JPS6136206B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a partially polarizing film, and more specifically to a method for producing a partially polarizing film, and more specifically, a method for producing a partially polarizing film, in which a region having polarization ability is provided in an arbitrary pattern on a single substrate. A method for manufacturing a polarizing film is provided.

Conventionally, display devices having polarizing ability in a pattern have been made by cutting a general polarizing plate into a predetermined size and shape and arranging it in a pattern, or by using a partially polarizing film that has been dyed with iodine in a pattern in advance. It is constructed using a partially polarizing plate.

However, in the former method of arranging cut polarizing plates in a pattern, the dimensional accuracy of the abutting portions is poor, which not only makes the appearance unsightly but also reduces the display performance. The disadvantage of this method is that the dimensional accuracy is poor because the film swells during dyeing.

The present invention provides a novel method for producing a partially polarizing film in which the boundary between a portion having polarizing ability and a portion not having polarizing ability is beautifully formed in a straight line. The method involves partially applying a solution containing iodide to a uniaxially stretched hydrophilic polymer film containing iodide, and then subjecting it to a humidification treatment.

The method for producing a partially polarized film of the present invention has good dimensional accuracy by causing an oxidizing agent in a uniaxially stretched hydrophilic polymer film to undergo an oxidation reaction with an iodide in an iodide-containing solution to be partially applied. The purpose of the present invention is to provide a partially polarizing film that is durable and has excellent durability.

As a method for incorporating boric acids and an oxidizing agent into a uniaxially stretched hydrophilic polymer film, boric acids such as orthoboric acid, metaboric acid, tetraboric acid or their salts, ferric chloride, cupric chloride, copper sulfate, etc. Polyvinyl alcohol film, partially formalized polyvinyl alcohol film, ethylene-
Hydrophilic polymer films such as saponified vinyl acetate copolymer (EVOH) films are generally
It is preferable to uniaxially stretch the hydrophilic polymer film by about 3 to 5 times while or after dipping for a minute. A method of immersing in a mixed aqueous solution of an acid and an oxidizing agent may also be used. It can also be obtained by adding boric acids and an oxidizing agent at the stage of producing a hydrophilic polymer film and stretching the film.

In this way, a uniaxially stretched hydrophilic polymer film containing boric acids and an oxidizing agent contains potassium iodide,
A solution containing iodides such as ammonium iodide, sodium iodide, and iron iodide is applied in the desired pattern, optionally dried, and then humidified under tension (generally 60-80℃ x 90-98℃). %RH×
(preferably for about 1 to 15 minutes), the oxidation reaction proceeds rapidly to generate an iodine compound, thereby obtaining a partially polarized film in which the polarizing ability is partially (patterned) formed.

In addition to iodide, a suitable amount of a gelling agent that adjusts the viscosity of the solution, such as sodium alginate, should be added to the solution containing iodide to adjust the solution to 50 poise or more (preferably 100 to 500 poise). is desirable for forming a linear pattern.

Furthermore, when performing humidification treatment, the purpose of performing the humidification treatment under tension as described above is to prevent the uniaxially stretched hydrophilic polymer film from shrinking due to the humidification treatment. A plastic film having good heat resistance may be adhered to one side of the film to prevent the stretched film from shrinking during humidification before processing. Examples of the plastic film include polyester film, polyacrylic film, and acetate film.

An optically transparent plastic film or the like as a surface protective layer is adhered to one or both sides of the partially polarizing film thus produced to form a partially polarizing plate. Furthermore, the plastic film adhered to prevent shrinkage during the humidification process described above can be used as it is as a surface protective layer.

As described above, in the production method of the present invention, a uniaxially stretched hydrophilic polymer film containing an oxidizing agent is partially coated with an iodide-containing solution and subjected to a humidification treatment. It has the characteristics that it can be easily formed with a portion that does not have polarizing ability, and that a linear boundary between the two can be obtained.

Examples of the present invention will be shown below. % in the text means weight %.

Example A 75 μm thick polyvinyl alcohol film was immersed in an aqueous solution containing 2% orthoboric acid and 2% ferric chloride (liquid temperature 30°C) for 1 minute, stretched 4 times, and then dried at 70°C for 10 minutes. do.

Next, a gel-like aqueous solution (viscosity 200 poise) containing 0.1% potassium iodide and 0.5% sodium alginate
Apply it in stripes at 5 mm intervals with a width of 10 mm and air dry.
This is left under tension at 70°C x 95% RH for 2 minutes to obtain a partially polarized film.

The light transmittance of the portion of this film having polarization ability was 40%, and the degree of polarization was 98%.

Claims (1)

[Claims] 1. A method for producing a partially polarized film, which comprises partially applying an iodide-containing solution to a uniaxially stretched hydrophilic polymer film containing boric acids and an oxidizing agent, and then humidifying the film.