KR20160051820A - Optical film copolymer - Google Patents

Abstract

A copolymer for an optical film exhibiting negative orientation birefringence and having excellent transparency, heat resistance, film strength and optical properties. A vinyl aromatic monomer unit, an aromatic vinyl monomer unit in an amount of 65 to 90 mass%, a vinyl cyanide monomer unit in an amount of 5 to 25 mass% and an unsaturated dicarboxylic acid anhydride monomer unit in an amount of 5 to 20 mass%, a weight average molecular weight (Mw) , And a blur of 2 mm or less as measured on the basis of ASTM D1003 of 1% or less.

Description

[0001] OPTICAL FILM COPOLYMER [0002]

The present invention relates to a copolymer for an optical film. More specifically, the present invention relates to a copolymer for an optical film which exhibits negative orientation birefringence and is excellent in transparency, heat resistance, film strength and optical properties.

BACKGROUND OF THE INVENTION [0002] Transparent resins are used in various applications such as parts for home appliances, food containers, and miscellaneous goods. In recent years, as optical components such as a thin film liquid crystal display element instead of a CRT television monitor and an electroluminescence element such as a retardation film, a polarizing film protective film, an antireflection film, a diffusing plate and a light guide plate, Productivity, and cost.

In particular, a stretched film obtained by uniaxially or biaxially stretching a resin film is widely used as an optical film of a liquid crystal display. As a typical example of the optical film, there is a retardation film, a lambda / 2 plate for converting the oscillation direction of polarized light, a lambda / 4 plate for converting circularly polarized light into linearly polarized light or linearly polarized light into circularly polarized light is widely used.

The retardation film is required to be optically compensated in a wide visual field range, and it is extremely important that the retardation does not change with respect to the incident light in the oblique direction. Regarding such a demand characteristic, Patent Document 1 discloses a liquid crystal display device including a laminate of a transparent stretched film having negative orientation birefringence and a transparent stretched film having positive orientation birefringence.

Patent Document 2 discloses a film obtained by laminating a stretched film exhibiting negative orientation birefringence and a stretched film exhibiting positive orientation birefringence such that the slow axes of the stretched films are parallel to each other, 300 nm and an optical compensation film having an orientation parameter (Nz) in the range of 0.5 +/- 0.1 is used, thereby widening the viewing angle of the liquid crystal display device. It is also disclosed that the stretched film exhibiting negative intrinsic birefringence is a resin composition of a copolymer comprising an? -Olefin and an N-phenyl substituted maleimide and an acrylonitrile-styrene copolymer.

Thermoplastic resins exhibiting positive orientation birefringence include polycarbonates and amorphous cyclic polyolefins. They are suitably used for optical films because of their excellent heat resistance, transparency, film strength, and phase difference developability. On the other hand, since thermoplastic resins exhibiting negative orientation birefringence are poor in heat resistance, transparency, film strength, and retardation developability, there are few examples of practical use, and a commercially available stretched film exhibiting positive orientation birefringence And they are joined at a plurality of suitable angles. As a result, the optical compensation design becomes complicated and the cost becomes high, and the optical compensation performance is also insufficient. From the viewpoints of improvement of optical compensation performance, simplification of optical design, and cost reduction, the emergence of thermoplastic resins exhibiting practically usable negative birefringence for optical films is expected.

With respect to these requirements, Patent Document 3 proposes a thermoplastic resin copolymer excellent in transparency, heat resistance, film formability, film strength and phase difference development, and a stretched film exhibiting negative orientation birefringence. In the case of an optical film, an extremely fine film free from foreign matter is required. However, when the film is produced by melt extrusion, a polymer filter having a very small scale is used for removing the foreign matter And the thermoplastic resin copolymer of Patent Document 3 has a high melt viscosity, so that it tends to stay in the polymer filter and a high set temperature is required for measures against pressure loss. In some cases, There is a problem that a practical range is limited.

Japanese Patent Application Laid-Open No. 256023/1993 Japanese Patent Laid-Open No. 2007-24940 WO2009 / 031544

An object of the present invention is to provide a copolymer for an optical film which exhibits negative oriented birefringence and is excellent in transparency, heat resistance, film strength and optical properties.

The present invention is based on the following points.

(1) A thermoplastic resin composition comprising (A) from 65 to 90% by mass of an aromatic vinyl monomer unit, from 5 to 25% by mass of a vinyl cyanide monomer unit and from 5 to 20% by mass of an unsaturated dicarboxylic acid anhydride monomer unit, And a haze of 2 mm and a haze of 1% or less as measured on the basis of ASTM D1003.

(2) The copolymer for an optical film according to (1), wherein the aromatic vinyl monomer unit is 70 to 80 mass%, the vinyl cyanide monomer unit is 10 to 20 mass%, and the unsaturated dicarboxylic acid anhydride monomer unit is 10 to 15 mass%.

(3) The copolymer for an optical film according to (1) or (2), wherein the aromatic vinyl monomer unit is a styrene unit.

(4) The copolymer for an optical film according to any one of (1) to (3), wherein the vinyl cyanide monomer unit is an acrylonitrile unit.

(5) The copolymer for an optical film according to any one of (1) to (4), wherein the unsaturated dicarboxylic acid anhydride monomer unit is a maleic anhydride unit.

(6) The copolymer for an optical film according to any one of (1) to (5), which is used for a polarizing film protective film, a retardation film or an antireflection film.

(7) A film A obtained by stretching a thermoplastic resin film exhibiting negative orientation birefringence and a film B obtained by stretching a thermoplastic resin film exhibiting positive orientation birefringence are laminated to form a refractive index distribution of nx> nz> ny (1) to (6), characterized in that it is a thermoplastic resin for an optical film which is used for a film A and is a thermoplastic resin for a film A.

(8) The copolymer for an optical film according to (7), wherein the film A is formed by stretching a film produced by melt extrusion.

(9) The copolymer for an optical film according to (7) or (8), wherein the Nz coefficient is 0.4 to 0.6.

(10) The in-plane retardations Re (450), Re (590) and Re (750) at 450 nm, 590 nm and 750 nm of Re (450) ) ≪ Re (750). [7] The copolymer for an optical film according to any one of [7] to [9]

The present invention provides a copolymer for an optical film which exhibits negative orientation birefringence and is excellent in transparency, heat resistance, film strength and optical properties.

<Explanation of Terms>

In the present specification, the symbols &quot; to &quot; mean &quot; ideal &quot; and &quot; below &quot;, and for example, the base material with "A to B" means A and B or less.

Hereinafter, embodiments of the present invention will be described in detail.

Examples of the aromatic vinyl monomer unit include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, p- And styrene-based monomers such as methylstyrene. Among them, a styrene unit is preferable. These aromatic vinyl monomer units may be used alone or in combination of two or more.

