JP2016071218A - Optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film which has excellent MIT flex resistance while keeping heat resistance and transparency of an acrylic resin having a glass transition temperature of 120°C or higher.SOLUTION: An optical film contains (A) an acrylic resin having a glass transition temperature of 120°C or higher, and (B) an acrylic block copolymer formed of a polymer block (B1) containing a structural unit derived from acrylic ester and a polymer block (B2) containing a structural unit derived from methacrylate ester. In an MIT flex resistance test, both a longitudinal direction (MD) and a width direction (TD) of the optical film are 500 times or more, and an internal haze is 1.0% or less.SELECTED DRAWING: None

Description

  The present invention relates to an optical film made of an acrylic resin composition having heat resistance, and relates to an optical film in which the flexibility of the film is improved while maintaining the heat resistance.

  In recent years, electronic devices have become increasingly smaller and thinner, as represented by notebook computers, large television sets, mobile phones, personal digital assistants, and the like. In an electronic device including a display device such as the electronic device exemplified above, a liquid crystal display device that takes advantage of light weight and compactness is often used.

  In these liquid crystal display devices, various films such as a polarizing film are used in order to maintain the display quality. Furthermore, in these liquid crystal display devices, in order to further reduce the weight of the liquid crystal display device for portable information terminals and mobile phones, a resin film or sheet (hereinafter, unless otherwise specified) A liquid crystal display device using a film) is also put into practical use.

  In this case, the resin film is required to be optically transparent, have low birefringence, and be optically homogeneous in order to handle polarized light. In other words, in a liquid crystal display device, a resin film used in place of a glass substrate is required to have a small phase difference expressed by the product of birefringence and thickness, and in addition, use of temperature, humidity, etc. It is required that the phase difference of the film does not easily change (low photoelasticity) due to external stress or the like, for example, dimensional change of the film due to the environment.

  By the way, in the liquid crystal display device, a resin film made of an amorphous thermoplastic resin is suitably used as the resin film. More specifically, for example, resin films made of engineering plastics such as polycarbonate, polyarylate, polysulfone, and polyethersulfone, and cellulose plastics such as triacetyl cellulose can be given.

  In the background described above, acrylic resin has been put to practical use in place of triacetyl cellulose, which has been used in the past, as a resin composition that satisfies the properties of transparency, low birefringence, low moisture permeability, and low photoelasticity. ing. A typical acrylic resin is polymethylmethacrylate (PMMA). However, since PMMA is inferior in heat resistance, introduction of glutarimide groups (see, for example, Patent Documents 1 and 2) and introduction of lactone groups ( For example, refer to Patent Document 3) to provide heat resistance.

  On the other hand, optical films made of acrylic resins may lack mechanical properties, especially flexibility, depending on the application, compared to resin films made of cellulose plastics such as triacetyl cellulose. It has been demanded.

International Publication No. 2005/054311 International Publication No. 2005/108438 JP 2005-281589 A

  The present invention has been made in view of the above-mentioned problems of conventional techniques, and an object thereof is to provide an optical film excellent in MIT flex resistance while maintaining the heat resistance and transparency of an acrylic resin. To do.

  As a result of intensive studies to solve the above problems, the present inventors have found that (A) an acrylic resin having a glass transition temperature of 120 ° C. or higher and (B) a polymer block (B1) containing a structural unit derived from an acrylate ester And an acrylic block copolymer composed of a polymer block (B2) containing a structural unit derived from a methacrylic ester, and in the MIT bending resistance test, the longitudinal direction (MD) and the width direction (TD) of the optical film In any case, the optical film having 500 times or more and having an internal haze of 1.0% or less has obtained the knowledge that the above-mentioned problems can be solved, and has reached the present invention based on these knowledge. is there.

  That is, the present invention comprises (A) an acrylic resin having a glass transition temperature of 120 ° C. or higher and (B) a polymer block (B1) containing a structural unit derived from an acrylate ester, and a structural unit derived from a methacrylate ester. An acrylic block copolymer composed of a polymer block (B2) containing, and in the MIT bending resistance test, both the longitudinal direction (MD) and the width direction (TD) of the optical film are 500 times or more, An optical film having an internal haze of 1.0% or less.

  Moreover, it is preferable that the average refractive index of the said (A) component is 1.48 or more, and the refractive index difference of the said (A) component and the said (B) component is 0.02 or less.

Moreover, it is preferable that Rth defined below of the said optical film is 50 nm or less.
[Rth = {(nx + ny) / 2−nz} × d. Refractive indexes in the slow axis direction, fast axis direction, and thickness direction of the film are nx, ny, and nz, respectively, and the direction in which the in-plane refractive index is maximum is the slow axis direction. d (nm) is the thickness of the film. ]
The elongation of the optical film is preferably 5% or more in both the longitudinal direction (MD) and the width direction (TD) of the optical film.

  The component (B) preferably has one or more polymer blocks (B1) and two or more polymer blocks (B2).

  The component (A) preferably has a ring structure in the main chain.

  The ring structure is preferably at least one selected from the group consisting of a glutarimide ring, a lactone ring, maleic anhydride, maleimide and glutaric anhydride.

  Moreover, it is preferable that content of the ring structure in the said (A) component is 2 to 30 weight%.

  Moreover, it is preferable that the said ring structure contains following General formula (1).

(Wherein R ¹ and R ² each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms; R ³ represents an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or carbon; Represents an aryl group of formula 6 to 10.)

  The optical film is preferably obtained by a melt extrusion method.

  The optical film is preferably obtained by biaxial stretching.

  Moreover, it is preferable that the said optical film is a polarizer protective film.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the optical film excellent in MIT bending resistance, maintaining the heat resistance and transparency of acrylic resin.

  The present invention includes (A) an acrylic resin having a glass transition temperature of 120 ° C. or higher and (B) a polymer block (B1) containing a structural unit derived from an acrylate ester and a heavy polymer containing a structural unit derived from a methacrylic acid ester. An acrylic block copolymer composed of a combined block (B2) is contained, and in the MIT bending resistance test, both the longitudinal direction (MD) and the width direction (TD) of the optical film are 500 times or more, and the internal haze Is an optical film having 1.0% or less.

  The MIT bending resistance test here uses a MIT soft fatigue tester model D manufactured by Toyo Seiki Co., Ltd., uses a strip-shaped test piece with a width of 15 mm, and has a bending radius of curvature R of 0.38 mm. It is defined as the number of reciprocating folds until cutting measured under the conditions of a bending angle of 135 degrees, a bending speed of 175 times / minute, and a load of 1.96 N. The internal haze is a haze value measured by using a haze meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. for a glass cell in which a film obtained in a glass cell for liquid measurement is put and pure water is filled in its periphery. It is defined as Further, the glass transition temperature is defined as a value obtained by measuring with a differential scanning calorimeter (DSC, manufactured by SII, DSC7020) in a nitrogen atmosphere at a heating rate of 20 ° C./min and analyzing by a midpoint method. .

  Here, the optical film of the present invention was found to be excellent in MIT flex resistance, which originally had room for improvement in acrylic films, while maintaining heat resistance and transparency, for the following reason. I guess that. That is, an acrylic block copolymer composed of a polymer block (B1) containing a structural unit derived from an acrylate ester as the component (B) and a polymer block (B2) containing a structural unit derived from a methacrylic ester. Since the molding temperature of the coalescence is close to the acrylic resin that is the component (A), in the melt mixing with the acrylic resin that is the component (A), the dispersion of the component (B) into the component (A) is promoted. It is estimated that no film defects due to poor dispersion occur. Furthermore, the polymer block (B1) containing the structural unit derived from the acrylic resin which is (A) component and the acrylate ester which is (B) component, and the polymer block (B2) containing the structural unit derived from the methacrylic ester Dispersion is controlled by the appropriate compatibility of the acrylic block copolymer composed of the above, and the dispersion of the component (B) is excellent in flexibility as a result of absorbing the stress with respect to the bending of the film. I guess it will be a film.

