WO2005015275A1

WO2005015275A1 - Dye-containing polarizer

Info

Publication number: WO2005015275A1
Application number: PCT/JP2004/011340
Authority: WO
Inventors: Yuichi Sadamitsu; Kazuyuki Kawabe
Original assignee: Nippon Kayaku Kabushiki Kaisha; Polatechno Co.,Ltd.
Priority date: 2003-08-07
Filing date: 2004-08-06
Publication date: 2005-02-17
Also published as: CN100380146C; CN1833186A; KR20060037426A; TW200506423A; KR101013291B1; TWI237134B; JPWO2005015275A1; HK1092877A1

Abstract

A high-performance polarizer which is less influenced by by-products contained in a dye, has excellent polarizing performance in the visible light and ultraviolet regions, and has moisture resistance and heat resistance. The polarizer comprises: a dye-containing polarizing film comprising a polyvinyl alcohol resin film containing a water-soluble dye or a salt thereof which in their free acid form are represented by the following formula (1): (wherein R1 and R2 each represents hydrogen, halogeno, lower alkyl, lower alkoxy, or carboxy; R3 and R4 each represents hydrogen, halogeno, lower alkyl, lower alkoxy, or hydroxy; X represents oxygen, sulfur, NH, or NCH3; and l and m each is 0, 1, or 2, provided that l+m>0) and which have a purity as high as 90% or above; and a film having a transmittance at 380 nm of 70% or higher which has been laminated to at least one side of the dye-containing polarizing film.

Description

Specification

Dye-based polarizing plate

Technical field

The present invention relates to a dye-based polarizing plate comprising a high-purity azo compound-based water-soluble dye or a salt thereof.

Background art

A polarizing plate having a function of transmitting and shielding light is a basic component of a liquid crystal display (LCD) together with a liquid crystal having a function of switching light. The field of application of LCDs is wide ranging from small devices such as calculators and watches in the early days, to notebook computers, word processors, liquid crystal projectors, liquid crystal televisions, car navigation systems, and indoor and outdoor measuring instruments.

[0003] Further, a polarizing plate for the ultraviolet region (400 nm or less) is used for a spectrophotometer such as a fluorescence spectrophotometer, an exposure device for irradiating ultraviolet light, and the like. Also, as described in Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3, it is used for a liquid crystal display device having a fluorescent layer that emits light by the action of near-ultraviolet light (hereinafter, referred to as a photo display). A luminescent liquid crystal display device) can be used as a polarizing plate.

[0004] Currently, as such a polarizing plate having absorption in the ultraviolet region, a polarizing film is applied to a polarizing film substrate such as a film of stretch-oriented polybutyl alcohol or a derivative thereof, and iodine or a dichroic dye is used as a polarizing element. Or a polyene-based film in which polyene is generated and oriented by de-acidification of a polychlorinated butyl film or dehydration of a polybutyl alcohol-based film.

[0005] Among these, an iodine-based polarizing film using iodine as a polarizing element has excellent initial polarization performance in the visible light region, but has very poor polarization performance in the near-ultraviolet region, and is inferior to water. In addition, when used for a long time in a high-temperature, high-humidity state that is weak against heat, there is a problem in its durability. In order to improve the durability, treatment with an aqueous solution containing formalin or boric acid, and a method using a polymer film having low moisture permeability as a protective film have been considered, but this is not sufficient. On the other hand, a dichroic dye Although the dye-based polarizing films using these have excellent moisture resistance and heat resistance as compared with iodine-based polarizing films, their polarizing properties in the ultraviolet region are not yet sufficient.

[0006] Dyes used in the production of the dye-based polarizing film as described above include water-soluble compounds described in Patent Documents 1 and 2, and the like. There is a demand for an improvement in which one having good durability can be obtained.

[0007] On the other hand, when producing the compound represented by the formula (1), a method of treating the amino compound represented by the formula (2) with sodium hypochlorite in an aqueous solvent is generally used. In such a case, a large amount of azine conjugate produced as a by-product represented by the formula (3) is contained. Therefore, when used as a polarizing film, the azine compound of the formula (3) is also contained in the substrate at the same time, so that a problem arises in that the intended polarization characteristics cannot be obtained.

[0008] [Formula 01]

[0009] [Formula 02]

[0010] [Formula 03]

Therefore, it has been difficult to obtain a polarizing plate having excellent polarization performance in the visible light region and the ultraviolet region, as well as moisture resistance and heat resistance.

