WO2014098420A1 - Method for manufacturing hard-coated polarizing plate - Google Patents

Abstract

The present invention relates to a method for manufacturing a hard-coated polarizing plate comprising the steps of: (a) forming a coating layer by coating one surface of a cellulose resin film with a composition for forming a hard-coating layer; (b) laminating a release film on the coating layer of the cellulose resin film; (c) forming a hard-coating layer by hardening the coating layer laminated with the release film; (d) saponifying the cellulose resin film laminated with the hard-coating layer and the release film; and (e) laminating the other surface of the saponified cellulose resin film with a polarizer.

Description

Manufacturing method of hard coated polarizer

The present invention relates to a method of manufacturing a hard coated polarizing plate.

An expensive optical film such as a polarizer is stacked on a liquid crystal display device (LCD). The polarizer may be damaged or contaminated during assembling, bonding, or transportation and distribution with the liquid crystal cell.

Since fine damage and defects of the polarizer cause a defect of the liquid crystal display device, in order to prevent this, a polarizer protective film is laminated on the surface of the polarizer. In addition, to improve the hardness of the polarizer protective film is used by forming a hard coating layer on one surface of the protective film.

As a method for manufacturing a polarizing plate having a hard coating layer, Korean Patent No. 1,036,735 discloses a method of applying a composition for forming a hard coating layer on one surface of a polarizer protective film to form a coating layer and then photocuring the coating layer. . This is a method commonly used in the art to form a hard coat layer, the polarizer protective film thus prepared is used by bonding to the polarizer after saponification treatment.

 On the other hand, when using the conventional manufacturing method, a curl phenomenon occurs in which the end portion of the hard coat film rolls up. In particular, when the thickness of the hard coating layer is formed to increase the hardness, curling is intensified. This is because the curing shrinkage and thermal shrinkage in the curing step is increased, when curling occurs, it is difficult to bond the protective film and the polarizer and there is a problem that cracks occur in severe cases.

In addition, there is a problem in that the saponification process up to the surface of the hard coating layer in the process of saponification on the surface of the protective film in order to improve the adhesion with the polarizer. The damage of the hard coating layer is a factor of lowering the contact angle of the hard coating layer, deterioration of the scratch resistance to reduce the quality of the polarizing plate.

An object of the present invention is to significantly reduce the occurrence of curl in the cellulose-based resin film when forming a hard coating layer on the protective film to facilitate bonding with the polarizer, and to reduce the surface damage of the hard coating layer by the saponification solution excellent scratch resistance and surface hardness It is to provide a method of manufacturing a hard-coated polarizing plate having a.

In order to achieve the object of the present invention, (a) applying a composition for forming a hard coating layer on one surface of the cellulose-based resin film to form a coating layer; (b) bonding a release film on the coating layer of the cellulose resin film; (c) hardening the application layer to which the release film is bonded to form a hard coating layer; (d) saponifying a cellulose-based resin film in which the hard coating layer and the release film are laminated; And (e) bonding the polarizer to the other surface of the saponified cellulose-based resin film.

Before or after the step (e), (f) may further comprise the step of peeling the release film from the hard coating layer.

The hard coating layer-forming composition may include a photocurable light transmitting resin and an initiator, and further includes at least one selected from the group consisting of solvents, antioxidants, UV absorbers, light stabilizers, leveling agents, surfactants, and antifouling agents. can do.

The thickness of the coating layer may be 10 ~ 40㎛.

The surface hardness of the hard coated polarizing plate may be greater than or equal to 4H.

In the method for producing an anti-glare hard coating film according to the present invention, when the hard coating layer is formed on a cellulose-based resin film, curling is reduced in the cellulose-based resin film so that the polarizer and the cellulose-based resin film are easily bonded to each other. In the saponification process, there is an advantage of providing a hard coated polarizing plate having excellent surface hardness since there is no damage to the surface of the hard coating layer.

Method for producing a hard-coated polarizing plate of the present invention comprises the steps of (a) applying a composition for forming a hard coat layer on one surface of the cellulose-based resin film to form a coating layer; (b) bonding a release film on the coating layer of the cellulose resin film; (c) hardening the application layer to which the release film is bonded to form a hard coating layer; (d) saponifying a cellulose-based resin film in which the hard coating layer and the release film are laminated; And (e) bonding the polarizer to the other surface of the saponified cellulose resin film.

