WO2008002037A1

WO2008002037A1 - Reactive dichroic dyes, preparation method of the same, poly(vinyi-alcohol)-based film comprising reactive dichroic dyes and polarizing film.

Info

Publication number: WO2008002037A1
Application number: PCT/KR2007/003046
Authority: WO
Inventors: Sang Hyun Baek; Sang Bong Park; E Joon Choi; Seung Sock Choi; Il Hyun Park; Jin Ho Jang; Eun Chul Kim; Si Min Kim
Original assignee: Kolon Industries, Inc.; Kumoh National Institute Of Technology
Priority date: 2006-06-27
Filing date: 2007-06-22
Publication date: 2008-01-03

Abstract

Disclosed is a novel reactive dichroic dye. When the reactive dichroic dye is applied to the preparation of a polarizing film, a polarizing film having increased transmittance, in particular, superior durability, and maintaining polarizing efficiency may be prepared.

Description

[DESCRIPTION]

//''

[invention Title]

REACTIVE DICHROIC DYES, PREPARATION METHOD OF THE SAME, POLY(VINYI-ALCOHOL)-BASED FILM COMPRISING REACTIVE 5 DICHROIC DYES AND POLARIZING FILM

[Technical Field]

The present invention relates to a reactive dichroic dye, which includes a dihalotriazine group to thus be reactive to polyvinylalcohol , a method of preparing the

10 same, a polyvinylalcohol-based film including the same, and a polarizing film.

[Background Art]

A plurality of dyes has been developed for various applications, including fabric dyeing, textile printing,

15 plastic coloring, color imaging of photographs, etc. Such dyes are designed to have the molecular structure and bonding strength suitable for each application so as to impart essential properties, including hue, solubility, affinity for a substrate, chemical resistance, and

20 miscibility with a medium to which the dye is applied.

Dichroism is a property in which the orientation of assembled dye molecules has low absorption at a predetermined light wavelength in any one orientation state depending on the direction of polarization of a light source, and high absorption at the same wavelength in another orientation state. Thus, dyes having such dichroism may also be applied to the development of polarizing films, in addition to fabric dyeing.

In particular, a dichroic dye is applied to the dyeing of a polyvinylalcohol (hereinafter, referred to as "PVA") film constituting the polarizer of a polarizing film. A typical PVA film, serving as the polarizer, is obtained through the iodine immersion method. However, the iodine-doped PVA film is disadvantageous because it has high sublimation, drastically decreasing polarizing properties and durability, upon long exposure under conditions of high temperature and high humidity. Accordingly, instead of iodine, dyes having very low sublimation have been used.

Meanwhile, a polarizing film, which was first studied by E. H. Land in 1928, is very limited in the use thereof for industrial purposes. However, as the modern industrial society has advanced to the high information age, the demand for the polarizing film is increasing. This is considered to be due to an increase in the importance of electronic displays.

Polarizing films that are presently commercially available may be classified into various types depending on the kind and performance thereof. First, there is an iodine-based polarizing film, particularly suitable as a polarizing film for high definition LCDs having high transmittance and high polarizing properties, which is a film using iodine, having high dichroism, to impart a transparent PVA film with the ability to absorb light in the visible range. To date, the iodine-based polarizing film has been chiefly used as a polarizing film for LCDs. Second, there is a dye-based polarizing film, which has been studied to overcome the durability problems caused by the sublimation of iodine. This is a highly durable polarizing film which has low changes in optical properties even under conditions of high temperature and high humidity, and is useful for LCDs requiring high durability, thanks to the high durability thereof. Further, it is relatively easy to control the color of the dye-based polarizing film, thus enabling the preparation of polarizing films having various colors and making it suitable for use in the field of sunglasses. Third, there is a polarizing film for super twisted nematic LCD (STN- LCD) , called a phase difference polarizing film. Depending on the angle at which a phase difference film having predetermined properties is applied to the polarizing film, many various products may be obtained. The phase difference film is a film for correcting a phase difference occurring in liquid crystals, and presently useful is a phase difference film made of polycarbonate. Fourth, there is a transflective polarizing film having both transmission properties and reflection properties. The transflective polarizing film has an effect on power consumption efficiency, which is regarded as the most important factor in the display of a mobile apparatus. Because the lifespan of the product is undesirably decreased at high power consumption rates, in the LCD of the mobile apparatus, a conventional transmissive product having high power consumption has been replaced with a functional film useful as a material for the lower plate of a transflective LCD imparted with a reflection function using external light. The transflective film types vary depending on the kind of material used and the properties thereof. Exemplary are products (ST type) having adjusted transmittance through the addition of an adhesive with a pigment, and products composed of hundreds of polymer thin film layers having different refractive indexes. Fifth, there is a transflective polarizing film having high reflectance, which is a polarizing film having increased reflectance using a metal-deposited film and having an improved outer appearance using a diffusion adhesive, instead of the transflective polarizing film using a conventional pigment, in order to decrease the power consumption of an STN-LCD and to more clearly exhibit the outer appearance of the display, in recent years. Sixth, there is a polarizing film (AG/AR) for surface anti-reflection. Surface anti- reflection includes anti-glare (AG) and anti-reflection (AR) . The AG process is conducted by roughening the surface of a film to thus induce the diffuse reflection of external light from the surface thereof, so as to exhibit anti- reflection effects, and the AR process manifests anti- reflection effects by forming a thin film composed of a plurality of layers having different refractive indexes on the surface of a film through deposition or coating. The reflectance of a polarizing film not subjected to AR processing is about 4%, and the AG film has reflectance of about 2%, and the AR film has reflectance less than 1%. Finally, there is a reflective polarizing film, which is a product obtained by laminating a metal-deposited reflective film on a general iodine-based polarizing film to thus make it suitable for use in reflective LCDs.

Generally commercially available polarizing films include, as the polarizer thereof, a film having polarizing properties, in which PVA is treated with iodine or dichroic dye as mentioned above. Further, with the goal of preventing the deformation of the film due to the low durability and high sublimation of iodine, a protective layer is formed. To this end, the use of triacetyl cellulose, polyesters, polycarbonates, etc., which have no birefringence, high transmittance, no wavelength dependence, and high heat, moisture resistance and mechanical strength, is known. Moreover, it is known that the film may be treated with an adhesive and then the outermost surface thereof may be covered with a protective film. The principle of the polarizing film thus formed is as follows. The polarizing film functions to convert natural light, which is incident while vibrating in various directions, into light (that is, polarized light) vibrating in only one direction. In particular, because the LCD uses the birefringence of liquid crystals, it is very important to control the direction of vibration of light incident on the liquid crystal molecules.

The function of the polarizing film is assured by stretching the PVA film and subjecting the stretched PVA film to dyeing and immersion in a solution of iodine or dichroic dye such that iodine molecules or dye molecules are arranged parallel to the stretching direction. Because the iodine or dye molecules are dichroic, the polarizing film may have the function of absorbing light vibrating in the stretching direction and transmitting light vibrating in the direction perpendicular thereto.

