JPS59108A - Manufacture of polarizing film - Google Patents

Abstract

PURPOSE:To obtain a homogenious wide polarizing film efficiently, by laminating specified thermoplastic resin films on both sides of the film of a copolymer of saponified ethylene-vinyl acetate, stretching them in a specified condition, peeling both side films, and allowing the film to adsorb a polarizing element. CONSTITUTION:A dimethylsulfoxide soln. of ethylene-vinyl acetate copolymer contg. 60-90mol% vinyl acetate units having >=80mol% degree of saponification is cast on a belt subjected to peeling treatment and dried to form a 100mum thick film. A thermoplastic resin nonadhesive to this film, when heated and pressed, and stretchable by rolling, such as polyethylene, is laminated on both sides of this film. These 3-layered films are stretched at a temp. lower than the m.p. of each film so as to bring the film into <=1/2 thickness, both outside films are peeled off, immersed into a soln. of a dichroic dye (polarizing element), then washed and dried to obtain a polarizing film. A wide polarizing film having polarizing performance uniform on all the surface can be thus produced in high efficiency.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a polarizing film.

Conventional polarizing films are made of polyvinyl alcohol, ethylene-
It is manufactured by stretching a film such as vinyl acetate copolymer and then adsorbing a polarizing element, or by adsorbing a polarizing element to a mesh film and then stretching it. However, when adsorbed after stretching, the polarizing element The degree of polarization at the edges is lower than the center of the film due to adsorption, and the width of the film becomes narrow when stretched after adsorption, resulting in poor production efficiency and the need for wide polarizing films. I couldn't get it. Therefore, in order to obtain a wide polarizing film, a wider film must be manufactured and stretched, and the film manufacturing equipment and stretching equipment must be large-scale. If it is widened, it becomes an inner cone to make the thickness uniform, and it is also difficult to draw it to a uniform thickness.

In view of the above drawbacks, the present invention has been made with the aim of obtaining a wide-width polarizing film with high production efficiency. Then, a three-layer film in which a rollable thermoplastic resin film that is not thermocompression-bonded to the aphrodisiac film is laminated at a temperature lower than the softening temperature of each layer,
(2) A rolling step of obtaining a rolled film by rolling the saponified film so that the thickness of the saponified film becomes 1 F or less, and then peeling the thermoplastic resin film to obtain a rolled film; 99. A polarizing film consisting of an adsorption step for adsorbing a 1M optical element.

The saponified product of Egren-vinyl acetate copolymer used in Kihatsu [Moon] was obtained by saponifying a copolymer in which ezalene vinyl acetate was copolymerized,
The amount of vinyl acetate contained in the copolymer is 50 to 90 mol%, since the higher the vinyl acetate content, the lower the durability, and conversely, the lower the suction performance of the seven-piece optical element. It is preferable that the degree of saponification is 60 to 80 mol%, and if the degree of saponification is low, the adsorption property of the polarizing element will be low.
It is 6% or more.

The thermoplastic resin film used in the present invention may be a film made of a polyolefin resin, a special crystalline Yatopoly No. is preferably used.

The above-mentioned polyA fin resins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, ethylene-propylene copolymer, etc., as well as other copolymers within a reasonable range that impair the properties of polyolefin. It may also be a polyolefin copolymer containing a vinyl intermediate component such as vinyl acetate, vinyl chloride, acrylic acid, acrylic ester, etc. However, polyolefin restrictions still apply to poly(alpha)-molefins such as polyethylene, polypropylene, and ethylene-7'a-hylene copolymers, as well as unsaturated carboxylic acids such as 7-maric acid, maleic acid, and acrylic acid, their acid anhydrides, and esters. 10-4 to 10% by weight, preferably 1
It also contains modified dff IJ-4 fins graft copolymerized with t1o-3 to 5% TVI. still,
Of course, the polyolefin resin may contain a small amount of conventional additives such as a heat stabilizer, an ultraviolet kneading agent, an oxidation inhibitor (I-2 agent, and an antistatic agent) depending on the demand.

