KR100984660B1 - The method for producing a laminated polarizing film - Google Patents

Abstract

Provided is a method for producing a laminated polarizing film that does not generate substantial reverse curl.

It is set as the manufacturing method of the laminated polarizing film which laminated | stacked the linear polarizing film and the linear polarization separating film which has a moisture content adjusting process of adjusting the moisture content of a linear polarization separating film to 0.3-0.8 weight% before lamination | stacking.

Description

Manufacturing method of laminated polarizing film {THE METHOD FOR PRODUCING A LAMINATED POLARIZING FILM}

1 is a cross-sectional view illustrating a structure in which a polarizing film is laminated on a liquid crystal cell.

2 is a cross-sectional view illustrating the configuration of a laminated polarizing film.

3 is a schematic diagram of an apparatus for humidifying by continuously spraying water mist on a linear polarization separating film.

[Description of the code]

10: liquid crystal cell

12: adhesive layer

14: linear polarizing film

18: laminated polarizing film

20: linear polarizing film

22: linear polarized light separation film

24: adhesive layer

26: adhesive layer

28: release film

30: protective film                 

32: film delivery roll

34: film winding roll

36: mist sprayer

The present invention relates to a method of manufacturing a laminated polarizing film that is adhesively laminated on a light source side surface of a liquid crystal cell constituting a liquid crystal display panel.

As illustrated in FIG. 1, a linear polarizing film is attached to the light source side surface of the liquid crystal cell constituting the liquid crystal display panel. That is, the linear polarizing film 14 is adhesively laminated by the adhesive bond layer 12 on the light source side surface of the liquid crystal cell 10, and a liquid crystal display panel is comprised. The liquid crystal display panel is required to have a clearer image or to reduce power consumption of the light source every year. Therefore, in order to reduce the power consumption of the light source of the liquid crystal display panel, for the purpose of efficiently utilizing the light from the light source, the light that is not parallel to the transmission axis of the linear polarizing film is reflected on the light source side of the linear polarizing film once, A laminated polarizing film in which a linearly polarized light separating film that transmits light reflected by the reflecting plate separately installed is adhesively laminated is used. At present, this laminated polarizing film has a maximum of about 150 cm on one side.

The structural example of the laminated polarizing film 18 was shown in FIG. The linear polarizing film 20 and the linear polarizing separator film 22 are adhesively laminated through the adhesive layer 24. On the other side of the linear polarizing film 20, an adhesive layer 26 for adhering the laminated polarizing film to the liquid crystal cell and a release film 28 for protecting the adhesive layer 26 are formed. In addition, the protective film 30 is laminated on the opposite surface of the linearly polarized light separating film. The protective film 30 is peeled off in the final process.

The laminated polarizing film having the above structure is manufactured through a process of laminating a linear polarizing film and a linear polarizing separation film with an adhesive (for example, Japanese Patent Laid-Open No. 11-271534 (paragraphs [0005] to [0007]) and a patent 2000-275436 (paragraph [0034]).

By the way, when the laminated polarizing film obtained through the said process is left to stand, the linear polarizing film side (A surface side of FIG. 2) which is the side adhering to a liquid crystal cell will generate | occur | produce curl (henceforth "inverse curl"), as concave. This reverse curl turned out to be remarkable when one side of the laminated polarizing film was 8 cm or more, particularly 20 cm. This large inverse curl tends to leave bubbles on the adhesive surface when the peeling film 28 is peeled off and adhered to the liquid crystal cell 10, thereby causing defects in the liquid crystal panel.

Therefore, the laminated polarizing film is required to be a curl (hereinafter, referred to as a "positive curl") in which the linear polarizing film side is convex even if it does not curl or curls without generating substantially reverse curl.

It is an object of the present invention to provide a method for producing a laminated polarizing film which does not generate substantial reverse curl.

Means to solve the problem

The present inventors earnestly studied in order to obtain a laminated polarizing film that does not generate substantial reverse curl in order to achieve the above object, by adjusting the moisture content of the linear polarized light separation film to a certain range, by laminating with the linear polarizing film, reverse curl The present invention was completed by discovering that a laminated polarizing film which does not generate a film is obtained.

That is, the present invention is a method of manufacturing a laminated polarizing film in which a linear polarizing film and a linear polarization separating film are laminated.

It is characterized by having a moisture content adjustment process of adjusting the moisture content of a linearly polarized light separation film to 0.3-0.8 weight% before lamination.

By the method of the present invention, a laminated polarizing film free of substantial reverse curl is obtained.

Here, the substantially reverse curl refers to a reverse curl that is enough to cause a defect such as bubbles remaining when adhering to the liquid crystal cell, and a slight reverse curl is allowed, and the degree is a laminated polarizing film having a size of 20 inches. About 1 to 2 mm. When the amount of reverse curl is about 3 mm or more, it causes a defect, which is not preferable.