Examples of the vinyl cyanide monomer unit include units derived from respective vinyl cyanide monomers such as acrylonitrile and methacrylonitrile. Among these, an acrylonitrile unit is preferable. These vinyl cyanide monomer units may be used singly or in combination of two or more.

Examples of the unsaturated dicarboxylic acid anhydride monomer unit include units derived from respective anhydride monomers such as maleic anhydride, itaconic anhydride, citraconic anhydride, and aconitic anhydride. Among these, maleic anhydride units are preferable. The unsaturated dicarboxylic acid anhydride monomer units may be used singly or in combination of two or more.

The copolymer constitutional unit of the present invention is an aromatic vinyl monomer unit in an amount of 65 to 90 mass%, an acrylonitrile monomer unit in an amount of 5 to 25 mass%, and an unsaturated dicarboxylic acid anhydride monomer unit in an amount of 5 to 20 mass% A monomer unit of 70 to 80 mass%, an acrylonitrile monomer unit of 10 to 20 mass%, and an unsaturated dicarboxylic acid anhydride monomer unit of 10 to 15 mass%.

When the aromatic vinyl monomer unit is 90 mass% or less, the heat resistance or the film strength is improved, and when it is 80 mass% or less, the heat resistance or the film strength is further improved. When the acrylonitrile monomer unit is contained in an amount of 25 mass% or less, transparency or optical properties, particularly negative directional birefringence, are improved, and when it is 20 mass% or less, transparency or optical properties are further improved. When the amount of the unsaturated dicarboxylic acid anhydride monomer unit is 20% by mass or less, the film strength is improved, and when it is 15% by mass or less, the film strength is further improved. On the other hand, when the content of the aromatic vinyl monomer unit is 65 mass% or more, transparency or optical characteristics, particularly negative orientation birefringence, is improved, and when it is 70 mass% or more, transparency or optical characteristics are further improved. When the acrylonitrile monomer unit is 5 mass% or more, the film strength is improved, and when it is 10 mass% or more, the film strength is further improved, which is preferable. When the amount of the unsaturated dicarboxylic acid anhydride monomer unit is 5% by mass or more, the heat resistance is improved. When the amount of the unsaturated dicarboxylic acid anhydride monomer unit is 10% by mass or more, the heat resistance is further improved.

The copolymer of the present invention contains a copolymerizable vinyl monomer unit other than an aromatic vinyl monomer unit, a vinyl cyanide monomer unit and an unsaturated dicarboxylic acid anhydride monomer unit in a range that does not inhibit the effect of the invention in the copolymer And preferably not more than 5% by mass. Examples of the unit of the copolymerizable vinyl monomer include methacrylic acid such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, dicyclopentyl methacrylate and isobornyl methacrylate Acid ester monomers, acrylic ester monomers such as methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate and decyl acrylate, vinyl monomers such as acrylic acid and methacrylic acid Alkylmaleimide monomers such as N-methylmaleimide, N-ethylmaleimide, N-butylmaleimide and N-cyclohexylmaleimide, N-phenylmaleimide, N-methylphenylmaleimide, N - N-aryl maleimide monomers such as chlorophenylmaleimide, and the like. The unit of the copolymerizable vinyl monomer may be a combination of two or more kinds.

The copolymer of the present invention has a weight average molecular weight (Mw) of 120,000 to 250,000, preferably 130,000 to 230,000, and more preferably 140,000 to 200,000.

The weight average molecular weight (Mw) is a value measured in terms of polystyrene measured by gel permeation chromatography (GPC), and is a measured value under the measurement conditions described below.

Device name: SYSTEM-21 Shodex (manufactured by Showa Denko Co., Ltd.)

Column: 3 serial PL gel MIXED-B

Temperature: 40 ° C

Detection: differential refractive index

Solvent: tetrahydrofuran

Concentration: 2 mass%

Calibration curve: Standard polystyrene (PS) (manufactured by PL) was used.

When the weight average molecular weight (Mw) is 120,000 or more, the film strength is excellent and the film breakage during stretching is also improved. On the other hand, when the weight average molecular weight (Mw) is 250,000 or less, a film having good film formability and excellent transparency can be obtained.

The copolymer of the present invention has a fogging of 2% or less as measured on the basis of ASTM D1003 of 1% or less, preferably 0.8% or less, more preferably 0.6% or less. When the degree of fogging of 2 mm is 1% or less, the copolymer composition distribution is small and the film strength is satisfactorily manifested, and a film having excellent transparency can be obtained even by film forming or stretching.

The haze was measured using an injection molding machine (IS-50EPN manufactured by Toshiba Kagaku Co., Ltd.) under the conditions of a cylinder temperature of 230 占 폚 and a mold temperature of 40 占 폚, and a specular plate having a length of 90 mm, a width of 55 mm and a thickness of 2 mm was measured according to ASTM D1003 Measured using a haze meter (NDH-1001DP type, manufactured by Nippon Denshoku Kogyo K.K.).

The copolymer of the present invention is excellent in transparency that does not impair the image quality of the liquid crystal device, heat resistance that does not change the orientation birefringence even under a high temperature environment, film strength that can withstand film processing such as stretching and punching, It is suitably used for an optical film. Examples of the use include optical films such as a polarizing film protective film, a retardation film and an antireflection film.

The method for processing the copolymer of the present invention into an optical film is not particularly limited and can be performed by using a known technique such as melt extrusion or casting.

When used as a polarizing film protective film, it is preferable that the optical anisotropy is small, and the in-plane retardation (Re) calculated by the following (formula 1) is 20 nm or less, preferably 10 nm or less, more preferably 5 nm or less , The thickness direction retardation (Rth) calculated by the following formula (2) is 50 nm or less, preferably 20 nm or less, more preferably 5 nm or less. When the in-plane retardation (Re) is 20 nm or less and the retardation in the thickness direction is 50 nm or less, when the polarizing film protective film is used for a polarizing plate of a liquid crystal display device, problems such as lowered contrast of the liquid crystal display device do not occur.

Re = (nx-ny) xd ... (Equation 1)

Rth = {(nx + ny) / 2-nz} xd ... (Equation 2)

In the above formula, nx, ny, and nz indicate the directions in which the in-plane refractive index becomes maximum at the X axis, the direction perpendicular to the X axis is the Y axis, and the thickness direction of the film is the Z axis Direction, and d is the film thickness.

As an example of reducing the optical anisotropy, there is a method using a flexible roll capable of elastic deformation. However, any molding method that can reduce the optical anisotropy can be used. An unoriented film having a small optical anisotropy may be used as it is as a polarizing film protective film. However, in order to increase the film strength, a stretched film stretched in a range in which optical anisotropy is allowed may be used as a polarizing film protective film.