Hereinafter, the present invention will be described in more detail, but for the purpose of illustrating the present invention, it is not intended to limit the scope of the present invention.

First, a) the composition for hard-coat layer formation is apply | coated to one surface of a cellulose resin film, and an application layer is formed.

The cellulose resin is composed of cellulose and fatty acid ester, and specific examples thereof include cellulose triacetate resin, cellulose diacetate resin, cellulose tripropionate resin, cellulose dipropionate resin, and the like. Excellent cellulose triacetate (triacetyl cellulose) resin is preferred.

The thickness of a cellulose resin film may be 30-100 micrometers, More preferably, it may be 40-80 micrometers.

An application layer contains the composition for hard-coat layer formation, and is formed by apply | coating the composition for hard-coat layer formation on a cellulose resin film. In addition, the hard coating layer-forming composition includes a photocurable light-transmissive resin and an initiator.

The light-transmissive resin may include a photocurable (meth) acrylate oligomer and a monomer, and may be used alone or in combination of two or more.

As a photocurable (meth) acrylate oligomer, epoxy (meth) acrylate, urethane (meth) acrylate, etc. can be used, for example, It is more preferable to use urethane (meth) acrylate especially.

Urethane (meth) acrylate can manufacture the polyfunctional (meth) acrylate which has a hydroxyl group in a molecule, and the compound which has an isocyanate group in presence of a catalyst.

Examples of the (meth) acrylate having an intramolecular hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxyisopropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and caprolactone ring-opening hydroxide. One or more selected from the group consisting of oxyacrylate, pentaerythritol tri / tetra (meth) acrylate mixture, and dipentaerythritol penta / hexa (meth) acrylate mixture can be used.

Examples of the compound having an isocyanate group in the molecule include 1,4-diisocyanatobutane, 1,6-diisocyanatohexane, 1,8-diisocyanatooctane, 1,12-diisocyanatododecane, 1,5-dii Socyanato-2-methylpentane, trimethyl-1,6-diisocyanatohexane, 1,3-bis (isocyanatomethyl) cyclohexane, trans-1,4-cyclohexene diisocyanate, 4,4'-methylene Bis (cyclohexyl isocyanate), isophorone diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, xylene-1,4-diisocyanate, tetramethylxylene-1,3-di Derived from isocyanate, 1-chloromethyl-2,4-diisocyanate, 4,4'-methylenebis (2,6-dimethylphenylisocyanate), 4,4'-oxybis (phenylisocyanate), hexamethylene diisocyanate Trifunctional isocyanate and trimethylolpropane adduct toluene diisocyanate Eojin it can be used at least one member selected from the group.

As a monomer, what is normally used can be used, The thing which has unsaturated groups, such as a (meth) acryloyl group, a vinyl group, a styryl group, an allyl group, can be used as a photocurable functional group, Among these, (meth) acryl It is more preferable to use a diary.

Monomers having a (meth) acryloyl group include neopentyl glycol acrylate, 1,6-hexanediol (meth) acrylate, propylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and dipropylene glycol Di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylol ethane tri (meth) acrylate, 1,2, 4-cyclohexanetetra (meth) acrylate, pentaglycerol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipenta Erythritol penta (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaery Lithitol tri (meth) acrylate, tripentaerythritol hexatri (meth) acrylate, bis (2-hydroxyethyl) isocyanurate di (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (Meth) acrylate, hydroxybutyl (meth) acrylate, isooctyl (meth) acrylate, iso-decyl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, One or more types selected from the group consisting of phenoxyethyl (meth) acrylate and isobornol (meth) acrylate can be used.

The initiator may be used without limitation in the art, specifically 2-methyl-1- [4- (methylthio) phenyl] 2-morpholinepropanone-1, diphenylketone benzyldimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-1-one, 4-hydroxycyclophenylketone, dimethoxy-2-phenylatetophenone, anthraquinone, fluorene, triphenylamine, carbazole, 3- At least one selected from the group consisting of methyl acetophenone, 4-knoloacetophenone, 4,4-dimethoxyacetophenone, 4,4-diaminobenzophenone, 1-hydroxycyclohexylphenyl ketone, and benzophenone can be used. have

The initiator is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the total composition for forming the hard coat layer. When the content of the initiator is less than 0.1 parts by weight, the curing speed may be slow, and when it exceeds 10 parts by weight, cracks may occur due to overcuring of the anti-glare hard coating layer.

The hard coating layer-forming composition may further include a solvent in addition to the light transmitting resin and the initiator.

