JPH0430987B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a specific anthraquinone dye and a polarizing film using the same. [Background of the Invention] The polarizing film most commonly used today uses polyvinyl alcohol-based resin as the film base material, and is coated with an iodine compound and/or a dye such as an acid dye or a direct dye having a selected structure. It has polarization properties using a colored substance. Although this type of polarizing film exhibits excellent polarizing ability, its durability is insufficient, and it is usually made to last by covering both sides of the film with a film-like material (protective film) that is moisture-resistant and transparent on at least one side. gender is preserved. That is, measures have been taken to obtain practical durability by protecting the drawbacks of the internally polarizing film (layer), which is inherently extremely poor in durability, with protective films (layers) on both sides. In recent years, with the expansion of the use of liquid crystal display elements for automobiles, computers, industrial equipment, etc., it is necessary to improve the durability of the polarizing film used as one element, especially in terms of moisture resistance, weather resistance, and heat resistance. It is strongly requested. As one improvement means for this purpose, a polarizing film using a hydrophobic resin as a base material has been proposed, and as a known technique, JP-A No. 57-84409
No. 58-68008 and No. 60 by the present inventors.
-125804 etc. are exemplified. However, although such polarizing films have sufficient durability, the reality is that they are not necessarily satisfactory in terms of polarization properties. [Object of the Invention] The first object of the present invention is to provide a novel anthraquinone dye that is suitable as a coloring agent for hydrophobic resins and has excellent transparency, moisture resistance, weather resistance, and heat resistance. Another object of the present invention is to provide a novel polarizing film in which a hydrophobic resin is used as a film base material and the novel dye is oriented and contained therein. [Structure of the invention] The anthraquinone dye according to the present invention that achieves the above object has the general formula () [In formula (), X ₁ , X ₂ , X ₃ , X ₄ , X ₅ and X ₆
is an amino group optionally substituted with a hydrogen atom, a halogen atom, a hydroxy group, or an alkyl group having 1 to 3 carbon atoms, and X ₁ , X ₂ , X ₃ and
At least one of X ₆ is a hydroxy group or an amino group optionally substituted with an alkyl group having 1 to 3 carbon atoms, Z is an oxygen atom, a sulfur atom or an imino group, and n is 1, 2 or It is an integer of 3. Here, R ¹ and R ² may be the same or different and are each a hydrogen atom, a halogen atom, a methyl group, or a methoxy group, and R ³ is a formula (a) to (d) −CONH・R ⁴ (a) − NHCO・R ⁴ (b) (In formulas (a) to (d), R ⁴ is a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group.
However, when n is 1 or 2, it is not a phenyl group unsubstituted with a hydrogen atom. R ⁵ is a hydrogen atom, an alkyl group, an alkoxy group, a cycloalkyl group, an aryl group, or a halogen atom, Y is an oxygen atom or a sulfur atom, m is an integer of 1 or 2, and when m is 2, Together with the carbon atoms to which they are attached, they may form a ring. ) represents. ] It is a new substance represented by Furthermore, the polarizing film according to the present invention that achieves the above object is characterized in that the anthraquinone dye is oriented and contained in a hydrophobic resin. The anthraquinone dye of the present invention represented by the general formula () is suitable for coloring hydrophobic resins, and is particularly useful as a coloring agent for producing polarizing films with good durability and polarization performance. Also, among the dyes represented by the general formula (), n=2
The dyes are particularly suitable as dyes for polarizing films. The present invention will be explained in detail below. Specific examples of the substituent represented by R ⁴ in the general formula () include H; -CH ₃ , -C ₂ H ₅ , -
(CH ₂ ) ₂ CH ₃ , −CH(CH ₃ ) ₂ , −(CH ₂ ) ₃ CH ₃ , −
_CH2CH ( _CH3 ) ₂ , _-CH ( _CH3 ) _C2H5 , -C( _CH3 ) ₃ ,
−(CH ₂ ) ₄ CH ₃ , −(CH ₂ ) ₅ CH ₃ , −(CH ₂ ) ₆ CH ₃ , −
(CH ₂ ) ₇ CH ₃ , -(CH ₂ ) ₈ CH ₃ and other alkyl groups, -
