KR102166417B1 - Acrylic optical film and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an acrylic optical film and a method of manufacturing the same. More specifically, it relates to an acrylic optical film manufactured by a solvent casting method and a method of manufacturing the same. In addition, the present invention relates to a solvent casting dope solution for manufacturing the acrylic optical film.

Description

Acrylic optical film and manufacturing method thereof

The present invention relates to an acrylic optical film and a method of manufacturing the same. More specifically, it relates to an acrylic optical film manufactured by a solvent casting method and a method of manufacturing the same. In addition, the present invention relates to a solvent casting dope solution for manufacturing the acrylic optical film.

With the recent development of optical technology, liquid crystal displays are required to be thinner, lighter, and larger in the display industry, and technologies such as wide viewing angle, high contrast, uniform screen display and suppression of image change depending on the viewing angle are particularly important issues. Has become.

Various polymer films such as a polarizing film, a polarizing plate protective film, a retardation film, a light guide plate, and a plastic substrate are used in such display devices, and the required characteristics of such display polymer materials are becoming more advanced.

Cellulose ester films have been used for photography or as various optical materials because of their high strength and flame retardancy. In particular, a cellulose acylate film has been widely used as an optical transparent film for a liquid crystal display device because it has high optical transparency and optical isotropy. For example, in a polarizing plate, which is one of the optical films constituting a liquid crystal display, a cellulose acylate film that can be directly bonded to a polarizer, polyvinyl alcohol (PVA), in particular, a triacetyl cellulose film is laminated on both sides of the polarizer. It is mainly used as a polarizing plate protective film which is a film. In addition, it can be stretched under appropriate conditions and used as an optical compensation film.

However, when the cellulose ester film is molded into a thin film, it is generally poor in moisture permeability, causing a problem in storage stability due to expansion. In particular, the decrease in durability in a high-temperature and high-humidity environment greatly affects the deterioration of the function of the LCD Go crazy. In addition, there is a problem of lowering the strength and surface hardness of the film due to thinning.

In order to overcome the above problems, research for manufacturing an optical film using an acrylic polymer is being conducted. In Korean Patent Application Publication No. 10-2015-0039089 filed by the present applicant, a resin composition for an optical film including an acrylic copolymer and an optical film manufactured using the same are described. The above patent relates to a resin composition for an optical film for manufacturing an optical film by a melt extrusion method, but when the composition is manufactured by a solution casting method, film formation is difficult and peel-off is not good, so it is poor. This happens.

Korean Patent Publication No. 10-2015-0039089 (2015.04.09.)

An object of the present invention is to provide an acrylic optical film having excellent heat resistance and low moisture permeability under high-temperature, high-humidity conditions as compared to conventional cellulose acylate resins. More specifically, there is an object to provide an acrylic optical film for use as a polarizing plate protective film or a retardation film.

In addition, an object of the present invention is to provide an acrylic optical film that is manufactured by a solvent casting method and has excellent smoothness, has a uniform thickness over the entire width of the film, has a low haze, and has a uniform haze over the entire width of the film.

In addition, the present invention can further shorten the film forming time of the film by increasing the drying speed of the solvent in forming a film by the solvent casting method, thereby further improving the productivity. When the film is peeled off, local residues are not left and the width is An object of the present invention is to provide a dope solution capable of easily forming a film having a width of 2000 mm or more and a method of manufacturing an acrylic optical film using the same.

In addition, the present invention improves productivity by increasing the drying speed of the solvent and increases the molecular weight of the acrylic resin to the maximum molecular weight that can be polymerized, thereby enhancing the mechanical properties of the optical film and mixing a low molecular weight acrylic resin in a certain ratio. It is an object to further improve film processability by preparing a solution to provide an optical film having a uniform film thickness.

As a result of research in order to achieve the above object, it was found that by mixing and using two types of acrylic polymers having different molecular weights from each other, it was possible to solve the problem of molecular weight non-uniformity occurring during the production of acrylic polymers. That is, it was found that the viscosity of the dope solution can be uniformly prepared, and accordingly, a film of uniform quality can be prepared. In addition, it was found that by using the monomers in a specific combination in the manufacture of acrylic polymers, the drying speed of the solvent during film formation was improved, further improving the productivity of the film, and the film formation was possible by the solvent casting method, and an acrylic optical film having excellent physical properties was found. Thus, the present invention was completed.

More specifically, in order to achieve the above object, as an aspect of the present invention, it is prepared including methyl methacrylate and a heat-resistant monomer, and has a glass transition temperature of 120° C. or higher, and a weight average molecular weight of 80,000 to 200,000 g/mol. Polymethyl methacrylate resin (A) 10 to 40% by weight and methyl methacrylate, C4 to C8 alkyl (meth) acrylate and a heat-resistant monomer are included, the glass transition temperature is 110 ℃ or more, the weight average A bimodal polymethyl methacrylate resin mixture containing 60 to 90% by weight of a polymethylmethacrylate resin (B) having a molecular weight of 1,000,000 to 4,000,000 g/mol, a dope solution containing a core-shell rubber and an organic solvent is used. Thus, it is manufactured by a solvent casting method and provides an acrylic optical film having a thickness deviation of less than 5%.

In addition, as an aspect of the present invention, a) a polymethyl methacrylate resin comprising methyl methacrylate and a heat-resistant monomer, and having a glass transition temperature of 120° C. or higher, and a weight average molecular weight of 80,000 to 200,000 g/mol (A) 10 to 40% by weight and methyl methacrylate, a C4 to C8 alkyl (meth) acrylate and a heat-resistant monomer prepared, the glass transition temperature is 110 ℃ or more, the weight average molecular weight 1,000,000 to 4,000,000 g A bimodal polymethyl methacrylate resin mixture containing 60 to 90% by weight of a polymethyl methacrylate resin (B) of /mol, a dope solution containing a core-shell rubber and an organic solvent is applied to the support through a die Step to do;

b) evaporating the organic solvent and peeling the acrylic film from the support; And

c) a stretching step of uniaxially stretching or biaxially stretching the acrylic film;

It provides a method of manufacturing an acrylic optical film comprising a.

In addition, in an aspect of the present invention, a polymethyl methacrylate resin (A) is prepared including methyl methacrylate and a heat-resistant monomer, has a glass transition temperature of 120° C. or higher, and a weight average molecular weight of 80,000 to 200,000 g/mol (A ) 10 to 40% by weight and methyl methacrylate, C4 to C8 alkyl (meth) acrylate and a heat-resistant monomer are included, the glass transition temperature is 110 ℃ or more, the weight average molecular weight 1,000,000 to 4,000,000 g/mol It provides a dope solution for solvent casting containing a bimodal polymethyl methacrylate resin mixture containing 60 to 90% by weight of phosphorus polymethyl methacrylate resin (B), a core-shell rubber, and an organic solvent.

The dope solution containing the acrylic polymer according to the present invention has physical properties suitable for manufacturing an acrylic optical film by a solvent casting method, and by controlling the drying speed of the solvent more quickly, from application of the dope solution to drying of the solvent and peeling of the coating film. There is an effect that can further shorten the time required. Therefore, there is an effect that productivity can be improved by making the film production speed faster.

In addition, since the dope solution containing the acrylic polymer according to the present invention has a high drying speed of the solvent and excellent heat resistance and mechanical properties, there is an effect of easily manufacturing a wide film. More specifically, there is an effect that a wide film having a width of 2000mm or more can be easily manufactured. More specifically, in manufacturing a wide-width film, there is an effect of manufacturing a film having a uniform haze and a uniform thickness with respect to the entire width of the film. In addition, when the film is peeled from the support after film formation, no residue remains on the support, and thus there is an effect of minimizing defects.

In addition, the acrylic optical film manufactured using the dope solution according to the present invention has low moisture permeability, high heat resistance, excellent smoothness, and has an effect of having a small number of foreign matters. Accordingly, it is possible to provide a film suitable for use as a polarizing plate protective film or a retardation film.

In addition, the dope solution containing the acrylic polymer according to the present invention is easy to adjust the viscosity, and thus there is an effect of achieving productivity and uniformity of film properties during film production.

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

In addition, 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 belongs. The terms used in the description in the present invention are merely intended to effectively describe specific embodiments and are not intended to limit the present invention.

In addition, the singular form used in the specification and the appended claims may be intended to include the plural form unless otherwise indicated in the context.

In the present invention, the polymer includes a homopolymer or a copolymer, and the term “copolymer” means that an element referred to as a monomer in the present invention is polymerized and included as a repeating unit in the copolymer resin, and in the present invention, the copolymer May be a block copolymer or a random copolymer, but is not limited thereto.

One aspect of the present invention is an acrylic optical film, a polymethyl methacrylate resin prepared including methyl methacrylate and a heat-resistant monomer, a glass transition temperature of 120° C. or higher, and a weight average molecular weight of 80,000 to 200,000 g/mol (A) 10 to 40% by weight and methyl methacrylate, a C4 to C8 alkyl (meth) acrylate and a heat-resistant monomer prepared, the glass transition temperature is 110 ℃ or more, the weight average molecular weight 1,000,000 to 4,000,000 g /mol polymethyl methacrylate resin (B) by a solvent casting method using a bimodal polymethyl methacrylate resin mixture containing 60 to 90% by weight, a core-shell rubber, and a dope solution containing an organic solvent. It is manufactured, and the thickness deviation may be within 5%.

