KR20240003166A - Acrylic optical film and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a dope solution for manufacturing a polarizing plate protective film using a high heat resistance, high molecular weight acrylic polymer by a solution casting method, and an optical film such as a polarizing plate protective film using the same.
The optical film according to the present invention is a film containing a polarizing plate protective film using a dope solution, and has low moisture permeability and excellent optical properties, excellent dimensional stability, and excellent adhesion to polyvinyl alcohol-based optical films used as polarizing films. It works.

Description

Acrylic optical film and manufacturing method thereof}

The disclosure of the present invention relates to a dope solution for manufacturing a polarizer protective film by a solution casting method using a high heat resistance, high molecular weight acrylic polymer, and an optical film such as a polarizer protective film using the same.

The optical film according to the present invention is a film containing a polarizing plate protective film using a dope solution, and is characterized by excellent optical properties, high tensile strength, low hygroscopicity and high heat resistance, and thus has excellent dimensional stability and is a polarizing film. It has excellent adhesion with the polyvinyl alcohol-based optical film used.

The optical film according to the present invention provides an acrylic optical film that is a polarizer protective film or a retardation film.

Recently, with the development of optical technology, liquid crystal displays have been required to be thinner, lighter, and larger throughout the display industry, and technologies such as wide viewing angle, high contrast, uniform screen display, and suppression of image changes according to viewing angle have emerged as particularly important issues. It is becoming.

Various polymer films such as polarizing films, polarizing plate protective films, retardation films, light guide plates, and plastic substrates are used in these display devices, and the required characteristics of these display polymer materials are becoming more sophisticated.

Cellulose ester films have been used for photography and as various optical materials because they have high strength and flame retardancy.

For example, in a polarizer, which is one of the optical films that make up a liquid crystal display device, a cellulose acylate film, especially a triacetyl cellulose film, which can be directly bonded to the polyvinyl alcohol (PVA)-based film, which is a polarizer, is laminated on both sides of the polarizer. It is mainly used as a polarizing plate protective film. Additionally, it can be stretched under appropriate conditions and used as an optical compensation film.

However, when such a cellulose ester film is molded into a thin film, it has a significant impact on the function of the liquid crystal display device due to reduced durability in a high temperature and high humidity environment. There is also the problem of a decrease in the strength and surface hardness of the film due to thinning.

In order to overcome the above problems, research is being conducted to manufacture optical films using acrylic polymers.

Korean Patent Publication No. 10-2018-34188A, filed by the present applicant, describes a resin composition for optical films containing an acrylic copolymer and an optical film manufactured using the same.

However, the resin used in the acrylic dope still has high moisture permeability, so when used as an optical film, there are cases where it cannot be used for long-term use due to inferior optical properties.

In addition, the resin used in the conventional acrylic dope is still a new acrylic polymer that has heat decomposition resistance, transparency, and can reduce the content of residual monomers, and an optical film containing the same with improved optical properties and moisture permeability resistance. Improvement of the dope composition is necessary.

Prior Document 1: Republic of Korea Patent Publication No. 10-2018-34188A

One aspect of the present invention is to polymerize an acrylic polymer, modify it to form a grutaric anhydride group through intra ring formation inside the acrylic resin by applying heat history, and then form a grutaric anhydride group through intra ring formation inside the acrylic resin. By preparing a mixed dope solution of acrylic rubber particles and manufacturing an optical film through solution casting, an acrylic optical film with improved moisture resistance, transparency, mechanical strength, and adhesion to a polarizing film is provided.

Another aspect of the present invention is to provide an acrylate-based dope solution that reduces the content of unreacted monomers and has excellent transparency and heat resistance.

Another aspect of the present invention seeks to provide an optical film using the acrylate-based copolymer.

One aspect of the present invention provides an acrylic optical film manufactured by a solvent casting method using a composition containing an acrylic modified polymer and acrylic rubber modified with a hexagonal anhydride structure in the molecular chain.