(Optical film)
The optical film of the present invention comprises an acrylic resin having a glass transition temperature of 120 ° C. or higher, a polymer block (B1) containing a structural unit derived from an acrylate ester, and a polymer block containing a structural unit derived from a methacrylate ester ( And an acrylic block copolymer composed of B2). Here, an acrylic resin containing an acrylic block copolymer composed of a polymer block (B1) containing a structural unit derived from an acrylate ester and a polymer block (B2) containing a structural unit derived from a methacrylic ester. Is defined as an acrylic resin composition.

  In addition, the optical film of the present invention has an improved number of reciprocal folds until cutting in the MIT bending resistance test, and has an internal haze of 1.0% or less, and a glass transition temperature of 115 ° C. or higher. It is preferable that

  Further, the number of bendings in the MIT bending resistance test is 500 times or more in the longitudinal direction (MD) and the width direction (TD) of the optical film, preferably 700 times or more, and more preferably 1000 times or more. When it is 500 times or more, it is good in terms of risk of breakage due to the long film-forming process and reworkability after bonding to the liquid crystal panel. The optical film according to the present invention can be arbitrarily selected to perform uniaxial stretching or biaxial stretching. However, by performing biaxial stretching, the number of reciprocal bending until cutting in the MIT bending resistance test is further increased.

  Even if it is a film made only of an acrylic resin that does not contain the acrylic block copolymer, the MIT bending resistance test can be performed 500 times or more depending on processing methods such as stretching conditions. Since the stretching conditions are the direction of lowering the stretching temperature or the direction of increasing the stretching ratio, the risk of breakage in the stretching process increases. According to the present invention, even with a relatively high stretching temperature, the number of bendings in the MIT flex test can be 500 times or more, and the risk of breakage during stretching is low, and the acrylic resin composition has good transparency. An optical film can be obtained.

  The internal haze of the optical film of the present invention is 1.0% or less, preferably 0.5% or less, and more preferably 0.3% or less. Due to the low internal haze, the quality when mounted on a liquid crystal panel is improved.

  The average refractive index of the acrylic resin (A) having a glass transition temperature of 120 ° C. or higher of the present invention is preferably 1.48 or higher, and the optical film of the present invention comprises (A) an acrylic resin and (B). The refractive index difference of the acrylic block copolymer composed of a polymer block (B1) containing a structural unit derived from an acrylate ester and a polymer block (B2) containing a structural unit derived from a methacrylic ester is 0. It is preferably 02 or less, and more preferably 0.01 or less. The optical film of the present invention is an acrylic film composed of a polymer block (B1) containing a structural unit derived from an acrylate ester in a acrylic resin and a polymer block (B2) containing a structural unit derived from a methacrylic acid ester. Since the block copolymer is in a dispersed state, the internal haze of the optical film tends to decrease as the refractive index difference between the acrylic resin and the acrylic block copolymer decreases. The average refractive index here can be measured using an Abbe refractometer 3T manufactured by Atago Co., Ltd.

  The dispersion shape of the acrylic block copolymer in the acrylic resin constituting the optical film of the present invention is not particularly limited, but may be a thread shape, a spherical shape, or a disk shape depending on a molding method and a draw ratio. Although there is no restriction | limiting in particular about a dispersion particle diameter, In any dispersion shape, the average dispersion length of a major axis direction and a minor-axis direction is 30 nm-100 micrometers, and it is preferable that it is 100 nm-50 micrometers. When the average dispersion length is 30 nm or less, the glass transition point of the acrylic resin tends to decrease. When the average dispersion length exceeds 100 μm, the dispersion state becomes non-uniform and the MIT flex resistance tends to decrease.

  The average dispersion length of the acrylic block copolymer is generally measured visually using a transmission electron microscope (TEM).

The thickness direction retardation Rth of the optical film of the present invention is preferably 50 nm or less, more preferably 30 nm or less, and further preferably 10 nm or less. Since the use (part) used in the liquid crystal panel is restricted due to the development of the thickness direction retardation, Rth is preferably as low as possible. Rth is defined below.
[Rth = {(nx + ny) / 2−nz} × d. Refractive indexes in the slow axis direction, fast axis direction, and thickness direction of the film are nx, ny, and nz, respectively, and the direction in which the in-plane refractive index is maximum is the slow axis direction. d (nm) is the thickness of the film. ]
Rth can be measured using a phase difference measuring device KOBRA-WR manufactured by Oji Scientific Instruments, and the measurement wavelength was 590 nm.

The elongation of the optical film of the present invention is preferably 5% or more in both the longitudinal direction (MD) and the width direction (TD) of the optical film. When the elongation is 5% or more, the reworkability is excellent. The elongation can be measured according to JIS K7161 using an autograph AGS-J manufactured by Shimadzu Corporation.
[Measured with a film size of 150 mm × 15 mm strips, a distance between chucks of 50 mm, and a tensile speed of 200 mm / min].

(Optical film manufacturing method)
An embodiment of a method for producing an optical film according to the present invention will be described, but the present invention is not limited to this. That is, any conventionally known method can be used as long as it is a method capable of producing a film by molding the acrylic resin according to the present invention.

  Specific examples include injection molding, melt extrusion molding, inflation molding, blow molding, compression molding, and the like. In addition, the film according to the present invention can be produced by a solution casting method or a spin coating method in which the acrylic resin composition according to the present invention is dissolved in a soluble solvent and then molded.

  Among them, it is preferable to use a melt extrusion method that does not use a solvent. According to the melt extrusion method, it is possible to reduce the burden on the global environment and the working environment due to manufacturing costs and solvents.

  Hereinafter, as an embodiment of a method for producing a film according to the present invention, a method for producing a film by molding the acrylic resin according to the present invention by a melt extrusion method will be described in detail. In the following description, a film obtained by melt extrusion is distinguished from a film obtained by other methods such as a solution casting method and is referred to as “melt extruded film”.

  When the acrylic resin composition according to the present invention is formed into a film by a melt extrusion method, first, the acrylic resin composition according to the present invention is supplied to an extruder, and the acrylic resin composition is heated and melted.

  The acrylic resin composition is preferably pre-dried before being supplied to the extruder. By performing such preliminary drying, foaming of the resin extruded from the extruder can be prevented.

  The preliminary drying method is not particularly limited. For example, the raw material (that is, the acrylic resin composition according to the present invention) is formed into a pellet or the like, and is performed using a hot air dryer or a vacuum dryer. be able to.

  Next, the acrylic resin composition heated and melted in the extruder is supplied to the T die through a gear pump and a filter. If a gear pump is used at this time, the uniformity of the extrusion amount of resin can be improved and the thickness nonuniformity of a film longitudinal direction can be reduced. On the other hand, if a filter is used, the foreign material in an acrylic resin composition can be removed and the film excellent in the external appearance without a defect can be obtained.

  Next, an unstretched film can be easily formed by extruding the acrylic resin composition supplied to the T die as a sheet-like molten resin. As a method for cooling and solidifying the molten resin, the sheet-like molten resin extruded from the T-die is brought into close contact with a cooling roll by a method such as an air knife or electrostatic application, and is cooled and solidified, or sandwiched between two cooling rolls. There are methods such as cooling and solidification. When sandwiched between two cooling rolls and cooled and solidified, one of the two cooling rolls sandwiching the sheet-like molten resin is a rigid metal roll having a smooth surface, and the other is a smooth surface. A flexible roll provided with an elastically deformable metal elastic outer cylinder is preferable.

  When sandwiched between two cooling rolls and cooled and solidified, the sheet-like molten resin is sandwiched and cooled with such a rigid metal roll and a flexible roll having a metal elastic outer cylinder to form a film. By doing so, the fine unevenness | corrugation of a surface, a die line, etc. are corrected, and the film whose surface is smooth and thickness nonuniformity is 5 micrometers or less can be obtained.

  In this specification, “cooling roll” is used to mean “touch roll” and “cooling roll”.