In one aspect, the optical film may be a polarizing plate protective film or a retardation film.

In one aspect, the resin (A) is based on 100 parts by weight of a monomer mixture containing 90 to 98% by weight of methyl methacrylate and 2 to 10% by weight of a heat-resistant monomer, 0.1 to 0.4 parts by weight of a chain transfer agent and 0.01 to 0.5 of an initiator It may be a polymer prepared including parts by weight.

In one aspect, the resin (B) is 100% by weight of a monomer mixture comprising 75 to 89% by weight of methyl methacrylate, 10 to 20% by weight of C4 to C8 alkyl (meth)acrylate, and 1 to 10% by weight of a heat-resistant monomer With respect to parts, it may be a polymer prepared including 0.01 to 0.5 parts by weight of an initiator.

In one aspect, the heat-resistant monomer may be any one or a mixture of two or more selected from acrylic acid, methacrylic acid, acid anhydride, styrene-based monomer, and maleimide-based monomer.

In one aspect, the dope solution may include 10 to 40% by weight of the bimodal polymethyl methacrylate resin mixture and 1 to 40% by weight of the core-shell rubber, and may have a viscosity of 10,000 cps or more at 32°C.

In one aspect, the organic solvent may be a halogenated hydrocarbon alone or a halogenated hydrocarbon and any one or two or more mixed solvents selected from esters, ketones, ethers and alcohols.

In one aspect, the dope solution may further contain polycarbonate.

In one aspect, the core-shell rubber has a two-layer or three-layer structure including an acrylic rubber layer in a core layer or an intermediate layer, and may have an average particle diameter of 100 to 400 nm.

In one aspect, the acrylic optical film may have a moisture permeability of 200 g/m²·24hr or less, a number of foreign matters of 0.3/1M or less, and a haze of 2% or less.

In one aspect, the acrylic optical film may have a film thickness of 10 to 150 μm.

In one aspect, the acrylic optical film may be stretched under the condition that the residual solvent in the film is 5 to 20% by weight.

Another aspect of the present invention is a method of manufacturing an acrylic optical film, a) prepared by including methyl methacrylate and a heat-resistant monomer, a glass transition temperature of 120° C. or higher, and a weight average molecular weight of 80,000 to 200,000 g/mol. Polymethyl methacrylate resin (A) 10 to 40% by weight and methyl methacrylate, C4 to C8 alkyl (meth) acrylate and a heat-resistant monomer are included, the glass transition temperature is 110 ℃ or more, the weight average A bimodal polymethyl methacrylate resin mixture containing 60 to 90% by weight of a polymethylmethacrylate resin (B) having a molecular weight of 1,000,000 to 4,000,000 g/mol, a core-shell rubber, and a dope solution containing an organic solvent are distilled. Applying on the support through;

b) evaporating the organic solvent and peeling the acrylic film from the support; And

c) a stretching step of uniaxially stretching or biaxially stretching the acrylic film;

It may be to include.

In one aspect, in the step b), when the residual solvent of the acrylic film is 5 to 20% by weight, the film is peeled off, and the film is produced within 5 minutes from the application in the a) step to the peeling in the step b). have.

In one aspect, the optical film may be a polarizing plate protective film or a retardation film.

In one aspect, the stretching step may be stretching 1.1 to 4 times under the condition that the residual solvent in the film is 5 to 20%.

In one aspect, the dope solution may further contain polycarbonate.

In one aspect, when the dope solution containing the core-shell rubber is applied on the support, the viscosity change rate of the dope solution may be performed within a range of 20% or less.

Another aspect of the present invention is a dope solution for solvent casting, prepared including methyl methacrylate and a heat-resistant monomer, and having a glass transition temperature of 120° C. or higher, and a weight average molecular weight of 80,000 to 200,000 g/mol. A acrylate resin (A) 10 to 40% by weight and methyl methacrylate, C4 to C8 alkyl (meth) acrylate and a heat-resistant monomer are included, the glass transition temperature is 110 ℃ or more, the weight average molecular weight is 1,000,000 It may include a bimodal polymethyl methacrylate resin mixture, a core-shell rubber, and an organic solvent including 60 to 90% by weight of a polymethylmethacrylate resin (B) of 4,000,000 g/mol.

In one aspect, the dope solution may further contain polycarbonate.

In one aspect, the dope solution may include 10 to 40% by weight of the bimodal polymethyl methacrylate resin mixture and 1 to 40% by weight of the core-shell rubber, and may have a viscosity of 10,000 cps or more at 32°C.

Hereinafter, each configuration of the present invention will be described in more detail.

The acrylic optical film according to the present invention is manufactured by a solvent cast method using a dope solution. In the solvent casting method, a dope solution in which a resin is dissolved in an organic solvent is cast on a support, and the organic solvent is evaporated to form a film. If necessary, the film thus prepared may be stretched with a stretching machine to prepare a film as a final product.

When preparing a film by the solvent casting method, if the viscosity of the dope solution is too low or too high, it may be difficult to cast the dope solution on the support, so that the film may not be produced.In addition, the organic solvent used in the dope solution may be evaporated. If conditions such as time and evaporation temperature do not match the properties of the resin used in the dope solution, the organic solvent may not be sufficiently dried and the film may not be peeled off the support, or a residue may remain after peeling, resulting in contamination.

The inventors of the present invention have studied to prepare an acrylic optical film by a solvent casting method, and as a result, by mixing and using two types of acrylic polymers having a specific molecular weight and having different molecular weights, the acrylic polymer of the largest molecular weight that can be produced by polymerization The furnace can improve the physical properties of the film, and with the relatively low molecular weight acrylic polymer, the desired viscosity and the glass transition temperature of the film can be easily adjusted as desired, thereby improving the film processability and solving the problem of viscosity unevenness. Found that you can. In addition, productivity can be further improved by further shortening the evaporation time of the organic solvent, and contamination does not occur because no residue is left during peeling, and thickness uniformity and haze uniformity over the entire width even when manufactured as a wide film. The present invention was completed by discovering that it is excellent and can provide an optical film having excellent heat resistance and mechanical properties.

Specifically, the present invention uses a bimodal polymethyl methacrylate resin mixture having different molecular weights as an acrylic polymer. Hereinafter, in the present invention, the “acrylic polymer” refers to the bimodal polymethyl methacrylate resin mixture.

More specifically, a polymethyl methacrylate resin (A) having a glass transition temperature of 120° C. or higher and a weight average molecular weight of 80,000 to 200,000 g/mol and a glass transition temperature of 110° C. or higher, and a weight average molecular weight of 1,000,000 to 4,000,000 g It is characterized by mixing /mol polymethyl methacrylate resin (B).

More specifically, 10 to 40% by weight of a polymethyl methacrylate resin (A) having a glass transition temperature of 120° C. or higher, and a weight average molecular weight of 80,000 to 200,000 g/mol and a glass transition temperature of 110° C. or higher, and a weight average It is characterized by mixing 60 to 90% by weight of polymethyl methacrylate resin (B) having a molecular weight of 1,000,000 to 4,000,000 g/mol. In the above molecular weight and content range, when preparing a dope solution, it has a viscosity suitable for application to the solvent casting method when preparing a dope solution, and it is preferable because it is easy to peel the film from the support after the film is prepared. If the content of the resin (A) is less than 10% by weight, the viscosity is too high, making film processing impossible or impossible to prepare a dope solution, and if it exceeds 40% by weight, it is difficult to form the film due to a decrease in viscosity, and the mechanical strength of the film decreases. When the content of the resin (B) is less than 60% by weight, it is difficult to obtain the desired mechanical strength of the film, and when the content of the resin (B) is more than 90% by weight, the viscosity is too high or the dope solution cannot be prepared because it is not dissolved in a solvent.

More specifically, 10 to 40 weight of a polymethyl methacrylate resin (A) prepared including methyl methacrylate and a heat-resistant monomer and having a glass transition temperature of 120° C. or higher and a weight average molecular weight of 80,000 to 200,000 g/mol % And methyl methacrylate, C4 ~ C8 alkyl (meth) acrylate and a heat-resistant monomer. Polymethyl methacrylate having a glass transition temperature of 110 °C or higher and a weight average molecular weight of 1,000,000 to 4,000,000 g/mol It is characterized by mixing 60 to 90% by weight of the rate resin (B).

The bimodal polymethyl methacrylate resin mixture has a viscosity of 10,000 at 32° C. when mixed with an organic solvent so that the solid content of the acrylic polymer is 10 to 40% by weight within a range that satisfies the weight average molecular weight and glass transition temperature. cps or more, specifically 10,000 ~ 60,000 cps, more specifically 20,000 ~ 40,000 cps can be prepared a dope solution.

It is possible to cast a uniform thickness on the support in the range of the solid content and viscosity, and can be dried at a relatively high temperature when drying the organic solvent after casting on the support, so that a smooth and easy to peel optical film can be prepared within a short time. desirable. If the solid content is higher than the above range, the content of the solvent is relatively reduced, so even if the viscosity is satisfied, it is not easy to apply the dope solution when casting to the film support, and clogging of the nozzle may occur. In addition, when the solid content is lower than the above range, the amount of the solvent is relatively large, so that a lot of energy is required for drying the organic solvent, and it may be difficult to manufacture a smooth optical film.