Patent Document 1: JP 2002-357719 A

Patent Document 2: JP 2003-35819 A

Patent Document 3: JP-A-54-153648 Patent Document 4: Japanese Patent No. 1854685

Patent Document 5: Patent No. 2622748

Patent Document 6: JP-A-1-252904

Patent Document 7: JP 2001-27708 A

Patent Document 8: JP 2001-33627 A

Non-Patent Document 1: W.A.Crosland and 2 others Journal of the SID 6/2, 1998 ppl 17-124

Non-patent document 2: W.A.Crosland et al. 1 person SID 97 Digest pp837_840 Non-patent document 3: S.L.Njo et al. 3 people SID 00 Digest pp343_345

Disclosure of the invention

Problems to be solved by the invention

[0012] An object of the present invention is to provide a high-performance polarizing plate having excellent polarization performance and excellent moisture resistance and heat resistance in the visible light region and the ultraviolet region where the influence of by-products contained in the dye is small. It is to be.

Means for solving the problem

[0013] The present inventors have conducted intensive studies to achieve the object, and as a result, have found that a polarizing film and a polarizing plate containing a high-purity dye have excellent polarizing performance, moisture resistance, and heat resistance. Heading, the present invention has been completed.

[0014] That is, the present invention provides

(1) In the form of a free acid, the following formula (1)

[0015] [Formula 1]

(Wherein Rl and R2 represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxyl group or a carboxy group, and R3 and R4 represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxyl group or a hydroxyl group. , X represents 〇, S, NH or NCH. In addition, 1, m represents 0, 1 or 2, and l + m> 0. )

Is a dye-based polarizing film containing a water-soluble dye or a salt thereof having a purity of 90% or more in a polyvinyl alcohol-based resin film, wherein the polarizing film has a polarizing property in a near ultraviolet region. Polarizing film,

(2) A polarizing plate, characterized in that a film having a transmittance at 380 nm of 70% or more is bonded to at least one surface of the near-ultraviolet polarizing film according to (1).

(3) The method according to (1) or (2), wherein the polarizing film substrate contains one or more organic dyes or salts thereof other than the water-soluble dye of the formula (1) having a polarizing property in the visible light region. The polarizing plate described above.

The invention's effect

[0016] The polarizing film of the present invention shows a remarkable improvement in polarization characteristics as compared with a polarizing film containing an azo compound produced by a conventional production method. Further, the polarizing plate of the present invention has high polarization performance even in the near ultraviolet region and is excellent in durability, so that it is suitable for display applications of photoluminescence liquid crystal display devices and industrial instruments used in various environments. is there.

BEST MODE FOR CARRYING OUT THE INVENTION

[0017] The polarizing film of the present invention contains a high purity product of 90% or more of the azo compound represented by the formula (1) or a salt thereof. In the formula (1), Rl and R2 represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxyl group or a carboxy group, and R3 and R4 represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxyl group or X represents a hydroxyl group, and X represents 〇, S, NH or NCH. Also, 1 and m represent 0, 1 or 2, and l + m> 0.

Three

[0018] The high-purity azo compound represented by the formula (1) or a salt thereof is subjected to oxidative coupling by treating the amino conjugate represented by the general formula (2) with manganese dioxide as an oxidizing agent. Is obtained.

Next, typical examples of the azo compound represented by the formula (1) or a salt thereof used in the present invention are shown below.

[0021] [Ka 05]

When the azo compound of the formula (1) exists in the form of a salt, examples of the salt include an alkali metal salt such as a lithium salt, a sodium salt and a potassium salt, an ammonium salt and an organic amine salt. When dyeing a polarizing film, it is preferable to use a sodium salt or a potassium salt.

The substrate (polymer film) used for the polarizing film of the present invention may be a polyvinyl alcohol-based substrate, which is preferably a polyvinyl alcohol-based substrate, or polybutyl alcohol or a derivative thereof, or any of these. Examples thereof include those modified with olefins such as ethylene and propylene, and unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid. Above all, a film made of polybutyl alcohol or a derivative thereof is suitably used from the viewpoint of dye adsorption and orientation.

[0024] The compound represented by the formula (1) or a salt thereof of the present invention can be used alone or, if necessary, mixed with another organic dye having a polarizing property in the visible light region. A polarizing film having high polarization characteristics can be manufactured. As other organic dyes to be compounded, any dyes having absorption characteristics in a wavelength region different from the absorption wavelength region of the compound of the formula (1) of the present invention and having high dichroism can be used. For example, Sea, Eye, Direct, Yellow 12, Sea, Eye, Direct, Yellow 44, Sea, Eye, Direct, Orange 26, Sea, Eye, Direct, Oshi, Arrange 39, Sea, Eye, Direct , Orange 107, Sea, Eye, Direct, Red 2, Sea, Eye, Direct, Red 31, Sea, Eye, Direct, Red 79, Sea, Eye, Direct, Red 81, Sea, Eye, Direct, Red 2 47 , Sea, eye, direct, green 80, sea or eye, direct, green 59 and patents Dyes described in Literature 4, Patent Literature 5, Patent Literature 6, and Patent Literature 7, and the like are used. These dyes are used as free acids or salts such as alkali metal salts, ammonium salts, and amine salts.