Most of the polarizing films, which are presently available, are a PVA-I₂ based polarizing film obtained by immersing optical PVA in an aqueous solution of iodine and iodine-potassium complex to thus dye PVA, which is then uniaxially stretched about 400%. The PVA has properties such as high linearity, high film formability, high crystalUnity, superior alkali resistance even at a pH of 13.5 or more, and high adhesion, so that a PVA-I₂ polarizing film for LCDs, which is presently commercialized, may exhibit sufficient electrical and optical performance. Although the PVA-I₂ polarizing film has superior properties, it suffers because it has drastically deteriorated polarizing properties and durability, attributable to the high sublimation of iodine, when allowed to stand under conditions of high temperature and high humidity for a long period of time, undesirably causing problems in which a protective film must be applied on both surfaces of the film.

Therefore, these days, attempts are continuously made to overcome the problems of the PVA-I2 polarizing film by means of a PVA-dye polarizing film using a dichroic direct dye having very high vapor pressure.

However, in the case where the film is used after merely dyeing it with the dichroic dye, transmittance is remarkably decreased despite the high durability and polarizing properties equal to iodine.

[Disclosure] [Technical Problem]

Accordingly, the present invention is intended to develop, in place of iodine, a dichroic dye, which includes a trihalotriazine group, thereby exhibiting optical properties similar to iodine and further improving durability while transmittance is not decreased.

A first embodiment of the present invention is to provide a novel reactive dichroic dye, which is reactive to PVA-based resin.

A second embodiment of the present invention is to provide a method of preparing the novel reactive dichroic dye.

A third embodiment of the present invention is to provide a PVA-based film, which includes the reactive dichroic dye, in which a dichroic dye is introduced with trihalotriazine, thus exhibiting superior transmittance, in particular, high durability, while maintaining polarizing properties . The third embodiment of the present invention is to provide a PVA-based film having superior transmittance and improved durability while maintaining polarizing properties equal to those of an iodine-based polarizing film.

A fourth embodiment of the present invention is to provide a polarizing film having superior polarizing properties and transmittance and improved durability.

[Technical Solution]

According to the first embodiment of the present invention, there is provided a reactive dichroic dye represented by Formula 1 below, having an azo chromophore and at least one amine group (-NH₂) at the end portion thereof, in which at least one hydrogen atom of the amine group is substituted with a halotriazine group:

Formula 1 B-N=N-A-N=N-B'

wherein A is , or

, X is NH, N=N, CH=CH, NHCONH, NHOC or SO₂O, Ri and R₂, which are same as or different from each other, are H,

NH₂, OH, SO₃Na, CH₃ or OCH₃;

which R₃, R₄, R₅ and R₆, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of R₃ to R₆ being NH₂; R₇, R₈, R₉ and Rio, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃ or OCH₃; Rn and Ri₂, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Rn and R_i2 being NH₂; and

different from each other, are (wherein Xi is a halogen group), H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or

NHCH₂COONa, at least one of Ri₃ to Ri₆ being

; R₇, R₈, Rg and Rio are defined as above; Ri₇ and Ris, which are same as or different from each other, are

(wherein X₁ is a halogen group) , H, NH₂ , OH, SO₃Na, CH₃ , OCH₃ , COONa, COOH, SO₂NH₂ , SO₂NHCH₃ , SO₃Na, SO₃CH₃ , NHCOCH₃ , NHCONH₂ , NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₇

and Ri8 being

Rig, R₂o and R₂₁, which are same

as or different from each other, are (wherein

Xi is a halogen group), H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₉ to R_2i being

In the reactive dichroic dye according to the first embodiment of the present invention, A may be

, in which Ri and R₂ are H, R₃ is NH₂, R₄ and R₅

are H, R₆ is NaSO₃, R_i3 is

, Ri₄ and Ri₅ are H, and Ri6 is NaSO₃.

R₂ is NaSO₃, X is NH, R₇ is OH, R₈ and R₉ are H, R_i0 is NaSO₃,

Rn and Ri₂ are NH₂, Ri₇ is

, and Ri₈ is NH₂.

is OH, R₉ and Ri₀ are SO₃Na, Rn and Ri₂ are H, Ri₉ is

, R₂₀ is CH₃, and R₂i is NH₂.

In the reactive dichroic dye according to the present invention, Xi may be Cl.

According to the second embodiment of the present invention, there is provided a method of preparing a reactive dichroic dye, including reacting a dichroic dye represented by Formula 2 below, having an azo chromophore and at least one amine group at the end portion thereof, with a trihalotriazine compound represented by Formula 3 below, thus preparing a reactive dichroic dye represented by Formula 1 below, having an azo chromophore and at least one amine group

(-ISIH₂) at the end portion thereof, in which at least one hydrogen atom of the amine group is substituted with a halotriazine group:

Formula 1

B-N=N-A-N=N-B'

wherein A is or

NH₂, OH, SO₃Na, CH₃ or OCH₃;

which R₃, R₄, R₅ and Re, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of R₃ to R₆ being NH₂; R₇, Rs, Rg and Ri₀, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃ or OCH₃; Rn and Ri₂, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Rn and R₁₂ being NH₂; and

, m which Ri₃, Ri₄, Ri₅ and Ri₆, which are same as

or different from each other, are

(wherein Xi is a halogen group), H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH,

SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or

NHCH₂COONa, at least one of Ri₃ to Riβ being

; R₇,

R₈, Rg and Rio are defined as above; Ri₇ and Ris, which are same as or different from each other, are

(wherein Xi is a halogen group) , H, NH₂, OH,

SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃ , NHCONH₂ , NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₇

and Ri8 being

. R₁9, R20 sind R21 , which are same

as or different from each other, are (wherein

Xi is a halogen group) , H, NH₂, OH, SO₃Na, CH₃ , OCH₃ , COONa, COOH, SO₂NH₂ , SO₂NHCH₃ , SO₃Na, SO₃CH₃ , NHCOCH₃ , NHCONH₂ ,

NHCH₂SO₃Na or NHCH₂COONa, at least one of R₁₉ to R₂₁ being

B"-N=N-A-N=N-B wherein A and B are defined as in Formula 1, and B" is

which Ri₃', Ru' , R₁₅' and Riε', which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₃' to Ri₆' being NH₂; R₇, R₈, R₉ and Rio are defined as above; Ri₇' and Ris' , which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of R_i7' and Ri₈' being NH₂; Rig', R₂0' and R₂₁', which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₉' to R₂i' being NH₂; and Formula 3

wherein Xi is defined as in Formula 1.

In the method according to the second embodiment of the present invention, the reaction may be conducted at 10 to 30°C for 20 to 30 hours.