  Even when the rigid metal roll and the flexible roll are used, since the surface of each cooling roll is metal, if the film to be formed is thin, the surfaces of the cooling roll come into contact with each other. The outer surface may be scratched, or the cooling roll itself may be damaged.

  Therefore, when a sheet-like molten resin is sandwiched between two cooling rolls as described above to form a film, first, the sheet-like molten resin is sandwiched and cooled by the two cooling rolls, and the film is relatively thick. Get the original film. Thereafter, it is preferable to produce a film having a predetermined thickness by uniaxially or biaxially stretching the original film.

  More specifically, when a film having a thickness of 40 μm is manufactured, the sheet-like molten resin is sandwiched between the two cooling rolls and cooled to obtain a raw film having a thickness of 150 μm. Thereafter, the raw film may be stretched by vertical and horizontal biaxial stretching to produce a film having a thickness of 40 μm.

  Thus, when the film according to the present invention is a stretched film, the acrylic resin composition according to the present invention is once formed into an unstretched raw film, and then uniaxially stretched or biaxially stretched. Thus, a stretched film can be produced.

  In order to improve the MIT bending resistance in both the longitudinal direction (MD direction) and the width direction (TD direction) of the optical film of the present invention, biaxial stretching is preferably performed.

  In the present specification, for convenience of explanation, a film before being stretched after the acrylic resin composition according to the present invention is formed into a film, that is, an unstretched film is referred to as a “raw film”.

  When the original film is stretched, the original film may be continuously stretched immediately after forming the original film, or may be stored or moved once after the original film is formed, The anti-film may be stretched.

  In addition, when the raw film is stretched immediately after being formed into a raw film, in the film manufacturing process, when the state of the raw film is very short (in some cases, instantaneous), it is stretched. It is only necessary to maintain a sufficient film shape, and it is not necessary to have a complete film state. Moreover, the said raw film may not have the performance as a film which is a finished product.

(Stretching method of optical film)
The method for stretching the original film is not particularly limited, and any conventionally known stretching method may be used. Specifically, for example, transverse stretching using a tenter, longitudinal stretching using a roll, sequential biaxial stretching in which these are sequentially combined, and the like can be used.

  Moreover, the simultaneous biaxial stretching method which extends | stretches the length and the width | variety simultaneously can be used, or the method of performing the horizontal extending | stretching by a tenter can be used after performing roll vertical stretching.

  When stretching the original film, it is preferable to preheat the original film to a temperature 0.5 ° C to 5 ° C, preferably 1 ° C to 3 ° C higher than the stretching temperature, and then cool and stretch the film to the stretching temperature. .

  By preheating within the above range, the thickness in the width direction of the original fabric film can be maintained with high accuracy, and the thickness accuracy of the stretched film does not decrease and thickness unevenness does not occur. Further, the raw film does not stick to the roll and does not loosen due to its own weight.

  On the other hand, if the preheating temperature of the original film is too high, there is a tendency that the original film adheres to the roll or loosens due to its own weight. In addition, if the difference between the preheating temperature of the raw film and the stretching temperature is small, it tends to be difficult to maintain the thickness accuracy of the original film before stretching, the thickness unevenness increases, or the thickness accuracy tends to decrease. is there.

  In addition, when the acrylic resin composition according to the present invention is stretched after being formed into a raw film, it is difficult to improve the thickness accuracy by utilizing a necking phenomenon. Therefore, in the present invention, it is important to manage the preheating temperature in order to maintain or improve the thickness accuracy of the obtained film.

  The stretching temperature for stretching the raw film is not particularly limited, and may be changed according to the mechanical strength, surface property, thickness accuracy, and the like required for the stretched film to be produced. In general, when the glass transition temperature of the raw film (acrylic resin composition) obtained by the DSC method is defined as Tg, the temperature range is preferably (Tg-30 ° C) to (Tg + 30 ° C). A temperature range of (Tg−20 ° C.) to (Tg + 30 ° C.) is more preferable, a temperature range of (Tg) to (Tg + 30 ° C.) is more preferable, and a temperature of (Tg + 5 ° C.) to (Tg + 30 ° C.). More preferably, it is within the range. That is, the biaxial stretching temperature of the optical film is preferably in the temperature range of Tg-30 ° C. or higher and Tg + 30 ° C. or lower, where the glass transition temperature of the acrylic resin composition is Tg.

  When the stretching temperature is within the above temperature range, thickness unevenness of the obtained stretched film can be reduced, and further, the mechanical properties of elongation rate, tear propagation strength, and MIT flex resistance can be improved. Moreover, generation | occurrence | production of the trouble that a film adheres to a roll can be prevented.

  On the other hand, when the stretching temperature is higher than the above temperature range, the thickness unevenness of the stretched film obtained tends to be large, and the mechanical properties such as elongation, tear propagation strength, and fatigue resistance cannot be improved sufficiently. There is. Furthermore, there is a tendency that troubles such as the film sticking to the roll tend to occur.

  In addition, when the stretching temperature is lower than the above temperature range, the internal haze of the obtained stretched film becomes large, or in extreme cases, the process tends to cause problems such as tearing or cracking of the film. There is.

  When the raw film is stretched, the stretch ratio is not particularly limited, and may be determined according to the mechanical strength, surface properties, thickness accuracy, and the like of the stretched film to be produced. Although it depends on the stretching temperature, the stretching ratio is generally preferably selected in the range of 1.1 to 3 times, more preferably in the range of 1.3 to 2.5 times. Preferably, it is more preferable to select in the range of 1.5 times to 2.3 times.

  If the draw ratio is within the above range, the mechanical properties such as the elongation rate of the film, tear propagation strength, and fatigue resistance can be greatly improved. Therefore, a stretched film having a thickness unevenness of 5 μm or less and an internal haze of 1.0% or less can be produced.

(Acrylic resin)
The (A) acrylic resin used in the present invention has a glass transition temperature of 120 ° C. or higher. When the glass transition temperature of the acrylic resin is less than 120 ° C., the glass transition temperature of the acrylic resin composition film mixed with the acrylic block copolymer is lowered, and as a result, the dimensional change of the film under a high temperature environment is reduced. growing. In actual use, it is often laminated with another optical film, in which case warping may occur.

  Here, as the acrylic resin having a glass transition temperature of 120 ° C. or higher, an acrylic resin having a ring structure in the main chain can be suitably used. For example, the ring structure can include at least one ring structure selected from the group consisting of a glutarimide ring, a lactone ring, maleic anhydride, maleimide and glutaric anhydride. According to these, heat resistance can be imparted. Among these, it is particularly preferable that the ring structure is glutarimide from the viewpoint of production simplicity, cost, and quality stability against moisture.

  Examples of the acrylic resin having a glass transition temperature of 120 ° C. or higher include a method of introducing an acid structure such as methacrylic acid. The polymer block (B1) containing a structural unit derived from an acrylate ester, and methacrylic acid Depending on the type of the acrylic block copolymer (component (B)) composed of a polymer block (B2) containing a structural unit derived from an ester, there is a risk of forming a cross-linked product or when forming a film. Since the risk of foaming increases, it is preferable to suppress a certain amount or more. Specifically, the amount of the acid component in the acrylic resin is 0.6 mmol / g or less, preferably 0.4 mmol / g or less.

The content of the ring structure in the acrylic resin having a glass transition temperature of 120 ° C. or higher is preferably in the range of 2% by weight to 30% by weight. Within this range, if the ring structure content is large, the glass transition temperature is increased, and if the ring structure content is small, the phase difference tends to be small. The content of the ring structure in the acrylic resin was calculated by measuring the molar ratio between the target ring structure part and the other part using ¹ H-NMR BRUKER Avance III (400 MHz), and performing weight conversion.

  Hereinafter, each ring structure will be described.

  An acrylic resin having glutarimide as a ring structure is a resin containing a glutarimide unit represented by the following general formula (1) and a methyl methacrylate unit, and a poly (acrylic acid ester) unit is less than 1% by weight. It is obtained by heating and melting methyl methacrylate and treating the polymethyl methacrylate with an imidizing agent.

