JPS62265356A - Dichroic azo dye and polarizing film using the same - Google Patents

Abstract

NEW MATERIAL:Compds. of formula I or II (wherein X and Y are each an alkyl, an aryl or a 4-substd. cyclohexyl; R1, R2, R5 and R6 are each H, an alkyl, an alkoxy or a halogen; R3, R4, R7 and R8 are each H, an alkyl which may be substituted by cyano, an alkoxyalkyl or an alkyl-substd. benzyl; Z is -OR9 or a group of the formula III, IV, V or VI; R9 and R10 are each an alkyl; and R11 and R12 are each an alkyl or an alkoxy). EXAMPLE:A compd. of formula VII. USE:Dichroic azo dyes useful for the polarizing film of liquid crystal display elements. PREPARATION:A compd. formula VIII is diazotized and then coupled with a compd. of formula IX.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel dye suitable for resin coloring, and to a polarizing film using the dye.

[Conventional technology]

The polarizing film most commonly used today uses polyvinyl alcohol-based resin as the film base, and polarizes it with dichroic substances such as iodine compounds and/or acid dyes or direct dyes with selected structures. It has been given a gender.

The durability of this type of polarizing film is usually maintained by covering both sides of the film with a film-like material (hereinafter referred to as a protective film layer) that is moisture resistant and transparent on at least one side. That is, measures have been taken to obtain practical durability by protecting the drawbacks of the internal polarizing film layer (hereinafter referred to as polarizer layer), which is inherently extremely poor in durability, with protective film layers on both sides.

[Problem that the invention seeks to solve]

Polarizing films are already used in large quantities as an important component of liquid crystal display elements, but as the field of use for liquid crystal display elements expands, the durability of the polarizing films used needs to be improved, especially in terms of moisture resistance and heat resistance. is strongly requested.

Various proposals have been made to solve these demands, but
These can be summarized into three methods. The first method uses a polarizer that is a combination of a conventional polyvinyl alcohol resin and a water-soluble dichroic dye;
This is a method of protecting the protective film layer by replacing it with a more durable acetate cellulose resin, acrylic resin, polyester resin, polyurethane resin, etc., and this method can significantly improve durability. However, there is a limit to the durability improvement due to the low moisture resistance of the polarizer exposed at the cut portion of the polarizing film and the heat resistance of the polarizer base resin itself. The second method is to use a hydrophobic polymer film having a conjugated double bond in a polyene structure as a polarizing film, but although the moisture resistance is improved, there is a change in transmittance due to an increase in the polyene structure due to heat, etc. It has drawbacks such as a low degree of polarization, and has not yet been technically perfected. The third method is an attempt to obtain a polarizing film or polarizer by coloring a hydrophobic polymer represented by polyester, polyamide, etc. with a dichroic dye and stretching it. belongs to this method. It is easily understood that according to the third method, in principle, the fundamental problems such as moisture resistance and heat resistance can be solved. However, in reality, there are few proposals for dichroic dyes that exhibit high dichroism in such hydrophobic polymers, and the reality is that the completion of polarizing film manufacturing techniques using such methods is limited.

[Step to the problem]

In view of the current situation, the present inventors have focused on organic resin polymers, mainly hydrophobic polymers, which have excellent basic properties such as transparency, moisture resistance, heat resistance, and weather resistance, and have developed a film using these polymers. We conducted extensive research to develop a new polarizing film as a base material.

As a known technology for durable polarizing film,
JP 57-84409 and JP 57-84409 by the present inventors
-68008 etc. are exemplified. Both are dichroic dyes developed for liquid crystals that have been applied to polarizing films.

These films are initially manufactured using conventional PVA
It has a polarizing ability that is comparable to other polarizing films.

