JP2006206881A - Acrylic resin film and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic resin film excellent in heat resistance, transparency and optical isotropicity. <P>SOLUTION: The acryl resin film contains a glutaric anhydride unit shown by the formula (1), wherein R<SP>1</SP>and R<SP>2</SP>are same or different, and each a hydrogen atom or a 1-5C alkyl group, and the film has a haze value of 1% or less and a volatile content of 1% or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an acrylic resin film and a method for producing the same. The present invention also relates to an optical filter using an acrylic resin film.

  Acrylic resins are excellent in transparency, scratch resistance, and weather resistance, and are characterized in that birefringence due to flow orientation and residual stress during molding is less likely to occur. Taking advantage of these features, acrylic resin is used in a wide range of fields, including optical parts such as light guide plates, optical disks, and display films, automotive parts such as tail lamps and visors, weak electrical parts, signboards, displays, lighting, building materials, water tanks, and sundries. (For example, Non-Patent Document 1 and Non-Patent Document 2).

  The demands on the physical properties of these acrylic resins have been diversified and sophisticated in recent years, and improvements such as heat resistance and hygroscopicity have been demanded.

  Regarding the heat resistance of the acrylic resin, a method for improving the heat resistance by improving the polymer skeleton and composition, such as copolymerization with an acid anhydride or a maleimide compound or introduction of a glutarimide structure, is disclosed (for example, Patent Document 1). Has been.

However, in recent years, acrylic resin films used for optical parts have been required to have extremely high transparency and defect-freeness in addition to the above heat resistance and the like. In order to improve the transparency and defect-freeness of acrylic resin film, it is effective to remove foreign substances contained in the acrylic resin by polymer filtration. However, acrylic resin films by conventional melt film formation have high melt viscosity. Since the filtration accuracy is limited, transparency and defect-freeness were insufficient. Further, when the melting temperature is increased, there is a problem that the polymer is colored and the colorless transparency is deteriorated.
“Current status and future prospects of plastic films and sheets”, Fuji Chimera Research Institute, Inc. (Publisher: Ryoyoshi Omotesaki), June 4, 2004, p165-p168 "Transparent resin for optics", Technical Information Association, Inc. (Issue: Kazuhiro Takahisa), December 17, 2001, p59 JP-A-7-268036

  An object of the present invention is to solve the above-mentioned problems of the conventional film and provide an acrylic resin film excellent in heat resistance, transparency, defect-free property, and optical isotropy, and a method for producing the same.

  That is, the present invention is an acrylic resin film containing a glutaric anhydride unit represented by the following structural formula (1), having a haze value of 1% or less and a volatile content of 1% or less. It is an acrylic resin film.

  Moreover, it is the manufacturing method of the acrylic resin film which casts the acrylic resin solution melt | dissolved in the mixed solvent of a good solvent and a poor solvent on a base film, and dries.

(In the above formula, R ¹ and R ² represent the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms.)

  The present invention is a film made of an acrylic resin containing a glutaric anhydride unit represented by a predetermined structural formula, and the acrylic resin film has a haze value of 1% or less and a volatile content of 1% or less. An acrylic resin film excellent in heat resistance, transparency and optical isotropy could be provided.

  Moreover, the acrylic resin film excellent in impact resistance and toughness was able to be provided by containing 10-40 mass% of acrylic elastic body particles in the said film.

  The acrylic resin film of the present invention preferably contains an acrylic resin (A) containing a glutaric anhydride unit represented by the following structural formula (1).

(In the above ^formula, R 1, ^{R 2} represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)
Heat resistance can be improved by containing the glutaric anhydride unit of the said Structural formula (1). Moreover, as content with respect to the acrylic resin (A) of the glutaric anhydride unit of the said Structural formula (1), it is preferable that it is 20-40 mass%, and it is more preferable that it is 25-35 mass%. When the content of the glutaric anhydride unit is 20% by mass or more based on the acrylic resin (A), it is possible to obtain a resin having excellent heat resistance and chemical resistance. High acrylic resin can be used. Moreover, the toughness fall of resin can be suppressed as content of a glutaric anhydride unit is 40 mass% or less with respect to an acrylic resin (A). In particular, from the viewpoint of heat resistance, R ¹ and R ² are preferably hydrogen or a methyl group, and particularly preferably a methyl group.