(Wherein R ¹ and R ² each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms; R ³ represents an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or carbon; Represents an aryl group of formula 6 to 10.)

The content of the glutarimide ring according to the present invention is a value that can be measured, for example, by the following method. ¹ H-NMR ¹ H-NMR measurement of the resin is performed using BRUKER Avance III (400 MHz). From the area A of the peak derived from the O-CH ₃ proton of methyl methacrylate in the vicinity of 3.5 to 3.8 ppm and the area B of the peak derived from the N-CH ₃ proton of glutarimide in the vicinity of 3.0 to 3.3 ppm. Then, weight conversion is performed using the determined molar ratio.

  If the content of the glutarimide ring is less than 2% by weight, the desired heat resistance may not be imparted. If the content exceeds 30% by weight, the amount of the imidizing agent may increase, Odor due to an increase in the thickness and the thickness direction retardation Rth may increase.

  In this step, in addition to methyl methacrylate, for example, methyl acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, (meth) Benzyl acrylate, cyclohexyl (meth) acrylate and the like may be used in combination, but when these are used in combination, the acrylate unit is preferably less than 1% by weight. Further, the methyl acrylate unit is more preferably less than 0.5% by weight, and further preferably less than 0.3% by weight.

  In addition to the above monomers, nitrile monomers such as acrylonitrile and methacrylonitrile, and maleimide monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide can also be copolymerized. It is.

  The structure of the polymethyl methacrylate resin is not particularly limited, and may be any of linear (linear) polymer, block polymer, core-shell polymer, branched polymer, ladder polymer, and crosslinked polymer.

  In the case of a block polymer, it may be any of AB type, ABC type, ABA type, and other types of block polymers. In the case of the core-shell polymer, it may be composed of only one core and only one shell, or each may be composed of multiple layers.

  The production method of the polymethyl methacrylate resin is not particularly limited, and a known emulsion polymerization method, emulsion-suspension polymerization method, suspension polymerization method, bulk polymerization method, solution polymerization method and the like can be applied. In the case of use in the bulk polymerization method, the bulk polymerization method and the solution polymerization method are particularly preferable from the viewpoint of few impurities. For example, it can be produced according to the method described in JP-A-56-8404, JP-B-6-86492, JP-B-7-37482, or JP-B-52-32665.

  The manufacturing method of this invention includes the process (imidation process) which heat-melts the said polymethyl methacrylate resin, and processes it with an imidizing agent. Thereby, an acrylic resin having glutarimide can be produced.

  The imidizing agent is not particularly limited as long as it can generate the glutarimide ring represented by the general formula (1), and examples thereof include those described in WO2005 / 054311. Specifically, for example, an aliphatic hydrocarbon group-containing amine such as ammonia, methylamine, ethylamine, n-propylamine, i-propylamine, n-butylamine, i-butylamine, tert-butylamine, n-hexylamine, Mention may be made of aromatic hydrocarbon group-containing amines such as aniline, benzylamine, toluidine and trichloroaniline, and alicyclic hydrocarbon group-containing amines such as cyclohexylamine.

  In addition, urea-based compounds that generate amines exemplified above by heating, such as urea, 1,3-dimethylurea, 1,3-diethylurea, and 1,3-dipropylurea, can also be used.

  Of the imidizing agents exemplified above, methylamine, ammonia, and cyclohexylamine are preferably used from the viewpoint of cost and physical properties, and methylamine is particularly preferably used.

  Further, gaseous methylamine or the like at normal temperature may be used in a state dissolved in alcohols such as methanol.

  In this imidization step, by adjusting the addition ratio of the imidizing agent, the ratio of glutarimide units and (meth) acrylic acid ester units in the resulting acrylic resin can be adjusted.

  Moreover, by adjusting the degree of imidization, the physical properties of the obtained acrylic resin, the optical characteristics of an optical film formed by molding the acrylic resin according to the present invention, and the like can be adjusted.

  The imidizing agent is preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the polymethyl methacrylate resin. When the addition amount of the imidizing agent exceeds the above range, the imidizing agent may remain in the resin and induce appearance defects and foaming after molding. Moreover, when the addition amount of the imidizing agent is less than the above range, the content of the glutarimide ring in the finally obtained resin composition is lowered, so that its heat resistance is remarkably lowered, and an appearance defect after molding is induced. Sometimes.

  In this imidization step, a ring closure accelerator (catalyst) may be added as necessary in addition to the imidizing agent.

  The method of melting by heating and treating with an imidizing agent is not particularly limited, and any conventionally known method can be used. For example, the polymethyl methacrylate resin can be imidized by a method using an extruder, a batch type reaction vessel (pressure vessel) or the like.

  When heat-melting using an extruder and processing with an imidizing agent, the extruder to be used is not particularly limited, and various extruders can be used. Specifically, for example, a single screw extruder, a twin screw extruder, a multi-screw extruder, or the like can be used.

  Among these, it is preferable to use a twin screw extruder. According to the twin screw extruder, it is possible to promote mixing of an imidizing agent (in the case where a ring closing accelerator is used) with respect to the polymethyl methacrylate resin.

  Examples of the twin-screw extruder include a non-meshing type same direction rotating type, a meshing type same direction rotating type, a non-meshing type different direction rotating type, and a meshing type different direction rotating type. Among them, it is preferable to use a meshing type co-rotating type. Since the meshing type co-rotating twin-screw extruder can rotate at a high speed, mixing of the imidizing agent (in the case of using a ring closure accelerator and an imidization agent and a ring closure accelerator) with the raw polymer is further improved. Can be promoted.

  The above-exemplified extruders may be used alone, or a plurality of the extruders may be connected in series. For example, a tandem reaction extruder described in JP-A-2008-273140 can be used.

  When imidization is performed in an extruder, for example, polymethyl methacrylate resin is charged from the raw material charging part of the extruder, the resin is melted, the inside of the cylinder is filled, and then imidized using an addition pump. By injecting the agent into the extruder, the imidization reaction can proceed in the extruder.

  In this case, the reaction zone temperature (resin temperature) in the extruder is preferably 180 ° C. to 270 ° C., more preferably 200 to 250 ° C. When the temperature of the reaction zone (resin temperature) is less than 180 ° C., the imidization reaction hardly proceeds and the heat resistance tends to decrease. When the reaction zone temperature exceeds 270 ° C., the resin is significantly decomposed, and thus the bending resistance of the film that can be formed from the obtained acrylic resin tends to be lowered. Here, the reaction zone in the extruder refers to a region between the injection position of the imidizing agent and the resin discharge port (die part) in the cylinder of the extruder.

  By increasing the reaction time in the reaction zone of the extruder, imidization can be further advanced. The reaction time in the reaction zone of the extruder is preferably longer than 10 seconds, and more preferably longer than 30 seconds. In the reaction time of 10 seconds or less, imidation may hardly proceed.

  The resin pressure in the extruder is preferably in the range of atmospheric pressure to 50 MPa, and more preferably in the range of 1 MPa to 30 MPa. If it is less than 1 MPa, the solubility of the imidizing agent is low, and the progress of the reaction tends to be suppressed. On the other hand, if it is 50 MPa or more, the mechanical pressure limit of a normal extruder is exceeded, and a special apparatus is required, which is not preferable in terms of cost.

  Moreover, when using an extruder, in order to remove an unreacted imidizing agent and a by-product, it is preferable to attach the vent hole which can be pressure-reduced below atmospheric pressure. According to such a configuration, unreacted imidizing agent, or by-products such as methanol and monomers can be removed.

  In addition, for the production of the acrylic resin containing the glutarimide ring, instead of an extruder, for example, a horizontal biaxial reactor such as Vivolac manufactured by Sumitomo Heavy Industries, Ltd. A high-viscosity reaction apparatus such as an axial stirring tank can also be suitably used.

  When the acrylic resin containing the glutarimide ring is produced using a batch type reaction vessel (pressure vessel), the structure of the batch type reaction vessel (pressure vessel) is not particularly limited.