If it is left for a long time, especially if it is left in a heated state for a long time, the polarization ability will drop significantly, causing a practical problem. The reason for this is that dichroic dyes for liquid crystals are generally structurally selected to dissolve as much as possible in the liquid crystal material, so that the dye molecules can be used in hydrophobic resin-based films such as polyethylene terephthalate. This is thought to be because it can move easily in the base material, especially during heating. That is, the dye used in a polarizing film that uses a hydrophobic resin polymer as a film base material must (1) have high dichroism in the polymer, and (2) have uniform coloring properties when dispersed or dissolved. , (3) have excellent light resistance, heat resistance, and moisture resistance; (4) have strong affinity for the base polymer or substantially no migration or sublimation of the dye in the polymer when heated. It is necessary that the company has the following basic characteristics. The inventors of the present invention have completed the present invention as a result of extensive research into a dye structure that satisfies the above properties.

That is, the present invention provides formula (1) and formula (2) [formula (1)
where, represents an alkyl group, an alkoxyalkyl group, or an alkyl-substituted benzyl group. ] A [Formula (21m, Y is an alkyl group, an aryl group, or a 4-
is a substituted cyclohexyl group; s R5 and RJ are hydrogen atoms, alkyl groups, alkoxy groups, or ha, where R7 and islands are hydrogen atoms, alkyl groups or alkoxy groups that may be substituted with a cyano group, or alkyl group-substituted benzyl groups; R91RIG represents an alkyl group, and R12 represents an alkyl group or an alkoxy group. ] and a polarizing film characterized by using the dye. In particular, when the film base material is a hydrophobic resin polymer, an industrially extremely useful polarizing film having excellent polarizing ability, light resistance, moisture resistance, heat resistance, etc. is provided.

The dyes represented by formulas (1) and (2) of the present invention can be easily synthesized using conventional methods.

Typically, formula (3) [In formula (3), X is an alkyl group, an aryl group, or 4
- indicates a substituted cyclohexyl group. ] The compound represented by is diazotized to form formula (4) [formula (4)
In, R2 is a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, and F'se R4 is a hydrogen atom,
Indicates an alkyl group which may be substituted with a cyano group, an alkoxy group, or a benzyl group substituted with an alkyl group.

] A compound of formula (1) can be obtained by coupling with a compound represented by the following.

Both of the compounds represented by formula (1) and formula (2) have excellent properties as resin colorants and dyes for polarizing films.

x, y, z and R1 in formula (1) and formula (2)
A specific example of 82 is shown below. X or Y is a methyl group, ethyl group, isopropyl group, p-butylphenyl group,
Examples include p-ethoxyphenyl group, 4-ethylcyclohexyl group, and 4-butoxycyclohexyl group. 2 is 7 diethylamide groups.

butoxy group, butylcarbonyloxy group, p-butylphenoxy group, p-ethoxyphenoxy group.

Examples include p-ethylbenzoyloxy group.

R11R21R5 or R6 is a hydrogen atom or a methyl group.

Examples include substituents such as a methoxy group, a chloro group, a bromine group, and a fluorine group.

Ran R4, R7 or R8 is a hydrogen atom,
Examples include ethyl group, butyl group, 2-cyanoethyl group, 4-cyanobutyl group, p-ethylbenzyl group, p-butoxybenzyl group, and the like. Examples of R3 or RIO include methyl group, propyl group, butyl group, and examples of R11 or RL2 include ethyl group, butyl group, butoxy group, isopropyl group, and the like.

After synthesis, the pigment of the present invention can be used in its crude form, but it is preferably purified using recrystallization or other purification means, and it can also be used after being ground to a size of several microns or less. is preferred.

The polarizing film of the present invention contains at least one type of the above-mentioned dye, and several types can be mixed and used if necessary. Furthermore, it may be used in combination with a dye having dichroism, a dye without dichroism, or a polarizing substance.

The amount of the dye to be used relative to the base polymer is determined by taking into consideration the coloring ability of the dye and the desired thickness of the polarizing film, but preferably the visible light transmittance per polarizing film obtained is 30 to 30. Adjust so that it is 60%.

For standard dyes, the thickness of the polarizing film is 30-20
If it is 0μ, the amount of pigment to base resin is 0.01~
It is in the range of 10 weight units.