In the method according to the second embodiment of the present invention, the reaction may be conducted using one or more solvents selected from among dimethylformamide (DMF) , dimethylacetamide (DMAc) and N-methylpyrrolidone (NMP) .

According to the third embodiment of the present invention, there is provided a PVA-based film, including the reactive dichroic dye represented by Formula 1 below, having an azo chromophore and at least one amine group (-NH₂) at the end portion thereof, in which at least one hydrogen atom of the amine group is substituted with a halotriazine group:

Formula 1 B-N=N-A-N=N-B'

wherein A is or

, X is NH, N=N, CH=CH, NHCONH, NHOC or SO₂O, Ri and R₂, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃ or OCH₃;

which R₃, R₄, R₅ and Re, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of R₃ to R₆ being NH₂; R₇, Rs, Rg and Rio, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃ or OCH₃; Rn and Ri₂, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ru and Ri₂ being NH₂; and

, in which Ri₃, Ri₄, R1₅ and Ri₆, which are same as

or different from each other, are

NHCH₂COONa, at least one of R_i3 to Ri₆ being

; R₇,

Rs, Rg and Rio are defined as above; Ri₇ and Ris, which are same as or different from each other, are

(wherein Xi is a halogen group) , H, NH₂ , OH, SO₃Na, CH₃ , OCH₃ , COONa, COOH, SO₂NH₂ , SO₂NHCH₃ , SO₃Na, SO₃CH₃ , NHCOCH₃ , NHCONH₂ , NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₇

and Ri₈ being

; R₁₉, R₂₀ and R₂i, which are same

as or different from each other, are

(wherein

Xi is a halogen group), H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂ , SO₂NHCH₃ , SO₃Na, SO₃CH₃ , NHCOCH₃ , NHCONH₂ , NHCH₂SO₃Na or NHCH₂COONa, at least one of R₁₉ to R_2i being

In the PVA-based film according to the third embodiment of the present invention, A of the reactive

dichroic dye may be B thereof may be

, and B' thereof may be , in which

Ri and R₂ are H, R₃ is NH₂, R₄ and R₅ are H, Re is NaSO₃, Ri₃ is

Ri4 and Ri5 are H, and Ri₆ is NaSO₃.

dichroic dye may be , B thereof may be

and B' thereof may be

, in which Ri is H, R₂ is NaSO₃, X is NH, R₇ is OH, R₈ and R₉ are H, Ri₀ is NaSO₃, Rn and Ri₂ are

NH₂, Ri₇ is

, and R₁₈ is NH₂.

dichroic dye may be , B thereof may be

and B ' thereof may be

R₂ are H, R₇ is NH₂, R₈ is OH, R₉

and Rio are SO₃Na, Ru and Ri₂ are H, Ri₉ is

, R₂o is CH₃, and R₂χ is NH₂.

In the PVA-based film according to the third embodiment of the present invention, Xi of the reactive dichroic dye may be Cl. According to the fourth embodiment of the present invention, there is provided a polarizing film, including the PVA-based film.

[Advantageous Effects] According to the present invention, in the case where the reactive dichroic dye having a halotriazine group, which is reactive to PVA, is applied to the preparation of a polarizing film, a polarizing film having increased transmittance, in particular, superior durability, while maintaining polarizing efficiency, may be provided.

[Description of Drawings]

FIG. 1 illustrates the IR (KBr pellet) spectrum of Congo Red, which is the dichroic dye;

FIG. 2 illustrates the NMR (DMSOd₆) spectrum of Congo Red, which is the dichroic dye;

FIG. 3 illustrates the IR (KBr pellet) spectrum of the reactive dichroic dye having a chlorotriazine group, synthesized in Example 1 according to the present invention; FIG. 4 illustrates the NMR (DMSO-d₆) spectrum of the reactive dichroic dye having a chlorotriazine group, synthesized in Example 1 according to the present invention;

FIG. 5 illustrates the IR (KBr pellet) spectrum of Direct Black 22, which is the dichroic dye;

FIG. 6 illustrates the NMR (DMSOd₆) spectrum of Direct Black 22, which is the dichroic dye,-

FIG. 7 illustrates the IR (KBr pellet) spectrum of the reactive dichroic dye having a chlorotriazine group, synthesized in Example 2 according to the present invention;

FIG. 8 illustrates the NMR (DMSOd₆) spectrum of the reactive dichroic dye having a chlorotriazine group, synthesized in Example 2 according to the present invention;

FIG. 9 illustrates the IR (KBr pellet) spectrum of Direct Black 4, which is the dichroic dye;

FIG. 10 illustrates the NMR (DMSOd₆) spectrum of Direct Black 4, which is the dichroic dye;

FIG. 11 illustrates the IR (KBr pellet) spectrum of the reactive dichroic dye having a chlorotriazine group, synthesized in Example 3 according to the present invention; FIG. 12 illustrates the NMR (DMSO-d₆) spectrum of the reactive dichroic dye having a chlorotriazine group, synthesized in Example 3 according to the present invention;

FIG. 13 is a graph illustrating the transmittance and polarizing efficiency of the iodine-adsorbed PVA film (Comparative Example 1) ; FIG. 14 is a graph illustrating the transmittance and polarizing efficiency of the Congo Red-dyed PVA film (Comparative Example 2);

FIG. 15 is a graph illustrating the transmittance and polarizing efficiency of the Direct Black 22-dyed PVA film (Comparative Example 3) ;

FIG. 16 is a graph illustrating the transmittance and polarizing efficiency of the Direct Black 4-dyed PVA film (Comparative Example 4) ; FIG. 17 is a graph illustrating the transmittance and polarizing efficiency of the PVA film (Example 4) prepared through the reaction with the reactive dichroic dye of Example 1 according to the present invention;

FIG. 18 is a graph illustrating the transmittance and polarizing efficiency of the PVA film (Example 5) prepared through the reaction with the reactive dichroic dye of Example 2 according to the present invention;

FIG. 19 is a graph illustrating the transmittance and polarizing efficiency of the PVA film (Example 6) prepared through the reaction with the reactive dichroic dye of Example 3 according to the present invention;

FIG. 20 is a graph illustrating the results of evaluation of the durability of the iodine-adsorbed PVA film (Comparative Example 1) ; FIG. 21 is a graph illustrating the results of evaluation of the durability of the Congo Red-dyed PVA film (Comparative Example 2) ;

FIG. 22 is a graph illustrating the results of evaluation of the durability of the Direct Black 22-dyed PVA film (Comparative Example 3) ; FIG. 23 is a graph illustrating the results of evaluation of the durability of the PVA film (Example 4) , prepared through the reaction with the reactive dichroic dye of Example 1 according to the present invention;

FIG. 24 is a graph illustrating the results of evaluation of the durability of the PVA film (Example 5) , prepared through the reaction with the reactive dichroic dye of Example 2 according to the present invention; and

FIG. 25 is a graph illustrating the results of evaluation of the durability of the PVA film (Example 6) , prepared through the reaction with the reactive dichroic dye of Example 3 according to the present invention;

[Best Model

Hereinafter, a detailed description will be given of the present invention. The present invention relates to a novel reactive dichroic dye, the novel reactive dichroic dye of the present invention having a halotriazine group, and being specifically represented by Formula 1. In the reactive dichroic dye represented by Formula 1,

A may be or , in which Ri and R₂ is a hydrogen atom. In any case, at least one of Ri and R₂ may be NaSO₃. Further, in the reactive dichroic dye represented by

Formula 1, B may be

, in which R₃ is NH₂ and R₄ is NaSO₃.