C ₂ H ₄ OCH ₃ , −C ₂ H ₄ OC ₂ H ₅ , −C ₂ H ₄ O
Alkoxyalkyl _groups such as ( _{CH2 ) 2CH3 , -C2H4O} ( _CH2 ) _3CH3 ;

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[Formula], etc. can be mentioned. In the present invention, among the dyes represented by the general formula () above, those represented by the following general formula () are suitable as dyes for polarizing films. General formula () [In formula (), X ₇ , X ₈ , X ₉ and X ₁₀ are an amino group optionally substituted with a hydrogen atom, a halogen atom, a hydroxy group or a methyl group, and
At least one of X ₇ , X ₈ , X ₉ and X ₁₀ is an amino group optionally substituted with a hydroxy group or a methyl group, p is an integer of 1 or 2,
R ⁶ has the same meaning as R ³ in the above general formula (). ] Also, among the dyes represented by the general formula (), p=
The dye No. 2 is particularly suitable as a dye for polarizing film. The anthraquinone dye represented by the above general formula () can be synthesized according to a known method, for example, the method described in Japanese Patent Publication No. 41-3710. Typically, the anthraquinone dye represented by the general formula () is [In formula (), X ₁ , X ₂ , X ₃ , X ₄ , X ₅ , X ₆ and Z have the same meanings as already defined. ] and the general formula () [In formula (), R ¹ , R ² , R ³ and n have the same meanings as defined above. ] Compounds represented by alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol, methyl cellosolve, ethyl cellosolve, or benzene, toluene, xylene, monochlorobenzene,
By heating reaction in an organic solvent such as dichlorobenzene, nitrobenzene, N,N-dimethylformamide, N-methyl-2-pyrrolidone, etc.
Although the compound of formula () can be obtained, the compound of formula () can also be obtained by combining various other known unit reactions, and the synthesis method is not limited at all. These anthraquinone dyes of the present invention are suitable for polarizing films, have dichroism, and at the same time
Virtually insoluble in water, organic solvents and liquid crystals.
Here, "substantially insoluble" means that the dichroic dye is 0.05% by weight or less in each of water, organic solvent, and liquid crystal at room temperature, that is, about 25°C;
Preferably, it has a solubility of 0.01% by weight or less. In addition, the organic solvents used here include acetone, methyl alcohol, ethyl alcohol, chloroform, benzene, toluene, xylene, nitrobenzene, chlorobenzene, 0-dichlorobenzene, N,N-dimethylformamide, N-methyl-2-pyrrolidone, A readily available inert organic solvent with a boiling point of 250°C or less, such as ethyl acetate. Furthermore, liquid crystals include liquid crystals that have a nematic phase or smectic phase that is fluid at room temperature, Schiff-based liquid crystals, biphenyl-based liquid crystals,
These include phenylcyclohexane liquid crystals, ester liquid crystals, pyrimidine liquid crystals, and mixtures thereof. As mentioned above, an important property of the anthraquinone dye of the present invention is that it is substantially insoluble in organic solvents and liquid crystals, and this property indicates that the dye of the present invention has a certain pigment suitability. It shows that you are doing something. Such dyes are suitable for use in polarizing films based on hydrophobic resins, and it is important to select dichroic dyes for such polarizing films because they are soluble in liquid crystals and have excellent dichroism. This means that it is impossible to determine whether That is, the means for determining whether the dichroic dye of the present invention has excellent dichroism suitable for use in a polarizing film has not necessarily been clear. The present inventors have determined that the polarizing film of the present invention can be evaluated by measuring the dichroism of the dye in polyethylene terephthalate, which is a typical example of a hydrophobic resin, as a simple and effective means for evaluating the dichroism of such a dye. This method was used to determine the suitability of the dye to be applied. The method involves uniformly mixing an appropriate amount of dye into pellets of polyethylene terephthalate having an intrinsic viscosity of 0.6 to 0.75, forming a film by melting the film, and then rolling the film at least 3 times in the longitudinal direction at a temperature near or above the glass transition temperature.
