JPH0354506A - Polarizing plate - Google Patents

Abstract

PURPOSE:To obtain the polarizing plate which is free from unequalness by executing rubbing, corona treating and dyestuff applying stages in an atmosphere of <= 50% relative humidity (RH). CONSTITUTION:A triacetyl cellulose film, etc., are used for a base material and a fabric, paper, etc., are used in combination with polishing materials, such as alumina, at need for a rubbing material. The base material is then rubbed about 1 to 30 times. The corona treatment is executed required times at 50 to 300W.min/m<2> energy density per time. The dyestuff to be applied is properly selected according to the base material to be used and is dissolved in water or org. solvent. A surfactant is added at need to the dyestuff and the soln. is applied on the base material subjected to the rubbing and corona treatment. The coating method may be any and the coating amt. is specified to 0.1 to 0.8g/m<2>. The polarizing plate which has an excellent rate of polariza tion and has the axis of polarization in an arbitrary direction without having unequal polarization is easily obtd. if the respective stages mentioned above are executed in the atmosphere of <= 50% RH.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a polarizing plate coated with a dye, and more specifically to a polarizing plate which provides polarization in any direction and whose polarizing portion is continuously patterned. Regarding. BACKGROUND OF THE INVENTION Conventionally, a typical method for manufacturing a polarizing plate is to color a stretched polyvinyl alcohol film with iodine and then attach it to a transparent substrate. This type of polarizing plate is excellent in its high degree of polarization, uniformity of transmittance, and stability of the material.
However, this polarizing plate can obtain polarization only in the stretching direction of the polyvinyl alcohol film, and since this stretching can usually only be done in one direction, the polarizing direction is also limited to one direction, such as circular, radial, The disadvantage is that it is not possible to produce polarizing plates with waveforms, etc. Therefore, in order to obtain a polarizing plate in which the polarization axis extends radially using this type of polarizing plate, for example, a large number of polarizing plates cut into fan shapes and having polarizing properties in the radial direction are pasted in a circular shape. This method is difficult and expensive to manufacture, and it is difficult to obtain a polarizing plate with a continuous polarization axis. On the other hand, as a method for imparting polarization in any direction to glass, organic films, etc., for example, U.S. Patent No. 2,400,8
There is a method described in No. 77, etc. This method is a method in which a dichroic dye is oriented in the direction of rubbing a glass or organic film coated with cloth, paper, or the like. In this method, before coating the dichroic dye,
A rubbing process is applied to glass or an organic film, and the dichroic dye is oriented in the rubbing direction. By arbitrarily changing the rubbing direction, a continuously patterned polarizing plate with little unevenness can be formed. You can.
However, using the dichroic dye described in the US patent, glass
Alternatively, if polarization is directly imparted to an organic film, the drawback is that the polarization ability is low and the contrast is not excellent. Invention tries to solve! IN There is a need for a polarizing plate with high polarization ability, excellent contrast, polarization in any direction, continuously patterned polarization portion, and less unevenness. Means for Solving the Problems As a result of intensive research in order to obtain a polarizing plate coated with a dye, the polarization axis of which can be in any direction, high polarization ability, and excellent contrast, the present invention has been achieved. It's arrived. That is, the present invention manufactures a polarizing plate that can polarize light in any direction by rubbing the entire surface or a desired part of the substrate in any direction, applying corona treatment, and coating the dye thereon. The invention relates to a polarizing plate in which the rubbing process, corona treatment process, and dye coating process are performed in an atmosphere with a relative humidity of 50% or less. Corona treatment is a surface treatment method that is often used to improve the wettability of substrates, but in the production of polarizing plates coated with dyes, if corona treatment is applied after rubbing, the rubbed area will be activated. The dye is oriented efficiently and a high polarization rate is obtained. However, areas activated by rubbing and corona treatment are easily affected by the surrounding environment, and in some cases,
Area where the dye is not oriented at all (area where polarized light does not occur)
may occur in whole or in part. The present inventors have discovered that the cause of this is related to the amount of moisture inside and/or on the substrate and/or the amount of moisture in the air, and that by controlling the humidity, it is possible to prevent the occurrence of unoriented portions, and have developed the present invention. I have reached complete commandment. That is, by performing each step of rubbing, corona treatment, and dye coating in an atmosphere with a humidity of 50% or less, especially 45% or less, a polarizing plate with excellent polarization rate and no unoriented portions (not showing polarization) can be obtained. was completed. Examples of substrates used in manufacturing the polarizing plate of the present invention include triacetel cellulose film (hereinafter referred to as TAC film), diacetyl cellulose film, cellulose acetate film, polyester film (hereinafter referred to as PET film), vinyl chloride film ( Polystyrene film, polypropylene film (hereinafter referred to as PP film), polyethylene film (hereinafter referred to as PR film), polyether sulfone film (hereinafter referred to as PES film), polycarbonate film (hereinafter referred to as PC film) ) Examples include polymer films such as acrylic films and glass.

