JPH07124969A - Manufacture of antiglare optical sheet - Google Patents

Abstract

PURPOSE:To provide the method for industrially favorably manufacturing antiglare optical sheet having both antiglare properties and scratch resistance. CONSTITUTION:By irradiating active energy rays under the condition that active energy ray curing type resin liquid is changed between optical sheet 1 and molding film 3 having minute uneven surface, the surface roughness of which is + or -0.3-+ or -5mum, the layer of resin liquid is cured so as to be turned into resin cured matter layer 2 and then the molding film 3 is removed from the layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an antiglare optical sheet having both antiglare properties and scratch resistance.

[0002]

2. Description of the Related Art A typical structure of a liquid crystal display panel is "polarizing plate / liquid crystal cell / polarizing plate" or "polarizing plate / retardation plate / liquid crystal cell / polarizing plate". Is located on the front side.

As the polarizing plate, there are polyvinyl alcohol-iodine type, ethylene-vinyl alcohol copolymer-iodine type, polyvinyl alcohol-dichromatic dye type, ethylene-vinyl alcohol copolymer-dichromatic dye type, etc. A cellulose triacetate sheet called TAC is adhered and laminated as a protective sheet on both sides of the polarizing element film.

As described above, the incident side surface of the liquid crystal display panel serves as a protective sheet which is a component of the polarizing plate, but since the surface of the protective sheet is smooth, a display device incorporating the liquid crystal display panel is actually used. Feels dazzling when used for, and fatigue becomes significant when operating while watching the display screen for a long time.

Therefore, in a high-quality liquid crystal display panel, the protective sheet of the polarizing plate on the incident light side is subjected to antiglare processing.

Conventionally, as an antiglare processing method for this purpose,
A method of roughening the surface of a protective sheet (that is, a cellulose triacetate sheet), which is a component of a polarizing plate, by decomposing it with an alkaline solution or polishing it with sandpaper is used.

[0007] In addition, an antiglare film made of a polyester film having an antiglare surface is laminated or laminated on the polarizing plate on the incident light side of the liquid crystal display panel. In this case, the antiglare process is performed by coating a polyester film with a coating liquid containing an inorganic powder such as SiO ₂ or fine resin beads.

[0008]

However, the method of roughening the surface of the cellulose triacetate sheet used for producing a polarizing plate by decomposing it with an alkaline solution or sanding it with sandpaper is of a certain quality. It is difficult to obtain a product, since the cellulose triacetate sheet itself has a small hardness even after roughening, there is a problem that a surface layer having scratch resistance must be formed on it. As a result, there was no choice but to be disadvantageous in terms of quality and manufacturing costs.

Further, in the method of laminating or adhering a polyester film having an antiglare surface on the polarizing plate on the incident light side of the liquid crystal display panel, inorganic powder such as SiO ₂ or fine resin beads are added. When coating a coating liquid on a polyester film, uneven coating or coating streaks often occur due to a change in particle diameter due to secondary aggregation of added particles, and therefore, deterioration of quality, decrease of yield, It is easy to cause a decrease in productivity.

Under such a background, the present invention aims to provide a method for industrially advantageously producing an antiglare optical sheet having both antiglare properties and scratch resistance. .

The method for producing the antiglare optical sheet of the present invention comprises:
When the active energy ray-curable resin liquid is supplied between the optical sheet (1) and the mold film (3) having a fine uneven surface with a surface roughness of ± 0.3 μm to ± 5 μm The resin liquid layer is cured by irradiation to form a cured resin layer (2), and then the mold film (3)
Is to be removed.

The present invention will be described in detail below.

Examples of the optical sheet (1) include a protective sheet for protecting the polarizing element film and an antiglare film which is laminated or laminated on the polarizing plate of the liquid crystal display panel.