This is a method of measuring the dichroic ratio of a dye at the maximum absorption wavelength within the visible light region using a film obtained by stretching the free width at least twice as long as the sample. The novel anthraquinone dye of the present invention has a dichroic ratio of 7 or more as measured by the above method, and polarized light using a film base material of aromatic polyester resin such as polyethylene terephthalate and other hydrophobic resins. Suitable as a film dye. Conventionally, using the methods and standards described above,
It is now possible to easily select dyes for which it has been difficult to determine whether or not they have sufficiently high dichroism for use in polarizing films. The anthraquinone dye of the present invention is a dichroic dye having a novel structure suitable for a polarizing film based on a hydrophobic resin, which was discovered based on the above method and criteria. In the production of the polarizing film of the present invention, the dye used can be used in its crude form, but it is preferably purified using recrystallization or other purification means, and it is also ground to a size of several microns or less. It is preferable to use it as The polarizing film of the present invention contains at least one of the above dyes, and in order to obtain a desired hue,
In addition, several types can be selected and used in combination in order to obtain a polarizing film with a particularly neutral gray color. Furthermore, it may contain dichroic dyes other than those of the present invention, in some cases, additives such as non-dichroic dyes or ultraviolet absorbers, and other substances. 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 hydrophilic groups due to its molecular structure, but preferably has thermoplasticity.
Specific examples include halogenated vinyl polymer, acrylic, polyolefin, polyamide, polyimide, polyester, polycarbonate, and polyethersulfone resins. Among them, aromatics such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polyethylene bis-α,β-(2-chlorophenoxy)ethane-4,4′-dicarboxylate, which have particularly excellent heat resistance, moisture resistance, and transparency. A resin composition containing at least 80% by weight of a group polyester resin component is preferred. The amount of the dye to be used relative to the base resin, which is a hydrophobic resin as described above, is determined by taking into account the coloring ability of the dye and the desired thickness of the polarizing film, but preferably one polarizing film to be obtained. Adjust so that the visible transmittance per area is 30 to 60%.
For example, if the thickness of the polarizing film is 30 to 200 μm, the amount of the dye to the base resin is in the range of 0.01 to 10% by weight. In order to produce the polarizing film of the present invention, a base resin and at least one selected from the dyes of the present invention are used.
After melting and coloring with the seed and other pigments mixed if necessary, it is formed into a film or sheet, and then stretched 3 to 10 times in the longitudinal or transverse direction at a temperature of 50 to 150°C, and then 100 to 230°C. 1 second~
It can be produced by heat treatment for 30 minutes. Although it is sufficient to stretch the film in only one direction, if necessary, the film may be stretched approximately 1.1 to 2 times in a direction perpendicular to the main stretching direction to improve the mechanical strength of the film. The polarizing film manufactured in this way can be processed into various forms of films and sheets depending on the purpose and put to practical use. That is, (a) the film produced by the above method as is, (b) a protective film with excellent optical transparency and mechanical strength on one or both sides, such as colored or uncolored glass or synthetic resin. (c) Polarizing sheet or film with a protective film (layer) on one or both sides for ease of application to commonly used liquid crystal displays, window glasses, glasses, etc. (d) A polarizing film coated with a transparent conductive film such as indium-tin oxide by a well-known method such as vapor deposition, sputtering or coating. Illustrated. These can also be used as cell forming materials for liquid crystal display elements. In addition, the dye of the present invention can be applied not only to the polarizing film, but also to other forms by utilizing dichroism, such as melting and kneading the dye of the present invention with a hydrophobic resin similar to the case of the polarizing film. By processing the fiber into a post-stretched fiber, a fiber with rich color rendering properties can be obtained, and this fiber can also be used for clothing and the like. Furthermore, the dye of the present invention is also useful as a general resin colorant that does not necessarily utilize its dichroism. In other words, it basically has the properties required for resin colorants such as heat resistance, light resistance, sublimation resistance, and bleed resistance, and can be used with polyvinyl chloride, polystyrene, polypropylene, polyethylene, polyamide, polyimide, polyester, etc. It is also suitable for coloring hydrophobic resins, such as exemplified by , into colors with excellent transparency. In this way, the dye of the present invention can be used without being limited to polarizing films. [Examples] Hereinafter, representative examples of the dye of the present invention and a polarizing film using the dye will be specifically described with reference to Examples. Note that the degree of polarization in Examples is a value measured by the following method. In other words, the light transmittance (T ₁₁ ) at the maximum absorption wavelength in the visible region measured by stacking two polarizing films so that the stretching directions are parallel and placing them in the optical path of a spectrophotometer, and the stretching of the two polarizing films. The degree of polarization (V) was calculated from the light transmittance (T⊥) at the same wavelength, which was measured in layers so that the directions were perpendicular to each other, using the following formula. Example 1 Purified 1,4-diamino-anthraquinone-2,
31 g of 3-dicarboxylic anhydride and 4-(4-n
-butylphenylcarbamoyl) aniline in 500 ml of N-methyl-2-pyrrolidone (NMP),
Stir at 170℃ for 10 hours. After cooling to room temperature, the precipitate was collected by filtration, washed with a small amount of NMP, then methanol, and dried to obtain 45 g of the following dye. It is a greenish-blue needle-shaped crystal (mp>360℃),
The maximum absorption wavelength of the nitrobenzene solution was 690 nm. After heating 0.5 g of the dye represented by in 100 g of nitrobenzene, it was left to stand at 25°C for several hours. The supernatant liquid was slightly colored green-blue, but most of the dye had precipitated. In addition, it was heated to 90°C in liquid crystal E-8 (biphenyl nematic liquid crystal product name manufactured by BDH).