In one aspect of the present invention, the polymethyl methacrylate resin (A) is based on 100 parts by weight of a monomer mixture containing 90 to 98% by weight of methyl methacrylate and 2 to 10% by weight of a heat-resistant monomer, 0.1 to 0.1 to a chain transfer agent. It may be a polymer prepared including 0.4 parts by weight and 0.01 to 0.5 parts by weight of an initiator.

The heat-resistant monomer is not limited as long as it is a monomer for controlling the glass transition temperature of the polymethyl methacrylate resin (A) to 120° C. or higher, but more specifically, for example, acrylic acid, methacrylic acid, acid anhydride, styrene-based monomer And it may be any one or a mixture of two or more selected from maleimide-based monomers. In addition, the content of the heat-resistant monomer is not limited as long as it is an amount for adjusting the glass transition temperature to 120° C. or higher, but may be more preferably 2 to 10% by weight.

More preferably, as the heat-resistant monomer, a styrene-based monomer and a maleimide-based monomer may be mixed and used, and more specifically, 20 to 30: 70 to 80 by weight may be mixed and used. In the content range, a film having excellent optical properties and excellent heat resistance and mechanical strength can be prepared, so it is preferable, but is not limited thereto. In addition, by mixing and using a styrene-based monomer and a maleimide-based monomer in the above range, the effect of improving the polymerization efficiency between each monomer can be expected to reduce the residual monomer contained in the prepared copolymer, and improve heat resistance. An acrylic polymer having low moisture permeability can be obtained.

The acid anhydride may be specifically, for example, any one or a mixture of two or more selected from maleic anhydride and glutaric anhydride.

The styrene-based monomer may be specifically, for example, any one or a mixture of two or more selected from styrene, α-methylstyrene, p-bromo styrene, p-methyl styrene and p-chloro styrene.

Specifically, the maleimide-based monomer is, for example, phenylmaleimide, nitrophenylmaleimide, monochlorophenyl maleimide, dichlorophenyl maleimide, monomethylphenyl maleimide, dimethylphenyl maleimide, ethylmethylphenyl maleimide, and cyclohexyl It may be any one selected from maleimide or a mixture of two or more.

In addition to this, if necessary, a comonomer may be further included in order to adjust the physical properties of the acrylic polymer. The comonomer may be any one or a mixture of two or more selected from methyl acrylate, ethyl acrylate, isopropyl acrylate, ethyl methacrylate, and isopropyl methacrylate. By further including methyl acrylate, it is possible to further improve thermal decomposition and further improve flowability.

In one aspect, when preparing the polymethyl methacrylate resin (A), polymerization may be performed in the presence of an initiator and a chain transfer agent. More specifically, the initiator may be used without limitation as long as it is an organic peroxide initiator, and specifically, for example, t-butylperoxy-2-ethylhexanoate, t-amylperoxy- 2-ethylhexanoate (t-amylperoxy-2-ethylhexanoate), 1,1-bis (t-butylperoxy)-3,3,5-trimethyl cyclohexane (1,1-bis (t-butylperoxy)- 3,3,5-trimethyl cyclohexane), 1,1-bis (t-butyl peroxy) cyclohexane (1,1-bis (t-butylperoxy) cyclohexane), 1,1-bis (t-butyl peroxy) -2-methyl cyclohexane (1,1-bis (t-butylperoxy)-2-methyl cyclohexane), 2,2-bis (4,4-di-t-butylperoxy cyclohexyl) propane (2,2- bis(4,4-di-t-butylperoxy cyclohexyl)propane), 1,1-di-(t-amylperoxy) cyclohexane (1,1-di-(t-amylperoxy) cyclohexane), lauryl peroxide (lauroyl peroxide) and mixtures thereof, and the like, but are not limited thereto. The initiator may be included in an amount of 0.01 to 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight, based on 100 parts by weight of the total monomer content. The desired molecular weight can be obtained in the above range, and it is preferable because it is easy to control the reaction heat of the reactor.

The chain transfer agent may be used without limitation as long as it is a compound clearly known in the art, and specifically, for example, a C ₁ to C ₁₂ alkyl mercaptan having one thiol functional group or a poly having two or more thiol functional groups Thiol mercaptan can be used. Specifically, for example, isopropyl mercaptan, normal butyl mercaptan, tertiary-butyl mercaptan, tertiary-dodecyl mercaptan, normal-aryl mercaptan, normal-octyl mercaptan, normal-dodecyl mercaptan, etc. You can use The content may be 0.1 to 0.4 parts by weight, more specifically 0.2 to 0.3 parts by weight based on 100 parts by weight of the total weight of the monomer, and within the above range, an acrylic polymer having a weight average molecular weight of 80,000 to 200,000 g/mol is prepared. It is desirable because it can be done.

In one aspect of the present invention, the polymethyl methacrylate resin (B) is 75 to 89% by weight of methyl methacrylate, 10 to 20% by weight of C4 to C8 alkyl (meth)acrylate, and 1 to 10% by weight of a heat-resistant monomer Based on 100 parts by weight of the monomer mixture including %, it may be a polymer prepared including 0.01 to 0.5 parts by weight of an initiator.

The C4 to C8 alkyl (meth)acrylate is specifically, for example, n-butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, n-butyl acrylate, It may be any one or a mixture of two or more selected from t-butyl acrylate, cyclohexyl acrylate and isobornyl acrylate. More preferably, it may be n-butyl methacrylate, t-butyl methacrylate and n-butyl acrylate, t-butyl acrylate, and more preferably n-butyl methacrylate.

The C4 ~ C8 alkyl (meth) acrylate may be used in an amount of 10 to 20% by weight, more specifically 12 to 18% by weight, and drying of the organic solvent in the process of evaporating the organic solvent after film formation in the above range It may be to further improve the production speed of the film because the speed can be adjusted more rapidly.

The heat-resistant monomer is not limited as long as it is a monomer for adjusting the glass transition temperature of the polymethyl methacrylate resin (B) to 110° C. or higher, but more specifically, for example, acrylic acid, methacrylic acid, acid anhydride, styrene-based It may be any one or a mixture of two or more selected from monomers and maleimide-based monomers. In addition, the content of the heat-resistant monomer is not limited as long as it is an amount for adjusting the glass transition temperature to 110° C. or higher, but may be more preferably 1 to 10% by weight.

More preferably, as the heat-resistant monomer, a styrene-based monomer and a maleimide-based monomer may be mixed and used, and more specifically, 20 to 30: 70 to 80 by weight may be mixed and used. In the content range, a film having excellent optical properties and excellent heat resistance and mechanical strength can be prepared, so it is preferable, but is not limited thereto. In addition, by mixing and using a styrene-based monomer and a maleimide-based monomer in the above range, the effect of improving the polymerization efficiency between each monomer can be expected to reduce the residual monomer contained in the prepared copolymer, and improve heat resistance. An acrylic polymer having low moisture permeability can be obtained.

The acid anhydride may be specifically, for example, any one or a mixture of two or more selected from maleic anhydride and glutaric anhydride.

The styrene-based monomer may be specifically, for example, any one or a mixture of two or more selected from styrene, α-methylstyrene, p-bromo styrene, p-methyl styrene and p-chloro styrene.

Specifically, the maleimide-based monomer is, for example, phenylmaleimide, nitrophenylmaleimide, monochlorophenyl maleimide, dichlorophenyl maleimide, monomethylphenyl maleimide, dimethylphenyl maleimide, ethylmethylphenyl maleimide, and cyclohexyl It may be any one selected from maleimide or a mixture of two or more.

In addition to this, if necessary, a comonomer may be further included in order to adjust the physical properties of the acrylic polymer. The comonomer may be any one or a mixture of two or more selected from methyl acrylate, ethyl acrylate, isopropyl acrylate, ethyl methacrylate, and isopropyl methacrylate. By further including methyl acrylate, it is possible to further improve thermal decomposition and further improve flowability.

In one aspect, when preparing the polymethyl methacrylate resin (B), polymerization may be performed in the presence of an initiator. More specifically, the initiator may be used without limitation as long as it is an organic peroxide initiator, and specifically, for example, t-butylperoxy-2-ethylhexanoate, t-amylperoxy- 2-ethylhexanoate (t-amylperoxy-2-ethylhexanoate), 1,1-bis (t-butylperoxy)-3,3,5-trimethyl cyclohexane (1,1-bis (t-butylperoxy)- 3,3,5-trimethyl cyclohexane), 1,1-bis (t-butyl peroxy) cyclohexane (1,1-bis (t-butylperoxy) cyclohexane), 1,1-bis (t-butyl peroxy) -2-methyl cyclohexane (1,1-bis (t-butylperoxy)-2-methyl cyclohexane), 2,2-bis (4,4-di-t-butylperoxy cyclohexyl) propane (2,2- bis(4,4-di-t-butylperoxy cyclohexyl)propane), 1,1-di-(t-amylperoxy) cyclohexane (1,1-di-(t-amylperoxy) cyclohexane), lauryl peroxide (lauroyl peroxide) and mixtures thereof, and the like, but are not limited thereto. The initiator may be included in an amount of 0.01 to 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight, based on 100 parts by weight of the total monomer content. The desired molecular weight can be obtained in the above range, and it is preferable because it is easy to control the reaction heat of the reactor.