As an example of reducing the optical anisotropy, there are a method of blending polymers having positive intrinsic birefringence such as polycarbonate, polyethylene terephthalate and polyphenylene ether, a method of adding needle-like inorganic fine crystal particles, and the like However, any method that can reduce the optical anisotropy can be used.

When used as a retardation film or an antireflection film, a stretched film stretched by adjusting a stretching condition so as to have a desired in-plane retardation (Re) and a thickness direction retardation (Rth) is suitably used. When the stretched film is used as a retardation film or an antireflection film, it is usually laminated with another stretched film to form a lambda / 2 plate for changing the oscillation direction of the polarized light or a lambda / 2 plate for converting circularly polarized light into linearly polarized light or linearly polarized light into circularly polarized light It is often used as a? / 4 plate for conversion. Therefore, the retardation film may have an appropriate retardation and is used by being adjusted so that the in-plane retardation Re and the thickness retardation Rth of the other stretched films to be laminated have a desired retardation.

The method for use in the retardation film or the antireflection film is not particularly limited, but a stretched film A comprising the copolymer of the present invention and a stretched film B including a thermoplastic resin exhibiting positive orientation birefringence are laminated, > Ny, and particularly preferably the Nz coefficient is 0.4 to 0.6. Here, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, and nz is the refractive index in the direction perpendicular to the film surface, that is, the thickness direction. The slow axis refers to the direction in which the refractive index in the film plane becomes the maximum, and the fast axis refers to the direction perpendicular to the slow axis within the film plane. The Nz coefficient is represented by the following equation (1).

Nz = (nx-nz) / (nx-ny) (1)

a retardation film or an antireflection film formed by forming a refractive index distribution of nx &gt; nz &gt; ny, in particular, a retardation film or an antireflection film having an Nz coefficient of 0.4 to 0.6 in terms of substantially no phase difference with respect to incident light from an oblique direction , The refractive index distribution of the film obtained by the uniaxial stretching method or the biaxial stretching method which is a general stretching method of a thermoplastic resin having negative orientation birefringence is nz? Nx> ny, while the positive The refractive index distribution of the film obtained by the uniaxial stretching method or the biaxial stretching method which is a general stretching method of a thermoplastic resin having orientation birefringence is such that a refractive index distribution of nx> nz> ny is formed in that nx≥ny> nz The optical film comprises a film A obtained by stretching a thermoplastic resin having negative orientation birefringence and a thermoplastic resin having positive orientation birefringence An effective method of laminating a film B, and the copolymer of the invention is extremely suitable as a film for A.

As a method for use in a particularly preferable optical film, a stretched film A comprising the copolymer of the present invention and a stretched film B comprising a thermoplastic resin exhibiting positive orientation birefringence are laminated so that their slow axes are orthogonal to each other, And the in-plane retardations Re (450), Re (590) and Re (750) at 750 nm satisfy the relationship of Re (450) &lt; Re (590) &lt; Re (750). As a general optical film, there is a lambda / 2 plate for converting the oscillation direction of polarized light, a lambda / 4 plate for converting circularly polarized light into linearly polarized light or linearly polarized light into circularly polarized light, (450) = 225 nm, Re (590) = 295 nm and Re (750) = 375 nm in the case of the? / 2 plate, In general, however, the thermoplastic resin has such a characteristic that the in-plane retardation Re increases with shorter wavelength. This property is referred to as a normal wavelength dispersion property, and the opposite property, that is, the property that the in-plane retardation Re becomes smaller as the shorter wavelength is referred to as the reverse wavelength dispersion property. A method of obtaining a film that satisfies the relationship of Re (450) <Re (590) &lt; Re (750) by laminating a stretched film A and a stretched film B having a regular wavelength dispersion property so that their slow axes are directly aligned For example, when the stretched film A has a greater wavelength dependence of the in-plane retardation Re than the stretched film B, the stretched film is made so that the in-plane retardation Re becomes smaller than that of the stretched film B By lamination, a film having reverse wavelength dispersion characteristics can be obtained.

The method for producing the copolymer of the present invention will be described.

The polymerization mode is not particularly limited and can be produced by a known method such as solution polymerization and bulk polymerization, but solution polymerization is more preferable. The solvent used in the solution polymerization is preferably non-polymerized in view of difficulty in producing by-products and less adverse effects. Examples of the solvent include, but are not limited to, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and acetophenone, ethers such as tetrahydrofuran and 1,4-dioxane, toluene, , And aromatic hydrocarbons such as xylene and chlorobenzene. Methyl ethyl ketone and methyl isobutyl ketone are preferable from the viewpoints of solubility of the monomers and copolymers and ease of solvent recovery. The amount of the solvent to be added is preferably 10 to 100 parts by mass, more preferably 30 to 80 parts by mass, based on 100 parts by mass of the copolymer obtained. When it is 10 parts by mass or more, it is suitable for controlling the reaction rate and viscosity of the polymerization solution, and when it is 100 parts by mass or less, it is suitable for obtaining the aimed weight average molecular weight (Mw).

The polymerization process may be any of a batch polymerization method, a semi-batch polymerization method and a continuous polymerization method, but a batch polymerization method is suitable for obtaining a desired weight average molecular weight (Mw) and transparency.

The polymerization method is not particularly limited, but is preferably a radical polymerization method from the viewpoint of being capable of being produced with high productivity by a short process. The polymerization initiator is not particularly limited and examples thereof include dibenzoyl peroxide, t-butyl peroxybenzoate, 1,1-di (t-butylperoxy) -2-methylcyclohexane, t-butylperoxy-2-ethylhexanoate, t-butylperoxyacetate, dicumylperoxide, ethyl-3, 3-di- (t-butylperoxy) butyrate, and the like, and known organic peroxides such as azobisisobutyronitrile, azobiscyclohexanecarbonitrile, azobismethylpropionitrile and azobismethylbutyronitrile. An azo compound can be used. Two or more of these polymerization initiators may be used in combination. Among them, it is preferable to use an organic peroxide having a 10-hour half-life temperature of 70 to 110 ° C.

The copolymer of the present invention has a weight average molecular weight (Mw) of 120,000 to 250,000, and a haze of 2 mm in thickness measured on the basis of ASTM D1003 is 1% or less. When a copolymer satisfying these conditions is obtained, there is no particular limitation on the polymerization procedure thereof. However, in order to obtain a copolymer having transparency with a haze of 1% or less, the copolymer should be polymerized so that the copolymer composition distribution becomes small. The unsaturated dicarboxylic acid anhydride monomer is continuously added to correspond to the polymerization rate of the aromatic vinyl monomer and the vinyl cyanide monomer in that the aromatic vinyl monomer and the unsaturated dicarboxylic acid anhydride monomer have strong alternating copolymerizations The method is appropriate. The polymerization rate can be controlled by adjusting the polymerization temperature, the polymerization time, and the amount of the polymerization initiator added. Continuous addition of the polymerization initiator is preferable because it is easier to control the polymerization rate. The method of obtaining a copolymer having a weight average molecular weight (Mw) of 120,000 to 250,000 can be obtained by adjusting the addition amount of the solvent and the addition amount of the chain transfer agent in addition to the adjustment of the polymerization temperature, the polymerization time and the addition amount of the polymerization initiator. The chain transfer agent is not particularly limited, but known chain transfer agents such as n-dodecylmercaptan, t-dodecylmercaptan and 2,4-diphenyl-4-methyl-1-pentene can be used.

