KR20120047536A - Optical film and polarizing plate comprising the same - Google Patents

Abstract

PURPOSE: An optical film and a polarization plate including the same are provided to obtain low moisture permeability. CONSTITUTION: A coating layer(20) is formed on one side of a cellulose base film(10). The coating layer includes a cellulose resin and a cycloolefin resin. A haze of an optical film is 0.5 to 30%.

Description

Optical film and polarizing plate including same {OPTICAL FILM AND POLARIZING PLATE COMPRISING THE SAME}

The present invention relates to an optical film having excellent adhesion to an aqueous adhesive and at the same time excellent in durability in a high temperature and high humidity environment, and a polarizing plate including the same.

The polarizing plate is widely used as a supply element of polarization in a liquid crystal display device, and as a detection element of polarization.

In general, the polarizing plate has a structure in which a polarizer made of a polyvinylalcohol (PVA) resin in which a dichroic dye is adsorbed and aligned, and a transparent protective film for protecting the polarizer from heat and moisture on both surfaces of the polarizer are laminated by an adhesive. Has

As the transparent protective film, a cellulose acetate-based protective film mainly represented by triacetylcellulose (TAC) is used, and these are laminated on both sides of the polarizer with a water-soluble adhesive after performing a hydrophilization process such as a saponification process.

However, the cellulose acetate-based protective film has a high moisture permeability, so that the durability of the polarizing plate tends to decrease in a high temperature and high humidity environment. In addition, defects such as red dots appear on the surface by water droplets generated by condensation of external water vapor during transportation or storage of the polarizer.

In recent years, instead of the cellulose acetate-based protective film, a film having high temperature durability and low water permeability, such as a polynorbornene film, a polycarbonate film, and a cyclic olefin polymer (COP), has been used.

Such a film has a low moisture permeability and excellent high temperature durability, but has a problem in that the adhesion to the water-based adhesive for polarizer (PVA) adhesion is weak and causes peeling with the polarizer due to excessively low moisture permeability.

An object of the present invention is to provide an optical film having excellent durability in a high temperature and high humidity environment while having excellent adhesion to an aqueous adhesive agent and low moisture permeability.

In addition, an object of the present invention is to provide a polarizing plate applying the optical film as a protective film of the polarizer.

The present inventors are widely used as a protective film of the polarizer, the cellulose-based film has a high moisture permeability to lower the durability of the polarizing plate in a high temperature, high humidity environment; The cycloolefin-based films have been researched to improve the problem that it is not easy to apply these films to the polarizing plate by causing peeling with the polarizer due to low adhesion and water vapor transmission rate to the water-based adhesive.

As a result, using a cellulose-based film that is excellent in adhesion to the water-based adhesive and can maintain the adhesion with the polarizer as the base film, and the substrate so that the polarizing plate to which the film is applied in a high temperature, high humidity environment can have durability Forming a coating layer containing a cellulose resin and a cycloolefin resin at a predetermined ratio on one surface of the film to adjust the total moisture permeability in a specific range (100 to 400g / ㎠ ~ 24hr) film properties of easy to apply to the polarizing plate It was found that the present invention can complete the present invention.

Accordingly, the present invention provides a coating layer containing a cellulose-based resin and a cycloolefin-based resin on one surface of the cellulose base film, and provides an optical film having a total moisture permeability of 100 to 400 g / cm 2 · 24hr.

The cellulose resin may be selected from the group consisting of diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl ester cellulose, propionyl cellulose, butyryl cellulose and acetyl propionyl cellulose.

The cellulose resin may have a moisture permeability of 400 to 1200 g / cm 2? 24hr.

The cycloolefin-based resin may be an amorphous polyolefin resin having a water vapor transmission rate of 100 g / cm 2 ~ 24 hr or less.

The cycloolefin-based resin may contain 5 to 200 parts by weight based on 100 parts by weight of cellulose resin.

The optical film may have a haze of 0.5 to 30%.

In addition, in the polarizing plate of the present invention, the optical film may be bonded to one surface of the polarizer.

The optical film of the present invention is excellent in the adhesion to the water-based adhesive and durability in high temperature and high humidity environment, in particular can be usefully applied when applied as a protective film of the polarizer. Specifically, the polarizing plate including the optical film is easily bonded to the polarizer with the water-based adhesive, and can prevent polarizer damage and polarizing plate deformation caused by penetration of external water vapor and water droplets.