  Specifically, the polymethyl methacrylate resin can be melted by heating and stirred, and an imidizing agent (in the case of using a ring closure accelerator, an imidizing agent and a ring closure accelerator) can be added. However, it is preferable to have a structure with good stirring efficiency.

  According to such a batch-type reaction vessel (pressure vessel), it is possible to prevent the polymer viscosity from increasing due to the progress of the reaction and the stirring to be insufficient. As a batch type reaction tank (pressure vessel) having such a structure, for example, a stirred tank Max Blend manufactured by Sumitomo Heavy Industries, Ltd. can be exemplified.

  Specific examples of the imidization method include known methods such as those described in JP-A-2008-273140 and JP-A-2008-274187.

  In the manufacturing method of this invention, in addition to the said imidation process, the process processed with an esterifying agent can be included. By this esterification step, the acid value of the imidized resin obtained in the imidization step can be adjusted within a desired range.

  Examples of the esterifying agent include dimethyl carbonate, 2,2-dimethoxypropane, dimethyl sulfoxide, triethyl orthoformate, trimethyl orthoacetate, trimethyl orthoformate, diphenyl carbonate, dimethyl sulfate, methyl toluene sulfonate, methyl trifluoromethyl sulfonate. , Methyl acetate, methanol, ethanol, methyl isocyanate, p-chlorophenyl isocyanate, dimethylcarbodiimide, dimethyl-t-butylsilyl chloride, isopropenyl acetate, dimethylurea, tetramethylammonium hydroxide, dimethyldiethoxysilane, tetra-N-butoxy Silane, dimethyl (trimethylsilane) phosphite, trimethyl phosphite Trimethyl phosphate, tricresyl phosphate, diazomethane, ethylene oxide, propylene oxide, cyclohexene oxide, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and benzyl glycidyl ether. Among these, dimethyl carbonate and trimethyl orthoacetate are preferable from the viewpoints of cost and reactivity, and dimethyl carbonate is preferable from the viewpoint of cost.

  In this imidization step, the esterifying agent is preferably 0 to 12 parts by weight, and more preferably 0 to 8 parts by weight with respect to 100 parts by weight of the polymethyl methacrylate resin.

  If the esterifying agent is within the above range, the acid value can be adjusted to an appropriate range. On the other hand, if it is out of the above range, an unreacted esterifying agent may remain in the resin, which may cause foaming or odor generation when molding is performed using the resin.

  In addition to the esterifying agent, a catalyst may be used in combination. The type of the catalyst is not particularly limited, and examples thereof include aliphatic tertiary amines such as trimethylamine, triethylamine, and tributylamine. Among these, triethylamine is preferable from the viewpoint of cost and reactivity.

  In this esterification step, only heat treatment or the like can be performed without treatment with an esterifying agent. When only heat treatment (mixing / dispersion of molten resin in the extruder) is performed, dehydration reaction between carboxylic acids in the imide resin by-produced in the imidization step and / or dealcoholization of carboxylic acid and alkyl ester group A part or all of the carboxylic acid can be converted to an acid anhydride group by reaction or the like. At this time, it is also possible to use a ring closure accelerator (catalyst).

  Even in the case of treatment with an esterifying agent, acid anhydride grouping by heat treatment can be advanced.

  The imide resin that has undergone the imidization step and the esterification step contains an unreacted imidizing agent, an unreacted esterifying agent, a volatile component by-produced by the reaction, and a resin decomposition product. It is possible to attach a vent port that can be depressurized below. The acrylic resin having a lactone ring as a ring structure is not limited as long as it is a thermoplastic polymer having a lactone ring structure in the molecule (a thermoplastic polymer having a lactone ring structure introduced in the molecular chain). The production method is not limited, but preferably, the polymer (a) having a hydroxyl group and an ester group in the molecular chain is obtained by polymerization (polymerization step), and then the obtained polymer (a) is obtained. It is obtained by introducing a lactone ring structure into the polymer by heat treatment (lactone cyclization condensation step).

  In the polymerization step, a polymer having a hydroxyl group and an ester group in the molecular chain is obtained by performing a polymerization reaction of a monomer component containing an unsaturated monomer represented by the following general formula (2).

(However, R < ⁴ > and R < ⁵ > represents a hydrogen atom or a C1-C20 alkyl group each independently.).

  Examples of the unsaturated monomer represented by the general formula (2) include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, Examples thereof include normal butyl 2- (hydroxymethyl) acrylate and tertiary butyl 2- (hydroxymethyl) acrylate. Of these, methyl 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate are preferred, and methyl 2- (hydroxymethyl) acrylate is particularly preferred from the viewpoint of high heat resistance improvement effect. These unsaturated monomers may be used alone or in combination of two or more.

  The content ratio of the unsaturated monomer represented by the general formula (2) in the monomer component is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, and still more preferably 10 to 30%. % By weight. When the content is less than 5% by weight, the heat resistance, solvent resistance and surface hardness of the resulting lactone ring-containing polymer may be lowered. When the content is more than 50% by weight, a lactone ring structure is formed. In some cases, a cross-linking reaction occurs and the gelation easily occurs, and the fluidity is lowered and it is difficult to melt-mold. In addition, the unreacted hydroxyl group is likely to remain. There is a possibility that a silvery streak is likely to occur due to the generation of a chemical substance, or the thickness direction retardation Rth increases.

  It is preferable that a monomer component contains other monomers other than the unsaturated monomer represented by the said General formula (2). The other monomer is not limited as long as the effect of the present invention is not impaired. For example, (meth) acrylic acid ester, hydroxyl group-containing monomer, unsaturated carboxylic acid, the following general formula The unsaturated monomer represented by (3) is preferably mentioned. One of the other monomers may be used, or two or more may be used in combination.

(Wherein, ^{R 6} represents a hydrogen atom or a methyl group, X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, -OAc group, -CN group, ^{-CO-R 7} group, or -C- Represents an O—R ⁸ group, an Ac group represents an acetyl group, and R ⁷ and R ⁸ represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms).

  The (meth) acrylic acid ester is not limited as long as it is a (meth) acrylic acid ester other than the unsaturated monomer represented by the general formula (2). For example, methyl acrylate, acrylic acid Acrylic esters such as ethyl, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, benzyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, methacryl Methacrylic acid esters such as isobutyl acid, t-butyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate; these may be used alone or in combination of two or more. Of these, methyl methacrylate is particularly preferred from the viewpoint of heat resistance and transparency.

  When the (meth) acrylic acid ester is used, the content ratio in the monomer component is preferably 10 to 95% by weight, more preferably 10 to 90% by weight, in order to sufficiently exert the effects of the present invention. More preferably, it is 40 to 90% by weight, particularly preferably 50 to 90% by weight.

((B) Acrylic block copolymer composed of a polymer block (B1) containing a structural unit derived from an acrylate ester and a polymer block (B2) containing a structural unit derived from a methacrylic acid ester)
(B) Acrylic system composed of a polymer block (B1) containing a structural unit derived from an acrylate ester used in the present invention and a polymer block (B2) containing a structural unit derived from a methacrylic acid ester The block copolymer will be described.
The polymer block (B1) containing a structural unit derived from an acrylate ester is a polymer block characterized by being polymerized into a dimer or more using at least one acrylate ester as a raw material. The polymer block (B2) containing the derived constitutional unit refers to a polymer block characterized by being polymerized into a dimer or more using at least one kind of methacrylic acid ester as a raw material.

  An acrylic block copolymer composed of a polymer block (B1) containing a structural unit derived from an acrylate ester used in the present invention and a polymer block (B2) containing a structural unit derived from a methacrylic acid ester, The polymer block (B2), which is a copolymer composed of a hard block and a soft block, and contains a structural unit derived from a methacrylic ester constituting the hard block, preferably contains a polymethyl methacrylate unit, It is preferable that the polymer block (B1) containing the structural unit derived from the acrylic acid ester to comprise comprises a polybutyl acrylate unit.