After completion of the polymerization, the polymerization liquid may contain a heat stabilizer such as a hindered phenol compound, a lactone compound, a phosphorus compound or a sulfur compound, a light stabilizer such as a hindered amine compound or a benzotriazole compound, a lubricant, An additive such as a colorant, an antistatic agent, and a mineral oil may be added. It is preferable that the amount thereof is less than 0.2 parts by mass based on 100 parts by mass of the whole monomer unit. These additives may be used alone, or two or more of them may be used in combination.

The method for recovering the copolymer of the present invention from the polymerization solution is not particularly limited, and a known de-foaming technique can be used. For example, there may be mentioned a method in which a polymerization liquid is fed continuously to a biaxial demagnetizing extruder using a gear pump, and a polymerization solvent or an unreacted monomer is subjected to a devolatilization treatment. The depolymerization component containing a polymerization solvent and unreacted monomers can be recovered by condensation using a condenser or the like, and the condensation liquid is purified by a distillation column, whereby the polymerization solvent can be reused.

Example

EXAMPLES Hereinafter, the present invention will be further described by way of examples and comparative examples, but all of them are illustrative and do not limit the scope of the present invention.

~ Preparation of Copolymer ~

[Example 1]

A 20% maleic anhydride solution dissolved in methyl isobutyl ketone so that the maleic anhydride concentration is 20% by mass, and a 20% maleic anhydride solution diluted with methyl isobutyl ketone to make 2% by mass of t-butyl peroxy-2-ethylhexanoate A 2% t-butylperoxy-2-ethylhexanoate solution was prepared in advance and used for polymerization.

2.0 kg of a 20% maleic anhydride solution, 30 kg of styrene, 6 kg of acrylonitrile, 30 g of t-dodecylmercaptan and 2 kg of methyl isobutyl ketone were charged into a 120-liter autoclave equipped with a stirrer and the gas phase portion was replaced with a nitrogen gas After that, the temperature was raised to 85 캜 over 40 minutes while stirring. The temperature was maintained at 85 占 폚, and then 20% maleic anhydride solution at 1.38 kg / hour and 2% t-butyl peroxy-2-ethylhexanoate solution at 429 g / Followed by continuous addition. Thereafter, the addition of the 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 25 g of t-butylperoxyisopropyl monocarbonate was added. The 20% maleic anhydride solution was heated to 125 占 폚 over 6 hours at a heating rate of 6.7 占 폚 / hour while maintaining an autoclave rate of 1.38 kg / hr. The addition of the 20% maleic anhydride solution was stopped when the amount of the added amount reached 18 kg as a total. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 125 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization rates of the respective monomers were measured. The polymerization liquid was fed continuously to a biaxial extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomer were subjected to a devolatilization treatment to obtain copolymer A-1. The obtained copolymer A-1 was subjected to composition analysis by C-13 NMR. Further, molecular weight measurement was performed in a GPC apparatus. Further, a mirror-surface plate having a thickness of 2 mm was molded in an injection molding machine, and the haze was measured in a haze meter. Table 1 shows polymerization rates of monomers, compositional analysis results, molecular weight measurement results and haze measurement results.

[Example 2]

A 20% maleic anhydride solution and a 2% t-butylperoxy-2-ethylhexanoate solution were prepared in the same manner as in Example 1.

3.0 kg of a 20% maleic anhydride solution, 30 kg of styrene, 4 kg of acrylonitrile and 40 g of t-dodecylmercaptan were charged into a 120-liter autoclave equipped with a stirrer, and the gaseous portion was replaced with nitrogen gas. Lt; RTI ID = 0.0 &gt; 85 C. &lt; / RTI &gt; The temperature was raised to 85 ° C, and a 20% maleic anhydride solution at 1.8 kg / hr and a 2% t-butyl peroxy-2-ethylhexanoate solution at an addition rate of 375 g / Lt; / RTI &gt; Thereafter, the addition of 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 40 g of t-butylperoxyisopropyl monocarbonate was added. The 20% maleic anhydride solution was heated to 125 ° C over 7 hours at a heating rate of 5.71 ° C / hour while maintaining the autoclave at 1.8 kg / hr. The addition of the 20% maleic anhydride solution was stopped when the amount of the added amount reached 27 kg by the total amount. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 125 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization ratios of the respective monomers were measured. The polymerization solution was continuously fed to a biaxial demagnetization extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomers were subjected to devolatilization to obtain copolymer A-2. With respect to the obtained copolymer A-2, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 1.

[Example 3]

A 20% maleic anhydride solution and a 2% t-butylperoxy-2-ethylhexanoate solution were prepared in the same manner as in Example 1.

2.0 kg of a 20% maleic anhydride solution, 28 kg of styrene, 8.0 kg of acrylonitrile, 30 g of t-dodecylmercaptan and 2 kg of methyl isobutyl ketone were charged into a 120-liter autoclave equipped with a stirrer and the gaseous portion was purged with nitrogen gas After substitution, the temperature was raised to 88 DEG C over 40 minutes while stirring. The temperature was raised to 88 ° C, and then 20% maleic anhydride solution at 1.5 kg / hr and 2% t-butyl peroxy-2-ethylhexanoate solution at a sequential rate of 285.7 g / Lt; / RTI &gt; Thereafter, the addition of the 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 20 g of t-butylperoxyisopropyl monocarbonate was added. The temperature was raised to 125 캜 over 5 hours at a heating rate of 7.4 캜 / hour while maintaining the rate of addition of 20% maleic anhydride solution at 1.5 kg / hr. The respective additions of the 20% maleic anhydride solution were stopped when the total amount reached 18 kg. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 125 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization ratios of the respective monomers were measured. The polymerization solution was fed continuously to a biaxial degreasing extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomer were subjected to a devolatilization treatment to obtain copolymer A-3. With respect to the obtained copolymer A-3, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 1.

[Example 4]

A 20% maleic anhydride solution and a 2% t-butylperoxy-2-ethylhexanoate solution were prepared in the same manner as in Example 1.