In the reactive dichroic dye represented by Formula 1, when A is naphthalene, the preferred substitution position is 2,6- or 1,4-. In order to efficiently exhibit the properties of the dichroic dye, there is a need for anisotropy depending on the molecular orientation. This is because the linear substitution position is favorable for maintaining the linearity of molecules, and the linearity of molecules may positively affect the orientation of molecules when a film is stretched.

Also, in the reactive dichroic dye represented by

Formula 1, B may be , in which R₇ is OH, Rs and Rg are H, Rg is NaSO₃, and both Rn and Ri₂ are NH₂. Also, in the reactive dichroic dye represented by

Formula 1, B' may be in which R₁₃ is

(in which X₁ is a halogen group) , R₁₄ and R_1S are

H, and Ri6 is NaSO₃.

Also, in the reactive dichroic dye represented by

Formula 1, B' may be , in which R₇,

R₈, Rg and R_1O are defined as above, and R₁₇ is

(in which X₁ is a halogen group) , and R_1S is NH₂. Also, in the reactive dichroic dye represented by

Formula 1 , B' may be

, in which R₁ and R₂ are H, R₇ is NH₂, Rs is OH, R₉ and R₁₀ are SO₃Na, R₁₁ and R₁₂ are H, R₁₉ is

, R₂₀ is CH₃, and R₂₁ is NH₂. In the reactive dichroic dye represented by Formula 1, Xi is a halogen atom, preferably, Cl, Br or F, and more preferably Cl.

The reactive dichroic dye represented by Formula 1 may be obtained by reacting a dichroic dye represented by Formula 2, having an azo chromophore and at least one amine group at the end portion thereof, with a trihalotriazine compound represented by Formula 3.

Formula 2

B"-N=N-A-N=N-B wherein A and B are defined as in Formula 1, and B" is

which R₁₃ ' , Ri₄ ' , Ri₅ ' and Ri₆ ' , which are the same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₃' to Ri₆' being NH₂; R₇, R₈, R₉ and Ri₀ are defined as above; Ri₇' and Ris', which are the same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₇' and Ri₈' being NH₂; R₁₉', R₂₀' and R₂i', which are the same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₉' to R2₁' being NH₂. Formula 3

Preferred examples of the dichroic dye represented by Formula 2 include Congo red, Direct Black 4, 17, 19 and 22, Direct Red 2 and 28, Direct Blue 1 and 15, and Direct Violet 12.

Specific examples of the trihalotriazine compound represented by Formula 3 include 2,4, 6-trichloro-l,3, 5- triazine (cyanuric chloride), 1,2,3- and 1,2,4-triazine or triazine derivatives, such as melamine and benzoguanamine.

The reaction ratio of the dichroic dye to the trihalotriazine compound represented by Formula 3 may range from 1:0.9 to 1:1.5.

The reaction may take place at 10 to 3O⁰C for 20 to 30 hours. As such, a solvent, such as dimethylformamide (DMF), dimethylacetamide (DMAc) , or N-methylpyrrolidone (NMP) may be used.

For the reaction, an additive, such as triethylamine or pyridine, may be further added, if necessary. After the completion of the reaction, the solid precipitate is removed through filtration, and the solvent is removed using a vacuum distillation device. The residue obtained after the removal of the solvent is washed with alcohol, filtered, and vacuum dried at 40~60°C, thus obtaining the reactive dichroic dye represented by Formula 1 according to the present invention.

The structure of the reactive dichroic dye product may be confirmed using FT-IR and ¹H-NMR spectroscopy. In the FT- IR and ¹H-NMR spectroscopy, because the expected value of the product after the completion of the reaction is not greatly different from that of the mixture of the reaction materials, it is difficult to estimate the extent of progress of the reaction. Hence, in the present invention, after the completion of the reaction, the product is thoroughly washed using alcohol, which is a solvent of the reaction materials, but is not a solvent of the product, until there is no change in the weight thereof, thus indicating the complete removal of unreacted materials, followed by performing spectroscopy. In the reactive dichroic dye thus obtained, the PVA- based film is immersed, yielding a PVA-based film according to the present invention. The immersion method is not particularly limited, but is exemplarily conducted in a manner such that the reactive dichroic dye is dissolved in water and then the PVA-based film is immersed in the dye solution. The reactive dichroic dye is dissolved to a concentration of 0.0001 to 10 wt% in water, thus preparing a salt bath. As such, the pH is preferably set within the range from 8 to 12. The PVA-based film colored with the reactive dichroic dye is washed with an aqueous solution to thus eliminate the residual reactive dichroic dye. Then, stretching is conducted, thereby obtaining the PVA-based film in which the dichroic dye molecules are arranged parallel to the stretching direction. The stretching may be conducted through a wet process or a dry process, or alternatively, before the dyeing, a process of stretching the PVA-based film may be adopted.

Further, post-treatment, including boric acid treatment, may be conducted to improve beam transmittance, the degree of polarization and light resistance of the polarizing film. Although the boric acid treatment may vary depending on the type of dye used, it may be conducted at

30-8O⁰C using an aqueous boric acid solution prepared to have a concentration ranging from 1 to 15 wt%. Further, fix treatment using an aqueous solution containing a cationic polymer compound may be performed therewith, if necessary.

[Mode for Invention]

A better understanding of the present invention may be obtained through the following examples, which are set forth to illustrate, but are not to be construed as the limit of the present invention. Example 1

Congo Red [1] (1.88 g, 2.7xlO^"3 mol, available from

Aldrich) was added with dimethylformamide (25 ml) to thus be dissolved at room temperature in a nitrogen atmosphere, after which cyanuric chloride (0.5 g, 2.7 x 10^"3 mol) was added to the solution in which Congo Red was dissolved. After 1 min, 0.38 ml (2.7 x 10^"3 mol) of triethylamine was added in droplets thereto. Thereafter, stirring was conducted at 2O⁰C for 24 hours. After the completion of the reaction, the solid precipitate was removed through filtration using a filter device, and the solvent was removed using a vacuum distillation device. The residue obtained after the removal of the solvent was washed with ethanol, filtered again, and vacuum dried at 60⁰C, thus obtaining a compound [2] . The reaction route of the compound thus obtained is schematically represented by Scheme 1 below. Scheme 1

DMF triethylamine

The dichroic dye used as the starting material and the product were confirmed using FT-IR and ¹H-NMR spectroscopy.