The liquid crystal was hardly colored. Next, 1 g of the same dye was uniformly mixed with 1 kg of polyethylene terephthalate resin pellets having an intrinsic viscosity of 0.7, and the mixture was melt-extruded at 280° C. to form a film.
The film was stretched 5 times in the longitudinal direction using a roll stretching machine to obtain a film-like test piece having a thickness of 80 μm. The dichroic ratio of the dye at the maximum absorption wavelength of 690 nm was 17.8. Example 2 The dye of Example 1 was added to polyethylene terephthalate resin pellets until the single transmittance of the polarizing film was 40%.
After adding and mixing uniformly, the mixture was melt-extruded and formed into a film of about 200 μm. This film was stretched 5 times in the transverse direction at 80°C using a tenter stretching machine, and then heat treated at 150°C for 1 minute. A clear green-blue polarized film was obtained, and the degree of polarization at the maximum absorption wavelength of 690 nm was excellent at 96.5%. This polarizing film was left for 500 hours at 80° C. and 90% relative humidity, but virtually no change in hue or decrease in degree of polarization was observed. Also,
The shrinkage rate of the film is 1% in both the vertical and horizontal directions.
It had good dimensional stability. Example 3 4-amino-4'-(4-n-octylphenylcarbamoyl) instead of 4-(4-n-butylphenylcarbamoyl)phenyl in Example 1
The following dye (mp>360°C) in the form of a greenish-blue powder was obtained in the same manner except that -biphenyl was used. This dye was also almost insoluble in nitrobenzene and liquid crystal E-8, and the dichroic ratio of the dye in polyethylene terephthalate measured in the same manner as in Example 1 was 19.5 (maximum absorption wavelength 690 nm). Example 4 A clear green-blue polarizing film was obtained in the same manner except that the dye of Example 3 was used instead of the dye of Example 2. The degree of polarization is 98% (maximum absorption wavelength
690 nm), and as a result of the durability test, virtually no decrease in the degree of polarization was observed, and it had good dimensional stability. Example 5 20g of anitraquinone compound represented by concentrated sulfuric acid
It was dissolved in 300g and stirred at 50-60°C for 3 hours.
Discharge into ice water 2, filter the precipitated crystals, and wash with water. The crystals were then reslurried in N,N-dimethylformamide, filtered, washed with methanol, and dried to yield 17 g of blue pigment (mp>360°C).
I got it. This dye is almost insoluble in N,N-dimethylformamide and liquid crystal (E-8), and the dichroic ratio of the dye in polyethylene terephthalate film is
8.5 (maximum absorption wavelength 670 nm). Example 6 A bright blue polarizing film was obtained in the same manner except that the dye of Example 5 was used instead of the dye of Example 2. The degree of polarization was 83%, and as a result of the durability test, virtually no decrease in the degree of polarization was observed, and it had good dimensional stability. Example 7 5 g of the dye obtained in Example 5 was added to 1 part of o-dichlorobenzene, hydrogen sulfide gas was blown in at 130°C for 10 hours, and after cooling, the precipitate was collected by filtration, washed with methanol, and dried to give a dark blue color. The dye was obtained. This dye is almost insoluble in water, N,N-dimethylformamide, and liquid crystal (E-8), and the dichroic ratio in polyethylene terephthalate film is
8.1 (maximum absorption wavelength 740 nm). Example 8 A green polarizing film was obtained in substantially the same manner as in Example 2, except that the dye of Example 7 was used instead of the dye and nylon 6 was used instead of polyethylene terephthalate. The degree of polarization is 80% (maximum absorption wavelength
740nm). Examples 9 to 42 The dyes shown in Table 1 below were produced in the same manner as in Example 1, and the polarizing films were obtained in the same manner as in Example 2. The structural formula of the dye, the dichroic ratio at the maximum absorption wavelength in polyethylene terephthalate, the degree of polarization (%) at the maximum absorption wavelength of the polarizing film, and the hue are shown in Table 1 below.

