KR19980068290A - Dye-based polarizing film manufacturing method - Google Patents

Abstract

The present invention relates to a method of manufacturing a dye-based polarizing film used in liquid crystal display devices such as electronic clocks, calculators, liquid crystal televisions, notebook computers, etc., in particular, dyes having a high degree of polarization similar to that of iodine and having a neutral gray color It is an object to provide a system polarizing film.

The present invention is a method for achieving the above object, the dichroic dye to the PVA film direct yellow (DIRECT YELLOW): direct blue (DIRECT BLUE): direct red (DIRECT RED): direct black (DIRECT BLACK) is 1: 0.2 to 0.8: 0.3 to 0.9: 0.1 to 0.5 to provide a dye-based polarizing film characterized in that the high hydrophilic mixture is mixed using a direct dye having a minimum polarization coefficient of 75% or more in visible light, The polarizing film manufactured as described above has an effect of improving polarization degree and transmittance as compared with the conventional one.

Description

Dye-based polarizing film manufacturing method

The present invention relates to a method of manufacturing a dye-based polarizing film used in a liquid crystal display device, and more specifically, by using a direct dye mixture having a high degree of polarization similar to that of an iodine-based neutral gray color (Nutral Gray Color) It relates to a method for producing a dye-based polarizing film. Liquid crystal displays are a method of displaying information such as numbers, letters, and symbols in electronic devices, calculators, liquid crystal televisions, and notebook computers, and their use is rapidly increasing with the development of the electronics industry. It is manufactured by laminating an electrode film and laminating polarizing films on both sides, and the polarizing film used is excellent in polarization so that the contrast can be clear and the image can be made clear.

The conventionally developed polarizing film is made by adsorbing and stretching iodine onto a PVA film. In this case, the initial polarization property is excellent, but due to the sublimation property of iodine, the durability is poor, and especially in high temperature and high humidity, the physical property is very bad. There is a problem. As a way to secure these shortcomings, a method of treating PVA film with formalin aqueous solution or boric acid solution after adsorption of iodine or using a protective film that is difficult to transfer water vapor has been proposed, but has not reached such a satisfactory level in durability. . For this reason, iodine polarizing film has sufficient quality for display functions such as clock, electric equipment, audio, etc., but it is necessary to have durability such as dashboard, measuring equipment, liquid crystal TV of automobile because it is poor in heat, moisture, and sunlight. It is hard to use in place.

Recently, in order to solve the above problems, a method of using a dichroic dye instead of iodine has been proposed.As such, a polarizing film using a dichroic dye has various characteristics besides neutral gray color which iodine can produce in addition to excellent heat and moisture resistance. There is an advantage in that it can produce a color, and other polymer films such as PET can be used in addition to the PVA film. However, the polarization degree of the dye-based polarizing film is less than the iodine-based, it is difficult to obtain a thing having a certain degree of polarization in the visible light region because a mixture of various dyes to give a neutral gray color.

The present invention has been made in order to solve the above problems, it is an object of the present invention to provide a dye-based polarizing film having a high degree of polarization similar to the iodine-based and neutral gray color using a direct dye.

In the present invention, the mixing ratio of the dichroic dye to the PVA film is 1: 0.2 to 0.8: 0.3 to 0.9 of direct yellow, direct blue, direct red, and direct black. The present invention is described in detail below by using a direct fuel (DIRECT DYE) having a high hydrophilicity mixed at a ratio of 0.1 to 0.5 and having a minimum polarization coefficient of 75% or more in visible light.

The dichroic direct dye used in the present invention is a hydrophilic structure having a linear structure and an aromatic ring on the same plane and a main component of the film having the same functional group (OH group) as PVA, and having a wavelength of 400 nm to 700 nm. Highly durable dyes having a minimum polarization coefficient of 75% or more and a maximum and minimum light transmittance difference of 15% or less are maintained in visible light. Specific examples of such dyes include direct yellow 12, 24, 28, 33, 34, 44, 49, 67, 142 and direct blue 1, 3, 15, 71, 78, 98, 159, 168, 175, 176, 202 And direct red 2, 5, 31, 36, 81, 84, 98, 122, 194, 240, 247 and direct black 2, 17, 19, 22 and the like.

In the present invention, a dye is obtained by dyeing a PVA film, which has been subjected to a pretreatment process such as stretching, to a dye obtained by mixing the above dyes in a direct weight ratio of direct yellow: direct blue: direct red: direct black at a ratio of 1: 0.2 to 0.8: 0.3 to 0.9: 0.1 to 0.5. After rinsing with water and treating with an aqueous solution of boric acid, a polarizing film is prepared through a post-treatment process such as washing with water and drying.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1

After impregnating the PVA film with water at 45 ° C., the film stretched six times was transferred to a dye bath to mix 50 mg of Direct Yellow 12, 35 mg of Direct Blue 159, 28 mg of Direct Red 98, and 2 mg of Direct Black 22. After dyeing with a dye and washed with water, and then again treated with an aqueous solution of boric acid, and then washed with water and dried to prepare a polarizing film, and cut the central portion of the polarizing film prepared at a 45 degree angle to measure the transmittance and polarization degree The results of the measurement are shown in Table 1.

Example 2

The PVA film was impregnated with water at 45 ° C., stretched 6.5 times, except that 35 mg of Direct Yellow 67, 28 mg of Direct Blue 159, 25 mg of Direct Red 122, and 3 mg of Direct Black 22 were used as dyes. It carried out in the same manner as in Example 1, the physical properties are shown in Table 1.

Comparative Example 1

A dye was used in the same manner as in Example 1 except that 45 mg of Direct Yellow 33, 18 mg of Direct Blue 15, 18 mg of Direct Blue 202, and 32 mg of Direct Red 81 were used. Table 1 shows.

Comparative Example 2

The dyeing was carried out in the same manner as in Example 1, except that 29 mg of Direct Yellow 49, 22 mg of 175 Blue, 20 mg of Direct Blue 159, and 30 mg of Direct Red 194 were used as the dye. Is shown in Table 1.

Comparative Example 3

The dyeing was carried out in the same manner as in Example 1 except that a mixture of Direct Yellow 67, 30 mg, Direct Blue 159 25 mg, Direct Blue 176 8 mg, and Direct Red 84 11 mg was mixed. Is shown in Table 1.

TABLE 1

division % Polarization Permeability (%) Remarks Example 1 94 41.0 Great Example 2 96.8 41.5 Great Comparative Example 1 92 38.0 usually Comparative Example 2 90 38.5 usually Comparative Example 3 95.3 37.8 usually

As can be seen from the above examples and comparative examples, the dye-based polarizing film according to the present invention has improved polarization and transmittance as compared with the conventional ones, and thus requires a high polarization with durability, such as a watch, an electric device, and an audio display device. It is useful for extending the usage, such as being possible to use it.

Claims (3)

Pre-treated PVA film is a mixture of direct yellow: direct blue: direct red: direct black in a weight ratio of 1: 0.2 to 0.8: 0.3 to 0.9: 0.1 to 0.5, and has a minimum polarization coefficient of 75% or more in visible light. Dye-based polarizing film production method characterized in that the dyeing in the dye and then prepared through water washing, boric acid solution treatment and post-treatment process. The dye-based polarizing film production method according to claim 1, wherein the direct dye has a functional group having an OH group. The dye-based polarizing film production method according to claim 1, wherein the direct dye has a linear structure in which aromatic rings are coplanar.