In order to incorporate the compound represented by the formula (1) of the present invention or a salt thereof into a polymer film, a method of dyeing a polymer film is usually employed. Staining is performed, for example, as follows. First, a water-soluble dye is dissolved in water to prepare a dye bath. The concentration of the dye in the dye bath is not particularly limited, but is usually selected from the range of about 0.001 10% by weight. If necessary, a dyeing aid may be used. For example, it is preferable to use sodium sulfate at a concentration of about 0.110% by weight. The polymer film is immersed in the dyeing bath adjusted in this way to perform dyeing. The dyeing temperature is preferably about 40-80 ° C, more preferably 70 ° C and 80 ° C.

[0026] Orientation of the water-soluble dye is performed by stretching the dyed polymer film. As a stretching method, any known method such as a wet method and a dry method may be used. Stretching of the polymer film may optionally be performed before dyeing. In this case, the water-soluble dye is oriented at the time of dyeing. The polymer film containing the water-soluble dye and oriented is subjected to post-treatment such as boric acid treatment by a known method as necessary. Such a post-treatment is performed for the purpose of improving the light transmittance and the degree of polarization of the polarizing film. The conditions of the boric acid treatment vary depending on the type of the polymer film used and the type of the dye used, but generally the boric acid concentration of the aqueous boric acid solution is 0.1 to 15% by weight, preferably 1 to 10% by weight. The treatment is carried out in a temperature range of 30-80 ° C, preferably 40-75 ° C. Further, if necessary, the aqueous solution containing the cationic polymer compound may be subjected to the phytostat treatment.

The polarizing film obtained by the present invention is used as a polarizing plate with a protective film and as a polarizing plate for a spectrophotometer such as a fluorescence spectrophotometer and a photoluminescence liquid crystal display device. Including a polymer film together with another organic dye having a polarization property in the visible light region in this manner is suitable for inspecting defects such as disorder in the alignment of the LCD.

[0028] The dye-based polarizing film thus obtained is provided with a protective film having excellent optical transparency and mechanical strength on one or both surfaces thereof, such as a polyvinyl alcohol-based or isocyanate-based protective film. A polarizing plate can be obtained by laminating with an adhesive. The material for forming the protective film may be any of those conventionally used, for example, a fluorine-based material such as a cellulose acetate-based film or an acrylic film, such as a tetrafluoroethylene / propylene hexafluoride copolymer. A film made of a film, a polyester resin, a polyolefin resin or a polyamide resin is used. The protective film used here needs to have a transmittance at 380 nm of 70% or more, and preferably has a transmittance of 80% or more.

[0029] The surface of the polarizing plate of the present invention may be provided with a layer further subjected to an antireflection treatment, an antiglare treatment, an antistatic treatment, a corona treatment, and a hard coat treatment.

[0030] The dye-based polarizing plate thus configured is excellent in polarization performance, does not undergo discoloration or deterioration in polarization performance even in a high-temperature and high-humidity state, and leaks in the orthogonal position in the visible light and near ultraviolet regions. It has the characteristic of being blue.

Example

[0031] Hereinafter, the powers S for explaining the present invention in more detail by way of examples are mere examples, and do not limit the present invention in any way. The percentages and parts in the examples are on a weight basis unless otherwise specified.

Synthesis Example 1

Manganese dioxide (powder, manufactured by Junsei Chemical Co., Ltd.) in an aqueous solution in which 2_ (4-aminophenyl) _6_methylbenzothiazolone 7-sulfonic acid (purity: 78.3%) is dissolved in 260 parts of water. Add 350 parts of calorie, then add 200 parts of a 10% aqueous potassium permanganate solution to complete the oxidation coupling. Sodium thiosulfate was added to remove excess permanganate, and manganese dioxide was filtered off. The obtained filtrate was salted out with sodium salt and filtered to obtain 13.7 parts of a salt of the azo compound represented by the above formula (4).