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[Table] is the degree of polarization of the polarizing film.
Comparative Example 1 Same as in Example 2 except that a dichroic dye for liquid crystal (Structural formula A: dichroic ratio 8 in polyethylene terephthalate) was used instead of the dye ( ). A blue polarizing film was obtained. maximum absorption wavelength
The degree of polarization at 640 nm was as low as 52%. However, in the manufacturing process of this film, if the heat treatment process after stretching is omitted, at the same wavelength, 78%
It was clear that the degree of polarization decreased significantly during the heat treatment process. Furthermore, the shrinkage rate of the film after heat treatment is less than 1% in both the longitudinal and transverse directions, whereas the film without heat treatment shows a large shrinkage rate of 8% in the longitudinal direction and 15% in the transverse direction, and lacks dimensional stability. Ta. The solubility of dye A in liquid crystal (E-8) is about 2.0% by weight. Comparative Example 2 A polarizing film was prepared in the same manner as in Example 2, except that dyes of the following structural formulas B and C (dichroic ratios of 6.7 and 8.0, respectively, in polyethylene terephthalate) were used in place of the dye ( ) in Example 2. This polarizing film and the above-mentioned Example 4 and Examples
24 polarizing films were heated in an oven at 120°C for 1000 hours. The degree of polarization of each polarizing film before and after the heating test is shown in Table 2, and Comparative dye B,
The polarizing films using the dyes of Examples 4 and 24 exhibited more stable polarization than those of C. The solubility of B and C in liquid crystal (E-8) is 0.7% by weight and 1.0% by weight, respectively.

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Claims (1)

[Claims] 1 General formula () [In formula (), X ₁ , X ₂ , X ₃ , X ₄ , X ₅ and X ₆
is an amino group optionally substituted with a hydrogen atom, a halogen atom, a hydroxy group, or an alkyl group having 1 to 3 carbon atoms, and X ₁ , X ₂ , X ₃ and
At least one of X ₆ is a hydroxy group or an amino group optionally substituted with an alkyl group having 1 to 3 carbon atoms, Z is an oxygen atom, a sulfur atom or an imino group, and n is 1, 2 or It is an integer of 3. Here, R ¹ and R ² may be the same or different and are each a hydrogen atom, a halogen atom, a methyl group, or a methoxy group, and R ³ is a formula (a) to (d) −CONH・R ⁴ (a) − NHCO・R ⁴ (b) (In formulas (a) to (d), R ⁴ is a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group.
However, when n is 1 or 2, it is not a phenyl group unsubstituted with a hydrogen atom. R ⁵ is a hydrogen atom, an alkyl group, an alkoxy group, a cycloalkyl group, an aryl group, or a halogen atom, Y is an oxygen atom or a sulfur atom, m is an integer of 1 or 2, and when m is 2, Together with the carbon atoms to which they are attached, they may form a ring. ) represents. ] Anthraquinone pigment represented by. 2 General formula () in hydrophobic resin [In formula (), X ₁ , X ₂ , X ₃ , X ₄ , X ₅ and X ₆
is an amino group optionally substituted with a hydrogen atom, a halogen atom, a hydroxy group, or an alkyl group having 1 to 3 carbon atoms, and X ₁ , X ₂ , X ₃ and
At least one of X ₆ is a hydroxy group or an amino group optionally substituted with an alkyl group having 1 to 3 carbon atoms, Z is an oxygen atom, a sulfur atom or an imino group, and n is 1, 2 or It is an integer of 3. Here, R ¹ and R ² may be the same or different and are each a hydrogen atom, a halogen atom, a methyl group, or a methoxy group, and R ³ is a formula (a) to (d) −CONH・R ⁴ (a) − NHCO・R ⁴ (b) (In formulas (a) to (d), R ⁴ is a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group.
However, when n is 1 or 2, it is not a phenyl group unsubstituted with a hydrogen atom. R ⁵ is a hydrogen atom, an alkyl group, an alkoxy group, a cycloalkyl group, an aryl group, or a halogen atom, Y is an oxygen atom or a sulfur atom, m is an integer of 1 or 2, and when m is 2, Together with the carbon atoms to which they are attached, they may form a ring. ) represents. ] A polarizing film characterized by containing an oriented anthraquinone dye represented by the following.