When the optical sheet (1) is a protective sheet for protecting the polarizing element film, the protective sheet includes cellulose triacetate sheet, polyarylene ester, polycarbonate, polysulfone, polyether sulfone,
Examples thereof include a single-layer or multi-layer optically isotropic sheet formed of a polymer having a bicyclo group, an ethylene-vinyl alcohol copolymer, a phenoxy ether type crosslinkable resin, or the like. However, since the protective sheet located on the incident light side of the incident light side polarizing plate of the liquid crystal display panel may be an optically isotropic sheet or a sheet that is not optically isotropic, an orientation property such as polyester film may be used. The sheet can also be suitably used.

A polyester film is preferably used as the antiglare film when the optical sheet (1) is an antiglare film which is laminated or laminated on the polarizing plate of the liquid crystal display panel. In this case, the cured resin layer (2) when the active energy ray-curable resin liquid is cured may not adhere to the polyester film.In such a case, adhesion of copolyester or the like on the polyester film in advance It is desirable to form a layer of a functional resin as an anchor layer.

The mold film (3) has a surface roughness of ± 0.3 μm to ± 5 μm, preferably ± 0.5 μm to ± 3 μm.
A crystalline film having a fine irregular surface of m 2 is used, and films such as biaxially oriented polyester film and biaxially oriented polypropylene film are particularly important. What is polyester in biaxially stretched polyester film?
Examples thereof include polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate.

Molding film (3) having the above surface roughness
Is a film with a filler having an appropriate particle size internally added,
Although it can be easily obtained by stretching this, it can also be obtained by post-sandblasting the film.

In producing the antiglare optical sheet of the present invention, the active energy ray-curable resin liquid is supplied between the optical sheet (1) and the mold film (3) to activate the active energy ray. Is used to cure the resin liquid layer to form a resin cured product layer (2), and then the mold film (3) is removed.

As the active energy ray-curable resin liquid,
An ultraviolet curable resin liquid or an electron beam curable resin liquid is used.

The UV-curable resin liquid comprises a photopolymerizable prepolymer or / and a monomer, and optionally other monofunctional or polyfunctional monomers, various polymers, a photopolymerization initiator (acetophenones, benzophenones, Michler's ketone, benzyl, benzoin, benzoin ether, benzyl ketals, thioxanthones, etc.) and a sensitizer (amines, diethylaminoethyl methacrylate, etc.) are blended. Here, examples of the photopolymerizable prepolymer include polyester acrylate, polyester urethane acrylate, epoxy acrylate, and polyol acrylate, and examples of the photopolymerizable monomer include monofunctional acrylate, bifunctional acrylate,
A trifunctional or more than trifunctional acrylate etc. are illustrated. As the photopolymerizable prepolymer or monomer, in addition to the above, phosphazene resins are also preferably used. In order to improve the adhesiveness with the optical sheet (1), an adhesiveness improver such as a polyisocyanate compound may be added to the ultraviolet curable resin liquid, if necessary.

As the electron beam curable resin liquid, the same one as the above ultraviolet curable resin liquid is used. However, it does not need to add a photopolymerization initiator.

As a method of supplying the active energy ray-curable resin liquid between the optical sheet (1) and the mold film (3), a pair of rolls arranged in parallel with a slight gap between them is used. Optical sheet (1) and mold film
(3) is supplied, and the active energy curable resin liquid is discharged to the hollow portion of the roll, and is sandwiched between the optical sheet (1) and the mold film (3). In addition, optical sheet (1) or mold film
(3) A method of casting the active energy ray-curable resin liquid on one side while coating the other can also be adopted.

By irradiating with active energy rays,
Since the resin liquid layer is cured to form the resin cured product layer (2), the mold film (3) is peeled off at a necessary stage. Thereby, the intended antiglare optical sheet is obtained.

The antiglare optical sheet obtained by the method of the present invention is a protective sheet for protecting the polarizing element film at the time of producing a polarizing plate, or is laminated or laminated on the incident light side polarizing plate of the liquid crystal display panel. It is particularly useful as an antiglare film, an outermost layer on the input side in contact with a pen of a pen input type liquid crystal panel, and can be applied to other optical applications.