In one aspect, when preparing the polymethyl methacrylate resin (B), by not using a chain transfer agent, a weight average molecular weight of 1,000,000 to 4,000,000 g/mol may be prepared to prepare a polymethyl methacrylate resin (B). When a chain transfer agent is used, the molecular weight may be lowered, and when a small amount is used to match the molecular weight, it is difficult to measure, and there is a problem in that viscosity variation may occur due to non-uniform molecular weight for each polymerization batch.

In one aspect of the present invention, the polymethyl methacrylate resin (A) and the polymethyl methacrylate resin (B) may be prepared by emulsion polymerization or suspension polymerization, but more preferably suspension polymerization.

More specifically, in the case of suspension polymerization, by carrying out suspension polymerization in the presence of a dispersion agent for suspension polymerization, transparency is more excellent and optical properties are excellent, and an acrylic polymer having a high molecular weight and low particle agglomeration can be prepared. By this method, it becomes possible to manufacture a film excellent in optical properties. In addition, although not described as an example, when a dope solution is prepared from an acrylic polymer prepared using the suspension polymerization dispersant, an excellent effect of lowering the change over time of the dope solution may be exhibited.

The suspension polymerization dispersant is a compound represented by the following Formula 1, a suspension polymerization dispersant obtained by polymerizing a compound represented by Formula 2 and an alkyl (meth)acrylate, a suspension polymerization dispersant that is a copolymer of methyl methacrylate and methacrylic acid, or Polyvinyl alcohol or the like may be used, but is not limited thereto.

[Formula 1]

In Formula 1, R ₁ is hydrogen or C ₁ to C ₃ alkyl, n is an integer selected from 0 to 3, and M is any one selected from lithium, sodium, potassium and ammonium.

[Formula 2]

In Formula 2, R ₂ is hydrogen or C ₁ to C ₃ alkyl, and M is any one selected from lithium, sodium, potassium and ammonium.

More specifically, a monomer mixture consisting of 60 to 70% by weight of the monomer of Formula 1, 5 to 15% by weight of the monomer of Formula 2, and 15 to 35% by weight of an alkyl (meth)acrylate-based monomer is uniformly polymerized in an aqueous solution in the presence of an initiator. Can be. Examples of the initiator include 2,2-azobis(2-methylpropionamidine)dihydrochloride, 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2, 4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), 2, 2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate An azo initiator such as may be used, but is not limited thereto. By using the suspension polymerization dispersant, the dispersibility is further improved, the content of unreacted monomers is further reduced, the reaction is stable, and the particle diameter of the obtained copolymer is uniform, so that the film formation stability of the film is improved when manufacturing the polarizing plate protective film. It can be further improved.

The compound represented by Formula 1 is any one selected from 3-sulfopropyl acrylate potassium salt, 3-sulfopropyl methacrylate potassium salt, 2-sulfoethyl methacrylate sodium salt, and 2-sulfoethyl acrylate sodium salt. Or it may be a mixture of two or more.

remind The solid content of the suspension polymerization dispersant may be 1 to 10% by weight, more preferably 3 to 6% by weight.

When polymerizing the copolymer of the present invention, 0.001 to 1.0 parts by weight of the suspension polymerization dispersant having a solid content of 1 to 10% by weight, more preferably 0.005 to 0.6 parts by weight may be used based on 100 parts by weight of the total monomer mixture. . In the above range, good copolymer particles can be obtained, polymerization stability is excellent, and there is little loss of copolymer particles in washing and drying processes, so workability and economy are good.

The weight average molecular weight of the suspension polymerization dispersant may be 100,000 to 5,000,000 g/mol, and more specifically 500,000 to 3,000,000 g/mol. It is preferable because a polymer having a uniform shape and particle size distribution can be prepared within the above range.

Further, if necessary, a dispersion aid may be further included, and any dispersion aid selected from metal salts or ammonium salts clearly known in the art may be used without limitation. As a specific example, magnesium sulfate, sodium sulfate, ammonium sulfate, and the like may be used. The content of the dispersion aid is not limited, but the content of the dispersant: dispersion aid may be used in a ratio of 1:5 to 5:1 by weight. It is preferable because the average particle diameter and particle size distribution of the polymer particles can be controlled within the above range.

Further, when necessary when preparing the acrylic polymer, various additives generally used in the art, for example, a plasticizer, an antioxidant, a UV stabilizer, a heat stabilizer, and the like may be further included. In this case, the additives may be included in an appropriate amount within a range that does not harm the physical properties of the acrylic polymer, and for example, may be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the total monomer content.

In one aspect of the present invention, the dope solution contains the prepared acrylic polymer and an organic solvent.

The solid content of the acrylic polymer may be 10 to 40% by weight, more preferably 15 to 35% by weight. It has a viscosity suitable for continuously producing a film in the solid content range, can be completely dissolved in an organic solvent, and a film having a thickness of 5 to 200 μm, specifically 10 to 150 μm, preferably 20 to 80 μm It is preferable because it is suitable for manufacturing.

When the viscosity of the dope solution is less than 10,000 cps at 32° C. in the solid content range, it is difficult to form a film due to high fluidity. In the solid content range, the viscosity of the dope solution is at least 10,000 cps at 32°C, specifically 10,000 to 80,000 cps, more preferably 20,000 to 60,000 cps, more preferably 30,000 to 40,000 cps, and the weight average molecular weight is 80,000 to 200,000. Bimodal poly comprising 10 to 40% by weight of a polymethyl methacrylate resin (A) of g/mol and 60 to 90% by weight of a polymethyl methacrylate resin (B) having a weight average molecular weight of 1,000,000 to 4,000,000 g/mol It is suitable for continuous film formation using a dope solution using a methyl methacrylate resin mixture.

The organic solvent is not limited as long as it can dissolve the acrylic polymer, but preferably halogenated hydrocarbons can be used, and the halogenated hydrocarbons include chlorinated hydrocarbons, methylene chloride and chloroform, of which methylene chloride is the most used. desirable. Also, if necessary, an organic solvent other than halogenated hydrocarbons may be mixed and used. Organic solvents other than halogenated hydrocarbons include esters, ketones, ethers and alcohols. As esters, methyl formate, ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, pentyl acetate, etc. can be used, and as ketones, acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone , Cyclopentanone, cyclohexanone, methylcyclohexanone, etc. can be used, and as ethers, diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetra Hydrofuran, anisole, phenethyl, and the like can be used, and as alcohols methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl- 2-butanol, cyclohexanol, 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, and the like are used.

More preferably, methylene chloride may be used as the main solvent, and alcohol such as methanol and ethanol may be used as a side solvent. Specifically, methylene chloride and alcohol may be mixed in a weight ratio of 80 to 99: 20 to 1, more preferably 85 to 90: 15 to 10 by weight.

In addition, various additives such as plasticizers, ultraviolet rays inhibitors, deterioration inhibitors, fine particles, release agents, infrared absorbers, and optical anisotropy control agents may be added as needed. The specific types of these additives may be used without limitation as long as they are commonly used in the relevant field, and the content is preferably used in a range that does not deteriorate the physical properties of the film. The timing of adding an additive is determined by the type of additive. It is also possible to perform a step of adding an additive at the end of the dope preparation.

The plasticizer is used to improve the mechanical strength of the film, and when the plasticizer is used, the drying process time of the film may be shortened. The plasticizer may be used without limitation as long as it is commonly used, and examples thereof include carboxylic acid esters selected from phosphoric acid esters, phthalic acid esters, and citric acid esters. Examples of the phosphoric acid ester include triphenyl phosphate (TPP), biphenyl diphenyl phosphate, and tricresyl phosphate (TCP). Examples of the phthalic acid ester include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). have. Examples of the citric acid ester include o-acetyl triethyl citrate (OACTE) and o-acetyl tributyl citrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methyl acetyl lysine oleate, dibutyl sebacate and various trimellitic acid esters. Preferably, it is good to use a phthalic acid ester plasticizer. The content of the plasticizer may be 2 to 20 parts by weight, more preferably 5 to 15 parts by weight, based on 100 parts by weight of the acrylic polymer.

The ultraviolet inhibitor may be a hydroxybenzophenone compound, a benzotriazole compound, a triazine compound, a salicylic acid ester compound, a cyanoacrylate compound, or the like. The amount of the UV inhibitor may be 0.1 to 3 parts by weight, more preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the acrylic polymer.

As the deterioration inhibitor, for example, an antioxidant, a peroxide decomposition agent, a radical inhibitor, a metal deactivator, a deoxidant, a photostabilizer such as a hindered amine, and the like can be used. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA). The amount of the deterioration inhibitor may be 0.01 to 5 parts by weight, more preferably 0.1 to 1 part by weight, based on 100 parts by weight of the acrylic polymer.