The organic resin polymer which is the base material for the polarizing film of the present invention can basically be used without any restriction as long as it is an organic polymer compound with a linear molecular structure. For example, polyvinyl alcohol type, ethylene-vinyl acetate copolymer or its saponified product type, cellulose type, polyvinyl butyral type, halogenated vinyl polymer type, halogenated vinylidene polymer type, partially dehydrochlorinated halogenated vinylidene polymer type, polyamide type, Polyimide, polyester,
Examples include polycarbonate-based and polyethersulfone-based resins. In fields of use where durability is particularly required, halogenated vinyl polymers, polyamides, polyimides, polyesters and polyethersulfones are preferred, among which polyethylene terephthalate has excellent heat resistance, moisture resistance and transparency. Aromatic polyester resins such as polyethylene naphthalate, polybutylene terephthalate, etc. are preferred.

In order to produce the polarizing film of the present invention, the base polymer and at least one selected from the above-mentioned dyes are melted and colored together with the dye of the same color, mixed if necessary, and then formed into a film or sheet. Next, after stretching 3 to 10 times in the vertical direction or horizontal direction at 50 to 150°C,
It can be produced by heat treatment at 0 to 230°C for 1 second to 30 minutes. It should be noted that although it is sufficient to carry out the stretching in only one direction, if necessary, the stretching may be carried out in a direction perpendicular to the main stretching direction by approximately 1.1 to 1.
It is also possible to improve the mechanical strength of the film by stretching it twice.

The polarizing film manufactured in this way can be processed into various types of films and sheets depending on the purpose and put to practical use. That is, a) the film produced by the above method as it is, b) a protective film on one or both sides of which is impregnated with optical transparency and mechanical strength, such as a protective film made of colored or uncolored glass or synthetic resin. C) Polarizing sheet or film with a film layer; C) Polarizing sheet or film with an adhesive coated on one or both sides for ease of application to commonly used liquid crystal displays, window glasses, glasses, etc. In addition, fF+I refers to d) a polarizing film in which a transparent conductive film such as an indium-tin oxide is applied to the surface by a well-known method such as vapor deposition, sputtering, or coating. These can also be used as cell forming materials for liquid crystal display elements.

The dye of the present invention is also useful as a resin colorant. That is, the dye of the present invention basically has properties required for a resin coloring material such as heat resistance, light resistance, sublimation resistance, and bleed resistance, and it has properties required for resin coloring materials such as heat resistance, light resistance, sublimation resistance, and bleed resistance.
It is also suitable for coloring organic polymers, such as polypropylene, polyethylene, and polyester, with excellent transparency.

Hereinafter, representative examples of the dye of the present invention and a polarizing film using the dye will be specifically described with reference to practical examples. Note that the degree of polarization in Examples is a value measured by the following method. That is, the light transmittance (To) at the maximum absorption wavelength in the visible region measured by placing two polarizing films on top of each other so that the stretching directions are parallel to each other and placing them in the optical path of a spectrophotometer, and the light transmittance (To) of two polarizing films with the stretching directions perpendicular to each other. The degree of polarization (V) was calculated from the light transmittance (T) at the same wavelength measured overlappingly as much as possible using the following formula.

Note that "parts" in the examples indicate parts by weight.

Example 1 2.1 parts of the compound represented by the following formula was mixed with dimethylformamide (
Dissolve in 70 parts of DMF, add 35% salt @ 3 parts, and add 1
After stirring at room temperature for 6.3 hours, the temperature was adjusted to 0 to 56C.
IO parts of an aqueous sodium nitrite solution was added dropwise, and the mixture was stirred for 2 hours. After adding 0.5 part of sulfamic acid to this solution, 2 parts of N,N-diethylaniline was added and reacted for 2 hours. After adjusting the pH to 3 to 4 with soda carbonate, it was poured into 200 parts of water, the resulting precipitate was passed through, washed with water and methanol, and then dried to give the formula (/%1) (magic 1). 2.5 parts of the compound were obtained. It was a granular solid with a dark yellow color, and the maximum absorption wavelength of the acetone solution was 449 nm.

1 kg of polyethylene terephthalate resin pellets/
2 g of dye No. 161 was added, mixed uniformly, and melted to form a film at 280°C to obtain a film colored in vivid JF yellow.

This colored film was stretched 5 times in the transverse direction at 80° C. using a tenter stretching machine, and then heat treated at 180° C. for several seconds to obtain a polarizing film with a thickness of 70 μm.