Another aspect of the present invention includes the steps of a) applying a dope solution prepared by mixing a composition containing an acrylic-based modified polymer and acrylic rubber modified with a hexagonal anhydride structure in the molecular chain in an organic solvent onto a support;

b) preparing an acrylic film by evaporating the organic solvent; and

c) peeling off the acrylic film from the support;

A method for manufacturing an acrylic optical film comprising a is provided.

The acrylic optical film according to one aspect of the present invention has excellent heat resistance, moisture resistance, transparency, and mechanical strength, and can provide an acrylic optical film with further improved adhesion to a polarizing film.

The acrylic optical film according to one aspect of the present invention has excellent film forming properties, low haze, high total light transmittance, excellent tensile strength, low moisture permeability of 60 g/m2·24hr or less, and peel-off property. It is possible to provide an acrylic optical film with improved film forming workability and processability.

Hereinafter, the present invention will be described in more detail through specific examples or examples including the attached drawings. However, the following specific examples or examples are only a reference for explaining the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

Additionally, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. The terminology used in the description herein is merely to effectively describe specific embodiments and is not intended to limit the invention.

Additionally, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to also include the plural forms, unless the context clearly dictates otherwise.

One aspect of the present invention provides an acrylic optical film manufactured by a solvent casting method using a composition containing an acrylic modified polymer and acrylic rubber modified with a hexagonal anhydride structure in the molecular chain.

The optical film may be a polarizer protective film or a retardation film.

The acrylic modified polymer may have a weight average molecular weight of 150,000 to 400,000 g/mol.

The optical film may have a moisture permeability of 60 g/m2·24hr or less.

The organic solvent may be a halogenated hydrocarbon alone or a halogenated hydrocarbon and one or a mixed solvent of two or more selected from esters, ketones, ethers, and alcohols.

The acrylic modified polymer of the optical film may have a ring formation ratio of glutaric anhydride structure of 80% or more and a glass transition temperature of 110°C or more.

The acrylic modified polymer may be manufactured from a monomer composition containing 5 to 20 parts by weight of (meth)acrylic acid and 2 to 10 parts by weight of alkyl (meth)acrylate, based on 100 parts by weight of methyl methacrylate.

The acrylic modified polymer may be manufactured by further comprising 1 to 10 parts by weight of styrene based on 100 parts by weight of methyl methacrylate.

The acrylic rubber may have a two- or three-layer structure including an acrylic rubber layer in the core layer or middle layer, and may have an average particle diameter of 100 to 400 nm.

The acrylic rubber may have a content of 10 to 50% by weight in the composition.

The composition may contain 10 to 50% by weight of an acrylic modified polymer and have a viscosity of 10,000 cps or more at 32°C.

The acrylic optical film may have a haze of 0.2% or less.

The acrylic optical film may have a film thickness of 10 to 150㎛ and a width of 2000mm or more.

The acrylic optical film may be stretched under conditions where the residual solvent in the film is 1 to 20%.

Another aspect of the present invention includes the steps of a) applying a dope solution prepared by mixing a composition containing an acrylic-based modified polymer and acrylic rubber modified with a hexagonal anhydride structure in the molecular chain in an organic solvent onto a support;

b) preparing an acrylic film by evaporating the organic solvent; and

c) peeling off the acrylic film from the support;

A method for manufacturing an acrylic optical film comprising a is provided.

After step c), a stretching step of uniaxial stretching or biaxial stretching and a drying step may be further included.

The stretching step may be performed under conditions where the residual solvent in the film is 1 to 20%.

The optical film may be a polarizer protective film or a retardation film.

Another aspect of the present invention is to provide a dope solution for an optical film containing (A) an acrylic modified polymer modified with a hexagonal anhydride structure in the molecular chain, (B) an acrylic rubber polymer, and (C) an organic solvent.

The acrylic modified polymer may be manufactured from a monomer composition containing 5 to 20 parts by weight of (meth)acrylic acid and 2 to 10 parts by weight of alkyl (meth)acrylate, based on 100 parts by weight of methyl methacrylate.