2 kg of a 20% maleic anhydride solution, 32 kg of styrene, 4 kg of acrylonitrile, 30 g of t-dodecylmercaptan and 2 kg of methyl isobutyl ketone were charged into a 120-liter autoclave equipped with a stirrer and the gas phase portion was replaced with nitrogen gas Then, the temperature was raised to 95 캜 over 40 minutes while stirring. After heating, the temperature was maintained at 95 ° C, and a 20% maleic anhydride solution and a 2% t-butyl peroxy-2-ethylhexanoate solution were continuously applied at a rate of 200 g / Followed by continuous addition. Thereafter, the addition of the 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 60 g of t-butylperoxyisopropyl monocarbonate was added. The 20% maleic anhydride solution was heated to 120 ° C over 6 hours at a heating rate of 4.17 ° C / hour while maintaining the autoclave at 1.125 kg / hr. The addition of the 20% maleic anhydride solution was stopped when the amount of the added amount reached 18 kg as a total. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 120 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled and the polymerization rate of each monomer was measured. The polymerization liquid was fed continuously to a biaxial extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomer were subjected to devolatilization to obtain copolymer A-4. With respect to the obtained copolymer A-4, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 1.

[Example 5]

A 20% maleic anhydride solution and a 2% t-butylperoxy-2-ethylhexanoate solution were prepared in the same manner as in Example 1.

3.0 kg of a 20% maleic anhydride solution, 32 kg of styrene, 1.2 kg of acrylonitrile and 30 g of t-dodecylmercaptan were charged into a 120-liter autoclave equipped with a stirrer, and the gas phase portion was replaced with nitrogen gas, The temperature was raised to 90 DEG C over 40 minutes. The temperature was raised to 90 ° C and the temperature was raised to 1.8 kg / hour for a 20% maleic anhydride solution, 53.3 g / hour for acrylonitrile and 375 g / hour for a solution of 2% t-butylperoxy-2-ethylhexanoate Respectively, over a period of 8 hours continuously. Thereafter, the addition of the 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 80 g of t-butylperoxyisopropyl monocarbonate was added. 1.8 kg / hour of a 20% maleic anhydride solution, and acrylonitrile were heated to 125 DEG C over 7 hours at a heating rate of 5 DEG C / hour while maintaining an autoclave rate of 53.3 g / hour. The addition of the 20% maleic anhydride solution was stopped by adding 27 kg of the total amount and the amount of acrylonitrile was 800 g by the total amount. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 125 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization ratios of the respective monomers were measured. The polymerization solution was continuously fed to a biaxial extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomer were subjected to devolatilization to obtain copolymer A-5. With respect to the obtained copolymer A-5, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 1.

[Example 6]

A 10% maleic anhydride solution dissolved in methyl isobutyl ketone such that the concentration of maleic anhydride was 10 mass%, and a solution of maleic anhydride diluted with methyl isobutyl ketone so that the amount of t-butyl peroxy-2-ethylhexanoate became 2 mass% A 2% t-butylperoxy-2-ethylhexanoate solution was prepared in advance and used for polymerization.

2 kg of a 10% maleic anhydride solution, 28 kg of styrene, 10 kg of acrylonitrile, 48 g of t-dodecylmercaptan and 2 kg of methyl isobutyl ketone were charged into a 120-liter autoclave equipped with a stirrer and the gas phase portion was replaced with nitrogen gas Then, the temperature was raised to 90 캜 over 40 minutes while stirring. The temperature was raised to 90 ° C., and then the solution of 10% maleic anhydride at 1.64 kg / hour and the solution of 2% t-butyl peroxy-2-ethylhexanoate at a rate of 286 g / Followed by continuous addition. Thereafter, the addition of 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 30 g of t-butylperoxyisopropyl monocarbonate was added. The temperature was elevated to 120 DEG C over a period of 4 hours at a heating rate of 7.5 DEG C / hour while maintaining the rate of addition of the 10% maleic anhydride solution at 1.64 kg / hr. The addition of the 10% maleic anhydride solution was stopped when the total amount reached 18 kg. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 120 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization ratios of the respective monomers were measured. The polymerization solution was continuously fed to a biaxial extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomer were subjected to a devolatilization treatment to obtain copolymer A-6. With respect to the obtained copolymer A-6, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 1.

[Example 7]

A 25% maleic anhydride solution dissolved in methyl isobutyl ketone so that the maleic anhydride concentration is 25% by mass, and a 25% maleic anhydride solution diluted with methyl isobutyl ketone to make 2% by mass of t-butyl peroxy-2-ethylhexanoate A 2% t-butylperoxy-2-ethylhexanoate solution was prepared in advance and used for polymerization.

2.88 kg of a 25% maleic anhydride solution, 26.8 kg of styrene, 6 kg of acrylonitrile and 30 g of t-dodecylmercaptan were charged into a 120-liter autoclave equipped with a stirrer, and the gaseous portion was replaced with nitrogen gas, And the temperature was raised to 85 캜 over 40 minutes. The temperature was maintained at 85 占 폚, and then 25% maleic anhydride solution at 2.16 kg / hour and 2% t-butyl peroxy-2-ethylhexanoate solution at a sequential rate of 286 g / Followed by continuous addition. Thereafter, the addition of 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 40 g of t-butylperoxyisopropyl monocarbonate was added. The 25% maleic anhydride solution was heated to 120 캜 over 5 hours at a heating rate of 7 캜 / hour while maintaining an autoclave rate of 2.88 kg / hr. The addition of the 25% maleic anhydride solution was stopped when the amount of the added water reached 25.9 kg by the total amount. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 120 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization ratios of the respective monomers were measured. The polymerization solution was fed continuously to a biaxial demagnetization extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomers were subjected to a devolatilization treatment to obtain copolymer A-7. With respect to the obtained copolymer A-7, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 1.

[Example 8]

A 10% maleic anhydride solution and a 2% t-butylperoxy-2-ethylhexanoate solution were prepared in the same manner as in Example 6.

2.8 kg of a 10% maleic anhydride solution, 34.4 kg of styrene, 1.8 kg of acrylonitrile and 10 g of t-dodecylmercaptan were charged into a 120-liter autoclave equipped with a stirrer, and the gaseous portion was replaced with nitrogen gas, And the temperature was raised to 90 占 폚 over 40 minutes. After heating, the temperature was maintained at 90 占 폚, 1.2 kg / hr of a 10% maleic anhydride solution, 47.6 g / hr of acrylonitrile and 181 g / hr of a 2% t-butylperoxy-2-ethylhexanoate solution Respectively, over a period of 11 hours. Thereafter, the addition of the 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 80 g of t-butylperoxyisopropyl monocarbonate was added. The temperature was elevated to 125 DEG C over 10 hours at a heating rate of 3 DEG C / hour while maintaining the rate of addition of the 10% maleic anhydride solution at 1.2 kg / hr and the acrylonitrile at 47.6 g / hr. The addition of the 10% maleic anhydride solution was stopped when the addition amount was 25.2 kg as a total amount and 1 kg of acrylonitrile. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 125 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization ratios of the respective monomers were measured. The polymerization liquid was fed continuously to a biaxial extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomer were subjected to a devolatilization treatment to obtain copolymer A-8. With respect to the obtained copolymer A-8, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 1.