The polarizing plate including the optical film or the optical film of the present invention has a low moisture permeability and may be usefully used when transported through a high temperature or high humidity region such as a tropical region, an area adjacent to the sea, and an equator, or when used in such an area.

In addition, the optical film or the polarizing plate including the optical film of the present invention can be effectively used even when the distance between the polarizing plate and the backlight is reduced by using a backlight with a large amount of heat generation for better clarity, or a thinner image display device for lower clarity. Can be.

The polarizing plate including the optical film or the optical film of the present invention can implement anti-glare at the desired level.

1 is a vertical cross-sectional view of an optical film according to the present invention,
2 is a SEM image of the surface of the optical film according to the present invention,
3 is a vertical cross-sectional view of a polarizing plate laminated with an optical film according to the present invention.

The present invention uses the optical film excellent in the adhesion to the water-based adhesive and durable in high temperature and high humidity environment and the polarizer protective film using this as a polarizer protective film, excellent adhesion to the polarizer, and prevents polarizer damage and polarizer deformation due to moisture penetrated from the outside It relates to a polarizing plate that can be.

Hereinafter, the present invention will be described in detail.

In the optical film of the present invention, a coating layer containing a cellulose resin and a cycloolefin resin is formed on one surface of the cellulose base film. The total moisture vapor transmission rate of the optical film is 100 to 400 g / cm 2 · 24hr.

The base film uses a film made of a cellulose resin that can be adhered to the polarizer with an aqueous adhesive and can maintain the adhesion of the adhered base film. The film may be an unstretched, uniaxial or biaxially oriented film.

The cellulose resin has a moisture permeability of 400 to 1200 g / cm 2 to 24 hr. For example, diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl ester cellulose, propionyl cellulose, butyryl cellulose and acetyl propionyl cellulose may be used. It is preferable to use triacetyl cellulose, isobutyl ester cellulose in that it can be transparent and optically anisotropic.

Among them, cellulose-based films made of triacetyl cellulose, isobutyl ester cellulose and the like can be suitably used in terms of transparency and optically anisotropy.

The coating layer formed on one surface of the base film contains a cellulose resin and a cycloolefin resin. The cellulose resin and the cycloolefin resin are mixed so that the total moisture permeability of the optical film is 100 to 400 g / cm 2 to 24 hr. The total moisture permeability of the optical film is formed by a combination of the moisture permeability of the base film and the moisture permeability of the coating layer.

The coating layer contains 5 to 200 parts by weight of cycloolefin resin based on 100 parts by weight of cellulose resin to maintain the total water vapor transmission range.

If the total moisture permeability of the optical film is less than 100g / ㎠-24hr, the adhesion performance in the manufacturing process of the polarizing plate is late, the processability is lowered, the adhesion between the coating layer and the base layer may be a problem, if the excess exceeds 400g / ㎠-24hr The protection and deformation | transformation of the polarizer which are the objectives of this invention cannot be prevented.

In addition, the optical film is haze is expressed according to the mixing ratio of the cellulose resin and the cycloolefin resin, the haze of the optical film according to the present invention maintains 0.5 to 30% range.

The cellulose resin may be the same as the cellulose resin component used in the base film.

Cycloolefin resin is to control the total moisture permeability of the optical film and has a lower moisture permeability than the cellulose resin.

Cycloolefin resin can use a thing with a water vapor transmission rate of 100 g / cm <2> -24hr or less, As a typical material, amorphous polyolefin resin is mentioned. The amorphous polyolefin resin is a thermoplastic film of a cycloolefin resin having units derived from monomers containing cycloolefins (cyclic olefins) such as norbornene or polycyclic norbornene monomers.

Such a cycloolefin resin may be a ring-opening polymer of a cycloolefin or a hydrogenated product of a ring-opening polymer using two or more cycloolefins, and may be an addition copolymer of a cycloolefin and an aromatic compound having a chain olefin or a vinyl group. Also, a polar group is introduced.