The alkyl (meth)acrylate specifically includes, for example, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, Any one or a mixture of two or more selected from isobornyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butylacrylate, t-butylacrylate, cyclohexyl acrylate, and isobornyl acrylate. It may be.

The acrylic-based modified polymer may further include 1 to 10 parts by weight of styrene-based monomer based on 100 parts by weight of methyl methacrylate. The styrene-based monomer may be any one or a mixture of two or more selected from styrene, α-methylstyrene, p-bromo styrene, p-methyl styrene, and p-chloro styrene.

As used herein, polymers include homopolymers or copolymers, and copolymers mean that elements referred to as monomers herein are polymerized and included as repeating units within a copolymer resin. May be a block copolymer or a random copolymer, but is not limited thereto.

In the present invention, the optical film provides an acrylic optical film that is a polarizer protective film or a retardation film, and the average degree of polymerization of the acrylic polymer of the optical film is preferably 150,000 to 400,000 before modification.

In addition, in the present invention, the acrylic modified copolymer modified with the glutaric acid anhydride group is obtained by mixing the prepared acrylic copolymer with a basic compound, for example, sodium hydroxide or potassium hydroxide, and then heating and extruding it in an extruder. , can be manufactured by inducing internal reformation.

The heating temperature during extrusion kneading and reforming is not particularly limited, but heat treatment is preferably performed at 150 to 350 ℃, preferably 200 to 300 ℃, and the content of the anhydride of the hexagonal ring or pentagonal ring of glutaric anhydride is specifically limited. However, when measuring the Ring Closed Ratio below, a value of 80% or more, preferably 100% or more, is good for controlling moisture permeability and obtaining transmittance and other excellent optical properties of the present invention.

In the present invention, the method of measuring the content of the dog disease can be calculated by measuring the absorption band of 1805 cm ^-1 described in GB 001437176, and the method of calculating the ring formation ratio can be calculated by the following formula.

Ring formation ratio = (amount of anhydride prepared (g))/content of (meth)acrylic acid component (g)) × 100

In one aspect of the present invention, the acrylic rubber is an acrylic rubber, and may be a copolymerized acrylic rubber prepared by including an alkyl (meth)acrylate monomer having 1 to 18 carbon atoms and a crosslinkable monomer.

However, when using a core-shell type acrylic rubber in which the core part is crosslinked and the shell is formed as a non-crosslinked polymerized layer, or a three-layer core-shell type acrylic rubber in which the core layer or/and the middle layer is crosslinked, Since the miscibility with the modified acrylic-based modified polymer, which is a matrix material, is increased to produce an optical film with better surface and optical properties, using an acrylic-based rubber in the form of a core-shell in which the outermost layer is non-crosslinked is significantly better than others. It is even better because it exhibits excellent surface properties, optical properties, and moisture permeability resistance.

Examples of the two-layer rubber include, but are not limited to, a copolymerized acrylic core made of an alkyl acrylate monomer having 1 to 18 carbon atoms and a crosslinkable monomer, and an alkyl meta having 1 to 18 carbon atoms on the outside of the core portion. As a shell layer containing acrylate monomer, the core and shell layers may be polymerized with different compositions, and the outer layer may be an acrylic rubber in the form of a non-crosslinked core-shell.

In addition, as an example of a rubber with a three-layer core-shield structure, a polymerizable rubber manufactured by crosslinking the core and middle layers and non-crosslinking the outermost layer can be used.

The alkyl methacrylate monomers include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, and lauryl methacrylate. Use at least one member selected from the group consisting of cyclohexyl methacrylate, stearyl methacrylate, 2-ethylhexyl methacrylate, and cyclohexyl methacrylate. Preferably it may be methyl methacrylate.

For polyfunctional monomers, for example allyl methacrylate, allyl acrylate, poly(ethylene glycol) diacrylate, poly(ethylene glycol) dimethacrylate, poly(propylene glycol) diacrylate, poly(propylene glycol) diacrylate. It may be one or more selected from methacrylate, poly(ethylene propylene glycol) diacrylate, and poly(ethylene propylene glycol) dimethacrylate, but the multifunctional monomer is not limited to the above.