It exhibited a pale yellow color tone (maximum absorption wavelength λmax 455 nm), and the degree of polarization at λmax was as high as 99.7%. This polarizing film was tested for 500 hours under conditions of 8D''C1 relative humidity of 90 degrees, and virtually no change in hue or decrease in degree of polarization was observed.Example 2 N in Example 1 , N instead of N-diethylaniline
In the same manner except that -methyl-N-(p-ethoxybenzyl)aniline was used, a dye represented by the following formula (2) was obtained.

This is a yellow solid with a maximum absorption wavelength of 458 nm and a polarization degree of 99.
A 5% polarizing film was obtained.

Example 3 In place of N,N-diethylaniline in Example 1, α
- First, synthesize a compound represented by the following formula by carrying out a coupling reaction in the same manner using naphthylamine, and add 5 parts of this to a solution of 100 parts of dimethylformamide and 5 parts of 35% hydrochloric acid at room temperature.
After stirring for an hour, the temperature was adjusted to 0-5°C, and 10.3%
10 parts of aqueous sodium nitrite solution was added dropwise, and the mixture was stirred for 3 hours. After adding 1.2 parts of sulfamic acid to this solution,
5 parts of N,N-dibutylaniline was added dropwise and reacted for 4 hours. Add 15 parts of 10% sodium acetate aqueous solution to this,
After stirring for an hour, the resulting precipitate was poured into 400 parts of water and filtered, washed with water, washed with methanol, and dried to obtain 5.2 parts of a compound represented by the following formula (Fuku (Fuku 3). Purple dark color. The maximum absorption wavelength of the solid in acetone solution was 544 nm.

In addition, in the same manner as in Example 1, the maximum absorption wavelength was 545n.
A polarizing film having a polarization degree of 99.2% was obtained.

Examples 4-15 Dye 4-1 in Table 1 instead of Dye/161 in Example 1
A polarizing film was obtained in the same manner except that No. 15 was used. The dye structural formula is the maximum absorption wavelength (λmax) of the polarizing film.
and the degree of polarization are shown in Table 1.

(Margin below)

Claims (1)

[Claims] 1) Formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (1) [In formula (1), X is an alkyl group, an aryl group, or a 4-substituted cyclohexyl group, and R_1 and R_2 is a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, and R_3 and R_4 represent a hydrogen atom, an alkyl group optionally substituted with a cyano group, an alkoxyalkyl group, or an alkyl-substituted benzyl group. ] A monoazo dichroic dye represented by 2) Formula (2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (2) [In formula (2), Y is an alkyl group, an aryl group, or a 4-
It is a substituted cyclohexyl group, R_5 and R_6 are hydrogen atoms, alkyl groups, alkoxy groups, or halogen atoms, and Z is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, -OR_9, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ , ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, where R_
7 and R_8 are a hydrogen atom, an alkyl group optionally substituted with a cyano group, an alkoxy group, or an alkyl group-substituted benzyl group, R_9 and R_1_0 are an alkyl group, and R_1_1 and R_1_2 are an alkyl group or an alkoxy group. ] A disazo dichroic dye represented by 3) Formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) [In formula (1), X is an alkyl group, an aryl group, or a 4-
A substituted cyclohexyl group, R_1 and R_2 are a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, and R_3 and R_4 are a hydrogen atom, an alkyl group that may be substituted with a cyano group, an alkoxyalkyl group, or an alkyl group substituted. Indicates a benzyl group. ] Monoazo dichroic dye or formula (2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (2) [In formula (2), Y is an alkyl group, an aryl group, or 4
- Substituted cyclohexyl group, R_5 and R_6 are hydrogen atoms, alkyl groups, alkoxy groups, or halogen atoms, Z is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, -OR_9, ▲There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, where R_
7 and R_8 are a hydrogen atom, an alkyl group optionally substituted with a cyano group, an alkoxy group, or an alkyl group-substituted benzyl group, R_9 and R_1_0 are an alkyl group, and R_1_1 and R_1_2 are an alkyl group or an alkoxy group. ] A polarizing film characterized by using a disazo dichroic dye represented by: