JP2000338329A - Polarizing plate and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing plate allowing the stable production of a polarizing plate which lessens curling and deforming, facilitates the automatic sticking work to a liquid crystal cell and has a thin polarizing element. SOLUTION: This process for production has stages for forming a polyvinyl alcohol base resin layer 2 having a thickness of >=6 to <=30 μm on one surface of a thermoplastic resin film 1, then stretching the film to 2 to 5 times to form a composite film consisting of the two layers; the thermoplastic resin film layer and the transparent film element layer with the polyvinyl alcohol base resin layer as a transparent film element layer 2, then bonding an optically transparent resin film layer 3 via an adhesive to the transparent film element layer side of the composite film consisting of the two layers, then peeling away the thermoplastic resin film layer and further, dyeing and fixing the transparent film element layer to form a polarizing element layer 2", thereby obtaining the polarizing plate consisting of the two layers; the optically transparent resin film layer and the polarizing element layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate technology used for a liquid crystal display or the like, and more particularly, to a method of manufacturing a thin polarizing element polarizing plate.

[0002]

2. Description of the Related Art A polarizing element used for a polarizing plate used for a liquid crystal display or the like is generally prepared by dyeing a polyvinyl alcohol resin film having a thickness of about 75 μm with an aqueous solution of iodine, various dyes, boric acid, or the like. , A polarizing element obtained by stretching and fixing, usually having a thickness of about 32 to 34 μm.

The polarizing plate mainly has a three-layer structure in which such a polarizing element is centered and an optical transparent film such as a cellulose-based film is laminated on both sides for protection. In such a polarizing plate, with the recent increase in the size of the liquid crystal display, it has become increasingly difficult to automatically attach the liquid crystal cell to the liquid crystal cell due to curling or deformation.

Further, as electronic devices such as portable personal computers have become thinner and lighter, there has been a demand for thinner and lighter polarizing plates themselves. However, at present, polyvinyl alcohol-based resin film, which is a material of a polarizing element, is not used.
At present, there is no material having a thickness of less than 5 μm and a high quality capable of stably producing a polarizing plate when used as a material. Further, even if such a thin polyvinyl alcohol-based resin film is stably supplied, it is expected that the cost will increase. Further, in the case where a polarizing element is continuously produced using an extremely thin polyvinyl alcohol-based resin film, there are many problems to be solved, such as occurrence of frequent film breakage in the process.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, has little curl or deformation, is easy to automatically attach to a liquid crystal cell, and has a polarizing plate having a thin polarizing element. It is an object of the present invention to provide a polarizing plate that can be stably produced.

[0006]

In order to solve the above-mentioned problems, the method for manufacturing a polarizing plate according to the present invention has a thickness of 6 μm or more on one side of a plastic resin film.
After forming a polyvinyl alcohol-based resin layer having a thickness of 0 μm or less, the polyvinyl alcohol-based resin layer is stretched by a factor of 2 to 5 times to form a transparent film element layer. After forming an optically transparent resin film layer on the transparent film element layer side of the two-layered composite film via an adhesive, the thermoplastic resin film layer is peeled off. And a step of dyeing and fixing the transparent film element layer to obtain a polarizing element layer as a polarizing element layer to obtain a polarizing plate comprising two layers, an optical transparent resin film layer and a polarizing element layer.

According to a second aspect of the present invention, there is provided a polarizing plate manufacturing method comprising: forming a polyvinyl alcohol resin layer having a thickness of 6 μm or more and 30 μm or less on one surface of a thermoplastic resin film; The polyvinyl alcohol-based resin layer was stretched to 5 times or less to form a transparent film element layer, and then the transparent film element layer was dyed and fixed to form a polarizing element layer. After forming a composite film consisting of two layers, after bonding the optical transparent resin film layer to the polarizing element side of the resulting composite film consisting of two layers via an adhesive, the thermoplastic resin film layer is peeled off. Thus, the present invention provides a method for producing a polarizing plate, which comprises a step of obtaining a polarizing plate comprising two layers of an optical transparent resin film layer and a polarizing element layer.

Further, according to the method for producing a polarizing plate of the present invention, a polyvinyl alcohol resin layer having a thickness of 6 μm to 30 μm is formed on one surface of a thermoplastic resin film. A thermoplastic resin film is further laminated on the alcohol-based resin layer to form a three-layer structure of thermoplastic resin film layer / polyvinyl alcohol-based resin layer / thermoplastic resin film layer, and then stretched to 2 to 5 times. Then, the polyvinyl alcohol-based resin layer is used as a transparent film element layer, and one of the thermoplastic resin film layers sandwiching the polyvinyl alcohol-based resin layer is peeled off to form a two-layered thermoplastic resin film layer and a transparent film element layer. After forming an optically transparent resin film layer on the transparent film element layer side via an adhesive, Peel and remove the plastic resin film layer,
Further, the present invention provides a method for producing a polarizing plate, which comprises a step of dyeing and fixing a transparent film element layer to obtain a polarizing plate comprising an optical transparent resin film layer and a polarizing element layer as a polarizing element layer.