[0025]

In the present invention, the layer of the resin liquid is obtained by irradiating the active energy ray-curable resin liquid between the optical sheet (1) and the mold film (3) while irradiating the active energy ray. Is used to form a cured resin layer (2), and then the mold film (3) is removed.

Therefore, the cured resin layer (2) becomes uniform, and there is no possibility of causing unevenness or streaks in the formation of the layer. Also, during irradiation with active energy rays, both sides of the sandwiched resin liquid are covered with sheets and oxygen is blocked, so there are no reaction inhibiting factors, and the curing reaction does not occur even if no special reaction accelerator is added. Proceed quickly. Therefore, the productivity is improved, troubles such as hardness decrease due to the addition of the reaction accelerator do not occur, and the original performance of the resin is utilized.

Since the fine irregularities of the mold film (3) are transferred as they are to the surface of the cured resin layer (2), excellent antiglare properties are imparted.

In addition, since the cured resin layer (2) has extremely high hardness and excellent scratch resistance, it is most suitable as a layer located on the incident light side surface of the liquid crystal display panel.

[0029]

EXAMPLES The present invention will be further described with reference to examples. Hereinafter, “parts” means parts by weight.

Example 1 FIG. 1 is a process chart showing an example of a method for producing an antiglare optical sheet of the present invention.

As the optical sheet (1), an optically isotropic cellulose triacetate film having a thickness of 80 μm was prepared. As the mold film (3), a thickness of 100 μm,
A biaxially stretched polyethylene terephthalate film (“U-4” manufactured by Teijin Ltd.) having a surface roughness of ± 0.4 μm on average and a maximum of ± 4.5 μm and not subjected to corona discharge treatment was prepared.

Further, a 100% solids UV curable resin liquid (no accelerator is added) prepared by mixing 5 parts of a photopolymerization initiator with 100 parts of phosphazene resin "PPZ" manufactured by Idemitsu Material Co., Ltd. is prepared. did.

The above-mentioned optical sheet (1) is supplied to one of a pair of rolls arranged in parallel with a slight gap,
In addition, the above-mentioned mold film (3) was supplied to the other roll so that the roughened surface was the upper surface, and while rotating both rolls in the direction to bite each other when viewed from above, the gap between both rolls was increased. The above ultraviolet curable resin liquid was discharged toward.

As a result, since the ultraviolet curable resin liquid was sandwiched between the optical sheet (1) and the mold film (3), an output of 120 W / cm, one lamp, a lamp distance of 200 mm, Line speed 2m / min, 1 pass, light intensity 600
Ultraviolet irradiation is performed under the condition of mJ / cm ² to cure the sandwiched UV-curable resin liquid layer, and a resin cured product layer with a thickness of 4 μm.
(2)

After the completion of curing, the mold film (3) was peeled off to obtain an antiglare optical sheet having a layer structure of optical sheet (1) / cured resin layer (2). The surface roughness of the cured resin layer (2) side is ± 0.35 μm on average, and about ± 4.0 μm at maximum.
The pencil hardness was 3H under a load of 1 kg, and the scratch resistance was excellent. The haze of this antiglare optical sheet was 20%, the light transmittance was 60% (550 nm), and the water vapor transmission rate was 600 g / m ² · 24 hr.

Using the above antiglare optical sheet and the above-mentioned optical sheet (1), a polyvinyl alcohol-iodine type polarizing element film having a thickness of 35 μm was applied with a polyvinyl alcohol aqueous solution type adhesive. Adhesion-laminated, antiglare optical sheet / polarizing film / optical sheet (1), that is, antiglare layer (resin cured product layer (2)) / cellulose triacetate film / polarizing film / cellulose triacetate film layer A polarizing plate having the constitution was produced. A polarizing plate having a layer structure of optical sheet (1) / polarizing element film / optical sheet (1) was prepared using only the optical sheet (1) (cellulose triacetate film) described above. Then, when the liquid crystal display panel was produced by disposing the former polarizing plate on the incident light side and the latter polarizing plate on the opposite side, excellent antiglare properties were obtained.