The results of FT-IR spectroscopy of Congo Red used as the starting material are illustrated in FIG. 1. As seen in this drawing, N-H stretching vibration was observed at 3400 cm^"1 and 3300 cm^"1, aromatic C=C stretching vibration was observed at 1380 cm^"1 and 1584 cm^"1, and S=O stretching was observed at 1130 cm^"1.

The results of NMR spectroscopy of Congo Red dissolved with deuterium-substituted methylenesulfoxide (DMSOd₅) are illustrated in FIG. 2. As seen in this drawing, the resonance peaks for the protons of the phenyl groups were observed over 7.4-8.9 ppm.

The results of FIGS. 1 and 2 are summarized as follows. IR (KBr) w (cm ^l) : 3400, 3300, 1584, 1380, 1231, 1130, 1088.

¹H NMR (DMSO-Cl₆, 200MH?) δ(ppm);

8.59(d, J 4.53Hz, 2H, -N=N-C-CH-C-NaSO₃-), 8.49(d, J 4.92Hz, 4H₁ Ar-C=

CH-CH=C-N=N-), 8.40(s, 4H, Ar-C=CH-CH=C-N=N-), 8.23<d, J 5.74Hz,

2H, NH₂-C=C-Oi=), 8.04(d, J 6.45Hz, 2H, NH₂-C=C-CH=CU-CH ), 7.87(s,

The results of FT-IR of the compound [2] obtained through substitution are illustrated in FIG. 3. As seen in this drawing, N-H stretching vibration at 3448 cm^"1, and specifically stretching vibration of triazine at 2980 cm^"1, 3050 cm^"1, and 1610 cm^"1, were observed. Further, aromatic C=C stretching vibration at 1598 cm^"1, S=O stretching at 1145 cm^"1, and C-N stretching at 1084cm^""1 were observed. The results of NMR spectroscopy of the compound [2], dissolved using deuterium-substituted methylenesulfoxide (DMSO-de) , are illustrated in FIG. 4. As seen in this drawing, the protons of the phenyl groups manifested the same chemical shift as in FIG. 2, so that the positions of the resonance peaks over 7.4-8.9 ppm were equal to the expected values. The results of FIGS. 3 and 4 are summarized as follows.

IR (KBr ) v_raax (cm ^l) : 3448, 3050, 2980, 1610, 1598, 1387, 1145,

1084.

¹H NMR (DMSOd₆.200MHz ) δ(ppm);

S.45(d, J 4.23Hz, 2H, -N=N-C=CH-C-NaSO₃-), 8.52(d, J 5.56Hz, 4H, Ar-C=CH- CH=C-N=N-), 8.4Ks₁ 4H, Ar-C=CH-CH-C-N=N-), 8.27(t, J 7.87Hz, 2H, NH₂-C^C-CH=O, 8.05(d, J 6.58Hz, 2H, NH₂-C=C-CH=CJH-CH-), 7.68(t. J 7.23Hz, 2H. NH₂-C=C-CH=CH-CH=CH-), 7.67-7.56(m, J 11.00Hz, 2H₁ NH₂-C=C- CH=CH-CH=CH-)

Example 2

Direct Black 22 [4] (2.9 g, 2.7 x 10^"3 mol, available from CiBA specialty chemicals) was added with dimethylformamide (25 ml) to thus be dissolved at room temperature in a nitrogen atmosphere, after which cyanuric chloride (0.5 g, 2.7 x 10^~3 mol) was added to the solution in which Direct Black 22 was dissolved. After 1 min, 0.38 ml (2.7 x 10^"3 mol) of triethylamine was added in droplets thereto. Stirring was then performed at 20⁰C for 24 hours. After the completion of the reaction, the solid precipitate was removed through filtration using a filter device, and the solvent was removed using a vacuum distillation device. The residue obtained after the removal of the solvent was washed with ethanol, filtered again, and vacuum dried at 60°C, thus obtaining a compound [5] . The reaction route of the compound thus obtained is schematically represented by Scheme 2 below. Scheme 2

The dichroic dye used as the starting material and the synthesized product were confirmed using FT-IR (300E FT/IR spectrometer available from Jasco) , and ¹H-NMR spectroscopy (DPX 200MHx NMR spectrometer available from Bruker) .

The results of FT-IR spectroscopy of Direct Black 22, used as the starting material, are illustrated in FIG. 5. As seen in this drawing, N-H and O-H stretching vibrations were observed in a wide range from 3100 cm^"1 to 3700 cm^"1, and aromatic C=C stretching vibration was observed at 1412 cm^"1 and 1610 cm^"1, along with S=O stretching at 1112 cm^"1 and C-N stretching vibration at 1030 cm^"1.

The results of NMR spectroscopy of Direct Black 22, dissolved using deuterium-substituted methylenesulfoxide (DMSO-dg) , are illustrated in FIG. 6. As seen in this drawing, the protons of the phenyl groups were confirmed by resonance peaks of 5.8-9.3 ppm.

The results of FIGS. 5 and 6 are summarized as follows. IR (KBr ) v_max (cm ^l) : 3416, 1610, 1412, 1112, 1030.

¹H NMR (DMSO-da, 200MHz) δ(ppm);

9.27(s, IH, -N=N-C=Oi-C=), 8.49(s, IH , -N=N-C=CU-C=CH-C-NaSOa), 8.07(d, J 4.27Hz, IH, -N=N-C=CH-C=), 7.95(d, J 10.03Hz IH ,-N=N-C=CJl -CH=), 7.76(d, J 3.47Hz, 2H, NaSO₃-C=CH-C-N=N-), 7.6Kd, J 4.96Hz, IH, -N=N-C= CH-CH=NH-), 7.46(d, J 4.46Hz, 4H, NaSO₃-C=CH-C=CH-CH= C-N=N-C=CH-), 7.33(t, J 12.18Hz₁3H, -CHfC-NH-C=CH- ), 6.06(s, 2H, H₂N-CH-NH₂), 5.9Ks, 2H, H₂N-C-CH-CH=C-N=N-)

The results of FT-IR of the compound [5] obtained after the synthesis reaction are illustrated in FIG. 7. As seen in this drawing, N-H and 0-H stretching vibrations were observed at 3480 cm^"1, along with aromatic C=C stretching vibration at 1602 cm^"1, S=O stretching at 1150 cm^"1, and C-N stretching vibration at 1045 cm^"1, and triazine peaks were observed at 2730 cm^"1, 2815 cm^"1, and 1680 cm^"1.