Further, according to the method for producing a polarizing plate of the present invention, a polyvinyl alcohol-based resin layer having a thickness of 6 μm or more and 30 μm or less is formed on one surface of a thermoplastic resin film. A thermoplastic resin film is further laminated on the polyvinyl alcohol-based resin layer to form a three-layer structure of thermoplastic resin film layer / polyvinyl alcohol-based resin layer / thermoplastic resin film layer. The polyvinyl alcohol-based resin layer is stretched to form a transparent film element layer, and further, one of the thermoplastic resin film layers sandwiching the polyvinyl alcohol-based resin layer is peeled off to remove the thermoplastic resin film layer and the transparent film element layer. After forming a composite film consisting of two layers and laminating an optical transparent resin film layer to the polarizing element side of the obtained composite film via an adhesive And a step of removing the thermoplastic resin film layer to obtain a polarizing plate comprising two layers of an optical transparent resin film layer and a polarizing element layer. Further, the polarizing plate of the present invention is a polarizing plate in which the thickness of the polarizing element layer is 2 μm or more and 15 μm or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a polarizing plate of the present invention has the following features.
Conventionally, it could not be manufactured. The thickness of the polarizing element layer was 2 μm.
This enables stable production of a polarizing plate having a thickness of 15 μm or less. Such a method for producing a polarizing plate of the present invention will be described with reference to model sectional views 1 to 4.

Examples of the thermoplastic resin film (the cross section is indicated by reference numeral 1 in FIG. 1A) used in the method for producing a polarizing plate of the present invention include, for example, polyethylene, polypropylene, nylon, polyvinyl chloride, polycarbonate, polyethylene terephthalate. And films made of thermoplastic resins based on these polymers, but non-stretched ones are particularly preferred. It is necessary that the thickness of the thermoplastic resin film to be used is about 50 to 100 μm, which is easy to handle, and that the appearance defect and the thickness unevenness are small. Further, a polypropylene film is preferable because it has a certain degree of heat resistance and good stretchability and is relatively inexpensive.

Here, among commercially available thermoplastic resin films, those which have been subjected to a corona discharge treatment or the like in order to improve various affinity such as hydrophilicity are known. A thermoplastic resin film subjected to such an affinity improving treatment is preferable because high stretchability can be obtained.

On one surface of such a thermoplastic resin film, a polyvinyl alcohol-based resin layer (reference numeral 2 in FIG. 1B)
The saponification degree is 9 with the polyvinyl alcohol-based resin used here.
The main component is a completely saponified polyvinyl alcohol having a molecular weight of 8.0 to 99.9, and the degree of polymerization of the polyvinyl alcohol is 1700 to 2600. Such polyvinyl alcohols are commercially available in powder or pellet form. For example, Kuraray Povar 117, 117H, 1
20, 125, Gohsenol NH-1 manufactured by Nippon Gosei Kogyo
8, 20, 26, etc. are known.

These polyvinyl alcohols are dissolved in water while heating to prepare a 7 to 15% by weight aqueous solution of polyvinyl alcohol, coated on the thermoplastic resin film by a coater or the like, and dried to form a polyvinyl alcohol-based resin layer. I do.

It is necessary that the thickness of the polyvinyl alcohol resin layer is not less than 6 μm and not more than 30 μm. If it is less than 6 μm, it is difficult to sufficiently stretch in the stretching step, and a good and durable polarizing element cannot be obtained. On the other hand, when the thickness exceeds 30 μm, it takes time in the drying step, and it is difficult to obtain a uniform polyvinyl alcohol-based resin layer. It becomes longer or color unevenness occurs, and a uniform and good polarizing element cannot be obtained.

Next, the film is uniaxially stretched under heating so that the stretching ratio is in the range of 2 to 5 times, and the polyvinyl alcohol-based resin layer is used as a transparent film element layer (reference numeral 2 'in FIG. 1 (c)). A composite film comprising two layers, a thermoplastic resin film layer and a transparent film element layer, is formed. The heating temperature at this time is adjusted according to the softening temperature of the thermoplastic resin film 1. Here, if the low-rate stretching is less than twice, a polarizing element having good polarization properties cannot be obtained, and if the efficiency stretching is more than 5 times, stable production becomes extremely difficult.

Next, an optically transparent resin film (reference numeral 3 in FIG. 1 (d)) is applied with an adhesive to the transparent film element layer side of the composite film composed of the thermoplastic resin film layer and the transparent film element layer. And stick them together.

The optically transparent resin film used in the present invention must have good flatness, low optical anisotropy, and sufficient light transmittance, except in special cases. . Thereafter, the thermoplastic resin film layer 1 is peeled off to obtain a composite film composed of two layers, a transparent film element layer and an optical transparent resin film layer (see FIG. 1 (e)).

