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Dichroic azo dyestuff and the polarizing film making from the same

a technology of dichroic azo dyestuff and polarizing film, which is applied in the direction of polarizing elements, lighting and heating apparatuses, instruments, etc., can solve the problems of low polarized efficiency, still not meeting the requirements of heat and moisture proof in some situations, and reducing the efficiency of polarization within the elapsed tim

Inactive Publication Date: 2007-08-16
EVERLIGHT USA INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009]The present invention provides a dichroic azo dyestuff with heat proof and moisture proof characters. The present invention also provides a dye type polarizing film.

Problems solved by technology

The major disadvantage of Ioding Type Polarizing Film is that the polarized efficiency is reduced within the elapsed time under high temperature and moisture.
Although the utilization of boric acid, glyoxal, or heat treatment which can form polyethylene caused by the reduction of OH groups enhances the heat proof character, it is still not met the requirement of heat and moisture proof claimed in some situations.
However, the major disadvantage is the low polarized efficiency.

Method used

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  • Dichroic azo dyestuff and the polarizing film making from the same
  • Dichroic azo dyestuff and the polarizing film making from the same
  • Dichroic azo dyestuff and the polarizing film making from the same

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0036]Preparing the azo-dyestuff compound of formula (1):

[0037]The above azo-dyestuff compound of formula (1) can be obtained, according to the following three steps:

1. DiDiazotization:

[0038]

[0039]40 parts of 4-amino-4′-nitrostilbene-2,2′-disulfonic acid (A) was dissolved in 300 parts of water and 30 parts of 32% hydrochloride acid was added, followed by stirring at 0-5° C. Diazotization was realized with the addition of 8 parts of sodium nitrite at the same temperature range.

2. Coupling Reaction:

[0040]

[0041]35.12 parts of 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid (C) was dissolved in the mixture of 200 parts of cool water and 35 parts of sodium carbonate, to which the above reagent (B) from Diazotization was then added dropwise. Thereby, the coupling reaction was realized. After the reaction was completed, the monoazo compound of free acid (D) was obtained by filtration.

3. Semi-Reduction:

[0042]

[0043]The monoazo compound (D) was dissolved in 400 parts of water, followed by th...

examples 2 to 12

[0044]Repeat the reaction steps of Example 1, but the 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid of reactant (C) is replaced with the following reactant (C) as shown in Table 1. After completed the reaction, the reaction solution are filtered and dried to obtain the products of formula (2) to formula (12) as shown in Table 1. The A max of the compounds of formula (2) to formula (12) in water were presented in Table 1.

TABLE 1ExampleReagent (C)Productλ max 1Formula (1)530 nm 2Formula (2)600 nm 3Formula (3)538 nm 4Formula (4)600 nm 5Formula (5)555 nm 6Formula (6)575 nm 7Formula (7)532 nm 8Formula (8)522 nm 9Formula (9)532 nm10Formula (10)585 nm11Formula (11)585 nmExample12Formula (12)540 nm

The following is the structure of formula (1) to (12) compounds:

[0045]The following Examples 13 to 24 are related to the preparation of the dye type polarizing films of the present invention and the measurement of light polarization.

[0046]According to Example 13 to 24, the polarizing films can ...

example 13

[0051]The polyvinyl alcohol film of 75 μm thickness, Kuraray vinylon 7500 made from Kuraray, was stretched five-fold longer in one vertical direction and the base material of the polarizing film was obtained. The polyvinyl alcohol film in strain form was dipped in the 65° C. solution of 0.025% azo compound of formula (1) made from Example 1 and 2.0% sodium sulfate (served as a dyeing agent). Then, the film was dipped in 7.5% boric acid at 65° C. for five minutes, followed by taking out the film. The polarizing film was obtained after it was washed with 20° C. water for 20 seconds and dried at 50° C. The characteristics of the polarizing film are V=99.97 and Ts=45.07. The polarizing film with high-polarized efficiency does not discolor under the high-temperature and high-moisture condition.

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Abstract

The present invention relates to a azo dyestuff compound of the following formula (I), of which the free acid is represented by the following formula:wherein R1, R2, R3, R4, and n are defined as in the specification. The azo dyestuff compound of formula (I) of the present invention is used for preparing polarizing film. The present invention also relates to a polarizing film comprising the azo dyestuff compound of formula (I), which has excellent degree of polarization.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a novel dichroic azo dyestuff used for a polarizing film and the polarizing film thereof.[0003]2. Description of the Related Art[0004]The current polarizing films are grouped into Ioding Type and Dye Type.[0005]Ioding Type Polarizing Film: the polarizing film constituted with PVA and iodine is the major part of the market. The major disadvantage of Ioding Type Polarizing Film is that the polarized efficiency is reduced within the elapsed time under high temperature and moisture. Although the utilization of boric acid, glyoxal, or heat treatment which can form polyethylene caused by the reduction of OH groups enhances the heat proof character, it is still not met the requirement of heat and moisture proof claimed in some situations.[0006]A direct azo-dye is the major part of the dichroic dyestuff used for Dye Type Polarizing Film. It is the characteristic that the axial in the structure o...

Claims

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Application Information

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IPC IPC(8): C07C309/16C09K19/00C09B56/04
CPCC07C309/50C09B43/10Y10T428/1041C09K19/601C09B56/04C09K2323/031
Inventor CHENG, MING-CHIN
Owner EVERLIGHT USA INC
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