-I-, ii, ', The thickness of the natural plastic #il oil film is not limited to the special design, but it is sufficient that the above-mentioned saponified film is uniformly spread.
~150 It is preferred 1. <, more preferably
ij: 50-10071.

In the present invention, a thermoplastic resin film is laminated on both sides of the saponified film to form a three-layer film, but the lamination method may be adopted, and the prefecture may Three films may be simply superimposed, or they may be laminated by extrusion lamination, solution coating, three-layer co-extrusion, or rolled into a three-layer film. However, the r-E extension is 3-
The saponification is carried out at a temperature lower than the softening temperature of each resin constituting the film so that the thickness of the saponified film is 1 FVc or more.

In the above rolling process, the thickness is reduced by passing through at least a pair of rolls, and if the temperature is high, the resin layer will become soft and the saponified material layer will not be rolled uniformly. The rolling temperature is limited to a temperature lower than the softening temperature of 4Jl fat, and if the temperature is too low, it will be difficult to roll uniformly, so it is preferable to carry out the rolling at a temperature of 50° C. or higher. Therefore, it is preferable to heat the roll to a temperature of 50° C. or higher but lower than the softening temperature of each resin, and if necessary, prior to rolling, three-layer film!・Infrared heating,
Heating may be performed using methods such as far-infrared heating, high-frequency heating, hot air heating, and steam heating.

In addition, rolling is performed so that the thickness of the saponified film is not more than i, otherwise orientation will be insufficient, so rolling is carried out so that the thickness is less than i, preferably 17<Pi-H or less. .

A rolled saponified film is obtained by peeling off the thermoplastic resin film from the rolled three-film in the third step.

Note that the rolled saponified film is recommended for use and storage.

A manufacturing method consisting of a rolling step (1) to obtain a rolled saponified product, an adsorption step (2) of adsorbing a polarizing element to a saponified film of an ethylene-vinyl acetate copolymer, and After the rolling process (1), the adsorption process (2) may be performed, or after the adsorption process (2), the 1F rolling rod (1
) may be performed. Any conventionally known method may be employed in the adsorption step, for example, by absorbing a polarizing element such as iodine, a chelate compound, or a dye. In addition, when adsorbing the polarizing element, boric acid, polymerine, potassium iodide,
Combined use of dyeing aids such as monoammonium 1. It's okay.

As mentioned above, in the method for manufacturing the polarizing film of the present invention, thermoplastic resin films are laminated on both sides of the ethylene-vinyl acetate copolymer saponified filter and rolled, so that the entire saponified filter is uniformly coated. When rolled, a polarizing film is obtained in which the adsorption performance of the polarizing element I does not deteriorate at the end portions, and the entire film has uniform polarization performance. Therefore, according to the manufacturing method of the present invention, a wide polarizing film can be obtained with high production efficiency.

Next, Kinei q( will be explained with reference to an example.

The single transmittance was measured by cutting the obtained filter into 9 pieces at an angle of 45 degrees to the rolling direction (the stretching direction) to obtain a sample.
Transmittance was measured every 0 ml using spectroscopic light g8f, and the degree of polarization was determined by using the average value as the single transmittance and the 17th order equation.

Table 1 shows 1. Polarization degree from 350ml to 700
50m to mnol! It is the average value of the degree of polarization of @゛.

Further, the width after early rolling (snoring) for width shrinkage was 0 (1), and the width after rolling (stretching) was ff1j17?l, and 7)R was calculated using the following formula.

Example 1 Saponified product fill of saponified vinyl acetate copolymer with vinyl acetate content of 65 mol% and degree of curing of 99%!・
1 (I was.

t: A 50 l thick high-density polyethylene film extruded at a mold temperature of 160° C. was laminated on both sides of the twisted film to obtain a laminated film.

The m-layer fill 11 having a width of 367° was heated to 110°C.
LV! lt% 60 bars, face length 140 bars, addition 110
-Supplied to the 1. Then, after pricking a high-density polyethylene layer with PtE, heat treatment was performed at 110°C for 10 minutes under tension F to give a width of 36. A rolled film with a thickness of 24 mm was obtained.