Further, the transparent film element layer 2 'is dyed with a dyeing solution for a polarizing element to form a polarizing element layer (indicated by 2 "in FIG. 1 (f)) to obtain a polarizing plate. Dyeing liquids can be used as long as they do not adversely affect the optically transparent resin film among those used in the production of ordinary polyvinyl alcohol-based polarizing elements.In general, aqueous solutions of iodine and various dyes are used. Used.

In the prior art, the dyeing / fixing step (or the stretching / dyeing / fixing step;
In some cases, fixation was performed), since a polyvinyl alcohol resin film was immersed in a dyeing solution for a polarizing element, a sufficient amount of a chemical solution was required in the dyeing tank, fixing tank, or dyeing and fixing tank. there were.

Since the polarizing element layer is unstable as it is, it is fixed and stabilized using a boric acid aqueous solution or the like. Depending on the type of the dyeing solution for a polarizing element, for example, in the case of an iodine-based dyeing solution for a polarizing element, by adding boric acid to the dyeing solution for a polarizing element, dyeing and fixing should be performed simultaneously. Can be.

In the case of the present invention, the polyvinyl alcohol resin film is held by the optically transparent resin film, and the thickness of the polyvinyl alcohol resin film is much thinner than that of the conventional product. Sufficient dyeing becomes possible by the treatment. Therefore, dyeing treatment can be performed with a coater or the like, and a dyeing liquid tank for immersion dyeing, which was conventionally required, becomes unnecessary, and it is sufficient to prepare only a necessary amount of dyeing liquid for polarizing elements for dyeing. Become. Therefore, it is not necessary to discard the dyeing solution for the polarizing element even when the type of the dyeing solution for the polarizing element is changed by lot switching or the like. As a result, there is no need to collect and dispose the dyeing solution for the polarizing element. The effect is also obtained.

After dyeing and fixing, the polarizing element is sufficiently dried. In addition, since the polarizing plate in which only one side of the polarizing element layer after dyeing and fixing is protected has a problem in smoothness and durability,
Usually, as shown in FIG. 1 (g), an optical transparent resin film is further bonded via an adhesive to form a polarizing plate having a three-layer structure of an optical transparent resin film layer / a polarizing element layer / an optical transparent resin film layer. And At this time, the two optically transparent resin films may be the same, or may be different in material, thickness and the like depending on required performance and the like.

In the above, a polyvinyl alcohol resin layer having a thickness of 6 μm to 30 μm is formed on one surface of the thermoplastic resin film, and then stretched 2 times to 5 times to form the polyvinyl alcohol resin layer. As a transparent film element layer, a composite film composed of two layers of a thermoplastic resin film layer and a transparent film element layer is formed, and then an optical transparent resin film layer is formed on the transparent film element layer side of the composite film composed of the two layers. After laminating via an adhesive, the thermoplastic resin film layer is peeled off and removed, and the transparent film element layer is dyed and fixed to form a polarizing element layer. Is referred to as "manufacturing method 1")
Was explained.

Here, another method (manufacturing method 2) will be described. That is, on one side of the thermoplastic resin film, a polyvinyl alcohol-based resin layer having a thickness of 6 μm or more and 30 μm or less is formed, and then stretched 2 times or more and 5 times or less to make the polyvinyl alcohol-based resin layer a transparent film element layer, Next, the transparent film element layer is dyed and fixed to form a polarizing element layer, thereby forming a composite film including two layers of a thermoplastic resin film layer and a polarizing element layer. This is a method for producing a polarizing plate, comprising a step of bonding an optically transparent resin film layer to an element side via an adhesive, and then removing and removing the thermoplastic resin film layer. In this case, the process is performed in the same manner as in the above production method 1 until a composite film composed of two layers of the thermoplastic resin film layer and the transparent film element layer is formed. That is, FIGS. 2A to 2C correspond to FIGS. 1A to 1C, respectively.

The resulting transparent film element layer 2 'of the composite film composed of two layers, the thermoplastic resin film layer 1 and the transparent film element layer 2', is dyed and fixed to form a polarizing element layer. And a polarizing element layer 2 ″ (FIG. 2D). At this time, the thermoplastic resin film 1 functions as a reinforcing material and can be dyed by means of a coater or the like. Effects such as a small required amount of the dyeing liquid are the same as in the above-mentioned production method 1.

In this case, as the dyeing solution for the polarizing element, all of the dyeing liquids used in the production of ordinary polyvinyl alcohol-based polarizing elements which do not adversely affect the thermoplastic resin film 1 are used. It is possible. However, since the thermoplastic resin film 1 is separated and removed before a polarizing plate, which is a product, is obtained, there is not much problem even if dyeing or the like occurs, and the range of options is wide.

Next (after sufficient drying), an optical transparent resin film 3 is bonded to the polarizing element layer 2 ″ side of the composite film via an adhesive (see FIG. 2 (e)).
The thermoplastic resin film layer 1 is peeled off to obtain a polarizing plate composed of two layers of an optical transparent resin film layer 3 and a polarizing element layer 2 ″ (see FIG. 2 (f)).

