ° or 75 ° with respect to the absorption axis or the polarization axis of the polarizing element is that such an angle has a formula showing a retardation of 1⁄4 for a wide range of wavelengths ( This is because the axis angle is generally used in a wide band achromatic retardation plate). This enables arbitrary control of the polarization axis or absorption axis of the polarizing element.

  The layer containing the dichroic dye of the present invention produced as described above is in a solid state such as amorphous or crystalline, but the layer containing the dichroic dye is usually inferior in mechanical strength. The surface of the layer is provided with a lake treatment, a crosslinking treatment with a silane coupling agent, or a protective layer. Lake is to electrically bond a metal ion or the like to a water-soluble dichroic dye. Making a dichroic dye into lake is sometimes called lakeing or insolubilization. Examples of compounds suitable for lake include aluminum chloride, iron chloride, calcium chloride, barium chloride, nickel chloride, magnesium chloride, copper chloride, barium acetate, nickel acetate and the like, and a dichroic dye such as metal ion and the like It is not particularly limited as long as it can be bonded and the dichroic dye can be insolubilized in water. Further, the crosslinking treatment with a silane coupling agent is not particularly limited either, and for example, the crosslinking treatment is carried out by heating using a silane coupling agent as described in JP-A-2011-53234, The layer containing the color pigment can be immobilized. The protective layer is usually a layer containing a dichroic dye coated with a UV curable or thermosetting transparent polymer film, or a laminate with a transparent polymer film such as a polyester film or a cellulose acetate film, etc. Provided by the coating method of The protective layer can be provided as a polymer coated layer or as a laminate layer of a film. The transparent polymer or film forming the transparent protective layer is preferably a transparent polymer or film having high mechanical strength and good heat stability. As a substance used as a transparent protective layer, for example, cellulose acetate resin such as triacetyl cellulose and diacetyl cellulose or a film thereof, acrylic resin or a film thereof, polyvinyl chloride resin or a film thereof, nylon resin or a film thereof, polyester resin or the same Film, polyarylate resin or film thereof, cyclic polyolefin resin or film thereof using cyclic olefin such as norbornene, polyethylene, polypropylene, polyolefin having cyclo or norbornene skeleton or copolymer thereof, main chain or side chain Examples thereof include imide and / or amide resins or polymers or films thereof. In addition, as the transparent protective layer, a resin having liquid crystallinity or a film thereof can also be provided. The thickness of the protective layer is, for example, about 0.5 to 200 μm. One or more layers of resin or film to be a protective layer can be provided on one side or both sides of the polarizing element, and when using a plurality of protective layers, these protective layers may be the same or different. Good.

  The polarizing element of the present invention can be used for polarizing sunglasses, goggles and the like. Furthermore, in the polarizing element of the present invention, when a stretched film produced from the above-mentioned material is used as a substrate, it is required when a normal polyvinyl alcohol-based film base is used in the production of the polarizing element of the present invention. It does not require the adsorption of dichroic dyes or the stretching process in boric acid solution. Therefore, it is possible to obtain a polarizing element without dimensional change of the substrate and without contraction. The ability to manufacture a polarizing element without dimensional change is particularly effective for displays that require the polarizing element to be provided on one side of a display device such as a flexible display or an organic electroluminescent display (commonly referred to as an OLED). Therefore, the polarizing element of the present invention can be provided in a display device such as a flexible display or an organic electroluminescent display. In addition, unlike the conventional manufacturing method of a polarizing element, the stretched film of the present invention can be used as a substrate without imposing the strict conditions required for the coating of a dichroic dye. The manufacturing of the polarizing element of the present invention is very simple, since the polarizing element can be easily obtained simply by applying a solution containing H.sub.2 followed by drying and providing a layer containing the dichroic dye on the substrate. It is.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In addition, evaluation of the transmittance | permeability shown to an Example was performed as follows.

  The transmittance and dichroic ratio (Rd) of each wavelength were measured using a spectrophotometer (manufactured by JASCO Corporation: V-7100). At this time, the transmittance of each wavelength when the layer containing the dichroic dye is measured in one layer is the transmittance Ts, and the layers containing the two dichroic dyes have the same absorption axis direction. The transmittance in the case of overlapping is referred to as parallel transmittance Tp, and the transmittance in the case where the layers containing two dichroic dyes are overlapped such that their absorption axes are orthogonal to each other is referred to as orthogonal transmittance Tc.