The results of NMR spectroscopy of the compound [5] dissolved using the deuterium-substituted methylenesulfoxide (DMSO-d₆) are illustrated in FIG. 8. As seen in this drawing, the protons of the phenyl groups were confirmed by the same resonance peaks as the materials before the reaction over 5.8-9.3 ppm because they were hardly affected by the change in structure of triazine relative to the reaction materials .

The results of FIGS. 7 and 8 are summarized as follows.

IR (KBr ) v_max (cm ^l) : 3480, 2730, 2815, 1680, 1602, 1150, 1045.

¹H NMR (DMSOd₅.200MHz) δ(ppm);

9.29(S, IH, -N=^-C=CH-C=), 8.49(s, IH , -N=N-C-CiI-C=CH-C-NaSO₃), 8,1Kd, J 12.19Hz, IH, -N=N-C=CE-C=), 7>98(s, IH , -N=N-C-CH-CH=), 7.9Kd, J 1.05Hz, 2H,

7.47(d, J 4.50Hz, 4H, NaSθ3-C-C£_-C=CH-CH-C-N-N-C=CU-), 7.39-7.24(m, J 15.8Hz, 3H. -CH=C-NH-C=CH-), 6.18(s, ?H. H₂N-QH-C NH₂), 5.90(s, 2H, H₂N-C=CH-CH=C-N=N-)

Example 3

Direct Black 4 [6] (1.88 g, 2.7 x ICT³ mol, available from Aldrich) was added with dimethylformamide (25 ml) to thus be dissolved at room temperature in a nitrogen atmosphere, after which cyanuric chloride (0.5 g, 2.7 x 10^~3 mol) was added to the solution in which Direct Black 4 was dissolved. After 1 min, 0.38 ml (2.7 x lO^""3 mol) of triethylamine was added in droplets thereto. Stirring was then performed at 20°C for 24 hours. After the completion of the reaction, the solid precipitate was removed through filtration using a filter device, and the solvent was removed using a vacuum distillation device. The residue obtained after the removal of the solvent was washed with ethanol, filtered again, and vacuum dried at 6O⁰C, thus obtaining a compound [7] . The reaction route of the compound thus obtained is schematically represented by Scheme 3 below. Scheme 3

[7]

The results of FT-IR spectroscopy of Direct Black 4, used as the starting material, are illustrated in FIG. 9. As seen in this drawing, N-H and 0-H stretching vibrations were observed in a wide range from 3099 cm^"1 to 3667 cm^"1, along with aromatic C=C stretching vibration at 1490 cm^"1 and 1635 cm^"1, S=O stretching at 1176 cm^"1, and C-N stretching vibration at 1145 cm^"1.

The results of NMR spectroscopy of Direct Black 4, dissolved using deuterium-substituted methylenesulfoxide (DMSOd₅) , are illustrated in FIG. 10. As seen in this drawing, the protons of the phenyl groups were confirmed by the resonance peaks of 5.8-10.4 ppm, and the resonance peak of the methyl group was observed at 2.05 ppm.

The results of FIGS. 9 and 10 are summarized as follows.

IR (KBr)₁^_x(Cm^"1): 3443, 1635, 1490, 1176, 1145. 1H-NMR(DMSO-D₆, 200MHz) δ (ppm) ; 10.39 (d, J 0.05ppm, IH, NaSO₃-C=CH-C-CH=C-NaSO₃) , 8.15 (S , 4H, -N=N-C=CH-C=) , 7.93- 7.82 (m, 4H, -N=N-C=CH-CH=C- ) , 7.50 (S , 2H, -N=N-C=CH-CH=CH- CH=CH) , 7.42(S, IH, NH₂-C=C-CH=C-N=N-) , 7.32 (s, 3H, -N=N- C=CH-CH=CH-CH=), 6.96 (d, J 0.03ppm, IH, -N=N-C=CH-CH=NH-) , 5.97 (d, J 0.06ppm, IH, IH, H₂N-C=CH-C-NH₂) , 2.05(s, 3H, NH₂- C=CH₃)

The results of FT-IR of the compound [7] obtained through substitution are illustrated in FIG. 11. As seen in this drawing, N-H and 0-H stretching vibrations were observed at 3451 cm^"1, along with aromatic C=C stretching vibration at 1566 cm^"1, S=O stretching at 1180 cm^"1, and C-N stretching vibration at 1040 cm^"1, and triazine peaks were observed at 2776 cm^"1, 2674 cm^"1, and 1715 cm^"1. The results of NMR spectroscopy of the compound [7] dissolved using the deuterium-substituted methylenesulfoxide (DMSO-de) are illustrated in FIG. 12. As seen in this drawing, the protons of the phenyl groups manifested the same chemical shift as in FIG. 10, so that the positions of the resonance peaks over 8.37-12.08 ppm were equal to the expected values. The results of FIGS. 11 and 12 are summarized as follows .

IR (KBr) _maxfcm^"1) : 3451, 2776, 2674 1715, 1566, 1180, 1040.

¹H-NMR(DMSO-D₆, 200MHz) δ (ppm); 12.08 (d, J 0.02ppm, IH, NaSO₃-C=CH-C-CH=C-NaSO₃), 11.19 (s, 4H, -N=N-C=CH-C=), 8.85- 8.73 (m, 4H, -N=N-C=CH-CH=C-), 8.49 (s, 2H, -N=N-C=CH-CH=CH- CH=CH), 8.37 (s, IH, NH₂-C=C-CH=C-N=N-), 8.11(s, 3H, -N=N- C=CH-CH=CH-CH=), 7.92 (d, J 0.02ppm, IH, -N=N-C=CH-CH=NH-), 7.05 (d, J O.Oβppm, IH, IH, H₂N-C=CH-C-NH₂), 2.09(s, 3H, NH₂- C=CH₃)

Examples 4 to 6

Each of the reactive dichroic dyes obtained in

Examples 1 and 3 was prepared, dissolved to a concentration of 1 wt% in 100 ml of distilled water, added with 1 wt% of Na₂SO₄ to increase the adsorption of the dye, and added with

NaOH little by little to adjust the pH to 11.

In the solution thus prepared, a 4 cmx 4 cm sized PVA film, which was washed with distilled water and dried, was allowed to react for 30 min. After the completion of the reaction, the PVA was washed with distilled water, further washed several times with an aqueous solution having a pH adjusted to 11 and distilled water to remove the unreacted doped dye, and then stretched five times in a 2 wt% aqueous boric acid solution. The stretched film was vacuum dried at 40°C for 24 hours.

The schematic reaction thereof using the compound [7] is exemplarily represented by Scheme 4 below.

Scheme 4

[7]

PVA

Comparative Example 1

A typical iodine-dyed PVA film was prepared. The preparation of the iodine-dyed PVA film was as follows.

PVA was simply washed with distilled water. 0.1 M iodine (I) and 0.2 M potassium iodide (KI) were dissolved in 100 ml of distilled water at 4O⁰C. In the solution thus obtained, the PVA film was immersed for 2 min. The iodine (I) , which was not doped, was removed through washing using cold distilled water. The PVA-I₂ sample film thus obtained was vacuum dried in an oven at 4O⁰C for 24 hours.