  The block copolymer is preferably a triblock copolymer, more preferably a (B2)-(B1)-(B2) triblock copolymer. By using the block copolymer, a stable dispersion state can be obtained from moderate compatibility with the acrylic resin, and as a result, a film with few defects can be obtained.

  In addition, due to the moderate flexibility of the block copolymer, the block copolymer can absorb stress against the bending of the film in the MIT flex resistance test, and the optical property has excellent flexibility. Become a film. Here, an acrylic block copolymer composed of a polymer block (B1) containing a structural unit derived from an acrylate ester used in the present invention and a polymer block (B2) containing a structural unit derived from a methacrylic ester is used. The Shore A hardness is preferably 150 or less, and more preferably 100 or less. Although there is no restriction | limiting in particular as a minimum of the said Shore A hardness, 20 or more are preferable. The Shore A hardness was measured using a type A durometer in accordance with ISO 7619-1.

  The number average molecular weight of the block copolymer is preferably 10,000 to 500,000, and more preferably 30,000 to 200,000. When the number average molecular weight is lower than 10,000, the liquid state or tackiness (adhesiveness) increases at room temperature, and handling in the molding process becomes complicated. When the number average molecular weight is higher than 200,000, the average dispersion length may increase, and the internal haze may exceed 0.3%.

The methacrylic ester content in the block copolymer is preferably 10 mol% to 80 mol%, more preferably 20 mol% to 60 mol%. If the methacrylic ester content is lower than 10 mol%, the refractive index difference from the acrylic resin (component A) may be 0.02 or more, and the internal haze may exceed 0.3%. When the methacrylic ester content is higher than 80 mol%, the flexibility of the block copolymer is lowered, and may be 500 times or less in the MIT flex resistance test. Incidentally, the methacrylic acid ester content is ¹ by using the ^H-NMR, and methacrylic acid ester moiety of interest can be obtained by measuring the molar ratio of acrylic acid ester moiety.

(Acrylic resin composition)
The blending ratio of the acrylic block copolymer (component B) in the acrylic resin composition constituting the optical film of the present invention is preferably 1 to 40 when the acrylic resin (component A) is 100 parts by weight. Parts by weight, more preferably 2 to 30 parts by weight, still more preferably 2 to 15 parts by weight, and even more preferably 2 to 10 parts by weight. If the blending ratio of the acrylic block copolymer (component B) is low, the MIT flex resistance is not sufficient, and if the blending ratio is large, the transparency may deteriorate, or the glass transition of the acrylic resin composition. The decrease in temperature may be large.

  The glass transition temperature of the acrylic resin composition constituting the optical film of the present invention is preferably 115 ° C. or higher, and more preferably 120 ° C. or higher. The glass transition temperature here is defined as a value measured using a differential scanning calorimeter (DSC, manufactured by SII, DSC7020) under a nitrogen atmosphere at a heating rate of 20 ° C./min and analyzed by the midpoint method. did. When the glass transition temperature is 115 ° C., the dimensional change is small when laminated as a film constituting a liquid crystal panel typified by a polarizer protective film, the warpage of the laminated film accompanying the dimensional change is small, and the retardation change is small. It becomes smaller and there are few problems in actual use.

  For the above acrylic resin composition, light-resistant stabilizers such as antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, radical scavengers, retardation adjusting agents, catalysts, etc. , Plasticizers, lubricants, antistatic agents, colorants, antishrinking agents, antibacterial / deodorizing agents, fluorescent whitening agents, compatibilizing agents, etc., alone or in combination of two or more, so long as the object of the present invention is not impaired. If necessary, it may be added.

  Examples of the ultraviolet absorber include triazine compounds, benzotriazole compounds, benzophenone compounds, cyanoacrylate compounds, benzoxazine compounds, and oxadiazole compounds. Among these, triazine compounds are preferable from the viewpoint of volatility when ultraviolet absorption performance with respect to the added amount or melt extrusion is performed.

  About a phase difference adjusting agent, when providing a negative phase difference, what is necessary is just a compound which has a styrene skeleton, for example, and an acrylonitrile styrene copolymer is illustrated.

  The method for mixing the acrylic resin (component A) and the acrylic block copolymer (component B) is not particularly limited, and any conventionally known method can be used. For example, an extruder, (A) component, and (B) component are mixed in the state of a solution with a soluble solvent, etc. are mentioned.

  When mixing using an extruder, the extruder to be used is not specifically limited, Various extruders can be used. Specifically, a single screw extruder, a twin screw extruder, a multi-screw extruder, or the like can be used. Among these, it is preferable to use a twin screw extruder. According to the twin screw extruder, the degree of freedom of the conditions for uniformly mixing the component (A) and the component (B) is wide.

  In the state of the component (A) before mixing with the component (B) in the present invention and / or in the state where the component (A) and the component (B) are mixed, the end of the extruder is used for the purpose of reducing foreign matters in the resin. It is also possible to install a filter in It is preferable to install a gear pump in front of the filter in order to pressurize the acrylic resin / acrylic resin composition. As the type of filter, it is preferable to use a stainless steel leaf disc filter capable of removing foreign substances from the molten polymer, and it is preferable to use a fiber type, a powder type, or a composite type thereof as the filter element.

  (Use) The use of the film according to the present invention is not particularly limited. For example, the field of images such as a camera, a VTR, a photographing lens or finder for a projector, a filter, a prism, a Fresnel lens, a CD player, Lens field such as pickup lens for optical disk such as MD player, optical recording field for optical disk such as CD player, DVD player, MD player, liquid crystal display film such as light guide plate for liquid crystal, polarizer protective film and retardation film It can be suitably used in the field of information equipment such as surface protection films, the field of optical communications such as optical fibers, optical switches, and optical connectors, and the field of vehicles such as automobile headlights, tail lamp lenses, inner lenses, and instrument covers.

  The film according to the present invention can be suitably used for a polarizer protective film because it is optically transparent as described above and an acrylic material is a main material and has excellent moisture resistance. . The polarizer here is not particularly limited, and any conventionally known polarizer can be used. Specific examples include a polarizer obtained by adding iodine to stretched polyvinyl alcohol.

  The present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to this. Those skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention.

(Glass-transition temperature)
Using a differential scanning calorimeter (DSC, manufactured by SII, DSC7020) using 10 mg of acrylic resin and acrylic resin composition, measurement was performed at a temperature rising rate of 20 ° C./min in a nitrogen atmosphere. Determined by law.

(MIT bending resistance test)
A film was formed into a strip-shaped test piece having a width of 15 mm, and using a MIT soft fatigue tester model D manufactured by Toyo Seiki Co., Ltd., a test load of 1.96 N, a speed of 175 times / minute, and a radius of curvature of the bending clamp R was measured at 0.38 mm, and the bending angle was 135 ° to the left and right.

(Internal haze)
The film was measured using a Nippon Denshoku Industries Co., Ltd. haze meter NDH2000. The internal haze was measured so that the film obtained in the glass cell for liquid measurement was placed and pure water was in contact with both surfaces of the film.

(Average refractive index)
Measurement was performed using an Abbe refractometer 3T manufactured by Atago Co., Ltd.

(Calculation of ring structure content)
The obtained acrylic resin was measured using ¹ H-NMR BRUKER Avance III (400 MHz). Calculation was performed by weight conversion from the molar ratio of the target ring structure portion and other portions. Specifically, in the case of glutarimide, the area A of the peak derived from the O—CH ₃ proton of methyl methacrylate in the vicinity of 3.5 to 3.8 ppm and the N—CH of glutarimide in the vicinity of 3.0 to 3.3 ppm. _From the area B of the peak derived from ₃ protons, it can be calculated by weight conversion using the determined molar ratio.

(Elongation)
The film was measured according to JIS K7161 using an autograph AGS-J manufactured by Shimadzu Corporation. The film size was prepared in a strip shape of 150 mm × 15 mm, the distance between chucks was 50 mm, and the tensile speed was 200 mm / min.