Thereafter, in order to protect the polarizing element 2 ", the optical transparent resin film layer 3 is bonded to the polarizing element layer 2" side of the polarizing plate composed of the optical transparent resin film layer 3 and the polarizing element layer 2 ". A polarizing plate having a three-layer structure of optical transparent resin film layer 3 / polarizing element layer 2 ″ / optical transparent resin film layer 3 is obtained (see FIG. 2 (g)).

As described above, a polyvinyl alcohol resin layer having a thickness of 6 μm or more and 30 μm or less is formed on one surface of the thermoplastic resin film, and then stretched 2 times or more and 5 times or less to form a polyvinyl alcohol resin layer. A transparent film element layer, and then the transparent film element layer is dyed and fixed to form a polarizing element layer to form a composite film composed of a thermoplastic resin film layer and a polarizing element layer, and the resulting two layers After laminating an optically transparent resin film layer on the polarizing element side of the composite film comprising an adhesive via an adhesive, the thermoplastic resin film layer is peeled off, and two layers of an optically transparent resin film layer and a polarizing element layer The polarizing plate obtained through the process of obtaining a polarizing plate consisting of consists of almost no warpage or curl, which has been a problem in the prior art, and does not interfere with the work of attaching it to a liquid crystal cell or the like in a later process. It is an excellent material that does not cause any trouble even when handled by an automatic sticking machine.

According to the method for producing a polarizing plate of the present invention, a polarizing plate having a thin polarizing element, which has not been obtained conventionally, can be stably obtained. In the production, it is possible to make a so-called batch using cut films, but by using a long film continuously, productivity can be dramatically improved.

When a long film is used as described above,
Usually, stretching is performed in the length direction, but in the case of the present invention, since the polyvinyl alcohol-based resin layer is reinforced with a thermoplastic resin film, for example, using a special tenter, It is also possible to stretch in an oblique direction such as a 45-degree direction, and even in the production of a polarizing plate having a rectangular shape and its polarization direction is oblique with respect to its side, the entire film can be effectively used, Productivity can be improved.

When such special stretching is performed, a composite film having a two-layer structure as described above may be used.
Forming a composite film having a three-layer structure of a thermoplastic resin film layer / polyvinyl alcohol-based resin layer / thermoplastic resin film layer, and stretching the polarizing film to provide a polarizing plate having a predetermined polarization performance is more stable. Can be produced.

In the composite film having such a three-layer structure, a polyvinyl alcohol-based resin layer having a thickness of 6 μm or more and 30 μm or less is formed on one surface of the thermoplastic resin film, and then, further formed on the polyvinyl alcohol-based resin layer. It can be formed by laminating thermoplastic resin films. The two thermoplastic resin films in the composite film having a three-layer structure usually need to be made of the same material, and desirably have the same thickness.

The composite film having a three-layer structure was
After stretching the polyvinyl alcohol-based resin layer to a transparent film element layer, one of the thermoplastic resin film layers sandwiching the transparent film element layer is peeled off and removed to form a thermoplastic resin film layer. And a transparent film element layer, and thereafter, a polarizing plate can be formed in the same manner as in the above-mentioned production method 1 or production method 2.

In the present invention, the polarizing element may be prepared by a dyeing / fixing method or a dyeing method using a polarizing ink and a fixing ink. Further, in the above, a polarizing plate having a two-layer structure composed of a thin film polarizing element layer and an optical transparent resin film layer or a thin film polarizing element layer
Although a polarizing plate having a three-layer structure bonded between two optically transparent resin films has been described, at least one of these optically transparent resin films is a film having optical functionality or a layer having optical functionality. May be replaced, and the polarizing element may be bonded to the optically transparent resin film via a film having optical functionality or a layer having optical functionality, and further, an optically transparent resin film A film having various optical functionalities or a layer having optical functionalities may be provided through the film, and these also belong to the present invention.

Examples of the film or layer having such optical functionality include a hard coat layer, an anti-glare hard coat layer, a multi-coat layer, an AR layer and other antireflection layers, a reflection layer, and the like. A retardation polarizing element, a retardation polarizing plate, a composite optical element, etc. obtained by laminating an optical functional film such as an anisotropic film, etc., as necessary, such as in the direction of the polarization axis or at an angle of 45 ° to the axis direction according to the application. Examples include an isotropic polarizing element and a composite optically anisotropic polarizing plate.

The polarizing plate of the present invention can meet the demands of consumers
In addition to the film having the optical functionality or the layer having the optical functionality, an adhesive release layer or the like can be laminated. These facilitate compounding with a liquid crystal cell or the like.

Here, these application examples will be described with reference to the drawings. However, these are examples and do not limit the present invention. FIG. 3 shows a polarizing plate comprising two optically transparent resin films 3 and a thin polarizing element 2 ″ according to the present invention disposed therebetween, and an adhesive layer 4 and a release layer 5 composed of a polyester release film. The example of the thin polarizing plate with an adhesive layer provided in order is shown.