  The degree of polarization ρ was determined from the parallel transmittance Tp and the orthogonal transmittance Tc according to equation (5).

Example 1
On the non-easy-adhesion treated side of a drawn film (Cosmoshine SRF film manufactured by Toyobo Co., Ltd.) having a retardation of 10500 nm and a thickness of 100 μm, C.I. I. A solution containing 4 parts by mass of Direct Blue 67, 0.15 parts by mass of polyoxyethylene polyoxypropylene alkyl ether (Emulgen MS-110 manufactured by Kao Corporation), and 100 parts by mass of water and having a distance of 3 μm from the stretched film It applied using the coating machine provided with the glass rod set so that it might become. The obtained coated film was left to stand in an environment of 25 ° C. and a humidity of 70% for 1 minute to dry the solvent. Furthermore, the dried coated film was heat treated and humidified in an environment of 60 ° C. and humidity 90% for 5 minutes to obtain a layer containing a dichroic dye having a thickness of 0.15 μm. An acrylic resin-based ultraviolet-curable resin composition (SPC-920C manufactured by Nippon Kayaku Co., Ltd.) on the layer containing the obtained dichroic dye so that the thickness of the protective layer after curing becomes 3 μm The resin composition was cured by coating with a spin coater and then irradiation with ultraviolet light, and a protective layer was provided on the layer containing the dichroic dye. The polarizing element thus obtained was used as a measurement sample.

Example 2
On the non-easy-adhesion treated surface of the stretched film having a retardation of 10500 nm used in Example 1, a rubbing cloth (Mk0012 manufactured by Myonaka Pile Textile Co., Ltd.) along the direction of 0 ° with respect to the slow axis of the stretched film. A measurement sample was produced in the same manner as in Example 1 except that rubbing was further performed by a wound roll under a condition of a speed of 100 rpm and a load of 5 kgf. At this time, the angle with respect to the slow axis of the stretched film was measured by KOBRA-21ADH (manufactured by Oji Scientific Instruments).

Example 3
The non-easy-adhesion treated surface of the stretched film having a retardation of 10500 nm used in Example 1 is rubbed with a roll in which a rubbing cloth is wound along the direction of 45 ° with respect to the slow axis of the stretched film. In the same manner as in Example 2 except for the above, a measurement sample was produced.

Example 4
The non-adhesion treated surface of the stretched film having a retardation of 10500 nm used in Example 1 was rubbed with a roll in which a rubbing cloth was wound along the direction of 90 ° with respect to the slow axis of the stretched film. A measurement sample was produced in the same manner as Example 2 except for the above.

Example 5
As a substrate, in place of the stretched film having retardation of 10500 nm used in Example 1, a stretched film of polyethylene terephthalate having retardation of 35000 nm (SKYGREEN PETG K 2012 (made by Mitsubishi Plastics Co., Ltd.) is melted at 230 ° C. A measurement sample was produced in the same manner as in Example 1 except that an unstretched PET film molded to have a film thickness of 100 μm was a film uniaxially stretched by about 4 times).

Example 6
As a substrate, in place of the film having a retardation of 10500 nm used in Example 1, a stretched film of polyethylene terephthalate (SKYGREEN PETG K 2012 (Mitsubishi Plastics Co., Ltd.) is melted at 230 ° C. to 100 μm. A measurement sample was produced in the same manner as in Example 1 except that an unstretched PET film molded to have a film thickness of 1 was used a film uniaxially stretched about 2.1 times).

Comparative Example 1
An unstretched PET film molded by melting SKYGREEN PETG K 2012 (manufactured by Mitsubishi Plastics Co., Ltd.) at 230 ° C. to a film thickness of 100 μm instead of the stretched PET film of Example 1 as a substrate A measurement sample was produced in the same manner as in Example 1 except for using.

Comparative example 2
A measurement sample was produced in the same manner as in Example 1 except that the unstretched PET film of Comparative Example 1 was uniaxially stretched 1.5 times to be a film having a retardation of 1000 nm.

  Table 1 shows Ts, Tp, Tc, ρ, and Rd at a wavelength at which the degree of polarization is the highest, obtained by measuring the samples obtained in Examples 1 to 6 and Comparative Examples 1 and 2.