Next, the dope solution of the present invention will be described.

The dope solution of the present invention is a dope solution for acrylic optical films with a solid content of 1 to 40% by weight, and the main components of the solid content include an acrylic modified polymer modified with glutaric anhydride (ring-forming) and an acrylic rubber. components, and the composition ratio of the modified polymer and the rubber component is not particularly limited in the present invention, but preferably 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the modified polymer. It is better in terms of physical properties such as optical properties and water resistance.

In the present invention, considering the processing characteristics, film forming properties, etc., the viscosity of the dope solution is more than 10,000 cps at 32°C, preferably 10,000 to 100,000 cps, which is better in terms of film forming properties and surface smoothness.

In the present invention, the solvent of the dope solution is not limited as long as it can dissolve or swell the acrylic modified polymer and acrylic rubber, for example, a halogenated hydrocarbon alone or a halogenated hydrocarbon and any selected from esters, ketones, ethers and alcohols. It is preferred to use one or more mixed solvents.

Next, the manufacturing method of the polarizing plate protective film of the present invention will be described in more detail.

In one aspect of the present invention, the polarizer protective film can be manufactured according to a conventional solvent cast method. To explain more specifically, the prepared dope solution is temporarily stored in a storage tank, and the bubbles contained in the dope solution are degassed.

The defoamed dope is sent from the dope outlet to the pressurized die through a pressurized constant-quantity gear pump that can deliver a fixed amount of liquid with high precision depending on the number of rotations, and the dope is transferred from the spinneret (slit) of the pressurized die onto a metal support that runs endlessly. By casting uniformly, the less dry casting film is peeled from the metal support at the peeling point where the metal support has traveled almost all the way.

Both ends of the produced web are clipped and conveyed by a tenter to dry while maintaining the width. Then, it is conveyed to the roller of a drying device, dried, and wound to a predetermined length by a winder. In addition, when manufacturing the casting film, it is possible to uniaxially stretch or biaxially stretch in the machine direction and the width direction after peeling while the residual solvent amount is 0 to 40% by weight, more specifically 0.1 to 20% by weight.

Alternatively, it is also possible to stretch the cast film off-line after production. The stretching of the film can be done in the machine direction or the width direction, or simultaneously or sequentially in two directions. The degree of elongation may be adjusted as needed, and may specifically range from 0 to 100%, for example, and may specifically range from 0.1 to 100%. In the above elongation, % means length%. For example, for a film with a length of 1 m before stretching, 100% elongation means being stretched to 2 m. Additionally, the step of additionally drying the film after stretching may be included. At this time, the drying temperature is not limited as long as it is a temperature at which the organic solvent can be completely dried, but is preferably 50 to 120°C.

The temperature during stretching is preferably ±10°C, which is the glass transition temperature (T _g ) of the acrylic polymer used in the dope solution. The space temperature when applying the solution is preferably -50°C to 50°C, more preferably -30°C to 40°C, and most preferably -20°C to 30°C. The dope solution applied at a low space temperature is instantly cooled on the support and the gel strength is improved, resulting in a film with a large amount of organic solvent remaining. Therefore, the film can be peeled off from the support in a short time without evaporating the organic solvent. The gas that cools the space can be ordinary air, nitrogen, argon, or helium. The relative humidity is preferably 0 to 70%, and more preferably 0 to 50%.

The temperature of the support to which the dope solution is applied is preferably -50 to 100°C, more preferably -30°C to 25°C, and most preferably 10°C to 25°C. In order to cool the casting part, cooled gas can be introduced into the casting part. A cooling device can also be placed in the casting to cool the space. In cooling, it is important to take care to prevent water from adhering to the casting. When cooling with gas, it is desirable to keep the gas dry.

The thickness of the optical film according to the present invention may be preferably in the range of 20 to 140 ㎛, more preferably in the range of 20 to 80 ㎛.

The polarizer protective film according to the present invention can be used not only for polarizers but also for optical films such as optical compensation sheets or optical filters for stereoscopic images, and can be used by stacking one or two or more sheets.