In FIG. 4, a hard coat layer or a hard coat anti-glare layer 6 is provided on one side of the polarizing plate and an antireflection layer 7 is further provided thereon, and the adhesive layer 4 is provided on the other side.
An example of an antireflection thin polarizing plate with an adhesive layer in which a release layer 5 made of a polyester release film and a release film 5 are provided in this order is shown.

In FIG. 5, a retardation film and an optically anisotropic film 8 are disposed on one surface of a polarizing plate via an adhesive layer 4 ′. FIG. 5 shows an example of a composite thin polarizing plate provided with an adhesive layer in which an adhesive layer 4 and a release layer 5 composed of a polyester release film are provided in this order.
Examples of a composite thin polarizing plate with an adhesive layer in which a hard coat layer or a hard coat anti-glare layer 6 is provided on the other surface of the polarizing plate and an anti-reflection layer 7 is further provided thereon are shown.

FIG. 7 shows an adhesive layer 4 'on one side of the polarizing plate.
An example of a transflective thin polarizing plate having a reflective layer and a semi-transmissive layer 9 interposed therebetween and a release layer 5 provided on the other surface via an adhesive layer 4 is shown. By adding various films or layers as described above to the thin polarizing plate according to the present invention,
Various functions required by consumers can be handled.

[0043]

EXAMPLES The method for producing a polarizing plate of the present invention will be specifically described below. (Example 1) As polyvinyl alcohol resin, Kuraray's Poval PVA-117H (polymerization degree 1700, complete saponification type, powder), Nippon Synthetic Chemical Industry Gohsenol NH-
26 (degree of polymerization 2600, complete saponification type, powder)
These are dissolved in water while heating, and each is 8% by weight.
Was prepared.

On the other hand, the size is 230 mm × 330 mm,
As a thermoplastic resin film (reference numeral 1 in FIG. 1) on a glass plate having a thickness of 2 mm, a non-stretched polyethylene film (thickness 90 μm, size A4, Sunny Chemical PAC4K-90R manufactured by San-A Kaken Co., Ltd.) (Having a copolymer layer).

The surface of the thermoplastic resin film on the side of the ethylene-vinyl acetate copolymer layer was coated with the aqueous polyvinyl alcohol solution prepared above using a bar coater (No. 8 manufactured by Yoshimitsu Seiki Co., Ltd.). For 5 minutes to form a 5 μm polyvinyl alcohol layer (reference numeral 2 in FIG. 1B).

Next, these composite films were uniaxially stretched three times by a heating stretching machine at a temperature of 55 ° C. to make the polyvinyl alcohol layer 2 into a transparent film element layer 2 ′.
A composite film whose cross section was modeled was obtained. The thickness of the transparent film element layer of each of these composite films is about 2 μm.
As a result of observation, it was confirmed that there was no unevenness in thickness.

An optically transparent resin film (corresponding to the reference numeral 3 in FIG. 1D) was formed on the transparent film element layer side of these composite films by using a polyvinyl alcohol-based adhesive. Fuji Photo Film FTUV80F, thickness 80 μm. )
To obtain a composite film composed of three layers (see FIG. 1 (d)).

A polyethylene film (reference numeral 1 in FIG. 1 (d)) is peeled off from the composite film, and a transparent film element layer 2 'and an optical transparent resin film 3 are bonded to each other to form a composite film (FIG. 1 ( e) see).

Further, the transparent film element layer 2 ′ of this composite film was dyed to obtain a polarizing element layer (corresponding to the symbol 2 ″ in FIG. 1 (f)). Iodine and potassium iodide in a weight ratio of 1: 3, and
A 0.5% by weight aqueous solution of iodine / potassium iodine prepared so that the concentration of these solutes becomes 0.5% by weight is applied by a coater , dried at room temperature, and further a 5% by weight aqueous solution of boric acid (fixing solution) is applied by a coater. After coating and drying at room temperature, a drying treatment was performed at 50 ° C. for 5 minutes, and FIG.
A composite film having a polarizing element layer represented by a middle code was obtained.

The same optically transparent resin film as described above was bonded to the polarizing element layer side of the composite film having the polarizing element layer using an adhesive, and dried at 50 ° C. for 20 minutes to obtain the polarizing plate of the present invention. (See FIG. 1 (g)).

The degree of polymerization of the polyvinyl alcohol resin is 17
The polarizing plate using the polarizing plate of No. 00 and the polarizing plate using the polarizing plate of 2600 both have a single transmittance of 41.8 to 42.3.
%, The degree of polarization was in the range of 99.1 to 99.2%, which was excellent with smoothness.

