JPH0517697A - Anthraquinone dye and polarizing film using the dye - Google Patents

Abstract

(57) [Abstract] [Objective] The anthraquinone dye of the present invention has excellent polarization performance and excellent durability, and further contains a hydrophobic resin as a film base material by orienting the dye. Polarizing film to be used is excellent in polarization performance, heat-resistant dimensional stability, wet heat resistance, etc.
It is possible to provide a useful polarizing film for liquid crystal display. [Structure] An anthraquinone dye represented by the following general formula (1) and a polarizing film containing at least one of the dyes. (In the formula, R ¹ represents a hydroxyl group, an amino group or a lower alkylamino group, X represents a nitrogen atom or a methine group, A represents an aromatic bifunctional group, and n represents an integer of 0 or 1. However, when n is 0, X represents NN.)

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an anthraquinone dye and a polarizing film containing the dye in an oriented manner.

[0002]

2. Description of the Related Art The most commonly used polarizing film today uses a polyvinyl alcohol-based resin as a film substrate, and an iodine compound or an acidic dye or a direct dye having a selected structure is used as the film. It is a coloring agent imparted with a polarizing property. This type of polarizing film shows excellent polarizing performance, but has insufficient durability,
Further, durability is maintained by covering at least one surface with a transparent film-like material (protective film). That is, a measure is taken to obtain substantial durability by protecting the defects of the internal polarizing film (layer), which is inherently extremely poor in durability, with the protective films (layers) on both sides.

In recent years, with the expansion of applications of liquid crystal display elements for in-vehicle use, computers, industrial equipment, etc., the durability of the polarizing film used as one element has been improved, especially moisture resistance, weather resistance and heat resistance. There is a strong demand for improvements in. As one improvement means for this, a polarizing film using a hydrophobic resin as a substrate has been proposed, and as a known technique, JP-A-57-84409 and JP-A-1-1036 are known.
No. 67 publication and the like. However, although such a polarizing film has a sufficient durability, it is not necessarily satisfactory in terms of polarization.

[0004]

An object of the present invention is to provide an anthraquinone dye suitable for a polarizing film having a hydrophobic resin as a film substrate and a polarizing film containing the dye in an oriented manner.

[0005]

Means for Solving the Problems As a result of intensive studies in view of such circumstances, the present inventors have found a new dichroic dye having excellent polarization performance and excellent durability. .

That is, the present invention is based on the general formula (1)

[0007]

[Chemical 3] (In the formula, R represents a hydroxyl group, an amino group or a lower alkylamino group, X represents a nitrogen atom or a methine group,
A represents an aromatic bifunctional group, and n represents an integer of 0 or 1. However, when n is 0, X represents NN. The present invention relates to a dichroic dye having a novel anthraquinone skeleton and a polarizing film containing the anthraquinone dye in a hydrophobic resin in an oriented manner.

The reason why the dye of the present invention is suitable as a dye for a polarizing film is that anthraquinone, which is a chromophore, is bonded to an aromatic bifunctional group with a linking group of -CH = CH- or -CH = N-. In addition, a functional group is introduced at the 1- and 5-positions of anthraquinone, whereby a linear rod-shaped structure having a longer molecular structure than the known anthraquinone dye disclosed in JP-A-1-103667. Therefore, the coplanarity is easily maintained, and the angle between the molecular length and the transition moment approaches 0, so that the polarization performance is significantly improved.

The anthraquinone dye of the present invention is represented by the general formula (1), and the substituent R ¹ is a hydroxyl group, an amino group or a lower alkylamino group. Here, the lower alkylamino group has 1 to 10 carbon atoms.
Alkylamino group of is mentioned, but it is preferably an alkylamino group having 1 to 4 carbon atoms.

As the aromatic bifunctional group represented by A, groups represented by the following formulas (2a to 2g) (Formula 4) and the like can be mentioned as preferable ones. In addition, a bifunctional group having a property equivalent to that is also included in the scope of the present invention.

[0011]

[Chemical 4] (In the formula, R ^{2 to} R ¹³ each independently represent a hydrogen atom, a halogen atom, a methyl group, a hydroxyl group or a methoxy group. Y ₁
Is -CO- or -O-, Y ₂ is -NHCO
-, - O -, - S -, - SO 2 -, or a -CO-, Y ₃ represents -O- or -S-. ) The anthraquinone dye represented by the general formula (1) of the present invention is a compound represented by the following general formula (3)

[0012]

[Chemical 5] (In the formula, R ¹ has the same meaning as in the general formula (1).)
And a compound represented by the following general formula (4): R ¹⁴ -A-R ¹⁴ (4) (wherein, R ¹⁴ is NH ₂ , X ¹ R ₂ P-CH _2- , (R ₂ O) ₂ (PO) --CH _2- , wherein R ₂ represents a phenyl group, a methyl group or an ethyl group, and X ¹ represents a halogen atom) in the presence of a solvent under the following conditions.