The fine particles are added in order to suppress curling of the film, transport property, prevent adhesion in a roll form, or maintain good scratch resistance, and any selected from inorganic compounds and organic compounds may be used. For example, inorganic compounds include compounds containing silicon, silicon dioxide, titanium oxide, zinc oxide, aluminum oxide, barium oxide, zirconium oxide, strontium oxide, antimony oxide, tin oxide, tin oxide, antimony, calcium carbonate, talc, Clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, and the like are preferable, and more preferably, inorganic compounds containing silicon, zirconium oxide, and the like can be used. The fine particles may have an average primary particle diameter of 80 nm or less, preferably 5 to 80 nm, more preferably 5 to 60 nm, and particularly preferably 8 to 50 nm.

In addition, if necessary, a wavelength dispersion modifier or the like may be further added. These additives can be used without limitation as long as they are commonly used in the relevant field.

In addition, if necessary, in order to further increase or lower the retardation, an optional retardation additive may be further included. The retardation additive may be used without limitation, as long as it is commonly used to control retardation in the relevant field. In general, an additive for increasing retardation may be used for an optical film applied to a liquid crystal display of VA mode, and an additive for reducing retardation may be used for an optical film for applying to a liquid crystal display of IPS mode. The retardation additive may be used in an amount of 1 to 15 parts by weight, more preferably 3 to 10 parts by weight, based on 100 parts by weight of the acrylic polymer, and bleeding may not occur in the above range, and high-quality images can be formed. I can.

In addition, the dope solution of the present invention may additionally contain polycarbonate if necessary. The polycarbonate may include 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the acrylic polymer. The polycarbonate may have a weight average molecular weight of 5,000 to 50,000 g/mol. By adding the polycarbonate, the optical retardation of the acrylic optical film may be reduced, and more specifically, the acrylic optical film may be prepared as a zero retardation protective film.

In addition, the dope solution of the present invention may further contain a core-shell rubber, more specifically a core-shell type acrylic rubber, if necessary. The core-shell rubber may be an acrylic latex powder having a two-layer or three-layer structure including an acrylic rubber layer in a core layer or an intermediate layer. By further including the core-shell rubber, it was confirmed that not only the impact resistance of the film but also the peel-off property during the manufacture of the film was improved, thereby improving the film forming workability and processability. The core-shell rubber may have an average particle diameter of 100 to 400 nm, and has little effect on smoothness when manufacturing a film having a thickness of 20 to 80 μm in the above range, excellent optical properties of the film, and improvement in impact resistance can be expected. have. In addition, the core-shell rubber may be contained in an amount of 1 to 50% by weight in the dope solution, but is not limited thereto, while further improving the target impact resistance within the above range, it is possible to prevent the deterioration of the physical properties of the film, It is preferable because it can satisfy the physical properties that the viscosity change rate of the dope solution is 20% or less among the time required for film formation.

In addition, when the core-shell rubber is further included, the viscosity of the dope solution may be changed due to the swelling of the core-shell rubber, but after the dope solution is prepared, it is before swelling within the process time of manufacturing the film by the solvent casting method. Film production is possible. More preferably, when the core-shell rubber is included, it is possible to form a film in a range of 20% or less, specifically 0 to 20%, and more preferably 0 to 10%, of the dope solution. Good because it has excellent performance. The viscosity change can be calculated by Equation 1 below.

[Equation 1]

Viscosity change rate = (last viscosity-initial viscosity)/initial viscosity × 100

In Equation 1, the initial viscosity refers to the viscosity measured initially after preparation of the dope solution, and the final viscosity refers to the viscosity measured before solvent casting after storing the prepared dope solution.

More specifically, the first aspect of the core-shell rubber is a two-layered core-shell rubber composed of a core layer and a shell layer, and the core layer may be made of an acrylic rubber.

The second aspect of the core-shell rubber is a three-layered core-shell rubber consisting of a seed layer, a core layer, and a shell layer, and the core layer or the intermediate layer may be formed of acrylic rubber.

The first aspect and the second aspect are only exemplified to explain the core-shell rubber of the present invention, but are not limited thereto.

The core-shell rubber according to an aspect of the present invention includes a layer made of acrylic rubber, thereby improving the tensile strength of the film. The acrylic rubber layer is not limited, but is preferably made of 40 to 80% by weight, more preferably 50 to 70% by weight of the total weight of the core-shell rubber to satisfy the physical properties, but is not limited thereto.

remind The core-shell rubber may be prepared by emulsion polymerization. More specifically, the three-layered core-shell rubber is a first-stage polymerization of preparing seed particles having a glass transition temperature of 20°C or higher by adding an acrylic monomer, an emulsifier, a graft agent, and an initiator to ion-exchanged water; A second-stage polymerization in which an acrylic monomer, a comonomer, a crosslinking agent, an emulsifier, an initiator, and a graft agent are added to the polymer obtained by the first-stage polymerization to graft a rubbery core having a glass transition temperature of 0° C. or less to the seed particles; It is prepared including a third-stage polymerization in which an acrylic monomer and an initiator are added to the polymer obtained by the second-stage polymerization, and a glass-like shell having a glass transition temperature of 20°C or higher is grafted to the core to produce a core-shell rubber I can.

When the temperature of the ion-exchanged water in the reactor reaches 70 to 90° C. in the first stage of polymerization, an acrylic monomer, an emulsifier, a graft agent, and an initiator are added to obtain glass seed particles. The acrylic monomer used in the first stage polymerization is preferably used in an amount of 1 to 40% by weight based on the total weight of the monomers used in manufacturing the core-shell rubber.

In the second stage polymerization, an acrylic monomer capable of forming a rubber phase in the polymer by the first stage polymerization and a styrene derivative substituted with styrene or halogen or an alkyl or aryl group having 1 to 20 carbon atoms to control the refractive index as a comonomer. It may be polymerized using a small amount. The content of the acrylic monomer and comonomer for grafting the rubber-like core onto the seed particles is 40 to 80% by weight, more preferably 50 to 70% by weight, based on the total monomer weight used in manufacturing the core-shell rubber. It is preferable because it exhibits excellent impact resistance physical properties, but is not limited thereto. At this time, the acrylic monomer and the comonomer may be used by mixing in a weight ratio of 4 to 9: 1.

The three-step polymerization is for grafting a glass-like shell on the core, and the content of the acrylic monomer used at this time is preferably used in an amount of 10 to 40% by weight based on the total weight of monomers used in manufacturing the core-shell rubber. In addition, the particle size of the core-shell rubber obtained by grafting the final glass-like shell is also preferably uniform.

As the acrylic monomer used in the manufacture of the core-shell rubber, any one or two or more selected from an aromatic vinyl monomer, an alkyl (meth)acrylate monomer having 1 to 15 carbon atoms, and a (meth)acrylic acid monomer having 1 to 15 carbon atoms Mixtures can be preferably used. For a specific example, styrene can be used as an aromatic vinyl monomer, and as an alkyl (meth)acrylate monomer having 1 to 15 carbon atoms, ethyl acrylate, ethyl methacrylate, methyl acrylate, methyl methacrylate, butyl Any one or a mixture of two or more selected from acrylate and butyl methacrylate may be used, but are not limited thereto.

In one aspect of the present invention, the acrylic rubber may be a polymer of an aromatic vinyl monomer and an alkyl (meth) acrylate monomer having 1 to 15 carbon atoms among the acrylic monomers, and more specifically, for example, of butyl acrylate and styrene. It may be a polymer.

As the emulsifier, anionic emulsifiers such as alkaline alkyl phosphate having 4 to 30 carbon atoms and alkyl sulfate salts such as sodium dodecyl sulfate and sodium dodecylbenzene sulfate may be used, but are not limited thereto, and the amount of these is not limited to core-shell It is preferable to use 0.02 to 4 parts by weight based on 100 parts by weight of the total monomer used in rubber production.

Examples of the crosslinking agent include 1,2-ethanedioldi(meth)acrylate, 1,3-propanedioldi(meth)acrylate, 1,3-butanedioldi(meth)acrylate, and 1,5-pentanedioldi( Meth)acrylate, 1,6-hexanediol di(meth)acrylate, divinylbenzene, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, Any selected from triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polybutylene glycol di (meth) acrylate and allyl (meth) acrylate, etc. One or a mixture of two or more may be used, but the amount thereof is not limited thereto, and the amount thereof may be 0.1 to 10 parts by weight based on 100 parts by weight of the total monomers used in manufacturing the core-shell rubber.

As the graft agent, one or more monomers having double bonds having different reactivity, such as allyl (meth) acrylate or diallyl maleate, may be used, but are not limited thereto. It is preferable to use 0.1 to 10 parts by weight based on 100 parts by weight of the total monomer used.

The initiator used in the production of the core-shell rubber is any one or a mixture of two or more selected from azo-based compounds, peroxide-based compounds, etc. in the presence of ferrous sulfate, sodium ethylenediaminetetraacetate, and sodium formaldehydesulfoxylate It may be to use, but is not limited thereto.

The azo compound is, for example, 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4 -Methoxy-2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), 2,2'-azobis[2-(2-imidazoline-2- One) propane] dihydrochloride and 2,2'-azobis [N-(2-carboxyethyl) -2-methylpropionamidine] hydrate may be any one or a mixture of two or more selected from, and is limited thereto. no.