(Average dispersion length)
The obtained stretched film was observed using a transmission electron microscope H-7650 manufactured by Hitachi High-Technologies Corporation. The average dispersion length is the maximum length in the long axis direction of the dispersion by extracting 5 points from the larger one of the deeply dyed dispersions in the cross section where the central part is cut in the MD direction when divided into 5 in the thickness direction of the stretched film. The arithmetic average was calculated by adding all the maximum lengths in the minor axis direction.

(Thickness direction retardation Rth)
The obtained stretched film was measured using a phase difference measuring device KOBRA-WR manufactured by Oji Scientific Instruments. The measurement was performed at a wavelength of 590 nm.

(Still heat stability test)
The obtained acrylic resin composition was measured using Capillograph 1D PMD-C manufactured by Toyo Seiki Seisakusho. A cylinder heated in advance at 270 ° C. was filled with the acrylic resin composition in a molten state, and the presence or absence of an increase in viscosity was evaluated when extruded under the condition of a shear rate of 24 sec-1.

(Acrylic resin production example 1)
The extruder used was a meshing type co-rotating twin screw extruder (L / D = 90) with a diameter of 40 mm. The set temperature of each temperature control zone of the extruder was 250 to 280 ° C., and the screw rotation speed was 85 rpm. A polymethyl methacrylate resin (Mw: 105,000) was supplied at 42.4 kg / hr, and the polymethyl methacrylate resin was melted and filled with a kneading block, and then the polymethyl methacrylate resin 100 was fed from a nozzle. 1.8 parts by weight of monomethylamine (Mitsubishi Gas Chemical Co., Ltd.) was injected with respect to parts by weight. A reverse flight was placed at the end of the reaction zone to fill the resin. By-products and excess methylamine after the reaction were removed by reducing the pressure at the vent port to -0.092 MPa. Resin (I) was obtained by cooling the resin which came out as a strand from the die | dye provided in the extruder exit with the water tank, and pelletizing with a pelletizer.
Next, in a meshing type co-rotating twin screw extruder having a diameter of 40 mm, the set temperature of each temperature control zone of the extruder was 240 to 260 ° C. and the screw rotation speed was 102 rpm. Resin (I) obtained from the hopper was supplied at 41 kg / hr, and the resin was melted and filled with a kneading block, and then 0.56 parts by weight from the nozzle to 100 parts by weight of the polymethyl methacrylate resin. Dimethyl carbonate was injected to reduce the carboxyl groups in the resin. A reverse flight was placed at the end of the reaction zone to fill the resin. The by-product after reaction and excess dimethyl carbonate were removed by reducing the pressure at the vent port to -0.092 MPa. The resin that emerged as a strand from the die provided at the exit of the extruder was cooled in a water tank and then pelletized with a pelletizer to obtain an acrylic resin (A1) having a glutarimide ring.
The acrylic resin (A1) had a glutarimide content of 6% by weight, a glass transition temperature of 125 ° C., and an average refractive index of 1.50.

Example 1
Clarity LA2140e (made by Kuraray Co., Ltd., acrylic PMMA-PnBA-PMMA) as an acrylic block copolymer (component B) with respect to 100 parts by weight of the acrylic resin (A1) produced in the acrylic resin production example 1 A mixture of block copolymer, average refractive index 1.48, hardness (type A) 32) weighed to 2 parts by weight is a meshing type co-rotating twin screw extruder (L / D = 30) having a diameter of 15 mm. Kneaded. The resin mixture was supplied from the hopper at 2 kg / hr, the set temperature of each temperature control zone of the extruder was 260 ° C., and the screw rotation speed was 300 rpm. The resin that emerged as a strand from a die provided at the exit of the extruder was cooled in a water tank and then pelletized with a pelletizer to obtain an acrylic resin composition (C1).
After the obtained acrylic resin composition (C1) was dried at 100 ° C. for 5 hours, a mesh type co-rotating twin screw extruder (L / D = 30) having a diameter of 15 mm equipped with a T die at the exit of the extruder. Was used to form a film. The acrylic resin composition (C1) was supplied from the hopper at 2 kg / hr, the set temperature of each temperature control zone of the extruder was 260 ° C., and the screw rotation speed was 150 rpm. The sheet-like molten resin extruded from the T die provided at the exit of the extruder was cooled with a cooling roll to obtain an original film (D2) having a width of 120 mm and a thickness of 160 μm.
With respect to this film, the glass transition temperature was measured in accordance with the above-mentioned method, and as a result, it was 125 ° C.
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the resulting raw film (D2) was stretched twice (longitudinal / lateral) at a temperature 7 ° C. higher than the glass transition temperature. Simultaneous biaxial stretching was performed to prepare a biaxially stretched film.
According to the above method, the MIT bending resistance test, the elongation, the internal haze, and the thickness direction retardation Rth were measured. The results are shown in Table 1.

(Example 2)
Clarity LA2330 (manufactured by Kuraray Co., Ltd., acrylic PMMA-PnBA-PMMA block copolymer) as an acrylic block copolymer (component B) with respect to 100 parts by weight of the acrylic resin (A1) produced in the acrylic resin production example 1. A raw film (D3) was obtained in the same manner as in Example 1 except that the coalescence, average refractive index 1.48, and hardness (type A) 32) were weighed to 2 parts by weight.
As a result of measuring the glass transition temperature of this film according to the above method, it was 125 ° C.
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the obtained raw film (D3) was simultaneously stretched at a stretch ratio of 2 (longitudinal / lateral) at a temperature 7 ° C. higher than the glass transition temperature. Biaxial stretching was performed to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT flex test, elongation, internal haze, and thickness direction retardation Rth were measured according to the above methods. The results are shown in Table 1.

(Example 3)
Clarity LA2330 (manufactured by Kuraray Co., Ltd., acrylic PMMA-PnBA-PMMA block copolymer) as an acrylic block copolymer (component B) with respect to 100 parts by weight of the acrylic resin (A1) produced in the acrylic resin production example 1. A raw film (D4) was obtained in the same manner as in Example 1 except that the coalescence, average refractive index 1.48, and hardness (type A) 32) were weighed to 4 parts by weight.
The glass transition temperature of this film was measured according to the method described above and found to be 126 ° C.
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the obtained raw film (D4) was simultaneously stretched at a double magnification (longitudinal / horizontal) and a temperature 7 ° C. higher than the glass transition temperature. Biaxial stretching was performed to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT flex test, elongation, internal haze, and thickness direction retardation Rth were measured according to the above methods. The results are shown in Table 1.

Example 4
Clarity LA3250 (made by Kuraray Co., Ltd., acrylic PMMA-PnBA-PMMA block copolymer) as an acrylic block copolymer (component B) with respect to 100 parts by weight of the acrylic resin (A1) produced in the acrylic resin production example 1. A raw film (D5) was obtained in the same manner as in Example 1 except that the coalescence, average refractive index 1.48, and hardness (type A) 41) were weighed to 4 parts by weight.
The glass transition temperature of this film was measured according to the method described above and found to be 126 ° C.
Using the biaxial stretching device (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the resulting raw film (D5) was simultaneously stretched at a double magnification (longitudinal / lateral) and a temperature 7 ° C. higher than the glass transition temperature. Biaxial stretching was performed to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT flex test, elongation, internal haze, and thickness direction retardation Rth were measured according to the above methods. The results are shown in Table 1.

(Example 5)
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the original fabric film (D5) obtained in Example 4 was stretched twice (longitudinal and lateral), 20 ° C. from the glass transition temperature. Biaxial stretching was performed at a high temperature to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT flex test, elongation, internal haze, and thickness direction retardation Rth were measured according to the above methods. The results are shown in Table 1.