More specifically, the polarizing plate protective film of the present invention can be used as a protective film for a polarizing plate. An example of the polarizer of the present invention may be composed of a polarizer and two polarizer protective films that protect both sides thereof, and at least one of the protective films may be composed of the polarizer protective film of the present invention.

Additionally, the present invention also includes an image display device including the above polarizing plate within the scope of the present invention. For example, the display device may be a liquid crystal display device. The optical film of the present invention can be used in liquid crystal displays of various display modes, specifically, TN, IPS, FLC, AFLC, OCB, STN, ECB, VA, and HAN modes.

One aspect of the liquid crystal display device according to the present invention includes a liquid crystal cell; And it may include a polarizing plate disposed on at least one side of the liquid crystal cell. At this time, the polarizing plate is a polarizer; And it may include at least one layer of the polarizing plate protective film. Additionally, the optical compensation sheet may include an optically anisotropic layer on at least one side of the polarizer protective film, and the optically anisotropic layer may contain a hybrid alignment-treated disk-shaped compound.

The specifications of the optical film of the present invention can be manufactured by adjusting appropriately as needed, and are not particularly limited, but may be, for example, an acrylic optical film with a thickness of 10 to 150㎛ and a width of 2000mm or more.

In terms of the optical properties of the optical film of the present invention, a haze of 1.1 or less, preferably 1.0 or less, is preferred because it has excellent performance characteristics, and is an acrylic optical film stretched under conditions where the residual solvent in the film is 0.1 to 20%. It is generally recommended to manufacture the film by stretching it 1.1 to 3 times under conditions where the residual solvent in the film is 5 to 20%, but it is not limited to this.

The present invention will be described in more detail below based on examples and comparative examples. However, the following Examples and Comparative Examples are only one example to explain the present invention in more detail, and the present invention is not limited by the following Examples and Comparative Examples.

Hereinafter, the physical properties of the film of the present invention were measured using the following measurement method.

1. Glass transition temperature (T _g ): Measured using a differential scanning calorimeter (DSC) at a temperature increase of 10°C/min.

2. Weight average molecular weight: The prepared beads and film were dissolved in tetrahydrofuran and measured using gel osmosis chromatography (GPC). The weight average molecular weight was measured using gel permeation chromatography (GPC) equipment manufactured by Waters. The equipment consists of a mobile phase pump (M515 Pump), column heater (ALLCOLHTRB), detector (2414 R.I. Detector), and injector (2695 EB automatic injector). The analysis column used was Styragel HR from WATERS, and polymethyl methacryl was used as a standard material. PMMA American polymer standard corporation STD was used. HPLC grade tetrahydrofuran (THF) is used as the mobile phase solvent, and the measurement is performed under the conditions of a column heater temperature of 40°C and a mobile phase solvent flow rate of 1.0 mL/min. The copolymer prepared for sample analysis was dissolved in tetrahydrofuran (THF), a mobile phase solvent, and then injected into GPC equipment to measure the weight average molecular weight.

3. Phase difference: The phase difference of the produced film was measured using a birefringence meter (Axoscan, Axometrics), and the measurement wavelength was 550 nm.

4. Haze and light transmittance: Measured according to ASTM1003 method.

5. Tensile strength: Measured according to the ASTM D638 test method using a universal testing machine (UTM, Zwick).

6. Moisture permeability: Using a moisture permeability meter (LabThink, PERME (W3/0120)), the temperature applied to the film specimen in the sealed chamber was 38°C, RH (relative humidity) of the external cell was 90%, and N ₂ carrier gas was measured. The moisture permeated from the outer cell through the film to the inner cell was measured over a period of 24 hours.

7. Coating adhesion: The coated surface on the film was cut to create a total of 100 squares, 10 horizontal and 10 vertical, and then the degree of adhesion of the coating layer was evaluated by attaching and detaching 3M tape. Here, if there are more than 95 left, it is good, if there are more than 85, it is average, and if there are less than 85, it is bad.