[Comparative Example 1]

A 20% maleic anhydride solution and a 2% t-butylperoxy-2-ethylhexanoate solution were prepared in the same manner as in Example 1.

2.0 kg of a 20% maleic anhydride solution, 30 kg of styrene, 6 kg of acrylonitrile, 60 g of t-dodecylmercaptan and 2 kg of methyl isobutyl ketone were charged into a 120-liter autoclave equipped with a stirrer and the gas phase portion was substituted with a nitrogen gas After that, the temperature was raised to 95 캜 over 40 minutes while stirring. The temperature was maintained at 95 ° C., and then 20% maleic anhydride solution at 1.38 kg / hour and 2% t-butyl peroxy-2-ethylhexanoate solution at a sequential rate of 375 g / Followed by continuous addition. Thereafter, the addition of the 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 20 g of t-butylperoxyisopropyl monocarbonate was added. The 20% maleic anhydride solution was heated to 125 캜 over 5 hours at a temperature raising rate of 6.0 캜 / hour while maintaining an autoclaving rate of 1.38 kg / hr. The addition of the 20% maleic anhydride solution was stopped when the amount of the added amount reached 18 kg as a total. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 125 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization rates of the respective monomers were measured. The polymerization solution was continuously fed to a biaxial extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomer were subjected to devolatilization to obtain copolymer A-9. With respect to the obtained copolymer A-9, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 2.

[Comparative Example 2]

A 20% maleic anhydride solution and a 2% t-butylperoxy-2-ethylhexanoate solution were prepared in the same manner as in Example 1.

10 kg of a 20% maleic anhydride solution, 30 kg of styrene, 6 kg of acrylonitrile, 30 g of t-dodecylmercaptan and 2 kg of methyl isobutyl ketone were charged into a 120-liter autoclave equipped with a stirrer and the gas phase portion was replaced with nitrogen gas Then, the temperature was raised to 85 캜 over 40 minutes while stirring. The temperature was maintained at 85 占 폚, and then 80% of the 20% maleic anhydride solution and the 2% t-butyl peroxy-2-ethylhexanoate solution were continuously fed at an addition rate of 375 g / Followed by continuous addition. Thereafter, the addition of the 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 20 g of t-butylperoxyisopropyl monocarbonate was added. The 20% maleic anhydride solution was heated to 120 캜 over 5 hours at a heating rate of 7 캜 / hour while maintaining an autoclaving rate of 769 g / hr. The addition of the 20% maleic anhydride solution was stopped when the amount of the added water reached 10 kg by the addition. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 120 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization rates of the respective monomers were measured. The polymerization liquid was fed continuously to a biaxial extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomer were subjected to devolatilization to obtain copolymer A-10. With respect to the obtained copolymer A-10, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 2.

[Comparative Example 3]

A 20% maleic anhydride solution and a 2% t-butylperoxy-2-ethylhexanoate solution were prepared in the same manner as in Example 1.

3 kg of 20% maleic anhydride solution, 30 kg of styrene, 4 kg of acrylonitrile and 4 g of t-dodecylmercaptan were charged into a 120-liter autoclave equipped with a stirrer, and the gas phase portion was replaced with nitrogen gas. Lt; 0 &gt; C. The temperature was maintained at 86 占 폚, and a 20% maleic anhydride solution and a 2% t-butyl peroxy-2-ethylhexanoate solution were continuously applied at a rate of 1.17 kg / hour and 100 g / Followed by continuous addition. Thereafter, the addition of the 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 60 g of t-butylperoxyisopropyl monocarbonate was added. The 20% maleic anhydride solution was heated to 115 ° C over 8 hours at a heating rate of 3.63 ° C / hour while maintaining the autoclave at 1.17 kg / hr. The addition of the 20% maleic anhydride solution was stopped when the amount of the added amount reached 27 kg by the total amount. After elevating the temperature, the polymerization was terminated at 115 ° C for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization ratios of the respective monomers were measured. The polymerized liquid was fed continuously to a biaxial extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomers were subjected to devolatilization to obtain copolymer A-11. With respect to the obtained copolymer A-11, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 2.

[Comparative Example 4]

A 20% maleic anhydride solution and a 2% t-butylperoxy-2-ethylhexanoate solution were prepared in the same manner as in Example 1.

2 kg of a 20% maleic anhydride solution, 22 kg of styrene, 14 kg of acrylonitrile, 30 g of t-dodecylmercaptan and 4 kg of methyl isobutyl ketone were charged into a 120-liter autoclave equipped with a stirrer and the gas phase portion was replaced with nitrogen gas Then, the temperature was raised to 85 캜 over 40 minutes while stirring. The temperature was raised to 85 ° C., and a 20% maleic anhydride solution and a 2% t-butyl peroxy-2-ethylhexanoate solution were continuously applied at a rate of 83.3 g / hour for 6 hours Followed by continuous addition. Thereafter, the addition of the 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 10 g of t-butylperoxyisopropyl monocarbonate was added. The 20% maleic anhydride solution was heated to 120 deg. C over 3 hours at a heating rate of 11.67 deg. C / hour while maintaining an autoclaving rate of 2 kg / hour. The addition of the 20% maleic anhydride solution was stopped when the amount of the added amount reached 18.0 kg as a total. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 120 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization ratios of the respective monomers were measured. The polymerized liquid was fed continuously to a biaxial extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomer were subjected to devolatilization to obtain copolymer A-12. With respect to the obtained copolymer A-12, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 2.

[Comparative Example 5]

A 25% maleic anhydride solution and a 2% t-butyl peroxy-2-ethylhexanoate solution were prepared in the same manner as in Example 7.

4 kg of 25% maleic anhydride solution, 26 kg of styrene, 4 kg of acrylonitrile and 30 g of t-dodecylmercaptan were charged into a 120-liter autoclave equipped with a stirrer, and the gas phase portion was replaced with nitrogen gas. Lt; 0 &gt; C. The temperature was raised to 85 ° C, and then 2.77 kg / hour of a 25% maleic anhydride solution and a solution of 2% t-butyl peroxy-2-ethylhexanoate at an addition rate of 375 g / Lt; / RTI &gt; Thereafter, the addition of the 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 20 g of t-butylperoxyisopropyl monocarbonate was added. The 25% maleic anhydride solution was heated to 125 DEG C over 5 hours at a heating rate of 8 DEG C / hour, while maintaining an autoclave rate of 2.77 kg / hr. The addition of the 25% maleic anhydride solution was stopped when the amount of the added water reached 36 kg by the total amount. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 125 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization ratios of the respective monomers were measured. The polymerization liquid was fed continuously to a biaxial extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomer were subjected to a devolatilization treatment to obtain copolymer A-13. With respect to the obtained copolymer A-13, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 2.