When the cycloolefin resin is a copolymer of a cycloolefin and an aromatic compound having a chain olefin or a vinyl group, examples of the chain olefin include ethylene and propylene, and examples of the aromatic compound having a vinyl group include styrene and α-methyl. Styrene and the like. The unit of monomers comprising cycloolefins in such copolymers may be up to 50 mole percent, for example 15 to 50 mole percent. In particular, in the case of a ternary copolymer of a cycloolefin, a chain olefin, and an aromatic compound having a vinyl group, the unit of the monomer including the cycloolefin may be a relatively small amount. In the ternary copolymer, the monomer unit containing the chain olefin is usually 5 to 80 mol%, and the monomer unit containing the aromatic compound having a vinyl group is usually 5 to 80 mol%.

The coating layer laminated on the base film is prepared by dissolving a resin component in which a cellulose resin and a cycloolefin resin are mixed in a predetermined ratio in an organic solvent to prepare a coating layer forming composition, and then coating and drying the same in a conventional manner.

The organic solvent is not particularly limited as long as it can dissolve the resin component, and examples thereof include acetone, methyl ethyl ketone, cyclohexanone, chloroform, cyclopentanone, tetrahydrofuran (THF), and the like. The coating layer-forming composition contains a resin component of 0.001 to 30 parts by weight based on 100 parts by weight of the organic solvent in consideration of the thickness of the coating layer, ease of coating process, and the like.

Examples of the coating method include spin coating, wire bar coating, micro gravure coating, scriber coating, dip coating and spray coating. Examples of the drying method include drying in a drying oven and drying using infrared rays.

The present invention can form a polarizing plate using the optical film as a protective film of the polarizer. The polarizing plate is bonded to the base film surface of the optical film and the surface of the polarizer, the optical film may be bonded to one side or both sides of the polarizer.

Bonding of a polarizer and a protective film is performed through the water-based adhesive agent.

The water-based adhesive is not particularly limited as long as it can sufficiently bond the polarizer and the protective film, and has excellent optical transparency and no change in yellowing over time, for example, an adhesive composition containing a polyvinyl alcohol-based resin and a crosslinking agent. Can be mentioned.

Examples of the polyvinyl alcohol-based resin contained in the adhesive composition include a polyvinyl alcohol resin or a polyvinyl alcohol resin having an acetoacetyl group. Among them, the polyvinyl alcohol resin having an acetoacetyl group has a polyvinyl alcohol having a highly reactive functional group. It is preferable at the point which the durability of a polarizing plate improves as a type adhesive agent.

Polyvinyl alcohol resins include polyvinyl alcohol and derivatives thereof obtained by saponifying polyvinyl acetate; Saponified products of copolymers of vinyl acetate with monomers copolymerizable with vinyl acetate; And modified polyvinyl alcohols obtained by acetalization, urethaneization, etherification, graftting and phosphate esterification of polyvinyl alcohols, and these may be used alone or in combination of two or more thereof. Examples of the monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids such as maleic anhydride, fumaric acid, crotonic acid, itaconic acid and (meth) acrylic acid and esters thereof; Α-olefins such as ethylene and propylene; (Meth) allyl sulfonic acid (soda), sodium sulfonic acid (monoalkyl maleate), disulfonic acid sodium alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N-vinylpyrrolidone and derivatives thereof Can be mentioned. The average degree of polymerization of the polyvinyl alcohol-based resin is not particularly limited, but considering the adhesiveness, the average degree of polymerization is preferably 100 to 5,000, preferably 1,000 to 4,000, and the degree of saponification is 85 to 100 mol%, preferably 90 to It is good that it is 100 mol%.

In addition, the polyvinyl alcohol resin having an acetoacetyl group can be obtained by reacting the polyvinyl alcohol-based resin with diketene by a known method. For example, a method of dispersing a polyvinyl alcohol-based resin in a solvent such as acetic acid and then adding diketene thereto, or dissolving the polyvinyl alcohol-based resin in a solvent such as dimethylformamide or dioxane beforehand It can obtain by the method of adding ten, or the method of directly contacting a diketene gas or a liquid diketene with polyvinyl alcohol. The polyvinyl alcohol-based resin containing acetoacetyl group is not particularly limited as long as the acetoacetyl group modification is 0.1 mol% or more, preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%, most preferably It is good that it is 2-7 mol%. When the degree of denaturation of the acetoacetyl group is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient and inadequate, and when it exceeds 40 mol%, the effect of improving the water resistance may be insignificant.

In addition, in order to increase the adhesion to the surface of the polarizer to be bonded to the protective film, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment or saponification treatment may be appropriately performed.