For example, the molar ratio of the anthraquinone derivative represented by the general formula (3) to the compound represented by the general formula (4) is preferably 1 when the total number of moles of the general formula (3) is 1.
The reaction may be performed with the number of moles of the general formula (4) being about 0.3 to 0.5.

In the general formula (4), R ¹⁴ is X ¹ R ₂ P-CH _2-
Or when reacting a compound which is (R ₂ O) ₂ (PO) -CH _2- ,
As the base used, NaOH, KOH, Ca (OH) ₂ , MgO, N
Inorganic substances such as aH, NH ₄ OH, CH ₃ ONa, CH ₃ OLi, C ₂ H ₅ ONa,
Alkoxides such as C ₄ H ₉ OK, CH ₃ COONa, CH ₃ COOK, CH ₃ C
Carboxylates such as OONH _4, diazabicycloundecene, nitrogen-containing compounds such as piperidine and pyridine, CH ₃ Li,
_{C 4 H 9 Li, C 6} H 5 MgBr, and the like alkyl metal compounds such as _{(C 3 H 7) 2 NLi} .

The solvent used is preferably an aprotic polar solvent such as dimethylformamide, dimethylsulfoxide, sulfolane, dimethylimidazolidinone, benzene, toluene, xylene, chlorobenzene,
They are aromatic solvents such as dichlorobenzene, chloronaphthalene and nitrobenzene, alcohols such as methanol, ethanol and propanol, and carboxylic acids such as acetic acid and propionic acid. The amount of the solvent used is represented by the general formula (1)
It is preferred to use 1 to 100 times the weight of the compound of.

The reaction temperature is from room temperature to 200.
C. is preferred, and the reaction time is about 1 to 20 hours.

The dye used in the production of the polarizing film of the present invention can be used as it is,
Those purified by recrystallization or other purification means are preferable, and it is preferable to grind them to several microns or less before use.

The polarizing film of the present invention contains at least one kind of the dye, and in order to obtain a desired hue,
Several types can be selected and mixed and used in order to obtain a polarizing film having a neutral gray color. Further a dye having a dichroism other than the present invention, in some cases,
A dye having no dichroism, an additive such as an ultraviolet absorber, or other substance may be contained.

The hydrophobic resin used in the polarizing film of the present invention is not particularly limited as long as it is an organic polymer compound having a linear structure that does not contain a hydrophilic group in its molecular structure, but it has thermoplasticity. The preferred examples include vinyl halide polymer system, acrylic system, polyolefin system, polyamide system, polyimide system, polyester system polycarbonate system and polyether sulfone system resin. Among them, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, which are particularly excellent in heat resistance, moisture resistance and transparency,
Polyethylene bis-α, β- (2-chlorophenoxy)
A resin composition containing at least 80% by weight of an aromatic polyester resin component such as ethane-4,4'-dicarboxylate is preferable.

The amount of the dye used is determined in consideration of the coloring ability of the dye with respect to the above-mentioned hydrophobic base resin and the desired thickness of the polarizing film, but preferably the obtained polarized light is used. The visible light transmittance per film is adjusted to 30 to 60%. For example, when the thickness of the polarizing film is 30 to 200 μm, the amount of the dye with respect to the resin is in the range of 0.01 to 10% by weight.

To produce the polarizing film of the present invention, at least one selected from the base resin and the dye of the present invention is used.
It can be produced by melting and coloring together with seeds and, if necessary, other pigments to be mixed, molding into a film or sheet, and stretching. The polarizing film produced in this manner can be further processed into various forms of films and sheets for practical use depending on the application. That is, a) a film produced by the above method as it is, b) a protective film having excellent optical transparency and mechanical strength on one or both sides, for example, a colored or uncolored glass, or a synthetic resin protective film. Polarizing sheet or film provided with (layer), c) A form in which an adhesive is applied to one side or both sides for ease of application to commonly used liquid crystal displays, window glasses, glasses, etc. Further, d) and a form in which a transparent conductive film such as indium-tin oxide is added to the surface of the polarizing film by a known method such as vapor deposition, sputtering or coating method. These can also be used as a cell forming material for a liquid crystal display element.

[0022]

EXAMPLES Representative examples of the dye of the present invention and a polarizing film using the dye will be specifically described with reference to examples. The polarization degree in the examples is a value measured by the following method. That is, the two polarizing films are overlapped so that the stretching directions are parallel to each other and placed in the optical path of the spectrophotometer to measure the light transmittance (T _// ) at the maximum absorption wavelength in the visible region, and the two polarizing films are oriented in the stretching direction. The degree of polarization (V) was calculated from the light transmittance (T⊥) at the same wavelength, which was measured overlappingly so as to be orthogonal to each other, using the following formula (Equation 1).