Embodiments of the Invention

In the present invention, the moisture content of the linear polarized light separating film is adjusted to 0.3 to 0.8% by weight, more preferably 0.4 to 0.6% by weight, and then laminated with the linear polarizing film. Normally, the linear polarization separation film can be humidified in a dry state and adjusted to a predetermined moisture content. For example, a method of immersing the film in water, a method of contacting the water in a fog shape, a mist shape, a shower shape, and a chamber in a high humidity state can be adjusted. The moisture content may be adjusted by passing through or preserving a whole cloth in a chamber of high humidity.

As a method of adjusting the moisture content, a method of spraying water into a mist shape on the film while running the linear polarized light separating film is preferably used. The film to which moisture was affixed is wound up and left to stand. It is preferable to run the film continuously at a constant speed. What is necessary is just to change the running speed of a film, when changing moisture content.

The linear polarization separating film is usually handled in a state where the protective film is adhered, and in that case, it is preferable to spray moisture onto the protective film.

Moisture content is generally measured by the measuring method used for measuring the moisture content of resin or inorganic powder. Specifically, the measurement object is heated to remove moisture, and the moisture content is determined from the difference in weight before heating and after heating.

In the above-described invention, it is preferable that the linear polarization separating film is a polyester film.

The linear polarization splitting film is preferably a film containing polyester as a main component, and a film based on polyethylene naphthalate or a copolymer containing polyethylene naphthalate unit as a main component is preferable from the viewpoint of its performance, and for example, the trade name "DBEF" ( What is marketed as Sumitomo 3M company) can be illustrated. Since the linear polarized light separation film made of such polyester is wound and supplied as a raw material after manufacture, the moisture content of the raw film is 0.1 to 0.2% by weight, and is lower than the saturated moisture content (about 0.8% by weight) of the film. When laminated | stacked with the linear polarization separator film with high moisture content, it is thought that reverse curl is more likely to generate | occur | produce by transfer of moisture.

In addition, the linearly polarized light separating film is a film having a function of transmitting light parallel to the transmission axis direction as described above and reflecting light parallel to the reflection axis direction orthogonal to the transmission axis. Since the non-absorptive polarizing film or the reflected light is reused to improve the brightness, it is also referred to as a brightness rising film.

On the other hand, a linear polarizing film is a film which has a function which permeate | transmits light parallel to a transmission axis direction, and absorbs light parallel to the absorption axis direction orthogonal to a transmission axis, and is also called an absorption type polarizing film.

The linear polarizing film uses a known linear polarizing film. A linear polarizing film is usually composed of a triacetyl cellulose (TAC) film as a main material, and a preferred configuration is a laminated film of a TAC film and a polyvinyl alcohol-based film, specifically, a TAC film / polyvinyl alcohol-based film / TAC film. It is illustrated having a configuration of three or more layers. The resin materials constituting these linear polarizing films are all materials having high polarity and high saturated moisture content. In general, a linear polarizing film having a multilayer structure as described above is adjusted to a relatively high moisture content, for example, about 2.5% by weight in order to suppress its own curl. For this reason, it is thought that moisture transfers from a linear polarizing film to a linear polarization separating film side, for example, by lamination | stacking with a polyester-type linear polarization separating film in a dry state, and curling arises.                     

It is not clear why the laminated polarizing film obtained does not easily generate inverse curl by setting the moisture content adjusting process for adjusting the moisture content of the linear polarization separating film, but the linear polarization separating film having a low moisture content in the linear polarization film having a high moisture content is not clear. It is presumed that one large cause is that the dimensional change of each film due to the transfer of moisture is suppressed.

Usually, a protective film made of polyethylene terephthalate or the like is laminated on one side of the linear polarized light separating film. The linear polarizing film is laminated on the surface opposite to the surface on which the protective film is laminated. The protective film is peeled off after sticking to the liquid crystal cell.

Example

Next, Examples, etc. which show the structure and effect of this invention concretely are demonstrated.

Moreover, the curl amount was calculated | required as the average value of the height from the flat plate of 4 normal points of a laminated polarizing film, when the linear polarizing film side was put down on the flat plate. Plus indicates positive curl and minus reverse curl.

(Example 1)

A linear polarized light separation film "DBEF" made of polyethylene terephthalate (thickness 132 μm) (manufactured by Sumitomo 3M, having a polyethylene terephthalate protective film laminated on one side, and a moisture content of about 0.2% by weight) was cut to 308 mm x 235 mm. Five were prepared, and each was left to stand for 24 hours in an environment with a relative humidity of 80% and a temperature of 20 ° C. The moisture content after standing was 0.62 weight% (the moisture content is measured by peeling a protective film). The linear polarization separating film was immediately placed in a moisture-proof bag and sealed, taken out after 2 hours, and the linear polarizing film was laminated on the surface where the protective film was not laminated to obtain a laminated polarizing film. An adhesive roller was used for lamination.