The peroxide-based compound is tetramethylbutylperoxy neodecanoate, bis(4-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl)peroxy carbonate, butylperoxy neodecanoate, Dipropyl peroxy dicarbonate, diisopropyl peroxy dicarbonate, diethoxyethyl peroxy dicarbonate, diethoxyhexyl peroxy dicarbonate, hexyl peroxy dicarbonate, dimethoxybutyl peroxy dicarbonate, bis(3-me) Oxy-3-methoxybutyl) peroxy dicarbonate, dibutyl peroxy dicarbonate, dicetyl peroxy dicarbonate, dimyristyl peroxy dicarbonate, 1,1,3,3-tetramethylbutyl peroxypivalate, Hexyl peroxy pivalate, butyl peroxy pivalate, trimethyl hexanoyl peroxide, dimethyl hydroxybutyl peroxyneodecanoate, amyl peroxyneodecanoate, butyl peroxyneodecanoate, t-butylperoxy Neoheptanoate, amylperoxy pivalate, t-butylperoxy pivalate, t-amyl peroxy-2-ethylhexanoate, lauryl peroxide, dilauroyl peroxide, didecanoyl peroxide, Benzoyl peroxide, dibenzoyl peroxide, 2,2-bis(tert-butylperoxy)butane, 1,1-bis(tert-butylperoxy)cyclohexane, 2,5-bis(butylperoxy)-2 ,5-dimethylhexane, 2,5-bis(tert-butylperoxy)-1-methylethyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert -Butyl hydroperoxide, tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxy isopropyl carbonate, cumene hydroxyperoxide, dicumyl peroxide, lauroyl peroxide, 2,4 -It may be any one or a mixture of two or more selected from pentanedione peroxide, tert-butyl peracetate, peracetic acid and potassium persulfate, but is not limited thereto.

The amount of these may be 0.001 to 10 parts by weight based on 100 parts by weight of the total monomers used in the production of the core-shell rubber, but is not limited thereto.

In the production of the core-shell rubber of the present invention, the production of the two-layered core-shell rubber of the first aspect omits the first step of polymerization during the production of the three-layered core-shell rubber of the second aspect. It may be the same as the manufacturing method of the second aspect. Specifically, a first-stage polymerization in which an acrylic monomer, a comonomer, a crosslinking agent, an emulsifier, an initiator, and a graft agent are added to ion-exchanged water to prepare a rubber-like core having a glass transition temperature of 0° C. or less; And a second-stage polymerization of grafting a glass-like shell having a glass transition temperature of 20°C or higher on the core by adding an acrylic monomer and an initiator to the polymer obtained by the first-stage polymerization to produce a core-shell rubber.

In one aspect of the present invention, in order to prepare the acrylic optical film, the dope solution is prepared, and the dope solution is cast to the surface of the support through a die, applied in a sheet form, and the solvent present in the casting stock solution is evaporated by a drying facility. It may be to form an acrylic film. The die is for extruding the casting stock solution, and for example, a conventional T-die may be used. The support is a support that forms a film by transporting the casting stock solution and drying it, and a metal support in the form of a conveyor belt may be used, and more specifically, a stainless steel conveyor belt may be used, and by adjusting the movement or rotation speed of the belt The thickness of the film can be adjusted.

The casting stock solution applied to the belt moves with the belt for a sufficient time and distance to be formed into a film, and then is peeled from the belt by a peeling roller which is a guide roller. The peeled film is transferred to a drawing machine, uniaxially stretched in the width direction or biaxially stretched in the width direction and machine direction, dried in a dryer to form a final acrylic film, and then wound in a winder and shipped as a product.

More specifically, a) 10 to polymethyl methacrylate resin (A) prepared including methyl methacrylate and a heat-resistant monomer, having a glass transition temperature of 120° C. or higher, and having a weight average molecular weight of 80,000 to 200,000 g/mol 40% by weight and methyl methacrylate, C4 ~ C8 alkyl (meth) acrylate and a heat-resistant monomer is prepared, the glass transition temperature is 110 ℃ or more, the weight average molecular weight of 1,000,000 to 4,000,000 g/mol polymethyl Applying a dope solution containing a bimodal polymethyl methacrylate resin mixture containing 60 to 90% by weight of a methacrylate resin (B), a core-shell rubber, and an organic solvent on a support through a die;

b) evaporating the organic solvent and peeling the acrylic film from the support; And

c) a stretching step of uniaxially stretching or biaxially stretching the acrylic film;

It may be to include.

At this time, by using the bimodal polymethyl methacrylate resin mixture, the production speed of the film may be further improved. More specifically, the production speed of the film may be improved to 50 ~ 100 m/min. In addition, when peeling the film when the residual solvent of the acrylic film is 5 to 20% by weight, it may be produced within 5 minutes from the application of the step a) to the peeling of the step b).

In other words, by using a bimodal polymethyl methacrylate resin mixture and a core-shell rubber, the drying speed of the solvent can be adjusted more quickly, and accordingly, the production speed of the film can be further improved, and haze when manufacturing a wide film. And it is possible to prepare a film having a low rate of thickness change. In addition, when peeling after film formation, peeling can be performed well without foreign matter remaining on the support.

It will be described in more detail with respect to the manufacturing method of the acrylic optical film of the present invention.

In one aspect of the present invention, the acrylic optical film can be prepared according to a conventional solvent casting method. More specifically, the prepared dope solution is once 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 fixed-quantity gear pump capable of quantitatively delivering liquid according to the number of rotations from the dope outlet, and the dope is sent from the detention (slit) of the pressurized die to the metal support running endlessly. By casting evenly, the less dry casting film is peeled from the metal support at the peeling point where the metal support is almost round. Both ends of the produced film are inserted into a clip and conveyed by a tenter to dry while maintaining the width, and then conveyed by a roller of a drying device, dried, and wound to a predetermined length by a winder. In addition, it is also possible to uniaxially stretch in the machine direction or width direction or biaxially stretch in the machine direction and width direction after peeling in a state where the amount of residual solvent is 0 to 40% by weight, more specifically 5 to 20% by weight, when manufacturing the casting film. Do. Alternatively, it is possible to stretch the cast film offline after production. The stretching of the film may be stretched in the machine direction or in the width direction, and simultaneous or sequential biaxial stretching may be used. The degree of elongation may be adjusted as necessary, and specifically, for example, may be 1.1 to 4 times, more specifically 2 to 3 times. In addition, it may include the step of additionally drying the film after the stretching. In this case, the drying temperature is not limited as long as the organic solvent can be completely dried, but may be preferably 50 to 120°C.

The temperature during stretching is preferably the glass transition temperature (T _g )±10°C of the acrylic polymer used in the dope solution. The space temperature at the time of application of the solution is preferably -50°C to 50°C, more preferably -30°C to 40°C, and most preferably -20°C to 30°C. More specifically, the temperature during stretching may be 100 to 200 °C. The dope solution applied at a low space temperature is instantly cooled on the support and the gel strength is improved, so that a film in which a large amount of organic solvent remains is obtained. Therefore, the film can be peeled off from the support in a short time without evaporating the organic solvent. As the gas for cooling the space, ordinary air, nitrogen, argon, or helium can be used. 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, a gas cooled by the casting part may be introduced. It is also possible to cool the space by placing a cooling device on the casting part. In cooling, it is important to take care that water does not adhere to the casting part. In the case of cooling with gas, it is preferable to dry the gas.

The thickness of the optical film according to the present invention may preferably be in the range of 10 to 150 μm, more preferably in the range of 20 to 80 μm. In addition, the width of the film may be 1000 mm or more, more preferably 2000 mm or more.

The acrylic optical film according to the present invention may be used not only for a polarizing plate protective film or a retardation film, but also for an optical film such as an optical compensation sheet or an optical filter for a stereoscopic image, and may be used by stacking one or two or more sheets.

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

In addition, the present invention also includes an image display device including the polarizing plate in 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 a liquid crystal display device of various display modes, and specifically, can be used in modes such as TN, IPS, FLC, AFLC, OCB, STN, ECB, VA and HAN.

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

The acrylic optical film according to the present invention satisfies the moisture permeability of 200 g/m 2 ·24 hr or less in the range of 20 to 80 μm in film thickness. The moisture permeability was measured using a moisture permeability meter (product name PERME (W3/0120), LabThink), and the temperature applied to the film specimen was 38°C, the relative humidity (RH) of the outer cell was 90%, and under N ₂ carrier gas conditions. It is a measure of the moisture transmitted from the outer cell through the film and into the inner cell.

In addition, since the moisture permeability is very low compared to the conventional cellulose acylate film, it is suitable for application as an optical film of a thin-film liquid crystal display device, and since the moisture permeability satisfies the above range, it is possible to prevent damage to the polarizer when manufacturing a polarizing plate, and It is possible to prevent the physical properties of the optical film from being deformed even under high temperature and high humidity conditions during the manufacturing process and transport of the display device.

In addition, a retardation value in the plane direction represented by Equation 1 below may be -50 to +50 nm, and a retardation value in a thickness direction represented by Equation 2 below may be -50 to +50 nm.