The method of bonding the protective film to the polarizer with an adhesive may use a method commonly known in the art, for example, a polarizer, a protective film by a casting method, a wire bar coating method, a gravure coating method, a die coating method, or a spraying method. Or the method of apply | coating an adhesive agent to all these bonding surfaces, and bonding them is mentioned. Here, the casting method is a method in which a polarizer or a protective film to be coated is moved in a substantially vertical direction, in a substantially horizontal direction, or in an inclined direction between the two, while expanding and spreading the adhesive on the surface of the coated object. After apply | coating an adhesive agent, a polarizer and a protective film are pinched together and bonded together.

A polarizer is normally manufactured through the process of uniaxially stretching a polyvinyl alcohol-type film, the process of dyeing and adsorbing with a dichroic dye, the process of treating with boric acid aqueous solution, and the process of washing with water and drying.

The process of uniaxially stretching the polyvinyl alcohol-based film may be performed before dyeing, simultaneously with dyeing, or after dyeing. If uniaxial stretching is carried out after dyeing, it may be carried out before or during boric acid treatment. Of course, it is also possible to perform uniaxial stretching in a plurality of stages in which each of them is combined. Uniaxial stretching may use rolls or thermal rolls having different circumferential speeds, and may be dry stretching in the air or wet stretching in a state swelled with a solvent. The draw ratio is usually 3 to 8 times.

For the process of dyeing the stretched polyvinyl alcohol-based film with a dichroic dye, for example, a method of immersing the polyvinyl alcohol-based film in an aqueous solution containing a dichroic dye may be used. Specific examples of the dichroic dye include iodine or a dichroic organic dye. In addition, the polyvinyl alcohol-based film is preferably swelled by dipping in water before dyeing.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type film in the dyeing aqueous solution containing iodine and potassium iodide can be used normally. Usually, the content of iodine in the aqueous solution for dyeing is 0.01 to 1 part by weight based on 100 parts by weight of water (distilled water), and the content of potassium iodide is 0.5 to 20 parts by weight based on 100 parts by weight of water. The temperature of the aqueous solution for dyeing is usually 20 to 40 ° C., and the immersion time, for example, the dyeing time is usually 20 to 1800 seconds.

On the other hand, in the case of using a dichroic organic dye as a dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based film in an aqueous dyeing solution containing a water-soluble dichroic organic dye can be used. The content of the dichroic organic dye in the aqueous solution for dyeing is usually 1 × 10 ^-4 to 10 parts by weight, preferably 1 × 10 ^-3 to 1 part by weight based on 100 parts by weight of water. The aqueous dyeing solution may further contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the aqueous solution for dyeing is usually 20 to 80 ° C., and the immersion time such as dyeing time is usually 10 to 1,800 seconds.

Boric acid treatment of the dyed polyvinyl alcohol-based film can be carried out by immersing in a boric acid-containing aqueous solution. Usually, the content of boric acid in the aqueous solution containing boric acid is 2 to 15 parts by weight, preferably 3 to 12 parts by weight, based on 100 parts by weight of water. The boric acid-containing aqueous solution in the case of using iodine as a dichroic dye preferably contains potassium iodide, and its content is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight with respect to 100 parts by weight of water. The temperature of the boric acid containing aqueous solution is 50 degreeC or more, Preferably it is 50-85 degreeC, More preferably, it is 50-80 degreeC. The immersion time is 60 to 1,200 seconds, preferably 150 to 600 seconds, more preferably 200 to 400 seconds.

After the boric acid treatment, the polyvinyl alcohol-based film is washed with water and dried. Washing treatment may be performed by immersing the boric acid-treated polyvinyl alcohol-based film in water, the temperature of the water during the washing treatment is 5 to 40 ℃, immersion time is 1 to 120 seconds. The polarizer can be obtained by drying after washing with water. The drying treatment may be generally performed using a hot air dryer or a far infrared heater, and the drying treatment temperature is usually 30 to 100 ° C., preferably 50 to 80 ° C., and the drying time is usually 60 to 600 seconds, preferably 120 to 80 ° C. 600 seconds is good.

The polarizer may have a thickness of 5 to 40 μm.