(Example 2) The same polyvinyl alcohol solution (two kinds) as used in Example 1 was used, and a thermoplastic resin film having a thickness of 50 μm was used.
m, a non-stretched polypropylene film (Lamigrade GHC # 50, manufactured by Tocelo Co., Ltd.), and the corona-treated surface thereof was the same as in Example 1, except that No. Using 50, a polyvinyl alcohol resin layer was formed and dried under drying conditions at 80 ° C. for 10 minutes. As a result, a composite film (corresponding to FIG. 2B) in which the thickness of the polyvinyl alcohol resin layer was 9 μm was obtained.

Next, these composite films are uniaxially stretched three times at 60 ° C. by a heating stretching machine, and the cross section is modeled in FIG. 2 (c) using the polyvinyl alcohol resin layer as a transparent film element layer 2 ′. A composite film was obtained. The thickness of each of the transparent film element layers of these composite films was about 4 μm, and as a result of observation, it was confirmed that the thickness was not uneven.

Further, the transparent film element layer 2 ′ of the composite film was dyed to obtain a polarizing element layer (corresponding to the symbol 2 ″ in FIG. 2D). Iodine and potassium iodide in a weight ratio of 1: 3, and
A 0.5% by weight aqueous solution of iodine / potassium iodine prepared so that the concentration of these solutes becomes 0.5% by weight is applied by a coater, and after drying at room temperature, a 5% by weight aqueous solution of boric acid (fixing solution) is further applied by a coater. After coating and drying at room temperature, a drying treatment was performed at 50 ° C. for 5 minutes, and FIG.
A composite film having a polarizing element layer whose cross section was modeled was obtained.

An optically transparent resin film (corresponding to the reference numeral 3 in FIG. 2 (e); Fuji Photo Film FTUV80F) is attached to the surface of the composite film on the polarizing element layer side using a polyvinyl alcohol-based adhesive. A composite film composed of three layers (see FIG. 2E) was obtained. Then
A polypropylene film (reference numeral 1 in FIG. 2 (e)) which is a thermoplastic resin film is peeled off from the composite film, and a transparent film element layer and an optical transparent resin film are bonded together (FIG. 2 ( f)).

The same optically transparent resin film as described above was attached to the polarizing element layer side of the composite film having the polarizing element layer using an adhesive, and dried at 50 ° C. for 20 minutes to obtain the polarizing plate of the present invention. (See FIG. 2 (g)).

At this time, a polarizing plate using a polyvinyl alcohol resin having a polymerization degree of 1700, and 2600
The polarizing plate using the same has a single transmittance of 41.2.
-42.5%, and the degree of polarization was in the range of 99.3-99.4%, which was excellent with smoothness.

Example 3 The same polyvinyl alcohol solution (two kinds) as used in Example 1 was used, and a non-stretched nylon film (Ifan NOT-14 manufactured by Toray Synthetic Film Co., Ltd.) was used as the thermoplastic resin film.
No. 01 # 50, thickness 50 μm, and one surface is a corona-treated surface). 8 was used to form a polyvinyl alcohol resin layer. As a result, a composite film having a polyvinyl alcohol resin layer having a thickness of 5 μm and a cross section modeled in FIG. 1B was obtained.

Next, these composite films were uniaxially stretched three times at 70 ° C. by a heating stretching machine to make the polyvinyl alcohol layer into a transparent film element layer 2 ′. I got The thickness of the transparent film element layer 2 ′ of these composite films was about 2 μm, and as a result of observation, it was confirmed that the thickness was not uneven.

The transparent film element layer 2 ′ of these composite films
An optically transparent resin film (corresponding to reference numeral 3 in FIG. 1 (d); Fuji Photo Film Fujitack FTUV80F) is attached to the side surface using a polyvinyl alcohol-based adhesive to form a composite film having three layers (FIG. d) was obtained.

A film nylon film (reference numeral 1 in FIG. 1D), which is a thermoplastic resin layer, is peeled off from the composite film, and the transparent film element layer 2 'and the optical transparent resin film 3 are laminated. Composite film (Fig. 1 (e)
See)

Further, the transparent film element layer 2 'of this composite film was dyed to obtain a polarizing element layer (corresponding to the symbol 2 "in FIG. 2D). First, the composite film was dried at 50 ° C. for 5 minutes. Then, a 0.5% by weight aqueous solution of iodine / potassium iodide prepared by mixing iodine and potassium iodide as dyeing liquids for a polarizing element at a weight ratio of 1: 3 and a concentration of these solutes of 0.5% by weight. Is coated with a coater and dried at room temperature, and then a 5% by weight boric acid aqueous solution (fixing solution)
Is coated with a coater and dried at room temperature.
After performing a drying process for 5 minutes, a composite film having a polarizing element layer, which is modeled in FIG. 1F, was obtained.

The same optically transparent resin film as described above is attached to the polarizing element layer 2 ″ side of the composite film having the polarizing element layer using an adhesive, and dried at 50 ° C. for 10 minutes to obtain a polarized light according to the present invention. A plate was obtained (see FIG. 1 (g)).