[Comparative Example 6]

A 10% maleic anhydride solution and a 2% t-butylperoxy-2-ethylhexanoate solution were prepared in the same manner as in Example 6.

2.8 kg of a 10% maleic anhydride solution, 37.2 kg of styrene, 30 g of t-dodecylmercaptan, and a gaseous phase were purged with a nitrogen gas in a 120-liter autoclave equipped with a stirrer, Respectively. The temperature was raised to 95 ° C and the temperature was maintained at 95 ° C, while the 10% maleic anhydride solution and the 2% t-butylperoxy-2-ethylhexanoate solution were continuously fed at a rate of 1.48 kg / Lt; / RTI &gt; Thereafter, the addition of the 2% t-butylperoxy-2-ethylhexanoate solution was stopped, and 60 g of t-butylperoxyisopropyl monocarbonate was added. The 10% maleic anhydride solution was heated to 120 DEG C over 9 hours at a rate of 2.77 DEG C / h while maintaining the autoclave at 1.48 kg / hr. The addition of the 10% maleic anhydride solution was stopped when the amount of the added amount reached 25.2 kg as a total. After elevating the temperature, the polymerization was terminated by maintaining the temperature at 120 캜 for 1 hour. After completion of the polymerization, a small amount of the polymerization solution was sampled, and the polymerization ratios of the respective monomers were measured. The polymerization solution was continuously fed to a biaxial degreasing extruder using a gear pump, and methyl isobutyl ketone and a small amount of unreacted monomer were subjected to a devolatilization treatment to obtain copolymer A-14. With respect to the obtained copolymer A-14, the polymerization rate, compositional analysis, molecular weight and haze of the monomers were measured in the same manner as in Example 1, respectively. The measurement results are shown in Table 2.

[Comparative Example 7]

As for the styrene-acrylonitrile copolymer (grade name "AS-C-800", manufactured by Denki Kagaku Kogyo K.K.), the polymerization rate, composition analysis, molecular weight and haze of the monomers were measured Respectively. The measurement results are shown in Table 2.

The polymerization ratios of the respective monomers were obtained as follows.

(1) Polymerization ratio of styrene monomer and polymerization degree of acrylonitrile monomer

For each polymer solution sample, unreacted styrene monomer and acrylonitrile monomer were measured using the following apparatus.

Device name: Gas chromatograph (6890 series, manufactured by Agilent)

Column: Capillary column (DB-1 (polysiloxane), manufactured by Agilent)

The column temperature was measured at an initial temperature of 60 ° C.

(Temperature increase condition) 60 占 폚: hold 16 minutes

60 to 200 占 폚: heating at 20 占 폚 / min

200 ℃: Hold 8 minutes

From the analytical values obtained by measurement, the polymerization rate was calculated from the following formula.

Amount of unreacted styrene monomer = a (ppm)

Amount of unreacted acrylonitrile monomer = b (ppm)

Total amount of styrene monomer input = d (mass part)

Total amount of acrylonitrile monomer added = e (parts by mass)

Total amount of maleic anhydride monomer introduced = f (parts by mass)

Total amount of polymerization solvent input = g (parts by mass)

-Styrene monomer polymerization rate (%) = 100-a x (d + e + f + g) / 100d

Polymerization ratio (%) of acrylonitrile monomer = 100-b (d + e + f + g) / 100e

(2) Polymerization rate of maleic anhydride

For each polymer solution sample, the maleic anhydride monomer was measured using the following apparatus.

Apparatus: Liquid chromatograph (LC-10, manufactured by Shimadzu Corporation)

Detector and analysis wavelength: UV 230 nm

Column: Inverse phase column (YMC-PACK ODS-A A-312 (150 mm x 6 mm 5 m), YMC)

Mobile phase: H ₂ O / CH ₃ OH 50/50 (volume ratio) (pH 3.3 H ₃ PO ₄ )

Flow rate: 1 ml / min

Injection amount: 20 μl

Procedure: About 0.2 g of the sample is weighed into a 50 ml Erlenmeyer flask, and 5 ml of 1,2-dichloroethane is added to dissolve. Next, 5 ml of n-hexane is added, and the mixture is shaken in a shaker for 10 to 15 minutes to precipitate a polymer. The supernatant is filtered through a 0.45 占 퐉 membrane filter. Add 3 ml of supernatant and pure water to a 10 ml scalpel tube, shake for 1 hour, leave for 30 minutes, and measure the lower layer in the apparatus. The quantitative method is calculated from the maleic anhydride standard solution by an absolute calibration curve method.

From the analytical values obtained by measurement, the polymerization rate was calculated from the following formula.

Unreacted maleic anhydride monomer amount = c (ppm)

Total amount of styrene monomer input = d (mass part)

Total amount of acrylonitrile monomer added = e (parts by mass)

Total amount of maleic anhydride monomer introduced = f (parts by mass)

Total amount of polymerization solvent input = g (parts by mass)

Polymerization ratio (%) of maleic anhydride monomer = 100-c x (d + e + f + g) / 100f

~ Evaluation of film properties ~

[Examples 1 to 8, Comparative Examples 1 to 7]

Films were prepared as follows for Copolymers A-1 to A-14 and AS-C-800, respectively.

A gear pump, a polymer filter &quot; DENA FILTER, a scale of 5 mu m &quot; (manufactured by Nagaseishi Co., Ltd.), a width of 300 mm, and the like were placed in a 40 mmφ single screw extruder in a clean booth, A film having a width of 250 mm and a thickness of 100 占 퐉 and 5 占 퐉 was formed from a film made of a film provided with a single layer T-die and a take-up winding device "touch roll flexible type" (Plastic High Kenkenkusho). Further, film properties were measured in the obtained film. The measurement results are shown in Tables 3 and 4. The pellets of the copolymer used were dried at 90 캜 for 2 hours in advance, and then supplied to the extruder. The temperature of the T-die was set at 260 캜.

(1) film strength

The test piece was cut out from the unstretched film, and subjected to an impact resistance test under the following conditions to measure the 50% fracture energy.

Test specimen; 20 sheets of non-stretched film of 50 mm in width x 50 mm in width x 100 ± 5 μm in thickness

Central; 11 mm diameter, 5.45 g weight steel

Fixed state; Insert the film in a ring with an inner diameter of 34 mm, and clip the four places on the top, bottom, left and right sides.