The solvent can be used without limitation as long as it is known as a solvent of the composition for forming a coating layer in the art, and specifically, alcohol-based (methanol, ethanol, isopropanol, butanol, methylcellulose, ethyl solusorb, etc.), ketone-based (methyl) Ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, cyclohexanone, etc.), hexane (hexane, heptane, octane, etc.), benzene (benzene, toluene, xylene, etc.) At least one selected from the group can be used.

The solvent may be included in an amount of 10 to 95 parts by weight based on 100 parts by weight of the total composition for forming an antiglare hard coat layer. If the solvent is less than 10 parts by weight on the basis of the viscosity may be high workability, when exceeding 95 parts by weight may take a lot of time in the drying process may be economically inferior.

The coating method is not particularly limited, and a die coater, air knife, reverse roll, blade, casting, gravure, or the like can be used.

After application, a drying step may be performed as necessary. As a drying method, a method such as natural drying, air drying, heat drying, or the like may be used, and heat drying is preferably used. For example, it may be heat dried at 20 to 80 ° C. for 1 to 10 minutes.

The thickness of an application layer may be 500 micrometers or less normally, Preferably it is 10-40 micrometers. If the thickness of the coating layer is less than 10㎛ the hardness may fall, and if the coating layer of more than 40㎛ hard coating layer of the composition for forming a hard coat layer may be cured while curing. Such curl generation can make polarizer bonding difficult and can cause deterioration of the polarizer quality.

(B) A release film is bonded together on the application layer of the said cellulose resin film.

The release film serves to protect the hard coat layer in the curing step and the saponification step. The release film is not particularly limited as long as it is a film commonly used in the art.

Specifically, polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethylacryl Polyolefin-based films such as a late copolymer and an ethylene-vinyl alcohol copolymer; Polyester-based films such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; Polyacrylate film; Polystyrene film; Polyamide films such as nylon 6 and partially aromatic polyamides; Polyvinyl chloride film; Polyvinylidene chloride film; Or polycarbonate film etc. can be used. In addition, these can be appropriately released by a release agent such as silicon-based, fluorine-based, silica powder or the like.

Next, (c) hardening the coating layer bonded to the release film to form a hard coating layer, (d) saponification of the cellulose-based resin film laminated the hard coating layer and the release film.

Since the curing proceeds in the state where the release film is attached to the surface of the coating layer as described above, the degree of curling of the cellulose-based resin film with the hard coating layer can be reduced despite the volume shrinkage of the composition for forming the hard coating layer after curing. have. In addition, the release film is laminated on the hard coating layer even at the time of saponification so that the hard coating layer is not damaged.

Finally, (e) the polarizer is bonded to the other surface of the saponified cellulose resin film. In addition, before or after the step (e), (g) the release film is peeled from the hard coating layer.

The structure of the hard-coated polarizing plate of the present invention is not particularly limited, and the hard-coated protective film is laminated on one side of the polarizer, and various types of optical layers may be stacked on the other side to satisfy the required optical properties. Can be. For example, the protective film is laminated on one surface of the polarizer, and a surface treatment layer such as an antireflection layer, an anti-sticking layer, a diffusion preventing layer, an anti-glare layer, etc., in addition to the hard coating layer may be laminated on the other surface of the polarizer or a conventional protective film. Can be. In addition, an alignment liquid crystal layer or another functional film for compensating a viewing angle may be laminated on at least one surface of the polarizer or the protective film. In addition, depending on the situation, both sides of the polarizer may be stacked.

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples, and the following examples are only some specific examples of the present invention, and are not intended to limit or limit the protection scope of the present invention.

Example 1

(a) 10 parts by weight of urethane acrylate (Miwon Co., Ltd., MU9500), 10 parts by weight of pentaerythritol triacrylate (Miwon Co., M340), nano silica sol (catalyst, V8802 (12 nm, 40% solids)) 50 parts by weight, methyl ethyl ketone (Great Gold Co., Ltd.), 20 parts by weight, 7 parts by weight of propylene glycol monomethyl ether (Great Gold Co., Ltd.), 2.5 parts by weight of photoinitiator (Ciba, I-184), leveling agent (BYK Ke Sil, BYK3570 product) The composition for forming a hard coating layer containing 0.5 parts by weight was filtered using a filter made of PP material, and then applied to one surface of a triacetyl cellulose (TAC) film having a thickness of 80 μm and dried at 70 ° C. for 2 minutes. It was. At this time, the thickness of the coating layer after drying was set to 10㎛.