At this time, a polarizing plate using a polyvinyl alcohol resin having a polymerization degree of 1700, and 2600
The polarizing plate using the same has a single transmittance of 41.5.
-42.0%, and the degree of polarization was in the range of 99.0-99.1%, which was excellent with smoothness.

(Comparative Example (Prior Art Example)) A polyvinyl alcohol film (Kuraray vinylon film VF-P # 7500) having a thickness of 75 μm was fixed to a stretching machine and stretched three times in hot water at 40 ° C. After taking out water droplets on the film surface after stretching, the film was dyed with an iodine solution, dried at room temperature, and fixed with a 5% by weight aqueous solution of boric acid.

After drying at room temperature, drying was further performed at 50 ° C. for 10 minutes to obtain a polarizing element having a thickness of 33 μm. In the above stretching, a study was conducted to obtain a thinner polarizing element by further increasing the stretching ratio. However, the thickness of the polarizing element was not reduced, and when the stretching was further performed, the film was cut.

An optically transparent resin film (Fujitac FTUV80F, manufactured by Fuji Photo Film Co., Ltd.) was bonded to both sides of the obtained polarizing element via an adhesive, and dried at 50 ° C. for 20 minutes to obtain a polarizing plate. The single transmittance of this polarizing plate is 4
The degree of polarization was 1.8% and the degree of polarization was 99.0 to 99.6%.

(Presence or Absence of Curling and Deformation) The polarizing plates produced in Examples 1 to 3 and Comparative Example each have a length of 50
It was cut into squares of mm and left in a thermo-hygrostat set at 40 ° C. and 90% RH for 120 hours, and examined for the occurrence of curling. That is, the curl was placed on a surface plate such that the convex side was down, and the maximum height was measured. Table 1 shows the measurement results using a plurality of polarizing plates.

[0069]

[Table 1]

Table 1 shows that the curl height of the polarizing plate having the thin polarizing element obtained by the manufacturing method of the present invention is smaller than the curl height of the polarizing plate of the comparative example according to the prior art.

In the above example, an example using an optical transparent resin film of 80 μm is shown. However, by using a thin optical transparent resin film of 50 μm or less, for example, recent liquid crystal devices and the like which are required to be made thinner. Requirements can be satisfied. In addition, by combining the polarizing plate technology of the present invention with a polarizing plate technology having a thin polarizing element and a technology relating to a reflective film, a film having various optical functions, a thin film, and a layer, it is possible to meet various demands of users.

[0072]

The method for manufacturing a polarizing plate according to the present invention makes it possible to eliminate waste of a dyeing solution and a fixing solution for a polarizing element, and to manufacture a polarizing plate having a thin polarizing element which has not been obtained conventionally. It is an excellent polarizing plate. Obtained by this manufacturing method,
The polarizing plate of the present invention uses a thin polarizing element that could not be obtained conventionally, and can sufficiently cope with the field where thinning is particularly required, and also has less curl and deformation,
Even when a large polarizing plate is used, it is an excellent polarizing plate that can contribute to improvement in productivity such as automation and efficiency of laminating work of a liquid crystal cell or the like.

[Brief description of the drawings]

FIG. 1 is a view (model sectional view) showing an example of a method for producing a polarizing plate of the present invention.

FIG. 2 is a view (model sectional view) showing another example of the method for manufacturing a polarizing plate of the present invention.

FIG. 3 is a model sectional view showing an application example (an example in which a release layer with an adhesive is provided) of the polarizing plate of the present invention.

FIG. 4 is a model sectional view showing an application example (an example in which a hard coat layer or a hard coat anti-glare layer, an antireflection layer, an adhesive layer, and a release layer are provided) of the polarizing plate of the present invention.

FIG. 5 is a model sectional view showing an application example (an example in which a retardation layer, an optically anisotropic layer, and an adhesive release layer are provided) of the polarizing plate of the present invention.

FIG. 6 is a model sectional view showing an application example (an example in which a hard coat layer or a hard coat anti-glare layer, an antireflection layer, and an adhesive release layer are provided) of the polarizing plate of the present invention.

FIG. 7 is a model sectional view showing an application example (an example in which a reflective layer, a semi-transmissive layer, and an adhesive release layer are provided) of the polarizing plate of the present invention.

[Explanation of symbols]

 Reference Signs List 1 thermoplastic resin film 2 polyvinyl alcohol resin layer 2 'transparent film element layer 2 "polarizing element layer 3 optical transparent resin film 4 adhesive layer 5 release layer 6 hard coat antiglare layer 7 antireflection layer 7 antireflection layer 8 retardation film And optically anisotropic film 9 reflective layer and semi-transmissive layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Eiji Mameikuta 248, Oka Kouji, Fujioka-cho, Shimotsuga-gun, Tochigi Pref. F term (reference) 2H049 BA02 BA25 BB16 BB42 BB51 BB65 BB66 BC03 BC09 BC14 BC22 4F210 AA19 AH73 QA02 QC01 QD19 QG01 QL17 QW31

Claims (12)

