JPS6083903A - Polarizing element and electro-optical liquid crystal device using it - Google Patents

Abstract

PURPOSE:To obtain a polarizing element having high reliability and maintaining its polarizing power even in environment at high humidity and an electro-optical liq. crystal device using the polarizing element by holding a polarizing layer of polyvinyl alcohol contg. iodine between two protective films and by tightly sealing the peripheral parts with a material having low moisture permeability. CONSTITUTION:A polarizing layer 2 of polyvinyl alcohol contg. iodine is held between two protective films 1, 1' each having >=100mum thickness. The films 1, 1' are made of a polymer having <=100g.0.1mm./m<2>.24hr coefft. of moisture permeation at 25 deg.C such as polyethylene terephthalate or fluororesin. A tightly sealing layer of epoxy resin 3 having low moisture permeability is formed around the films 1, 1', or the films 1, 1' are entirely wrapped with a polyamide film 4. Thus, a polarizing element whose polarizing power is not deteriorated or lost by moisture is obtd. When a liq. crystal display device is manufacture by using the polarizing element, the moisture resistance is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polarizing element, and particularly to a highly reliable polarizing element when used in a liquid crystal electro-optic device.

BACKGROUND OF THE INVENTION Liquid crystal electro-optic devices are often used in combination with polarizing elements. However, polarizing elements generally have poor moisture resistance, and when exposed to moisture, their polarizing ability decreases and they no longer function as a polarizing element. Therefore, there is a problem that a liquid crystal electro-optical device using the same also stops functioning under high humidity. Therefore, in the case of devices used outdoors in high temperature, high humidity conditions such as in automobiles, consideration must be given to measures such as storing the device in an airtight container made of glass or other material to prevent moisture from entering. is required, making it a complicated and expensive device. In any case, under these circumstances, the emergence of a liquid crystal electro-optical device that is truly reliable under high humidity conditions is eagerly awaited.

Except for the polarizing element, liquid crystal electro-optical devices produced using current technology have high moisture distribution properties and can withstand use in outdoor environments. Therefore, if the moisture resistance of the polarizing element used in combination is improved, the reliability of the liquid crystal electro-optic device will also be immediately improved.

Another way of thinking is that if there were to be devices that did not require the use of polarizing elements, the problem of moisture resistance would be solved all at once. Based on this idea, there is a movement to adopt a guest-host system using a display principle that does not require a polarizing element as a device for outdoor equipment, but the display quality is still not satisfactory. The twisted-nematic system is a typical device that uses polarizing elements and elements, and in terms of display quality, it is currently the highest level of liquid crystal electro-optic devices, and its use is also preferred for outdoor equipment. become.

[Purpose of the invention]

The purpose of the present invention is, first of all, to provide a polarizing element with excellent moisture resistance, and ultimately, by using the polarizing element,
An object of the present invention is to provide a liquid crystal electro-optical device that does not deteriorate in function even under high humidity. Another object of the present invention is to provide a polarizing element that can also serve as a substrate for a liquid crystal electro-optic device and provide a device with excellent moisture resistance.

[Summary of the invention]

The present invention relates to a polarizing element having a structure in which an iodine-hollyhinyl alcohol-based polarizing layer is sandwiched between two protective films, and a polarizing element provided with a sealing layer at the periphery, and a polarizing element using the polarizing element. The present invention relates to a liquid crystal electro-optic device, particularly a liquid crystal electro-optic device in which the polarizing element also serves as a substrate of the device.

In order to solve the above-mentioned problems with polarizing elements, the present inventors first investigated how existing polarizing elements lose their polarizing ability under high humidity conditions. Ta. The situation will be explained based on FIG. FIG. 1 is a cross-sectional view of a polarizing element, with reference numerals 1 and 1' indicating protection layers and 2 indicating a polarizing layer. When an existing polarizing element as shown in Fig. 1 is placed under high humidity conditions, the polarizing ability is first lost from the end part of the polarizing layer made of PVA impregnated with iodine. It was found that it progressed internally over time. Therefore, a polarizing element as shown in FIG. 3 was made. In other words, around the polarizing element,
A sealing layer of approximately 0.05 to 1.0 mm was provided using epoxy resin.

In FIG. 6, numerals 1, 1' and 2 have the same meanings as in FIG. 1, and numeral 5 is a layer of epoxy resin.

By doing this, the loss of polarization ability from the edge was clearly improved. However, it was also found that the polarizing ability deteriorated gradually over the entire polarizing element due to moisture permeation through the reinforcing layer. This is thought to be because the material of the reinforcing layer that has been used in the past is mainly composed of acrylate resin, which has a relatively high moisture permeability. Therefore, when polyethylene terephthalate, which has a relatively low moisture permeability, was used as a retaining layer, it was found that the moisture resistance was significantly improved, and it showed performance that could withstand outdoor use without any practical problems. I arrived at the eggplant. That is, the gist of the present invention is to provide a sealing layer around the polarizing element so that the polarizing layer is not exposed, and to use a J-sized material with moisture permeability as the reinforcing layer. It is.

Examples of materials with low moisture permeability include polymeric materials such as polyethylene, polyamide, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, and fluororesin, in addition to the above-mentioned polyethylene terephthalate.