The linear polarizing film used had a water content of 2.5% by weight, had a three-layer structure of TAC / polyvinyl alcohol-based film / TAC (80 μm / 25 μm / 80 μm), and had an acrylic pressure-sensitive adhesive layer of 25 μm. .

The obtained laminated polarizing film was put into the moisture proof bag, and it sealed, and after the time shown in Table 1 passed at 20 degreeC, it took out and measured the curl amount. The measurement result of the curl amount was shown in Table 1.

(Example 2)

The linear polarization separating film "DBEF" was left to stand for 24 hours in an environment with a relative humidity of 64% and a temperature of 22 ° C. The moisture content after standing was 0.50 weight% (moisture content is measured by peeling a protective film). A laminated polarizing film was produced in the same manner as in Example 1 except that this linearly polarized light separating film was used.

The obtained laminated polarizing film was put into the moisture proof bag, and it sealed, and after the time shown in Table 1 passed at 20 degreeC, it took out and measured the curl amount. The measurement results are shown in Table 1.

(Comparative Example 1)

Five pieces of the linearly polarized light separation film "DBEF" having a thickness of 132 µm (0.17% by weight) cut to 308 mm x 235 mm were prepared and left for 24 hours in an environment having a relative humidity of 24% and a temperature of 22 ° C. The moisture content was 0.17 weight% as it was (the moisture content is measured by peeling a protective film).

A laminated polarizing film was produced in exactly the same manner as in Example 1 except that the film having a moisture content of 0.17% by weight was used as the linear polarization separating film.

The obtained laminated polarizing film was put into the moisture proof bag, and it sealed, and after the time shown in Table 1 passed at 20 degreeC, it took out and measured the curl amount. The measurement result of the curl amount was shown in Table 1.

Example 1 Example 2 Comparative Example 3 Moisture content (wt%) 0.62 0.50 0.17 Elapsed time (hours) 0 0.5 0.3 0.0 13 9.1 3.8 -4.7 23 9.6 4.5 -5.0 85 9.7 4.9 -4.3 253 8.9 4.0 -3.6

From the results in Table 1, after the moisture was adjusted by humidifying the linear polarized light separating film, the laminated polarizing film of the present invention laminated with the linear polarizing film was all curled and satisfies no bubbles when adhering with the liquid crystal cell. Although it was a product, the laminated polarizing film of the comparative example which did not set the moisture content adjustment process produced the reverse curl.

(Example 3)

The moisture content of the linear polarizing separation film was adjusted using the humidifier shown in FIG. The linear polarized light separating film was sprayed onto the protective film while continuously running at a constant speed in a state where the protective film was attached, and was then wound on another core. The running speed of the film was changed to change the amount of moisture attached. The rolled film roll was allowed to stand for 2 days to obtain a linear polarized light separating film in which the moisture content was adjusted.

The moisture content was measured by peeling the protective film of the linear polarized light separation film.

The obtained moisture-adjusted linear polarization separating film was immediately placed in a moisture-proof bag and sealed, taken out after 2 hours, and the linear polarizing film was laminated in the same manner as in Example 1 on the surface where the protective film was not laminated. A laminated polarizing film of 420 mm x 318 mm) was obtained.

The obtained laminated polarizing film was put into the moisture proof bag, sealed, and after passing at 20 degreeC for 65 hours, it took out and measured the curl amount. The measurement result of the curl amount was shown in Table 2.

Moisture content (wt%) Curl value (mm) (65 hours after adhesion) Exterior Whether or not to use Example 3 One 0.30 -1.4 Good possible 2 0.42 +0.4 Good possible 3 0.61 +5.8 Good possible 4 1.73 +13.9 Good possible

When the moisture content was 0.30% by weight, the curl amount was -1.4 mm and slightly reverse curled, but the laminated polarizing film obtained because it was in an acceptable range could be used without a problem.

When the adhesive is adhered to the liquid crystal cell according to the method of the present invention, a laminated polarizing film composed of a linear polarizing film and a linear polarizing separating film which does not generate substantial inverse curl, which causes bubbles to remain on the adhesive surface and causes defects in the liquid crystal panel. Obtained.

Claims (3)

In the method of manufacturing a laminated polarizing film in which a linear polarizing film and a linear polarization separating film are laminated, Before the lamination process of the linear polarizing film and the linear polarization separating film, it has a moisture content adjusting step of adjusting the moisture content of the linear polarization separating film to 0.3 to 0.8% by weight, wherein the linear polarization separating film is a polyester film, the linear polarizing film It is a laminated film of this polyvinyl alcohol-type film and a triacetyl cellulose film, The manufacturing method of the laminated polarizing film characterized by the above-mentioned. delete The method for producing a laminated polarizing film according to claim 1, wherein the moisture content is adjusted by spraying moisture on the film in a mist shape while running the linear polarization separating film.

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