(Example 6)
Clarity LA3250 (made by Kuraray Co., Ltd., acrylic PMMA-PnBA-PMMA block copolymer) as an acrylic block copolymer (component B) with respect to 100 parts by weight of the acrylic resin (A1) produced in the acrylic resin production example 1. The same operation as in Example 1 was carried out except that the coalescence, average refractive index 1.48, hardness (type A) 41) was 5 parts by weight, and Tinuvin 460 (manufactured by BASF Corporation) was 1 part by weight as an ultraviolet absorber. The raw film (D6) was obtained.
The glass transition temperature of this film was measured according to the method described above and found to be 126 ° C.
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the resulting raw film (D6) was stretched twice (vertical / horizontal) at the same time at a temperature 7 ° C. higher than the glass transition temperature. Biaxial stretching was performed to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT flex test, elongation, internal haze, and thickness direction retardation Rth were measured according to the above methods. The results are shown in Table 1.

(Example 7)
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the original fabric film (D6) obtained in Example 6 was stretched twice (longitudinal and lateral), 20 ° C. from the glass transition temperature. Biaxial stretching was performed at a high temperature to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT flex test, elongation, internal haze, and thickness direction retardation Rth were measured according to the above methods. The results are shown in Table 1. Further, the average dispersion length in the major axis direction of the obtained biaxially stretched film was 4 μm.

(Example 8)
Clarity LA4285 (manufactured by Kuraray Co., Ltd., acrylic PMMA-PnBA-PMMA block copolymer) as an acrylic block copolymer (component B) with respect to 100 parts by weight of the acrylic resin (A1) produced in the acrylic resin production example 1. A raw film (D7) was obtained in the same manner as in Example 1 except that the coalescence, average refractive index 1.48, and hardness (type A) 95) were weighed to 10 parts by weight. As a result of measuring the glass transition temperature of this film according to the above method, it was 125 ° C.
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the obtained raw film (D7) was simultaneously stretched at a stretch ratio of 2 (vertical / horizontal) and a temperature 7 ° C. higher than the glass transition temperature. Biaxial stretching was performed to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT bending resistance test, the elongation, the internal haze, and the thickness direction retardation Rth were measured according to the above methods. The results are shown in Table 1.

(Comparative Example 1)
The same operation as in Example 1 was performed except that only 100 parts by weight of the acrylic resin (A1) produced in the acrylic resin production example 1 was not added and the acrylic block copolymer as the B component was not added. A raw film (D1) was obtained.
When the residence heat stability test was conducted using the acrylic resin (A1), no increase in viscosity was observed.
As a result of measuring the glass transition temperature of this film according to the above method, it was 125 ° C.
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the resulting raw film (D1) was simultaneously stretched at a stretch ratio of 2 (longitudinal / lateral) at a temperature 7 ° C. higher than the glass transition temperature. Biaxial stretching was performed to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT flex test, elongation, internal haze, and thickness direction retardation Rth were measured according to the above methods. The results are shown in Table 1.

(Comparative Example 2)
With respect to 100 parts by weight of the acrylic resin (A1) produced in the acrylic resin production example 1, instead of the acrylic block copolymer (component B), Septon S4099 (manufactured by Kuraray Co., Ltd., styrene thermoplastic elastomer) ) Was used in the same manner as in Example 1 except that the mixture weighed 2 parts by weight was used to obtain an original film (D8).
The glass transition temperature of this film was measured according to the method described above and found to be 126 ° C.
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the obtained raw film (D8) was simultaneously stretched at a double magnification (longitudinal / lateral) at a temperature 7 ° C. higher than the glass transition temperature. Biaxial stretching was performed to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT flex test, elongation, internal haze, and thickness direction retardation Rth were measured according to the above methods. The results are shown in Table 1.

(Comparative Example 3)
With respect to 100 parts by weight of the acrylic resin (A1) produced in the acrylic resin production example 1, Septon S2006 (manufactured by Kuraray Co., Ltd., styrene thermoplastic elastomer instead of the acrylic block copolymer (component B)) ) Was used in the same manner as in Example 1 except that the mixture weighed 10 parts by weight was used to obtain an original film (D9).
The glass transition temperature of this film was measured according to the above method, and was found to be 124.1 ° C.
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the resulting raw film (D9) was simultaneously stretched at a stretch ratio of 2 (longitudinal / lateral) at a temperature 7 ° C. higher than the glass transition temperature. Biaxial stretching was performed to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT flex test, elongation, internal haze, and thickness direction retardation Rth were measured in accordance with the above methods. The results are shown in Table 1.

(Comparative Example 4)
For 100 parts by weight of the acrylic resin (A1) produced in the acrylic resin production example 1, instead of the acrylic block copolymer (component B), Alfon UH2032) (manufactured by Toagosei Co., Ltd., acrylic polyol) Resin) A raw film (D10) was obtained in the same manner as in Example 1 except that the mixture weighed in 10 parts by weight was used.
As a result of measuring the glass transition temperature of this film according to the above method, it was 125 ° C.
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the resulting raw film (D10) was simultaneously stretched at a double magnification (longitudinal / lateral) and a temperature 7 ° C. higher than the glass transition temperature. Biaxial stretching was performed to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT flex test, elongation, internal haze, and thickness direction retardation Rth were measured in accordance with the above methods. The results are shown in Table 1.

(Comparative Example 5)
Instead of acrylic block copolymer (component B), 100% by weight of the acrylic resin (A1) produced in the acrylic resin production example 1, Bond First 7L (manufactured by Sumitomo Chemical, ethylene-glycidyl methacrylate- (Methyl acrylate copolymer) A raw film (D11) was obtained in the same manner as in Example 1 except that the mixture weighed in 2 parts was used.
As a result of measuring the glass transition temperature of this film according to the above method, it was 125 ° C.
Using the biaxial stretching apparatus (IMC-1905) manufactured by Imoto Seisakusho Co., Ltd., the resulting raw film (D11) was simultaneously stretched at a double magnification (longitudinal / lateral) at a temperature 7 ° C. higher than the glass transition temperature. Biaxial stretching was performed to prepare a biaxially stretched film.
With respect to this biaxially stretched film, the MIT flex test, elongation, internal haze, and thickness direction retardation Rth were measured in accordance with the above methods. The results are shown in Table 1.

Claims (10)

It contains the following components (A) and (B), and the MIT bending resistance test is 500 times or more in the longitudinal direction (MD) and the width direction (TD) of the optical film, and the internal haze is 1.0% or less. Is an optical film.
(A) Acrylic resin having a glass transition temperature of 120 ° C. or higher (B) A polymer block (B1) containing a structural unit derived from an acrylate ester, and a polymer block (B2) containing a structural unit derived from a methacrylic acid ester Acrylic block copolymer composed of   The average refractive index of the (A) component is 1.48 or more, and the refractive index difference between the (A) component and the (B) component is 0.02 or less. Optical film. The optical film according to claim 1, wherein Rth defined below of the optical film is 50 nm or less.
[Rth = {(nx + ny) / 2−nz} × d. Refractive indexes in the slow axis direction, fast axis direction, and thickness direction of the film are nx, ny, and nz, respectively, and the direction in which the in-plane refractive index is maximum is the slow axis direction. d (nm) is the thickness of the film. ]   The elongation of the optical film is 5% or more in both the longitudinal direction (MD) and the width direction (TD) of the optical film, and the optical film according to any one of claims 1 to 3.   The optical film according to any one of claims 1 to 4, wherein the component (B) has one or more polymer blocks (B1) and two or more polymer blocks (B2). .   The optical film according to claim 1, wherein the component (A) has a ring structure in the main chain.   The optical film according to claim 6, wherein the ring structure is at least one selected from the group consisting of a glutarimide ring, a lactone ring, maleic anhydride, maleimide and glutaric anhydride.   The optical film according to claim 6 or 7, wherein the content of the ring structure in the component (A) is 2% by weight or more and 30% by weight or less. The said ring structure contains following General formula (1), The optical film as described in any one of Claims 6-8 characterized by the above-mentioned.

(Wherein R ¹ and R ² each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms; R ³ represents an alkyl group having 1 to 18 carbon atoms or a cycloalkyl having 3 to 12 carbon atoms; Group or an aryl group having 6 to 10 carbon atoms.)   The said optical film is a polarizer protective film, The polarizer protective film as described in any one of Claims 1-9 characterized by the above-mentioned.