In order to exhibit moisture resistance that does not cause any practical problems, the retention layer made of a polymeric material having a relatively low moisture permeability needs to have a thickness of 50 μm or more, preferably 100 pm or more. Furthermore, even if the moisture permeability of the polymer material mutually reinforcing layer is high, it is effective to provide an inorganic material film (silicon oxide, etc.) with almost no moisture permeability on the outside of the protective layer. be.

In this case, the object of the present invention can be sufficiently achieved if the thickness of the inorganic material film is 2000 mm or more.

In addition to silicon oxide films, indium oxide, titanium oxide, and magnesium fluoride II eggs have the effect of reducing moisture permeation, can be formed at low temperatures, and do not reduce polarization ability, so they are preferred film formation methods. It is the material.

In any case, in order to achieve the object of the present invention, it is not enough to use the above-mentioned protective layer with low moisture permeability, but it is essential to use it in conjunction with measures to prevent deterioration from the peripheral area of the polarizing element. .

Various measures can be considered, and some examples are shown in Figures 2 to 4.

Each figure shows a cross-sectional view of a polarizing element according to the present invention, and the dimensions are exaggerated.

Figure 2 shows that when sandwiching the polarizing layer with a protective layer (polyethylene terephthalate with a thickness of 100 μm), cut the polarizing layer to a predetermined size in advance, sandwich it with a slightly larger piece of mining film, and then By heat-sealing and integrating the parts, a sealing layer is formed so that the polarizing layer is not exposed at all around the peripheral part of the polarizing element.

Figure 3 shows that, like a conventional polarizing element, after cutting a large polarizing film into a predetermined size, a sealing layer is formed at the cut edge using an epoxy resin layer 3 with low moisture permeability. It is something.

Figure 4 shows a piece of polarizing film cut out to a predetermined size, and then the whole cut out piece is covered with a polyamide laminate film so that the polarizing layer is not exposed at all around the periphery. It is.

In FIGS. 2 to 4, numerals 1.1' and 2 have the same meanings as in FIG. 1, 6 and 4' represent end sealing layers, and 4 represents a laminate film.

Moreover, FIGS. 51 to 6 illustrate cross-sectional views of liquid crystal electro-optical devices using the polarizing element according to the present invention.

FIG. 5 shows a polarizing element 5-a according to the present invention on a glass substrate of a liquid crystal cell using a glass substrate 6.

FIG. 6 shows an example in which the polarizing elements 5-a and 5-a' according to the present invention also serve as a substrate of a liquid crystal cell.

In FIGS. 5 and 6, symbols 5-a and 5-a'
5-'b and 5-b' are the sealing layers, 6 is the glass substrate, 7 is the liquid crystal layer, and 8 is the sealing layer.

Next, some specific examples will be described in order to explain the present invention in detail.

A liquid crystal electro-optical device as shown in FIG. 5 or 6 was made using a comparative example and a polarizing element according to the present invention.
A field-effect liquid crystal was encapsulated and the display performance was investigated. After checking the initial condition, the device is installed at 70℃, 95%RH.
The sample was placed in a humidity bath for 100 hours, and then taken out and rechecked for displayability. Set the result to 1 and move on to the next page 51.
Shown in the table. The reason why the lighting state cannot be visually recognized in the comparative examples is that the polarizing ability of the polarizing element is lost. On the other hand, it is clear that the devices of Examples have significantly improved moisture resistance properties without any loss in initial performance (7>-).

Effects of the Invention] According to the present invention, highly reliable polarizing films and liquid crystal optical devices that do not lose their polarizing ability even under high humidity can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional polarizing element, FIGS. 2 to 4 are cross-sectional views of a polarizing element of the present invention, and FIGS. 5 and 6 are cross-sectional views of a conventional polarizing element. 1 shows a cross-sectional view of a liquid crystal electro-optic device. DESCRIPTION OF SYMBOLS 1... Retention layer, 2... Polarizing layer, 5.4'... Density layer, 4... Laminate film, 5-a, 5-a'.
・A region having 1 sum and 1 optical layer, s-b, s-b'...
Sealing layer, 6...Glass substrate, 7...Liquid crystal layer, 8...
・Sealing material. Patent Applicant Hitachi, Ltd. Agent Hiroshi Nakamoto Figure 1 Figure 2 Figure 3 tI-Figure/' Figure 5 Figure 6

Claims (1)

[Claims] 1. A polarizing element having a 4'Nj construction in which an iodine-polyvinyl alcohol polarizing layer is sandwiched between two reinforcing films, and a sealing layer is provided at the peripheral portion. 2. The protective film has a moisture permeability coefficient of 1007.0.1 rtr
m/m2e 24 hr (25° C.) or less and a thickness of 100 μm or more. In addition, a liquid crystal electro-optical device using a polarizing element having a structure in which an iodine-polyvinyl alcohol polarizing layer is sandwiched between two protective films. 4. Two protective films with a sealing layer provided on the periphery. The liquid crystal electro-optical device according to claim 6, wherein the polarizing element having a structure in which an iodine-polyvinyl alcohol polarizing layer is sandwiched between films also serves as a substrate of the device. 5. A sealing layer is provided in the peripheral area. The liquid crystal according to claim 6, wherein the polarizing element having a structure in which an iodine-polyvinyl alcohol polarizing layer is sandwiched between two reinforcing films is provided adjacent to a substrate of the device. Electro-optical device.