[Equation 1]

R _in = (n _x -n _y ) xd

[Equation 2]

R _th = (n _z -n _y ) xd

In Equations 1 and 2, n _x is the refractive index in the direction having the largest refractive index in the plane direction of the film, n _y is the refractive index in the vertical direction in the n _x direction in the plane direction of the film, and n _z Is the refractive index in the thickness direction, and d is the thickness of the film.

In addition, the optical film according to an aspect of the present invention satisfies physical properties in which thickness variation is within 5%. That is, for example, a film having a thickness of 60 μm means that the error range is within 5% when the thickness is measured at an arbitrary point with respect to the entire width of the film.

In addition, the haze is less than 2% and there are few foreign substances, so it shows excellent physical properties for use as an optical film. More specifically, the haze may be 2% or less, specifically 1.5% or less, more specifically 1% or less, and the number of foreign matters may be 0.3 or less per 1M, and more specifically 0 to 0.3.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. However, the following Examples and Comparative Examples are only one example for describing the present invention in more detail, and the present invention is not limited by the following Examples and Comparative Examples.

The physical properties of the film were measured by the following measuring method.

1. Glass transition temperature (T _g ): It was measured using a differential scanning calorimeter (DSC) at 10°C/min heating condition.

2. Weight average molecular weight: The prepared beads and films were dissolved in tetrahydrofuran and measured using gel permeation chromatography (GPC).

The weight average molecular weight was measured using a Gel Permeation Chromatography (GPC) equipment manufactured by Waters. The equipment consists of a mobile phase pump (M515 Pump), a column heater (ALLCOLHTRB), a detector (2414 RI Detector), and an injector (2695 EB automatic injector), and the analytical column is WATERS' Styragel HR, and the standard material is polymethylmethacrylic. Late (PMMA) American polymer standard corporation STD was used. As the mobile phase solvent, HPLC grade tetrahydrofuran (THF) was used, and the measurement was 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), which is a mobile phase solvent, and then injected into a GPC device to measure the weight average molecular weight.

3. Residual monomer: The monomer remaining in the resin after polymerization was quantitatively measured through a GC (Gas Chromatography) analyzer.

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

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

Haze deviation was calculated by the following equation after dividing the film into 5 equal parts in the width direction and measuring the haze at an arbitrary point of the 5 equalized film.

△ Haze = maximum value of haze-minimum value of haze

6. Tensile strength: It was measured according to ASTM D638 test method using a universal tester (UTM, Zwick).

7. Moisture permeability: Using a moisture permeability meter (LabThink, PERME (W3/0120)), the temperature applied to the film specimen in the sealed chamber is 38℃, the outer cell's RH (relative humidity) 90%, under N ₂ carrier gas conditions. Moisture permeated to the inner cell by passing through the film from the outer cell for 24 hr was measured.

8. Coating Adhesion: After cutting the coated side on the film to make a total of 100 cells each of 10 horizontally and vertically, the degree of adhesion of the coating layer was evaluated by attaching and removing 3M tape. Here, if more than 95 are left, it is good, if more than 85 is normal, if less than 85 is bad

9. Thickness deviation: The film thickness was measured at 50mm intervals over the entire width of the film, and was calculated by the following equation.

Thickness deviation (%) = (maximum thickness-minimum thickness) / minimum thickness × 100

The film thickness was measured by a Micrometer measuring instrument made by Mahr, Germany.

10. Foreign matter inspection: Non-melting black spots and white spots, including foreign matter such as dust, were detected, and the film running after film production was measured using a film inspection device of Nexteye. It is expressed as the number of foreign matters per 1M in the longitudinal direction of the film, and if one foreign matter occurs during 10M driving, it is expressed as 0.1pcs/1M.

11. Viscosity: After preparing the dope solution at 25°C, the viscosity was measured by the viscosity measurement method by the falling ball method. Brookfield's Falling Ball Viscometer Model KF40 was used, and measurement was made using a No. 6 ball.

12. Peel-off property: The dope solution was cast on the surface of a stainless steel support, dried so that the amount of residual solvent in the film was 20% by weight, and the film was peeled off and evaluated as follows.

Excellent: The film surface is smooth and easily peeled off, and there is no residue on the support.

Normal: When the film is peeled, it peels without breaking, and a small amount of residue is generated on the support.

Bad: When the film is peeled, a crackling sound is generated, some breakage occurs, or there is a residue on the support.

[Production Example 1] Preparation of a dispersant for suspension polymerization

In a three-necked flask with a condenser, 2700 g of water and 0.3 g of 2,2-azobis (2-amidinopropane) dihydrochloride were added, and 180 g of a compound of the following formula 1, 40 g of a compound of the following formula 2, and meta 70 g of methyl acrylate was added and reacted at 60° C. for 6 hours to obtain an aqueous polymer solution having a solid content of 5% by weight. 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.

[Production Example 2] Preparation of core-shell rubber

In the first step, 1500g of distilled water was added to the 5L reactor, and the temperature was raised to 80 ℃ after nitrogen substitution. 0.002 g of ferrous sulfate, 0.008 g of EDTA·2Na 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 crosslinking agent, 0.7 g of allyl methacrylate as a grafting agent, 6 g of sodium polyoxyethylene alkyl ether phosphate as an emulsifier, 0.5 g of tertiary butyl peroxide as an initiator After the mixed solution was added dropwise for 2 hours, emulsion polymerization was carried out while stirring at 80° C. and 500 rpm for 1 hour. The average particle size of the glass seed particles obtained at this time was 180 nm.

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

Here, butyl acrylate 250 g, styrene 55 g, graft agent allyl methacrylate 5 g, crosslinking agent 1,3-butanediol dimethacrylate 1 g, cumene hydroperoxide 1 g, polyoxyethylene alkyl ether phosphate A mixed solution containing 10 g of sodium was added dropwise over 3 hours, followed by polymerization at 80° C. for 2 hours. The average particle size of the polymer obtained at this time was 250 nm.

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

[Example 1]

1) Preparation of polymethyl methacrylate resin (A) and polymethyl methacrylate resin (B)

To a 5 liter reactor, 2000 g of distilled water, 12 g of a suspension polymerization dispersant having a solid content of 5% by weight prepared in Preparation Example 1, and 6 g of sodium sulfate were added and dissolved as a dispersion aid. The types and contents of the monomers were added as shown in the following [Table 1], and as shown in [Table 1], an initiator and a chain transfer agent were added and then dispersed in an aqueous phase while stirring at 400 rpm to prepare a suspension. At this time, Luperox 575 (T-Amyl peroxy 2-ethyl hexanoate) was used as the initiator, and normal octyl mercaptan (n-OM) was used as the chain transfer agent.

The suspension was polymerized at 65° C. for 1 hour and 30 minutes, heated to 105° C., further polymerized for 30 minutes, and then cooled to 30° C. The beads obtained by the polymerization reaction were washed and dehydrated with distilled water, and then dried. The physical properties of the prepared acrylic polymer beads were measured and shown in Table 1 below.

2) Preparation of dope solution

20% by weight of a bimodal polymethyl methacrylate resin mixture obtained by mixing the prepared polymethyl methacrylate resin (A) and polymethyl methacrylate resin (B) at the content ratio shown in Table 1 below, in Preparation Example 2 12% by weight of the prepared core-shell rubber and the remaining amount of the solvent were mixed, and 3 parts by weight of Tinuvin 918 manufactured by Ciba Specialty as an ultraviolet absorber was added to 100 parts by weight of the mixed solution to prepare a dope solution. As the solvent, a mixed solvent in which methylene chloride and methanol were mixed in a weight ratio of 9:1 was used.

The viscosity of the dope solution was measured and shown in Table 1 below.

3) Preparation of film

The dope solution was evenly coated on the surface of a stainless steel (SUS 304) support using a die. The solvent was evaporated on the stainless support and peeled off when the residual amount of the solvent was 20% by weight. At this time, the solvent drying time from application until the residual solvent became 20% by weight was measured and shown in Table 2. The amount of residual solvent was calculated by the following equation.

Residual solvent amount (%) = (weight of applied dope solution-weight of film)/weight of film × 100

Both ends of the peeled film are fixed, stretched 1.5 times in the width direction at 125°C when the residual solvent is 12% by weight, then relaxed and dried in a drying section set at 100°C to produce a film with a thickness of 60µm. I did. The physical properties of the film were measured at the point after the drying was completed and shown in Table 2 below.

[Examples 2 to 6]

An acrylic polymer, a dope solution, and a film were prepared in the same manner as in Example 1, except that the composition was changed as shown in Table 1 below.

Hereinafter, in Tables 1 and 2, abbreviations are as follows.