Example 1

The maximum absorption wavelength in water of the azo compound (4) prepared in Synthesis Example 1 was 389 nm. The purity of the azo compound of formula (4) was determined by high-performance chromatography using high-performance liquid chromatography. The purity was 97%, and no azine compound represented by the formula (6) was detected. [0034] [Formula 06]

Comparative Example 1

The maximum absorption wavelength of an aqueous solution of Solophenyl Yellow F FL (manufactured by Ciba-Geigy), which is generally commercially available as C.I. Direct Yellow 28, was 395 nm. Further, the purity of the azo compound of the formula (4) was determined to be 64% by high performance liquid chromatography using high performance liquid chromatography, and there was 27% of an azine compound as a by-product.

Example 2

75 μm thick polyvinyl alcohol (trade name VF—XS # 7500) was added to a 45 ° C aqueous solution containing 0.1% of the dye of compound (4) prepared in Synthesis Example 1 and 0.1% of sodium sulfate in a concentration of 0.1%. , Kuraray Co., Ltd.) for 4 minutes. This film was stretched 5 times at 50 ° C in a 3% aqueous solution of boric acid, washed with water while keeping the tension, and dried to obtain a polarizing film. The obtained polarizing film had a maximum absorption wavelength of 406 nm, and had a high degree of polarization of 98.5% when the single plate transmittance was 43.75%. The gripping force also showed durability for a long time even in a high temperature and high humidity state.

[0037] Comparative Example 2

The concentration of Solophenyl Yellow FFL (manufactured by Ciba-Geigy) described in Comparative Example 1 was 0.1% and sodium sulfate 0.1%. Polyvinyl alcohol (trade name: VF-XS # 7500, manufactured by Kuraray Co.) having a thickness of 75 zm was immersed in the aqueous solution of C for 4 minutes. This

The film was stretched 5 times at 50 ° C in a 3% aqueous solution of boric acid, washed with water while keeping the tension, and dried to obtain a polarizing film. The maximum absorption wavelength of the obtained polarizing film was 417 nm, and the polarizing ratio was 97.65% when the single plate transmittance was 43.75%.

Example 3 (Evaluation of Near Ultraviolet Polarizing Plate)

75 μm thick polyvinyl alcohol (trade name VF—XS # 7500) was added to a 45 ° C aqueous solution containing 0.5% of the dye of compound (4) prepared in Synthesis Example 1 and 0.1% of sodium sulfate in a concentration of 0.1%. , Kuraray Co., Ltd.) for 4 minutes. This film was stretched 5 times in a 3% aqueous solution of boric acid at 50 ° C., washed with water while keeping the tension, and dried to obtain a polarizing film. At 365nm of the obtained polarizing film Orthogonal transmittance of 0.1% or less and a high degree of polarization of 99.9%. A TAC film (trade name: Fujitac T80SZ, manufactured by Fuji Photo Film Co., Ltd.) is adhered to both sides of this polarizing film using PVA-based adhesive, and the polarizing plate produced can be used for a long time even at high temperature and high humidity. It showed durability.

[0039] Comparative Example 3

The concentration of a mixture mainly composed of the compound represented by the following formula (7) described in Patent Document 2 and Example 1 (mainly in the form of a sodium salt) was set at 0.5% and 0.1% of sodium sulfate. Polyvinyl alcohol (trade name: VF-XS # 7500, made of Kuraray clay) having a thickness of 75 μm was immersed in an aqueous solution of ° C for 4 minutes. This film was stretched 5 times in a 3% aqueous solution of boric acid at 50 ° C., washed with water while keeping the tension, and dried to obtain a polarizing film. The orthogonal transmittance of the obtained polarizing film at 365 nm was 1.2%.

[0040] [Formula 07] (7)

Industrial applicability

The polarizing film for near-ultraviolet light of the present invention has high polarization performance in the near-ultraviolet region and is also excellent in durability, so that it can be used in photoluminescent liquid crystal display devices and displays of industrial instruments used in various environments. Suitable for use.

Claims

Claims The following formula (1) in the form of free acid

[Chemical 1]

(Wherein Rl and R2 represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxyl group or a carboxy group, and R3 and R4 represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxyl group or a hydroxyl group. , X represents 〇, S, NH or NCH.

3 Also, 1, m represents 0, 1 or 2, and l + m> 0. )

A dye-based polarizing film containing a water-soluble dye or a salt thereof having a purity of 90% or more in a polyvinyl alcohol-based resin film, wherein the polarizing film has a polarizing property in a near ultraviolet region. Polarizing film.

[2] A polarizing plate, wherein a film having a transmittance at 380 nm of 70% or more is bonded to at least one surface of the near-ultraviolet polarizing film according to claim 1.

[3] The polarizing film substrate according to claim 1 or 2, wherein the polarizing film substrate contains one or more organic dyes or salts thereof other than the water-soluble dye of the formula (1) having a polarizing property in the visible light region. Polarizer.