(b) Bonding the silicone release film Lintec, trade name PET3811) on the coating layer of the triacetyl cellulose (TAC) film, and (c) UV irradiation to the accumulated light amount 500mJ / cm ² to the coating layer bonded to the release film. And hardened to form a hard coat layer.

Then, (d) triacetyl cellulose (TAC) film laminated with a hard coating layer and a release film was immersed in a KN aqueous solution of 5N concentration for 30 seconds and saponified, dried in an 80 degree oven for 2 minutes to remove moisture, ( e) A PVA polarizer was bonded to the other side of the saponified triacetyl cellulose (TAC) film using a modified polyvinyl alcohol-based adhesive. Thereafter, the release film bonded to the (f) coating layer was peeled off from the hard coat layer.

Example 2

In Example 1, except that the thickness of the coating layer was 40㎛ to prepare a hard-coated polarizing plate in the same manner as in Example 1.

Example 3

In Example 1, a hard-coated polarizing plate was manufactured in the same manner as in Example 1 except that the thickness of the coating layer was 45 μm.

Example 4

In Example 1, a hard-coated polarizing plate was manufactured in the same manner as in Example 1 except that the thickness of the triacetyl cellulose (TAC) film was 40 μm.

Example 5

In Example 1, a hard-coated polarizing plate was manufactured in the same manner as in Example 1 except that step (f) was performed before step (e).

Comparative Example 1

In Example 2, the polarizing plate hard-coated in the same manner as in Example 2, except that the steps (b) and (f) are not performed (the curing and saponification step is performed while the release film is not bonded to the coating layer). Was prepared.

Comparative Example 2

In Example 2, a hard-coated polarizing plate was prepared in the same manner as in Example 2, except that step (f) was performed after step (c) (sampling was carried out while the release film was not bonded to the coating layer). .

Experimental Example

Physical properties of the anti-glare hard coat film prepared in Examples and Comparative Examples were measured by the following method, and the results are shown in Table 1. Measurement and evaluation methods are as follows.

(1) pencil hardness evaluation

According to JIS K5600, it measured using the Pencil Hardness Tester (pencil hardness tester, masonry science). After fixing the pencil at an angle of 500 g of load and 45 °, it was determined whether the surface was scratched visually by pencil hardness.

(2) evaluation of the degree of curl occurrence

 A sample cut into a square shape of A4 size (29.7 X 21.0 cm) was placed on a flat glass plate with the coated surface of the film facing up, and the distance from the square glass plate was measured at 25 ° C. and 50% RH, and then averaged. Was taken as a measured value.

- Assessment Methods -

Very good: 0-15 mm

Good: 15 ~ 30mm

Poor: 30 ~ 50mm

Very bad: more than 50mm

(3) scratch resistance evaluation

The number of scratches generated by mounting the steel wool in a rubbing tester (KPD-301, Gibae ENT) and reciprocating 10 times under a load of 1 kg was evaluated.

- Assessment Methods -

A: 0-10

B: 11-20

C: 20 or more

TABLE 1

As shown in Table 1, the embodiment according to the present invention was confirmed that the degree of curling after curing was reduced, and the degree of damage on the surface of the hard coating layer was reduced after curing.

Claims (6)

1. (a) applying a composition for forming a hard coating layer to one surface of a cellulose resin film to form an application layer;

   (b) bonding a release film on the coating layer of the cellulose resin film;

   (c) hardening the application layer to which the release film is bonded to form a hard coating layer;

   (d) saponifying a cellulose-based resin film in which the hard coating layer and the release film are laminated; And

   (e) bonding the polarizer to the other surface of the saponified cellulose-based resin film.
2. The method of claim 1, further comprising, before or after the step (e), (f) peeling off the release film from the hard coating layer.
3. The method of claim 1, wherein the hard coating layer-forming composition comprises a photocurable light-transmitting resin and an initiator.
4. The method of claim 3, wherein the hard coating layer-forming composition further comprises at least one selected from the group consisting of solvents, antioxidants, UV absorbers, light stabilizers, leveling agents, surfactants, antifouling agents. Method of manufacturing a polarizing plate.
5. The method of claim 1, wherein the coating layer has a thickness of 10 μm to 40 μm.
6. 3. The method of claim 1, wherein the surface hardness of the hard coated polarizer is 4H or higher. 4.