8. Smoothness: Film thickness was measured at 50mm intervals across the entire width, and the value was obtained as the difference between the maximum and minimum values. The film thickness was measured using a Micrometer measuring device from Mahr, Germany.

9. Foreign matter inspection: Foreign substances such as dust, as well as unmelted black and white spots, were detected, and the running film after manufacturing was measured using NextEye's film inspection device. It is expressed as the number of foreign objects per 1M in the longitudinal direction of the film, and if 1 foreign object occurs during 10M driving, it is expressed as 0.1 objects/1M.

10. Viscosity: After preparing the dope solution at 25°C, the viscosity was measured using the falling ball method. Brookfield's falling ball viscometer Model KF40 was used, and measurement was performed using ball number 6.

11. Peel-off property: After casting the dope solution on the surface of a metal belt, drying the residual solvent in the film to 2% by weight, peeling the film was evaluated as follows.

Excellent: The film surface is smooth and peels off easily.

Normal: When the film is peeled, it peels off without breaking.

Bad: A crackling sound is heard when the film is peeled, and some breakage occurs.

[Preparation Example 1] Preparation of acrylic rubber

In the first step, 1500 g of distilled water was added to a 5L reactor, purged with nitrogen, and the temperature was raised to 80°C. 0.002 g of ferrous sulfate, 0.008 g of EDTA ₂ Na salt, and 0.2 g of sodium formaldehyde sulfoxylate were added to the reactor and stirred. 200 g of methyl methacrylate, 6.0 g of 1,3 butanediol dimethacrylate as a cross-linking agent, 0.7 g of allyl methacrylate as a grafting agent, 6 g of sodium polyoxyethylene alkyl ether phosphate as an emulsifier, and 0.5 g of tertiary butyl peroxide as an initiator. The mixed solution was added dropwise over 2 hours and then emulsion polymerized at 80°C for 1 hour while stirring at 500 rpm. The average particle size of the glass-like seed particles obtained at this time was 180 nm.

In the second step, following the glass seed particles prepared in the first step, 1.0 g of sodium formaldehyde sulfoxylate was dissolved in 20 g of distilled water and added into the reactor.

Here, 250 g of butylacrylate, 55 g of styrene, 5 g of allyl methacrylate as a graft agent, 1 g of 1,3-butanediol dimethacrylate as a cross-linking agent, 1 g of cumene hydroperoxide, and polyoxyethylene alkyl ether phosphate. A mixed solution containing 10 g of sodium was added dropwise over 3 hours and polymerized at 80°C for 2 hours. The average particle size of the polymer obtained at this time was 250 nm.

Finally, in step 3, 1 g of sodium formaldehyde sulfoxylate was added while maintaining the temperature at 80°C, followed by 285 g of methyl methacrylate, 15 g of methyl acrylate, 1 g of n-octyl mercaptan, and tertiary butyl peroxide. 0.5 g of the mixed solution was added dropwise over 2 hours and polymerized at 80°C for 1 hour. The average particle size of the final polymer, acrylic rubber, obtained at this time was 280 nm.

[Production Example 2]

2700 g of water and 0.3 g of 2,2-azobis(2-amidinopropane)dihydrochloride were added to a three-necked flask with a condenser, and 180 g of the compound of the following formula (1) (62.1% by weight of solid content) under a nitrogen atmosphere. 40 g of the compound of the following formula (2) (13.8 wt% of solid content) and 70 g of methyl methacrylate (25 wt% of solid content) were added and reacted at 60°C for 6 hours to obtain an aqueous polymer solution with a solid content of 5 wt%. The weight average molecular weight of the prepared dispersant was 2,000,000 g/mol.

[Formula 1]

In Formula 1, R ₁ is methyl, n is 1, and M is sodium.

[Formula 2]

In Formula 2, R ₂ is methyl and M is potassium.