As the rubbing agent, cloth, paper, leather, cotton, felt, puff, etc. can be used together with an abrasive agent such as clay, zirconia, alumina, etc., if necessary.

The degree of rubbing varies depending on the type of rubbing agent and the degree of subsequent corona treatment, but the number of times of rubbing is 1.
~30 times is recommended. As the corona treatment machine, various commercially available corona treatment machines can be used. The conditions for corona treatment vary depending on the type of substrate used and the strength of the dye-containing liquid applied after corona treatment.
For each treatment, the engineering energy density is 20
~400 W. +wln/rd preferably 50~
300 W. min/rrf is required. High energy treatment can cause deterioration of the base material and bleed of the filler to the surface, so low energy treatment is preferable, but depending on the base material, high energy may be required. If one time processing is insufficient, you can perform the processing two or more times. Examples of dichroic dyes to be coated include water-soluble dyes such as direct dyes and acid dyes, their ammonium salts, disperse dyes, and water-insoluble dyes such as oil-soluble dyes, although they vary depending on the type of substrate used. etc. These dyes are usually dissolved in water or a certain amount of solvent, and in some cases with the addition of a surfactant, they are applied to a substrate that has been subjected to rubbing or corona treatment. Organic solvents vary depending on the solvent resistance of the base material, but generally include alcohols such as methanol, ethanol, and isopropyl alcohol, cellosolves such as methyl cellosolve and ethyl cellosolve, ketones such as acetone and methyl ethyl ketone, and dimethyl formamine. Examples include amides such as chloride, N-methylpyrrolidone, and aromatic organic solvents such as benzene and toluene. The coating amount of the dye varies depending on the polarization performance of the dye, but is generally 0.05 to 1.0 g/po, preferably 0.1 to 0.
．． 8g/rrf. Various coating methods such as barcoder coating, spray coating, roll coating, and gravure coating can be used to apply the colored PfJ liquid to the substrate. The polarizing plate manufactured in this way can be used as is, and in fields where durability is required, it can be used as PE↑ film, PVC film, Pl! It is used as a highly durable polarizing plate by adhering a support film such as S film or coating it with special acrylic resin or epoxy resin. The polarizing plate of the present invention can be used in liquid crystal displays, various decorative displays, decorative material blinds, light control devices such as sunroofs, polarized glasses, and various cards. EXAMPLES The present invention will be explained in more detail with the following examples. Incidentally, here, the polarization ratio ρ (1ax) at the maximum absorption wavelength λlaX is determined by the parallel position, transmittance TI1 (■aX), and perpendicular position transmittance d. (old κ) is expressed by the following formula. Example 1 The relative humidity in the room is set to 45%. Commercially available AC film (thickness 80μ-, after applying Fuji film, washing with water and drying.
m/sec, set energy 150 Lain/nf
Te: 7rona processing was performed. In that film, C. I. D? rectOrange
72, c. LDirect BIue67, C. I
．． 1 of the black dyes to be warned from Direct Gvaen51
A 0% aqueous solution was applied using a gravure coater and dried to obtain a polarizing plate of the present invention. The luminous transparency of this polarizing plate y. is 39z
, the average polarization ratio ρ was 87%. Examples 2-3, Comparative Examples 1-2 Table 1 shows the results when the indoor relative humidity was changed in the same manner as in Example 1. Comparative polarizing plates were also obtained at relative humidity of 60% and 65% in the same manner as in Example 1. Table 1 Examples 4 to 10 Table 2 shows the results when the rubbing conditions and corona treatment conditions for various substrates were polarized using the same method as in Example 1 at an indoor relative humidity of 45%. Effects of the invention: It is now possible to easily obtain a polarizing plate with an excellent polarization rate and a polarization axis in any direction without polarization unevenness.

Claims (1)

[Claims] 1. In manufacturing a polarizing plate having polarization properties in any direction by rubbing the entire surface or a desired part of the substrate in any direction, applying corona treatment, and applying a dye thereon, the rubbing step, A polarizing plate in which the corona treatment process and the dye coating process are performed in an atmosphere with a relative humidity of 50% or less.