Comparative Examples 2 to 4 Each PVA film was prepared using the dichroic dye. The specific preparation procedure thereof was as follows.

As the starting material of the reactive dichroic dye of each of Examples 1 to 3, the dichroic dye was prepared, dissolved to a concentration of 0.5 wt% in 100 ml of distilled water, and added with 1 wt% of Na2SO4 to increase the adsorption of the dye. In the solution thus obtained, a 4 cm x 4 cm sized PVA film, which was washed with distilled water and dried, was immersed for 120 sec. After the completion of the immersion, the resultant PVA was washed with distilled water, further washed several times with distilled water to remove the dye, which was not doped but remained on the surface thereof, and then stretched four times in a 2 wt% aqueous boric acid solution. The stretched film was vacuum dried at 40°C for 24 hours .

Test Example

The optical properties and durability of the PVA films obtained in Examples 4 to 6 and Comparative Examples 1 to 4 were measured.

(1) Optical Properties The optical properties of the film were determined by measuring the UV-Vis absorption spectrum using an S-1100, available from Scinco.

The absorbance of the center portion of the film, having the greatest stretch ratio and being uniform, was measured. First, single-film transmittance was measured.

Second, parallel transmittance was measured by laminating two films parallel to the stretching direction. Third, perpendicular transmittance was measured by laminating two films perpendicular to each other.

The polarizing efficiency was calculated from Equation 1 below.

Equation 1

„ , . . „ .„ . .... I parallel transmit tance - perpendicular transmit tance . ..

Polarizing Efficiency (%) = I— — — x 100 f parallel transmit tance + perpendicular transmit tance

As the transmittance value, transmittance at a maximum absorption wavelength was used.

In FIG. 13, illustrating the transmittance and polarizing efficiency of the PVA-I₂ film (Comparative Example

1) , the single-film transmittance at a maximum absorption wavelength was determined to be 42.8%, and the polarizing efficiency was calculated to be 99.8%.

In FIG. 14, illustrating the optical properties of the Congo Red-dyed PVA film (Comparative Example 2), the single- film transmittance at a maximum absorption wavelength was determined to be 11.3%, and the polarizing efficiency was calculated to be 99.9%.

In FIG. 15, illustrating the optical properties of the

Direct Black 22-dyed PVA film (Comparative Example 3), the single-film transmittance at a maximum absorption wavelength was determined to be 4.3%, and the polarizing efficiency was calculated to be 99.8%.

In FIG. 16, illustrating the optical properties of the Direct Black 4-dyed PVA film (Comparative Example 4) , the single-film transmittance at a maximum absorption wavelength was determined to be 7.5% and the polarizing efficiency was calculated to be 88.4%. In FIG. 17, illustrating the optical properties of the PVA film (Example 4) obtained using the reactive dichroic dye of Example 1 according to the present invention, the single- film transmittance at a maximum absorption wavelength was determined to be 25.3%, and the polarizing efficiency was calculated to be 98.4%.

In FIG. 18, illustrating the optical properties of the PVA film (Example 5) obtained using the reactive dichroic dye of Example 2 according to the present invention, the single- film transmittance at a maximum absorption wavelength was determined to be 34.8%, and the polarizing efficiency was calculated to be 82.7%.

In FIG. 19, illustrating the optical properties of the PVA film (Example 6) obtained using the reactive dichroic dye of Example 3 according to the present invention, the single- film transmittance at a maximum absorption wavelength was determined to be 17.8%, and the polarizing efficiency was calculated to be 98.8%.

Thanks to the reaction of the reactive dichroic dye with the surface of the PVA, the PVA film (Example 4) obtained using the reactive dichroic dye of Example 1 was evaluated to have high polarizing efficiency of 98.4% and the PVA film (Example 5) obtained using the reactive dichroic dye of Example 2 exhibited slightly high polarizing efficiency of

82.7%, compared to the PVA-I₂ film (Comparative Example 1).

Although the PVA film (Example 6) obtained using the reactive dichroic dye of Example 3 had slightly lower polarizing efficiency and transmittance than the PVA-I₂ film

(Comparative Example 1) , it was improved both in transmittance and in polarizing efficiency over the PVA film

(Comparative Example 2) dyed with Direct Black 4 as the dichroic dye. Further, the films of Examples 4 and 5 had slightly lower polarizing efficiencies than the Congo Red- and Direct Black 22-dyed PVA films (Comparative Examples 2 and 3), but the single-film transmittance thereof was much higher. (2) Durability

In order to evaluate the durability of the PVA film, the durability test was conducted.

The test was carried out in a desiccator under conditions of temperature of 50°C and humidity of 85% or more for five days, and changes in transmittance and polarizing efficiency were measured at intervals of 24 hours.

FIG. 20 illustrates the results of evaluation of the durability of the PVA-I₂ film (Comparative Example 1) , FIG.

21 illustrates the results of evaluation of the durability of the Congo Red-dyed PVA film (Comparative Example 2), FIG. 22 illustrates the results of evaluation of the durability of the Direct Black 22-dyed PVA film (Comparative Example 3), FIG. 23 illustrates the results of evaluation of the durability of the PVA film (Example 4) using the dye of Example 1, FIG. 24 illustrates the results of evaluation of the durability of the PVA film (Example 5) using the dye of Example 2, and FIG. 25 illustrates the results of evaluation of the durability of the PVA film (Example 6) using the dye of Example 3.

As is apparent from the results of FIGS. 20 to 25, in the case of the iodine-based polarizing film (Comparative Example 1) , minimum single-film transmittance was determined to be 74.7% based on the rate of change in absorption wavelength of 31.9 for 120 hours, and accordingly the polarizing efficiency was determined to be 65.1% based on the rate of change thereof of 34.7, from which the polarizing properties were concluded to be drastically deteriorated. However, in the film (Example 4) obtained using the reactive dichroic dye of Example 1, according to the heat and humidity durability test, the initial polarizing efficiency of 98.4% was changed to 94.6%, and the rate of change was 3.8%. The transmittance was changed from 25.3% to 30.5%, and the rate of change was 5.8%. That is, the changes in polarizing efficiency and transmittance were not greater than in the case of the iodine-based polarizing film. Further, in the PVA film (Example 5) obtained using the reactive dichroic dye of Example 2, the initial polarizing efficiency of 82.7% was changed to 77.0% after 120 hours. In the PVA film (Example 6) obtained using the reactive dichroic dye of Example 3, according to the heat and humidity durability test, the initial polarizing efficiency of 98.8% was changed to 94.8%, and the rate of change was 4.0%. Transmittance was changed from 17.9% to 43.5%, and the rate of change was 25.6%. From this, even though the dyed film (Comparative Example 1) had excellent polarizing efficiency, the very poor transmittance thereof before the durability test was made much worse after the durability test, making it impossible to use the above film in practice.