Example 2 FIG. 2 is a process drawing showing another example of the method for producing the antiglare optical sheet of the present invention.

The optical sheet (1) has a thickness of 100 μm.
2. A smooth biaxially stretched polyester film (“A-4100” manufactured by Toyobo Co., Ltd., one side of which was subjected to an easy-adhesion treatment with an ultraviolet curable coating material) was prepared. As the mold film (3), a biaxially stretched polyethylene terephthalate film (thickness: 100 μm, average surface roughness: ± 0.4 μm, maximum: ± 4.5 μm, not subjected to corona discharge treatment (“U-made by Teijin Limited” 4 ”) was prepared.

2 parts of benzophenone was added to 100 parts of epoxy acrylic resin "V-2550P" manufactured by Nippon Steel Chemical Co., Ltd., and a resin solution of a UV curable resin composition having a solid content of 30% by weight was diluted with ethyl acetate. Got ready.

The above UV-curable resin liquid was applied to the surface of the above-mentioned optical sheet (1) which had been subjected to the easy-adhesion treatment using a Mayer bar of 0.2 m / mφ and dried at a temperature of 60 ° C. for 1 minute to give a thickness of 4 μm Layer is formed on the coated surface
(3) was crimped. Next, output 120W / cm, 1 lamp, lamp distance 200mm, line speed 2m / min, 1 pass, light intensity 60
Ultraviolet irradiation was performed under the condition of 0 mJ / cm ² , and the sandwiched layer of the ultraviolet curable resin liquid was cured to form a cured resin layer (2).

After the completion of curing, the mold film (3) was peeled off to obtain an antiglare optical sheet having a layer structure of optical sheet (1) / cured resin layer (2). The surface roughness of the cured resin layer (2) side is ± 0.35 μm on average, and about ± 4.0 μm at maximum.
The pencil hardness was 4H under a load of 1 kg, and the scratch resistance was excellent. The haze of this antiglare optical sheet was 18%, and the light transmittance was 60% (550 nm).

The antiglare optical sheet thus obtained is used as a surface of the liquid crystal display panel having a structure of polarizing plate / retardation plate / liquid crystal cell / polarizing plate on the incident light side (on the side where the retardation plate is present). When it was laminated on the surface of the polarizing plate) so that the resin cured product layer (2) side became the surface layer with an adhesive, excellent antiglare properties were obtained.

[0043]

According to the method of the present invention, an optical sheet
Since the curing proceeds with the active energy ray-curable resin liquid sandwiched between the (1) and the mold film (3), the curing reaction proceeds promptly with the oxygen blocked and the cured resin layer At the same time that (2) is formed, a resin cured product layer (2) to which the concavities and convexities of the casting film (3) are transferred is obtained.

Then, the obtained antiglare optical sheet is
The presence of the resin cured product layer (2) having fine irregularities has both excellent antiglare properties and scratch resistance.

[Brief description of drawings]

FIG. 1 is a process drawing showing an example of a method for producing an antiglare optical sheet of the present invention.

FIG. 2 is a process drawing showing another example of the method for producing the antiglare optical sheet of the present invention.

[Explanation of symbols] (1) ... Optical sheet, (2) ... Resin cured product layer, (3) ... Mold film

Claims (4)

[Claims] 1. The surface roughness of the optical sheet (1) is ± 0.3 μm.
Film for molds with fine uneven surface of ~ ± 5μm
The resin liquid layer is cured by irradiating the active energy ray with the active energy ray-curable resin liquid supplied between (3) and the cured resin layer (2), and then the mold film. A method for producing an antiglare optical sheet, which comprises removing (3). 2. The method according to claim 1, wherein the antiglare optical sheet is a protective sheet for protecting the polarizing element film. 3. The method according to claim 1, wherein the antiglare optical sheet is an antiglare film which is laminated or stuck on a polarizing plate of a liquid crystal display panel. 4. The method according to claim 1, wherein the antiglare optical sheet is a sheet for the outermost layer on the input side in contact with a pen of a pen input type liquid crystal panel.