The obtained rolled film was washed with a dichroic dye (Nippon Kayaku water washing and dried to obtain a polarizing film. Samples were prepared from the center part (A) and 151 point from the center (B) of the obtained polarizing film and were dyed separately. The results of 17 measurements of transmittance and degree of polarization are shown in Table 1. Also (A).

The sample thickness and width shrinkage of (B) and (B) were measured and are shown in Table 1.

Example 2 Both sides of a film (width 388 (7), thickness 100 horns) of an ethylene-vinyl acetate copolymer with a vinyl acetate content of 45 mol % and a saponification degree of 99.5% were molded at a mold temperature of 17 cm.
A laminated film was obtained by extruding at 0 °C and laminating high-density polyethylene with a thickness of 45 nm.1 The obtained laminated film was rolled in the same manner as in Example 1, and subjected to polarization treatment. A film was obtained, and 1) 1) closed vortex, degree of polarization, thickness, and width shrinkage were measured, and the results are shown in Table 1. The width of the 1f stretched film was 380 mm.

Example 3 A saponified film of edylene-vinyl acetate copolymer containing vinyl acetate [45 mol%, degree of saponification 995% (width 36%)]
8-1 A low density polyethylene film with a thickness of 80 knots is heat laminated on both sides of a 100 l) film at 85°C,
I got the 1M film.

The temperature of the heating roll was 100°C.
Rolled in the same manner as in Example 1 except that the
Polarization treatment 1. A polarizing film was obtained, and its body vorticity, degree of polarization, thickness, and width shrinkage were measured and are shown in Table 1. The width of the rolled film was 36.1 rys... Comparative Example 1 A film of ethylene-vinyl acetate copolymer poppy with a vinyl acetate content of 45% and a degree of saponification of 995% (width 38.1 rys).
Example 1 Temperature: 90-1
H Example 1 except that rolling was performed at 5°C intervals between 20°C
A rolled film was obtained in the same manner as in .

The width of the rolled film was 38.0 am, and the thickness was 2971 mm at the thinnest point, making it impossible to obtain a uniform thickness. Next, the rolled film rolled at a roll temperature of 100°C was subjected to polarization treatment in the same manner as in Example 1 to obtain a polarizing film, and the center part (A) and the part 15z from the center (B) of the polarizing film were A sample PI was prepared from a portion with a thickness of 29 nm, and the intermediate transmittance, degree of polarization, and width shrinkage were measured, and are shown in Table 1.

Comparative Example 2 A film of a saponified ethylene-vinyl acetate copolymer with a vinyl acetate content of M45% and a degree of saponification of 99.5% (width 38.5%).
7 cm, width 75) l) was stretched 4 times at 80°C using a -axial stretching machine, and heat treated in the same manner as in Example 1 to obtain a stretched film with a width of 27.1 cm and a thickness of 261 cm. . The obtained stretched film was made into a running shape as in Example 1 and subjected to polarization treatment to obtain a polarizing film, and the central part of the polarizing film (
Prepare samples from A) and center ridge 12- (B),
The intermediate transmittance, degree of polarization, sample thickness, and width shrinkage were measured and shown in Table 1.

(below F margin) Chapter 1 Table

Claims (1)

[Scope of Claims] 1. A rollable thermoplastic resin film that is not bonded by thermocompression to the combinated film is laminated on both sides of the saponified film of 1, +1 + polyethylene-vinyl acetate copolymer. layer film at a temperature lower than the softening temperature of each layer,
After rolling the saponified film to a thickness of 1 inch, the thermoplastic resin film is pierced to obtain a rolled film.The rolling step is to obtain a combinated film of +21 dylene-vinyl acetate copolymer. [Adsorption for adsorbing a polarizing element on] Method 2 for producing a polarizing film consisting of two presses, the vinyl acetate content of the ethylene-vinyl acetate copolymer is 60 to 9
The manufacturing method according to claim 1, wherein the content is 0 mol%. 3. The manufacturing method according to claim 1 or 2, wherein the degree of saponification of the saponified product is 80% or more.