[Examples 1 to 6]

<Manufacture of acrylic copolymer and modified copolymer>

In a 5-liter reactor, 2000 g of distilled water, the suspension polymerization dispersant with a solid content of 4% by weight prepared in Preparation Example 2 with a weight average molecular weight of 1,720,000 g/mol, 12g of an aqueous solution with a solid content of 5% by weight, and 6g of sodium sulfate as a dispersion aid were added. It was added and dissolved. The types and contents of monomers were added as described in [Table 1], and n-octyl mercaptan was added as an initiator and chain transfer agent, and then dispersed in the aqueous phase while stirring at 400 rpm to prepare a suspension. The suspension was polymerized at 80°C for 1 hour and 20 minutes, heated to 105°C and further polymerized for 30 minutes, and then cooled to 30°C. The beads obtained from the polymerization reaction were washed and dehydrated repeatedly with distilled water, and then dried.

Next is the glutaric anhydride modification step, in which 0.03 parts by weight of sodium hydroxide is mixed with a Henschel mixer based on 100 parts by weight of the beads, then kneaded in a compressor at 280°C and 50 rpm to pelletize, and the results are analyzed. It is listed in Table 1.

<Preparation of dope solution>

21% by weight of the acrylic polymer beads prepared above, 9% by weight of the acrylic rubber prepared in Preparation Example 1, and 70% by weight of a mixed solvent containing methylene chloride and methanol in a 9:1 weight ratio were mixed, and 100 parts by weight of the mixed solution was mixed. In contrast, a dope solution was prepared by adding 3 parts by weight of Tinuvin 918 from Ciba Specialty as an ultraviolet absorber.

<Manufacture of film>

The dope solution was extruded into a sheet with a thickness of 400 μm and a width of 800 mm on the surface of a metal belt at 20°C using a die. While rotating the metal belt, the solvent in the casting solution was evaporated and peeled off. The amount of residual solvent in the film upon peeling was 1.5% by weight. After peeling, it was stretched 1.5 times in the transverse direction and dried at 150°C to prepare a film with a total thickness of 40㎛. As a result of measuring the physical properties of the manufactured film, as can be seen in Table 2, it was found that the optical properties were excellent, and in particular, it had a significant synergistic effect in moisture permeability.

[Comparative Example 1]

In Example 2, the same procedure as Example 2 was performed, except that an acrylic copolymer obtained before modification of glutaric anhydride was used. The results are listed in Table 2.

[Comparative Example 2]

The same procedure as Example 1 was carried out, except that acrylic rubber was not used. The results are listed in Table 2.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative example 2 monomer content
(g) MMA 850 750 700 750 700 850 750 850 M.A.A. 100 100 150 150 200 100 100 100 Styrene - 100 100 - - - 100 - n-BMA 50 50 50 100 100 50 50 50 initiator
(g) Luperox
575 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 chain transfer agent
(g) n-OM 1.2 1.2 1.2 1.2 1.2 0.8 1.2 1.2 polymer
Properties Tg(℃) 119.1 116.5 120.8 117.4 121.3 119.2 117.0 119.4 Mw(k) 255 265 280 295 270 326 273 230 reformation
Acrylic polymer
Properties Tg(℃) 115.5 111.5 114.0 113.5 116.7 116.0 Not implemented 116.4 Ring Closing Ratio(%) 152 161 171 165 169 158 - 155 Solid content in dope solution
weight% 30 30 30 30 30 30 30 - Viscosity of dope solution cps, 32℃ 11,100 12,000 12,500 14,100 13,700 14,000 22,000 2,300