[0023]

[Equation 1] Example 1 1,5-Bis-methylamino-anthraquinone-2-carboxaldehyde, 2.6 g and 2,6-diamino-
1.0 g of anthraquinone was stirred under reflux in 200 ml of acetic acid for 8 hours. After cooling the reaction solution to room temperature, the precipitate was collected by filtration, washed with a small amount of acetic acid, then with N, N-dimethylformamide and methanol, and dried to obtain 2.8 g of the dye of the following formula (Formula 6). Obtained.

[0024]

[Chemical 6] Elemental analysis value C H N calculated value (%) 72.90 4.33 10.63 Measured value (%) 73.05 4.21 10.58 This dye was applied to polyethylene terephthalate resin pellets and the single transmittance of the polarizing film was 40. % So that
After mixing uniformly, the mixture was melt extruded and molded into a sheet having a thickness of about 200 μm. This sheet was stretched 5 times in the transverse direction at 80 ° C. using a tenter stretching machine and heat-treated at 150 ° C. for 1 minute to obtain a 100 μm-thick purple polarizing film. The degree of polarization at its maximum absorption wavelength of 535 nm is 99.
% Was excellent. This polarizing film is at 80 ° C and relative humidity of 9
When left for 500 hours under the condition of 0%, there was substantially no change in hue and no decrease in polarization degree. Further, the shrinkage rate of the film is 1% or less in both the longitudinal and transverse directions,
It had good dimensional stability.

Example 2 100 g of a solution of 9.1 g of 4,4'-bis (ethoxyphosphonomethyl) biphenyl in N, N-dimethylformamide was added to a solution of 1.4 g of metallic sodium in 100 ml of ethanol, and the mixture was stirred at room temperature for 30 minutes. After stirring for 1 minute, 1,5-dihydroxy-anthraquinone-2-carboxaldehyde (10.7 g) was added, and the mixture was stirred at room temperature for 4 hours, and then the precipitate was collected by filtration and washed with N, N-dimethylformamide and then methal. After drying, 11 g of a dye of the following formula (Formula 7) was obtained.

[0026]

[Chemical 7] Using this dye, film processing was carried out in the same manner as in Example 1 to obtain an orange-yellow polarizing film. Maximum absorption wavelength 470nm
The degree of polarization was 99.8%, and as a result of a durability test similar to that of Example 1, there was no decrease in the degree of polarization and good dimensional stability was obtained.

Examples 3 to 16 Examples 1 and 2 are different from Examples 1 and 2 except that the anthraquinone dyes shown in [Table 1] to [Table 3] (Table 1) are used instead of the dyes. The same experiment as 2 was repeated.
The structural formulas and color tones of the dyes are shown in Table 1, and the elemental analysis results thereof are shown in [Table 4] (Table 2). All of the obtained polarizing films had excellent polarization performance.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

Comparative Examples 1 and 2 Instead of the dye synthesized in Example 1, JP-A 1-1
A polarizing film was obtained in the same manner as in Example 1 except that the dye represented by the following structural formula (A, B) (Chemical Formula 8) disclosed in JP-A-03667 was used. The degree of polarization at the maximum absorption wavelengths of 605 nm and 640 nm is
(A) was 91% and (B) was 93%, which was inferior to the dye of the present invention.

[0033]

[Chemical 8]

[0034]

The film containing the anthraquinone dye of the present invention is excellent in polarization performance, heat-resistant dimensional stability, wet heat resistance and the like, and is extremely useful as a polarizing film for liquid crystal displays.

Continuation of front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication C09B 56/12 8619-4H G02B 1/08 7820-2K 5/30 7724-2K (72) Inventor Naoto Ito Kanagawa Mitsui Toatsu Chemical Co., Ltd., 1190 Kasama-cho, Sakae-ku, Yokohama, Japan

Claims (2)

[Claims] 1. An anthraquinone dye represented by the following general formula (1) (formula 1). [Chemical 1] (In the formula, R ¹ represents a hydroxyl group, an amino group or a lower alkylamino group, X represents a nitrogen atom or a methine group, A represents an aromatic bifunctional group, and n represents an integer of 0 or 1. However, when n is 0, X represents NN.) 2. A polarizing film comprising a hydrophobic resin containing at least one anthraquinone dye represented by the following general formulas (1) and (2). [Chemical 2] (In the formula, R ¹ represents a hydroxyl group, an amino group or a lower alkylamino group, X represents a nitrogen atom or a methine group, A represents an aromatic bifunctional group, and n represents an integer of 0 or 1. However, when n is 0, X represents NN.)