  As apparent from the results in Table 1, the polarizing element of the present invention using the stretched film having the retardation value in Examples 1 to 6 exhibits a high degree of polarization (() and a high dichroic ratio (Rd) I understand that.

  On the other hand, in Comparative Example 1 using an unstretched film having no retardation, and Comparative Example 2 in which the retardation value is out of the specification of the present invention, the degree of polarization (ρ) is less than 65%, and two colors Since the ratio (Rd) is also less than 5, it is understood that the function as a polarizing element is not sufficient.

  From the above results, the polarizing element of the present invention exhibits a high degree of polarization of 85% or more and a high dichroism of 5 or more. Furthermore, in the production of the polarizing element of the present invention, the adsorption of a dichroic dye required when using a normal polyvinyl alcohol-based film substrate, the stretching treatment in a boric acid solution, etc. are not required. It is possible to manufacture a polarizing element without dimensional change or shrinkage of the substrate. That is, in the polarizing element of the present invention, only a specific substrate and a layer containing a dichroic dye are laminated. From this, it is understood that the polarizing element of the present invention is a polarizing element which is excellent in polarization performance and can be easily manufactured.

  The polarizing element of the present invention is not a polarizing element using a polyvinyl alcohol resin film such as a conventional polarizing element, but by applying a solution containing a dichroic dye to a stretched substrate having a specific retardation. Since the polarizing element can be produced, processes such as swelling, dyeing, stretching and the like which are required in the conventional process are unnecessary, and the polarizing element can be produced easily. In addition, since a film of a polarizing element can be produced only with a dichroic dye as a component exhibiting a polarizing function, it is possible to form an ultrathin polarizing element. Furthermore, since the polarizing element can be produced by applying a solution containing a dichroic dye, it is not limited to the shape of a flat polarizing element such as a conventional polarizing plate, and a curved surface shape or the like according to film forming It is also possible to form a spherically shaped polarizing element. In particular, although the conventional stretched film can only form a polarizing plate which transmits polarized light perpendicular to the stretching direction, the polarizing element of the present invention can set the orientation direction arbitrarily to the substrate which is rubbed. Since this can be performed, it is possible to form a polarizing element provided with a minute pattern and polarizability in any direction.

Claims (8)

Laminating a stretched film having a retardation of 3000 to 50000 nm and a layer containing one or more dichroic dyes,
The thickness of the stretched film is 20 to 500 μm,
The dichroic dye is selected from the group consisting of azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes and anthraquinone dyes ,
A polarizing element characterized in that a molecular anisotropy larger than the molecular anisotropy given to the surface of the stretched film is further given in the same direction as the stretching axis of the stretched film .   The polarizing element according to claim 1, wherein the stretched film is made of polyethylene terephthalate.   The polarizing element according to claim 1 or 2, wherein the dichroic ratio is 5 or more. The retardation film according to any one of claims 1 to 3 , further comprising a retardation film having a slow axis or a fast axis of retardation at an angle of 10 ° to 100 ° with respect to the long axis direction of the film. The polarizing element as described in. The polarizing element according to any one of claims 1 to 4 , wherein at least one of the dichroic dyes is a compound represented by the following formula (1) or a salt thereof.

(In the formula (1),
X ₁ represents a phenyl group or a naphthyl group having one or two sulfonic acid groups and a hydroxyl group or an alkoxy group having 1 to 3 carbon atoms,
X ₂ and X ₃ each independently represent a phenylene group or a naphthylene group, and the phenylene group or the naphthylene group is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, And one or two or more types of substituents selected from the group consisting of a hydroxyl group and a sulfonic acid group,
R ₁ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an acetyl group, a benzoyl group, an unsubstituted phenyl group or an alkyl group having 1 to 4 carbon atoms, 1 to 4 carbon atoms Represents a phenyl group substituted by an alkoxyl group, an amino group or a sulfo group, m is 0 or 1, and n is 1 or 2). The polarizing element according to claim 5 , wherein X ₁ is a compound represented by the following formula (3) as a substituent or a salt thereof.

(In the formula (3), j is 1 or 2) The layer containing the dichroic dye further contains a polyoxyethylene polyoxypropylene alkyl ether or a polyoxyethylene polyoxypropylene block polymer, according to any one of claims 1 to 6 , Polarizing element. A display apparatus provided with the polarizing element according to any one of claims 1 to 7 .