Consequently, compared to the iodine-based polarizing film, the polarizing efficiency and transmittance of which were greatly changed due to the high sublimation of iodine, the PVA film obtained through the reaction of the reactive dichroic dye according to the present invention could be seen to have relatively lower rates of change.

Claims

[CLAIMS]

[Claim l]

A reactive dichroic dye represented by Formula 1 below, having an azo chromophore and at least one amine group (-ISIH₂) at an end portion thereof, in which at least one hydrogen atom of the amine group is substituted with a halotriazine group :

Formula 1

B-N=N-A-N=N-B'

wherein A is or

NH₂, OH, SO₃Na, CH₃ or OCH₃;

which R₃, R₄, R₅ and Re, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of R₃ to R₆ being NH₂; R₇, R₈, R₉ and Rio, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃ or OCH₃; Rn and Ri₂, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃ , SO₃Na, SO₃CH₃ , NHCOCH₃ , NHCONH₂ , NHCH₂SO₃Na or NHCH₂COONa, at least one of Rn and Ri₂ being NH₂ ; and

, in which Ri₃, Ri₄, R₁₅ and R₁₆, which are same as

or different from each other, are

(wherein Xi is a halogen group), H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or

NHCH₂COONa, at least one of Ri₃ to Ri₆ being . R₇, Rs, Rg and Rio are defined as above; Ri₇ and Ri₈, which are same as or different from each other, are

(wherein Xi is a halogen group) , H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃,

NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₇ and Ri ₈ being

. Rig, R20 and R₂I, which are same

as or different from each other, are

(wherein

[Claim 2]

The reactive dichroic dye according to claim 1,

wherein A is

B is and B' is

, in which Ri and R₂ are H, R₃ is NH₂, R₄ and R₅

are H, R₆ is NaSO₃ , Ri₃ is

, Ri4 and R1₅ are H, and Ri₆ is NaSO₃.

[Claim 3]

The reactive dichroic dye according to claim 1,

is NH, R₇ is OH, R₈ and R₉ are H, Ri₀ is NaSO₃, Rn and Ri₂ are

NH₂ , Ri₇ is

, and Ri8 is NH₂.

[Claim 4]

The reactive dichroic dye according to claim 1 ,

Ri and R₂ are H, R₇ is NH₂, R₈ is OH, R₉ and Rio are SO₃Na, Rn

and Ri2 are H, Ri₉ is R₂₀ is CH₃ , and R₂i is NH₂ .

[Claim 5]

The reactive dichroic dye according to any one of claims 1 to 4, wherein Xi is Cl .

[Claim 6]

A method of preparing a reactive dichroic dye, comprising reacting a dichroic dye represented by Formula 2 below, having an azo chromophore and at least one amine group at an end portion thereof, with a trihalotriazine compound represented by Formula 3 below, thus preparing a reactive dichroic dye represented by Formula 1 below, having an azo chromophore and at least one amine group (-NH₂) at an end portion thereof, in which at least one hydrogen atom of the amine group is substituted with a halotriazine group:

Formula 1

B-N=N-A-N=N-B'

wherein A is or

CH=CH, NHCONH, NHOC or SO₂O, R_x and R₂, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃ or OCH₃;

which R₃, R₄, R₅ and R₆, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of R₃ to R₆ being NH₂; R₇, R₈, Rg and Rio, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃ or OCH₃; Rn and Ri₂, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Rn and Ri₂ being NH₂; and

different from each other, are (wherein Xi is a halogen group), H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₃ to Ri₆ being

; R₇,

Rs, Rg and Ri₀ are defined as above; Ri₇ and Ris, which are same as or different from each other, are

(wherein X₁ is a halogen group) , H, NH₂ , OH, SO₃Na, CH₃ , OCH₃ , COONa, COOH, SO₂NH₂ , SO₂NHCH₃ , SO₃Na, SO₃CH₃ ,

NHCOCH₃ , NHCONH₂ , NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₇

and Ri₈ being

; Ri₉, R₂₀ and R₂i, which are same

as or different from each other, are

(wherein

Xi is a halogen group), H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of R_i9 to R_2x being

Formula 2 B"-N=N-A-N=N-B wherein A and B are defined as in Formula 1, and B" is

which R₁3', R₁₄', R₁5' and Riβ', which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₃' to Ri₆' being NH₂; R₇, R₈, Rg and Rio are defined as above; Ri₇' and Riβ', which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₇' and Ri₈' being NH₂,- R₁₉', R₂₀' and R₂i', which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₉' to R₂i' being NH₂; and Formula 3

wherein Xi is defined as in Formula 1,

[Claim 7]

The method according to claim 6, wherein the reacting is conducted at 10 to 30°C for a period ranging from 20 to 30 hours .

[Claim 8]

The method according to claim 6 or 7, wherein the reacting is conducted using one or more solvents selected from among dimethylformamide (DMF) , dimethylacetamide (DMAc) and N-methylpyrrolidone (NMP) .

[Claim 9]

A polyvinylalcohol-based film, comprising a reactive dichroic dye represented by Formula 1 below, having an azo chromophore and at least one amine group (-NH₂) at an end portion thereof, in which at least one hydrogen atom of the amine group is substituted with a halotriazine group:

Formula 1

B-N=N-A-N=N-B'

wherein A is or

, X is NH, N=N, CH=CH, NHCONH, NHOC or SO₂O, R_x and R₂, which are same as or different from each other, are H,

NH₂, OH, SO₃Na, CH₃ or OCH₃;

which R₃, R₄, R₅ and Re, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of R₃ to R₆ being NH₂; R₇, R₈, R₉ and Rio, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃ or OCH₃; Rn and Ri₂, which are same as or different from each other, are H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ru and R_i2 being NH₂; and

, xn which Ri₃, R₁₄, Ri₅ and Ri6, which are same as

or different from each other, are

NHCH₂COONa, at least one of R_i3 to Ri₆ being

. R₇,

R₈, R₉ and Rio are defined as above; Ri₇ and Ris, which are same as or different from each other, are

(wherein Xi is a halogen group) , H, NH₂ , OH, SO₃Na, CH₃ , OCH₃ , COONa, COOH, SO₂NH₂ , SO₂NHCH₃ , SO₃Na, SO₃CH₃ ,

NHCOCH₃ , NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₇

and Ri8 being

Ri₉, R₂₀ and R₂i, which are same

as or different from each other, are (wherein

Xi is a halogen group), H, NH₂, OH, SO₃Na, CH₃, OCH₃, COONa, COOH, SO₂NH₂, SO₂NHCH₃, SO₃Na, SO₃CH₃, NHCOCH₃, NHCONH₂, NHCH₂SO₃Na or NHCH₂COONa, at least one of Ri₉ to R₂i being