MMA: methyl methacrylate

AMS: Alpha methyl styrene

PMI: Phenylmaleimide

MA: methyl acrylate

MAA: methacrylic acid

n-BMA: n-butyl acrylate

AMPO: Luperox 575, (T-Amyl peroxy 2-ethyl hexanoate)

n-OM: Normal octyl mercaptan

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Resin (A)
Furtherance MMA(g) 930 930 940 940 940 940 AMS(g) 20 20 - - - - PMI(g) 50 50 - - - - MA(g) - - - - - - MAA(g) - - 60 60 60 60 AMPO(g) 2 2 2 2 2 2 n-OM(g) 2 2 2 2 4 4 Properties of resin (A) Tg(℃) 124.5 124.1 126.7 127.1 125.4 124.8 Mw 128,000 124,000 134,000 127,000 89,000 85,000 Total residual monomer
(ppm) 2680 2810 3200 3120 2450 2640 Resin (B)
Furtherance MMA(g) 830 830 840 840 840 840 AMS(g) 20 20 - - - - PMI(g) 50 50 - - - - MA(g) - - - - - - MAA(g) - - 60 60 60 60 n-BMA(g) 100 100 100 100 100 100 AMPO(g) 2 2 2 2 2 2 Properties of resin (B) Tg(℃) 120.7 121.1 122.0 120.0 118.2 117.9 Mw 3,240,000 3,100,000 3320000 3,082,000 3,009,000 3,120,000 Total residual monomer
(ppm) 3560 3300 3150 3250 3020 3520 Dope solution Resin (A)
weight% 20 30 30 30 30 30 Resin (B)
weight% 80 70 70 70 70 70 Core-shell rubber
weight% 10 10 10 20 10 20 Viscosity (cps, 32℃) 45,000 32,000 36,800 38,400 31,500 33,200

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Film production possible possible possible possible possible possible Solvent drying time 4 4 3 3 4 4 R _in /R _th
(nm) 0.8/-6 0.6/-5 0.5/-5 0.8/-7 0.9/-5 0.6/-5 Haze (%) 0.5 0.5 0.4 0.6 0.5 0.5 △Haze 0.05 or less 0.05 or less 0.05 or less 0.05 or less 0.05 or less 0.05 or less Light transmittance (%) 92.0 91.8 91.8 92.0 91.5 91.5 The tensile strength
(GPa) 2.9 2.8 2.8 3.2 2.6 2.6 Moisture permeability
(g/㎡·24hr) 74 75 78 78 74 74 Adhesion Good Good Good Good Good Good Thickness deviation
(%) 3 2 2 3 3 3 Foreign matter inspection 0.1 0.1 0.1 0.1 0.1 0.1 Peel-off Great Great Great Great Great Great

As shown in Table 2, it can be seen that the film according to the present invention can greatly improve the production speed of the film within 5 minutes of the solvent drying time up to 20% by weight of the residual solvent. In addition, it can be seen that there is little change in haze with respect to the entire width of the film, so that local increase in haze can be eliminated. In addition, it can be seen that a uniform and smooth film can be manufactured due to the small thickness deviation, and it was confirmed that the film was easily peeled without any foreign matter remaining on the support during peeling.

In addition, it was confirmed that it can be used in place of the existing cellulose film as it exhibits similar physical properties in optical properties compared to the conventional cellulose film, and it is confirmed that a film having lower moisture permeability and excellent optical properties and mechanical properties can be manufactured. I did.

In addition, it was confirmed that by preparing the film by the solvent casting method, it was possible to provide an acrylic optical film having excellent smoothness and superior adhesion due to less thickness variation compared to the film produced by melt extrusion.

As described above, the present invention has been described by specific matters and limited embodiments and drawings, but this is provided only to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, and the present invention is Those of ordinary skill in the relevant field can make various modifications and variations from this description.

Therefore, the spirit of the present invention is limited to the described embodiments and should not be defined, and all things that are equivalent or equivalent to the claims as well as the claims to be described later fall within the scope of the spirit of the present invention. .

Claims (21)

Polymethyl methacrylate resin (A) 10 to 40% by weight and methyl methacrylate prepared including methyl methacrylate and a heat-resistant monomer and having a glass transition temperature of 120° C. or higher and a weight average molecular weight of 80,000 to 200,000 g/mol Acrylate, C4 ~ C8 alkyl (meth) acrylate and a heat-resistant monomer comprising a polymethyl methacrylate resin having a glass transition temperature of 110 °C or higher, and a weight average molecular weight of 1,000,000 to 4,000,000 g/mol (B ) Prepared by a solvent casting method using a bimodal polymethylmethacrylate resin mixture containing 60 to 90% by weight, a dope solution containing a core-shell rubber and an organic solvent, and drying the solvent to 20% by weight of the residual solvent Acrylic optical film with a time of less than 5 minutes and a thickness deviation of less than 5%. The method of claim 1,
The optical film is an acrylic optical film that is a polarizing plate protective film or a retardation film. The method of claim 1,
The resin (A) contains 0.1 to 0.4 parts by weight of a chain transfer agent and 0.01 to 0.5 parts by weight of an initiator based on 100 parts by weight of a monomer mixture containing 90 to 98% by weight of methyl methacrylate and 2 to 10% by weight of a heat-resistant monomer. An acrylic optical film that is a polymer prepared. The method of claim 1,
The resin (B) is based on 100 parts by weight of a monomer mixture containing 75 to 89% by weight of methyl methacrylate, 10 to 20% by weight of C4 to C8 alkyl (meth)acrylate, and 1 to 10% by weight of a heat-resistant monomer, An acrylic optical film that is a polymer prepared including 0.01 to 0.5 parts by weight of an initiator. The method of claim 1,
The heat-resistant monomer is any one or a mixture of two or more selected from acrylic acid, methacrylic acid, acid anhydride, styrene-based monomer, and maleimide-based monomer. The method of claim 1,
The dope solution contains 10 to 40% by weight of the bimodal polymethyl methacrylate resin mixture and 1 to 40% by weight of the core-shell rubber, and the acrylic optical film has a viscosity of 10,000 cps or more at 32°C. The method of claim 1,
The organic solvent is a halogenated hydrocarbon alone or a halogenated hydrocarbon and any one or two or more mixed solvents selected from esters, ketones, ethers, and alcohols. The method of claim 1,
The dope solution is an acrylic optical film further comprising polycarbonate. The method of claim 1,
The core-shell rubber has a two-layer or three-layer structure including an acrylic rubber layer in a core layer or an intermediate layer, and an acrylic optical film having an average particle diameter of 100 to 400 nm. The method of claim 1,
The acrylic optical film is an acrylic optical film having a moisture permeability of 200 g/m²·24hr or less, a number of foreign matters of 0.3 pieces/1M or less, and a haze of 2% or less. The method of claim 1,
The acrylic optical film is an acrylic optical film having a film thickness of 10 ~ 150㎛. The method of claim 1,
The acrylic optical film is an acrylic optical film that is stretched under the condition that the residual solvent in the film is 5 to 20% by weight. a) 10 to 40% by weight of a polymethyl methacrylate resin (A) prepared including methyl methacrylate and a heat-resistant monomer and having a glass transition temperature of 120° C. or higher and a weight average molecular weight of 80,000 to 200,000 g/mol, and A polymethyl methacrylate resin having a glass transition temperature of 110° C. or higher and a weight average molecular weight of 1,000,000 to 4,000,000 g/mol, including methyl methacrylate, C4 to C8 alkyl (meth)acrylate and heat-resistant monomer (B) applying a dope solution containing a bimodal polymethylmethacrylate resin mixture containing 60 to 90% by weight, a core-shell rubber, and an organic solvent on a support through a die;
b) evaporating the organic solvent and peeling the acrylic film from the support; And
c) a stretching step of uniaxially stretching or biaxially stretching the acrylic film;
Including, the solvent drying time up to 20% by weight of the residual solvent is less than 5 minutes, and a method of manufacturing an acrylic optical film having a thickness deviation of less than 5%. The method of claim 13,
In the step b), when the residual solvent of the acrylic film is 5 to 20% by weight, the film is peeled off, and the acrylic optical film is produced within 5 minutes from the application in the a) step to the peeling in the step b). Manufacturing method. The method of claim 13,
The optical film is a polarizing plate protective film or a method of manufacturing an acrylic optical film that is a retardation film. The method of claim 13,
The stretching step is a method for producing an acrylic optical film to be stretched 1.1 to 4 times in the condition that the residual solvent in the film is 5 to 20% by weight. The method of claim 13,
The dope solution is a method of manufacturing an acrylic optical film further comprising polycarbonate. The method of claim 13,
When the dope solution is applied on a support, the method of manufacturing an acrylic optical film is performed within a range in which the viscosity change rate of the dope solution is 20% or less. Polymethyl methacrylate resin (A) 10 to 40% by weight and methyl methacrylate prepared including methyl methacrylate and a heat-resistant monomer and having a glass transition temperature of 120° C. or higher and a weight average molecular weight of 80,000 to 200,000 g/mol Acrylate, C4 ~ C8 alkyl (meth) acrylate and a heat-resistant monomer comprising a polymethyl methacrylate resin having a glass transition temperature of 110 °C or higher, and a weight average molecular weight of 1,000,000 to 4,000,000 g/mol (B ) Bimodal polymethyl methacrylate resin mixture containing 60 to 90% by weight, core-shell rubber and organic solvent, and the solvent drying time is within 5 minutes up to 20% by weight of the residual solvent, and the thickness deviation is 5% Solvent casting dope solution for manufacturing acrylic optical film within the range. The method of claim 19,
The dope solution is a dope solution for solvent casting further comprising polycarbonate. The method of claim 19,
The dope solution includes 10 to 40% by weight of the bimodal polymethyl methacrylate resin mixture and 1 to 40% by weight of the core-shell rubber, and a dope solution for solvent casting having a viscosity of 10,000 cps or more at 32°C.