[Claims] 1. A polyvinyl alcohol resin layer having a thickness of 6 μm or more and 30 μm or less is formed on one surface of a thermoplastic resin film, and then stretched 2 times or more and 5 times or less to form a transparent film on the polyvinyl alcohol resin layer. As a device layer, a composite film composed of two layers of a thermoplastic resin film layer and a transparent film device layer is formed, and then an optical transparent resin film layer is bonded to the transparent film device layer side of the composite film composed of the two layers with an adhesive. After laminating, the thermoplastic resin film layer is peeled and removed, and the transparent film element layer is dyed and fixed to form a polarizing element layer, which comprises two layers of an optical transparent resin film layer and a polarizing element layer. A method for producing a polarizing plate, comprising a step of obtaining a polarizing plate. 2. A polyvinyl alcohol-based resin layer having a thickness of 6 μm or more and 30 μm or less is formed on one surface of a thermoplastic resin film, and then stretched 2 to 5 times to form a transparent film of the polyvinyl alcohol-based resin layer. As an element layer, then, the transparent film element layer is dyed and fixed to form a polarizing element layer, thereby forming a composite film including two layers of a thermoplastic resin film layer and a polarizing element layer. After laminating the optical transparent resin film layer on the polarizing element side of the composite film via an adhesive, the thermoplastic resin film layer is peeled and removed, and is composed of two layers of an optical transparent resin film layer and a polarizing element layer. A method for producing a polarizing plate, comprising a step of obtaining a polarizing plate. 3. A polyvinyl alcohol-based resin layer having a thickness of 6 μm or more and 30 μm or less is formed on one surface of the thermoplastic resin film, and then a thermoplastic resin film is further laminated on the polyvinyl alcohol-based resin layer. After forming a three-layer structure of a plastic resin film layer / polyvinyl alcohol-based resin layer / thermoplastic resin film layer, it is more than twice 5
The film is stretched to 2 times or less to make the polyvinyl alcohol-based resin layer a transparent film element layer, and one of the thermoplastic resin film layers sandwiching the polyvinyl alcohol-based resin layer is peeled off to remove the thermoplastic resin film layer and the transparent film element layer. Then, after forming an optical transparent resin film layer on the transparent film element layer side via an adhesive, the thermoplastic resin film layer is peeled off and further removed, and a transparent film is formed. A method for producing a polarizing plate, comprising a step of dyeing and fixing an element layer to obtain a polarizing plate composed of an optical transparent resin film layer and a polarizing element layer as a polarizing element layer. 4. A polyvinyl alcohol-based resin layer having a thickness of 6 μm or more and 30 μm or less is formed on one surface of the thermoplastic resin film, and a thermoplastic resin film is further laminated on the polyvinyl alcohol-based resin layer. After forming a three-layer structure of a plastic resin film layer / polyvinyl alcohol-based resin layer / thermoplastic resin film layer, it is more than twice 5
The polyvinyl alcohol-based resin layer is stretched to 2 times or less to form a transparent film element layer, and further, one of the thermoplastic resin film layers sandwiching the polyvinyl alcohol-based resin layer is peeled off to remove the thermoplastic resin film layer and the transparent film element. After forming a composite film consisting of two layers with a layer, an optical transparent resin film layer is bonded to the polarizing element side of the obtained composite film via an adhesive, and the thermoplastic resin film layer is peeled off. And a step of obtaining a polarizing plate comprising two layers of an optical transparent resin film layer and a polarizing element layer. 5. An optical transparent resin film layer is bonded to the polarizing element layer side of a polarizing plate comprising two layers of the optical transparent resin film layer and the polarizing element layer via an adhesive, and the optical transparent resin film layer / polyvinyl The method for producing a polarizing plate according to any one of claims 1 to 4, further comprising a step of obtaining a polarizing plate having a three-layer structure of an alcohol-based resin layer and an optically transparent resin film layer. 6. The thermoplastic resin film according to claim 1, wherein the surface of the thermoplastic resin film on which the polyvinyl alcohol-based resin layer is formed has been subjected to an affinity improving treatment such as corona discharge. Method for producing a polarizing plate. 7. The polarizing element layer has a thickness of 2 μm or more and 15 μm or more.
A polarizing plate characterized by the following. 8. The polarizing plate according to claim 7, wherein at least one surface of the polarizing element layer is protected by an optically transparent resin film. 9. The polarizing plate according to claim 7, wherein the polarizing plate has at least one of optical functional layers such as a hard coat layer, an anti-glare layer, an anti-glare hard coat layer, an AR layer, and a multi-coat layer. Item 10. A polarizing plate according to item 8. 10. The polarizing plate according to claim 7, wherein at least one kind of an optical functional film such as a retardation film and an optically anisotropic film is laminated. 11. The polarizing plate according to claim 7, wherein a reflective / semi-transmissive functional film such as a reflective layer film and a semi-transmissive film is laminated. 12. The polarizing plate according to claim 7, further comprising an adhesive release layer.