The polarizing plate of the present invention can be subjected to surface treatment and the like on the protective film (coating layer of the optical film) for the purpose of high hardness treatment, low reflection treatment and antistatic treatment within the range of not damaging the polarizer. The high hardness treatment is carried out for the purpose of preventing damage to the surface of the polarizing plate. For example, a suitable UV curable resin such as silicone can be formed on the surface of the protective film by adding a cured film having excellent hardness and sliding properties to the surface of the protective film. have. The low reflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like. The antistatic treatment can achieve antistatic development, foreign matter adsorption, or adhesion to an adjacent layer.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Preparation Example 1 Preparation of Polarizer

A polyvinyl alcohol film (VF-PS, KURARAY Co., Ltd.) having a mean polymerization degree of 2,400 and saponification degree of 99.9 mol% or more was 6.0-fold uniaxially stretched 6.0 times in a dry manner, and water at 60 ° C (deionized water) while maintaining a tension state. ) For 1 minute and then immersed in an aqueous solution at 28 ° C. with a weight ratio of iodine / potassium iodide / water of 3.0 / 1.5 / 100 for 60 seconds. Thereafter, it was immersed for 300 seconds in an aqueous solution at 55 ° C. having a weight ratio of potassium iodide / boric acid / water of 11/4/100. Subsequently, the resultant was washed with water at 10 ° C. for 20 seconds, and then dried at 65 ° C. to obtain a polarizer in which iodine was adsorbed to the polyvinyl alcohol resin.

Preparation Example 2 Preparation of Adhesive

Water-soluble polyamide epoxy resin (Smireze Resin 650, Sumitomo Chemtex Co., Ltd.) 1.5 parts by weight of 3 parts by weight of carboxyl group-modified polyvinyl alcohol (Kurarefobal KL318, Kuraray Co., Ltd.) A polyvinyl alcohol adhesive was prepared by adding parts by weight.

Example 1

(1) optical films

1.5 parts by weight of a triacetylcellulose resin (TD60UL, Fuji) having a moisture permeability of 540 g / cm 2 to 24 hr and a cycloolefin resin of 70 g / cm 2 to 24 hr of a water vapor permeability (Arton, Okura) 0.4 parts by weight was dissolved to prepare a coating layer forming composition. The coating layer-forming composition prepared above was barcoated on one surface of a cellulose base film (KC8UX, KONICA) having a moisture permeability of 540 g / cm 2? 24hr, and dried at 120 ° C. for 3 minutes to form a coating layer, thereby preparing an optical film.

(2) polarizing plate

The polarizer and the polarizer protective film (TD60UL, Fuji) obtained in Preparation Example 1 and the optical film were bonded by using the water-based adhesive and Laminator prepared in Preparation Example 2 to prepare a polarizing plate. At this time, the base film surface of the optical film and one surface of the polarizer were bonded. Thereafter, the mixture was left to dry in an oven at 80 ° C. for 3 minutes.

Example 2

An optical film was manufactured in the same manner as in Example 1, using 3 parts by weight of a cycloolefin-based resin (Arton, Okura Co., Ltd.) having a moisture permeability of 70 g / cm 2 ~ 24 hr.

Example 3

An optical film was prepared in the same manner as in Example 1, using 1 part by weight of a cycloolefin resin (Arton, Okura Co., Ltd.) having a moisture permeability of 70 g / cm 2 -24 hr.

Example 4

An optical film was prepared in the same manner as in Example 1, using 2 parts by weight of a cycloolefin-based resin (Arton, Okura Co., Ltd.) having a moisture permeability of 70 g / cm 2 -24 hr.

Comparative Example 1

Except for the coating layer, an optical film was manufactured using only cellulose-based films (KC8UX, KONICA).

Comparative Example 2

Except for the coating layer, an optical film was prepared using only a cycloolefin-based film (Zeonor, Zeon).

Comparative Example 3

An optical film was prepared in the same manner as in Example 1, using 5 parts by weight of a cycloolefin-based resin (Arton, Okura Co., Ltd.) having a moisture permeability of 70 g / cm 2 ~ 24 hr.

Comparative Example 4

The optical film was manufactured in the same manner as in Example 1, but using 0.1 parts by weight of a cycloolefin resin (Arton, Okura Co., Ltd.) having a moisture permeability of 70 g / cm 2 ~ 24 hr.

Experimental Example

Physical properties of the optical film and the polarizing plate prepared in Examples and Comparative Examples were measured by the following method, and the results are shown in Table 1 below.