MMA: Methyl methacrylate

MAA: Methacrylic acid

Styrene: Styrene

MA: Methyl acrylate

Luperox575: t-amyl peroxy 2-ethyl hexanoate

Chain transfer agent: n-octylmercaptan

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 comparison
Example 1 comparison
Example 2 film unveiling possible possible possible possible possible possible possible impossible R _in /R _th
(nm) 0.6/
-1.2 0.7/
-2.5 0.6/
-3.1 0.5/
-1.8 0.3/
-2.0 0.6/
-1.5 3.2/
-6 - Haze (%) 0.9 0.8 1.0 1.0 1.1 0.9 1.7 - △Hayes 0.1 0.1 0.1 0.1 0.1 0.1 0.3 - light transmittance
(%) 91.1 90.2 90.7 91.4 91.0 90.8 88.6 - tensile strength
(GPa) 2.1 2.0 2.0 2.1 2.2 2.3 1.8 - moisture permeability
(g/㎡·24hr) 58 57 53 57 52 56 88 - Adhesion Good Good Good Good Good Good Good - Foreign matter inspection 0.1 0.1 0.1 0.1 0.1 0.1 0.1 - peel-off Great Great commonly Great commonly commonly bad -

As described above, the present invention has been described with specific details and limited embodiments, but these are provided only to facilitate a more general understanding of the present invention, and the present invention is not limited to the above embodiments, and the field to which the present invention pertains is not limited to the above embodiments. Those skilled in the art can make various modifications and variations from this description.

Accordingly, the idea of the present invention should not be limited to the described embodiments, and the scope of the patent claims described later as well as all things that are equivalent or equivalent to the scope of the claims will be said to fall within the scope of the idea of the present invention.

Claims (18)

An acrylic optical film manufactured by a solvent casting method using a composition containing an acrylic modified polymer and acrylic rubber modified with a hexagonal anhydride structure in the molecular chain. According to clause 1,
The optical film is an acrylic optical film that is a polarizer protective film or a retardation film. According to clause 1,
The acrylic modified polymer has a weight average molecular weight of 150,000 to 400,000. Acrylic optical film with g/mol. According to clause 1,
The optical film is an acrylic optical film with a moisture permeability of 60g/㎡·24hr or less. According to clause 1,
The organic solvent is an acrylic optical film that is a halogenated hydrocarbon alone or a mixed solvent of one or two or more halogenated hydrocarbons and esters, ketones, ethers, and alcohols. In paragraph 1
The acrylic modified polymer of the optical film has a ring formation ratio of glutaric anhydride structure of 80% or more and a glass transition temperature of 110°C or more. In paragraph 1
The acrylic modified polymer is an acrylic optical film manufactured from a monomer composition containing 5 to 20 parts by weight of (meth)acrylic acid and 2 to 10 parts by weight of alkyl (meth)acrylate, based on 100 parts by weight of methyl methacrylate. According to clause 7,
The acrylic modified polymer is an acrylic optical film manufactured by further comprising 1 to 10 parts by weight of styrene based on 100 parts by weight of methyl methacrylate. According to clause 1,
The acrylic rubber has a two- or three-layer structure including an acrylic rubber layer in the core layer or middle layer, and has an average particle diameter of 100 to 400 nm. According to clause 9,
The acrylic rubber is an acrylic optical film whose content in the composition is 10 to 50% by weight. According to clause 1,
The composition is an acrylic optical film containing 10 to 50% by weight of an acrylic modified polymer and having a viscosity of 10,000 cps or more at 32°C. According to clause 1,
The acrylic optical film is an acrylic optical film with a haze of 0.2% or less. According to clause 1,
The acrylic optical film has a film thickness of 10 to 150㎛ and a width of 2000mm or more. According to clause 1,
The acrylic optical film is an acrylic optical film stretched under conditions where the residual solvent in the film is 1 to 20%. a) applying a dope solution prepared by mixing a composition containing an acrylic-based modified polymer and acrylic-based rubber modified with a hexagonal anhydride structure in the molecular chain into an organic solvent onto a support;
b) preparing an acrylic film by evaporating the organic solvent; and
c) peeling off the acrylic film from the support;
A method of manufacturing an acrylic optical film comprising. According to clause 15,
After step c), the method of producing an acrylic optical film further includes a stretching step of uniaxial stretching or biaxial stretching and a drying step. According to clause 16,
The stretching step is a method of manufacturing an acrylic optical film, wherein the stretching step is performed under conditions where the residual solvent in the film is 1 to 20%. According to clause 15,
The optical film is a polarizer protective film or a retardation film. A method of manufacturing an acrylic optical film.