50% fracture height was measured at intervals of 1 cm in accordance with JIS K7211, and 50% fracture energy was calculated. In addition, since the jig can not cope with the measurement at less than 5 cm, the measurement results are shown as &quot; 3 (mJ) &quot; The 50% breakdown energy was 5 (mJ) or more.

(2) Film transparency

The degree of cloudiness of the unstretched film was measured according to ASTM D1003, and 2.0% or less was determined as acceptable.

(3) Optical characteristics <in-plane retardation Re (590), thickness retardation Rth>

Using a non-stretched film, the glass transition temperature was measured by a DSC apparatus (Robot DSC6200, manufactured by Seiko Instruments Inc.) and stretching was carried out under the following conditions.

Device name: biaxial stretching test apparatus (EX10-B, Toyo Seiki Seisakusho Co., Ltd.)

Test specimen; 90 mm × 90 mm × 100 ± 5 μm from the unstretched film

Stretching temperature; Glass transition temperature + 5 ° C

Elongation speed; 25 mm / min

A stretching method; Free width uniaxial stretching 2.0 times stretching

The in-plane retardation Re (590) and the thickness retardation Rth of the unstretched film and the uniaxially stretched film were measured using the following apparatus. For the stretched film, it was determined that the in-plane retardation Re (590) was 300 nm or more and the thickness retardation Rth was less than 0 nm (negative). However, with respect to the film which was broken at the time of stretching due to insufficient film strength, it was decided that the film was not acceptable because it was impossible to measure.

Device name: birefringence measurement device (KOBRA-WR, manufactured by Oji Keisoku Kikai)

Measured wavelength: 590 nm

(4) Heat resistance

The in-plane retardation Re (590) was measured after the film stretched in the step (3) was placed in a thermostatic chamber for 24 hours, and the temperature at which the decrease in Re (590) The Re (590) reduction start temperature was 110 占 폚 or higher. Also, the set temperature of the thermostatic chamber was set at an interval of 5 占 폚. The film broken in (3) was marked as &quot; x &quot; because it was not measured.

All of the examples of the copolymer for an optical film of the present invention were excellent in film strength, film transparency, optical characteristics, negative retardation and heat resistance, but in the comparative example of the copolymer not meeting the conditions of the present invention, The film was inferior in strength, film transparency, optical properties, negative retardation and heat resistance.

~ Evaluation of conformity to retardation film ~

[Example 9]

Using the copolymer A-1 obtained in Example 1, an unoriented film having a thickness of 0.25 mm was produced in the film-forming machine described in Example 1. [ The obtained unstretched film was cut into a square of 120 mm on one side and stretched 2.5 times in the machine direction at a temperature of 125 DEG C and a stretching speed of 25 mm / min by a biaxial stretching tester (EX10-B, Toyo Seiki Seisakusho Co., Ltd.) Elongation, and film A1 having a thickness of 0.10 mm which was 1.0-fold fixed and uniaxially stretched in the transverse direction.

Subsequently, an unoriented film having a thickness of 0.16 mm was prepared by using a norbornene resin (ZEONEX 690R, manufactured by Nippon Zeon Co., Ltd.). The resulting unstretched film was cut into a square having a size of 120 mm, (EX10-B, manufactured by Toyo Seiki Seisaku-sho) at a temperature of 136 占 폚 and a stretching speed of 25 mm / min to obtain a film B1 having a thickness of 0.10 mm stretched 2.0 times in the longitudinal direction.

The in-plane retardation Re (590), the Nz coefficient, and the three-dimensional refractive index of the film A1 and the film B1 were measured using a birefringence measuring apparatus "KOBRA-WR made by Oji Keisoku Co., The results are shown in Table 5.

In addition, the in-plane retardations Re (450), Re (590) and Re (750) at wavelengths of 450 nm, 590 nm and 750 nm, respectively, of the laminated film obtained by laminating the film A1 and the film B1 so as to have a straight- The coefficient was measured using a birefringence measuring device (KOBRA-WR, manufactured by Oji Chemical Industry Co., Ltd.). The results are shown in Table 5.

By using the copolymer for an optical film of the present invention, an optical film having characteristics of a retardation film for improving the viewing angle of the liquid crystal device, that is, satisfying the relationship of the in-plane retardation (Re) of 60 to 300 nm and the Nz coefficient of 0.4 to 0.6 It is possible to do. Furthermore, it is possible to produce an optical film that satisfies the relationship of Re (450) <Re (590) &lt; Re (750), which is considered to be ideal in terms of color compensation.

According to the present invention, it is possible to provide a copolymer for an optical film which exhibits a negative oriented birefringence and which is excellent in transparency, heat resistance, film strength and optical characteristics, and capable of obtaining a film suitable for an optical film.

Claims (10)

A vinyl aromatic monomer unit, an aromatic vinyl monomer unit in an amount of 65 to 90 mass%, a vinyl cyanide monomer unit in an amount of 5 to 25 mass% and an unsaturated dicarboxylic acid anhydride monomer unit in an amount of 5 to 20 mass%, a weight average molecular weight (Mw) , And a blur of 2 mm or less as measured on the basis of ASTM D1003 of 1% or less. The copolymer for an optical film according to claim 1, wherein the aromatic vinyl monomer unit is 70 to 80 mass%, the vinyl cyanide monomer unit is 10 to 20 mass%, and the unsaturated dicarboxylic acid anhydride monomer unit is 10 to 15 mass%. The copolymer for an optical film according to claim 1 or 2, wherein the aromatic vinyl monomer unit is a styrene unit. The copolymer according to any one of claims 1 to 3, wherein the vinyl cyanide monomer unit is an acrylonitrile unit. The copolymer for an optical film according to any one of claims 1 to 4, wherein the unsaturated dicarboxylic acid anhydride monomer unit is a maleic anhydride unit. The copolymer for an optical film according to any one of claims 1 to 5, which is used for a polarizing film protective film, a retardation film, or an antireflection film. The film according to any one of claims 1 to 6, wherein a film A obtained by stretching a thermoplastic resin film exhibiting negative orientation birefringence and a film B obtained by stretching a thermoplastic resin film exhibiting positive orientation birefringence are laminated , nx &gt; nz &gt; ny, and is a thermoplastic resin for use in the film A. The copolymer for an optical film according to claim 7, wherein the film A is formed by stretching a film produced by melt extrusion. The copolymer for an optical film according to claim 7 or 8, wherein the Nz coefficient is 0.4 to 0.6. The film according to any one of claims 7 to 9, wherein the in-plane retardations Re (450), Re (590) and Re (590) at wavelengths of 450 nm, 590 nm and 750 nm are obtained by laminating the film A and the film B orthogonal to the slow axis 750) satisfies a relationship of Re (450) &lt; Re (590) &lt; Re (750).