1. Transmittance and Haze

Measured at 25 ° C, 50% RH constant temperature and humidity using Murakami's HM-150 instrument

2. Permeability

Measured at 25 ℃ 50% RH constant temperature and humidity condition using Mocon equipment

3. Polarizer deformation degree (durability in high temperature and humidity environment)

After fabricating a polarizing plate using an optical film, the gauze containing moisture was placed on the surface of the optical film (coating layer present) and left for 12 hours in a constant temperature / humidity (40 ° C 90% RH) chamber, and then taken out. Evaluation (confirmation of occurrence of RED DOT, etc.) was confirmed.

<Evaluation Criteria>

○: appearance change and RED DOT occurred

×: appearance change and RED DOT does not occur

4. Adhesion with Water-based Adhesive

After drying the polarizing plate which bonded the polarizer and the optical film with the water-based adhesive for 3 minutes in an 80 ° chamber, it was evaluated whether the optical film was separated from the polarizer by the tester's hand.

<Evaluation Criteria>

○: optical film is separated

×: Optical film is not separated

5. Adhesion between base film and coating layer

Using a cutter, the surface of the coating layer of the optical film was scratched with a grid pattern having a width of 1 mm, and the adhesive tape was stuck on it and then peeled off in a 90 ° direction to visually check whether the surface of the coating layer fell on the adhesive tape. It was repeated.

<Evaluation Criteria>

○: All three times no damage

×: there is damage more than once

division Transmittance
(%) Hayes
(%) Total breathability
(g / ㎠? 24hr) Polarizer strain Optical film
Adhesion of Water-based Adhesives Coating layer
Adhesion of Base Film Example 1 92.3 1.4 390 ○ ○ ○ Example 2 91.1 8.2 126 ○ ○ ○ Example 3 91.7 5.7 343 ○ ○ ○ Example 4 91.3 6.9 210 ○ ○ ○ Comparative Example 1 92.6 0.2 540 × ○ -(No coating layer) Comparative Example 2 91.8 0.1 10 ○ × -(No coating layer) Comparative Example 3 91.4 10.5 90 ○ ○ × Comparative Example 4 92.4 0.4 480 × ○ ○

As shown in the table, a coating layer containing a cellulose-based resin and a cycloolefin-based resin is formed on one surface of the cellulose-based film according to the present invention, and an optical film having a total moisture permeability of 100 to 400 g / cm 2 -24hr and the optical film Examples 1 to 4 including the adhesive to the water-based adhesive and excellent durability in a high temperature and high humidity environment was able to prevent polarizer damage and polarizer deformation due to moisture penetrated from the outside.

On the other hand, Comparative Example 1 using a cellulose-based film without a coating layer and Comparative Example 4 having a high total moisture permeability of 480g / ㎠ ~ 24hr was confirmed that it is difficult to maintain durability because the degree of deformation of the polarizer is high in a high temperature and high humidity environment. In addition, Comparative Example 2 using a cycloolefin-based film without a coating layer had a low adhesive strength with the water-based adhesive, and Comparative Example 3 with a low total moisture permeability of 90 g / ㎠ ~ 24hr is separated from the low adhesion of the coating layer and the base film to protect the polarizer It was confirmed that the application to the film is difficult.

10: base film 20: coating layer
30: polarizer 40: aqueous adhesive layer

Claims (7)

An optical film having a coating layer containing a cellulose resin and a cycloolefin resin on one surface of a cellulose base film, and having a total water vapor transmission rate of 100 to 400 g / cm 2 -24 hr.
The optical film of claim 1, wherein the cellulose resin is selected from the group consisting of diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl ester cellulose, propionyl cellulose, butyryl cellulose, and acetyl propionyl cellulose.
The optical film of claim 1, wherein the cellulose resin has a water vapor transmission rate of 400 to 1200 g / cm 2 to 24 hr.
The optical film of claim 3, wherein the cycloolefin-based resin is an amorphous polyolefin resin having a water vapor transmission rate of 100 g / cm 2 to 24 hr or less.
The optical film of claim 1, wherein the cycloolefin resin contains 5 to 200 parts by weight based on 100 parts by weight of the cellulose resin.
The optical film of claim 1, wherein the haze is 0.5 to 30%.
The polarizing plate in which the optical film of any one of Claims 1-6 was bonded to one surface of the polarizer.

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