  The acrylic resin (A) preferably contains a vinyl carboxylic acid alkyl ester unit. By adopting a vinylcarboxylic acid alkyl ester unit as the basic structural unit of the acrylic resin, an acrylic resin that is stable against heat and water can be obtained.

As a vinylcarboxylic acid alkylester unit, what is represented by following Structural formula (2) can be mentioned, for example. R ³ represents hydrogen or an aliphatic or alicyclic hydrocarbon having 1 to 5 carbon atoms, and R ⁴ represents an aliphatic hydrocarbon having 1 to 5 carbon atoms.

(In the above formula, R ³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ⁴ represents an aliphatic or alicyclic hydrocarbon group having 1 to 5 carbon atoms.)
Preferable specific examples of the vinyl carboxylic acid alkyl ester unit include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic acid. t-butyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) Examples include 3-hydroxypropyl acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate and 2,3,4,5-tetrahydroxypentyl (meth) acrylate. 1 type may be included independently and 2 or more types may coexist. Of these, methyl (meth) acrylate is most preferred because of its excellent thermal stability.

  Here, as content of the vinyl carboxylic-acid alkylester unit with respect to an acrylic resin (A), 60-90 mass% is preferable, More preferably, it is 65-75 mass%. By setting it as 60 mass% or more, the transparency as an acrylic resin can be obtained. On the other hand, the upper limit value corresponds to the lower limit value of the preferable addition amount of the aforementioned glutaric anhydride unit.

  The acrylic resin (A) may contain vinyl units within a range not impairing the effects of the present invention, but the content of styrene units such as styrene and α-methylstyrene is 1% by mass or less, that is, It is preferable to set it as 0-1 mass%, More preferably, it is 0-0.1 mass%. By making content of a styrene-type unit 1 mass% or less, a heat resistant and transparency fall can be prevented.

  The acrylic resin (A) preferably has an unsaturated carboxylic acid unit content of 10% by mass or less, that is, 0 to 10% by mass, more preferably 0 to 5% by mass, and still more preferably 0 to 1. % By mass. By setting the content of the unsaturated carboxylic acid unit to 10% by mass or less, colorless transparency, retention stability, and moisture resistance can be maintained.

  The mass average molecular weight of the acrylic resin (A) is preferably in the range of 80,000 to 150,000. When the mass average molecular weight is 80,000 or more, an acrylic resin film excellent in mechanical strength can be obtained, and when the mass average molecular weight is 150,000 or less, resin coloring can be prevented.

  Moreover, it is preferable that the glass transition temperature (Tg) of an acrylic resin (A) is 120 degreeC or more from a heat resistant viewpoint. The upper limit of the glass transition temperature (Tg) is preferably higher, but is preferably 160 ° C. or lower from the viewpoint of workability.

  In order to set the glass transition temperature (Tg) within the above range, the content of the glutaric anhydride unit represented by the structural formula (1) with respect to the acrylic resin (A) as described above is 20 to 40% by mass. It is preferable to do. The glass transition temperature (Tg) of the present invention is measured at a rate of temperature increase of 20 ° C./min using a differential scanning calorimeter (for example, DSC-7 manufactured by Perkin Elmer).

  The acrylic resin film of the present invention preferably has a haze value of 1% or less, and more preferably 0.7% or less. The haze value of such a film is measured by a method based on JIS-K7136-2000. When the haze value of the acrylic resin film is 1% or less, a good film with little loss of transmitted light can be obtained in optical applications where transparency is required. As a method for reducing the haze value, it is preferable to remove foreign matter of the acrylic resin (A) as much as possible. Here, the foreign substance in the present invention is a composition other than the acrylic resin (A), and means a single substance or an aggregate having a size of 1 μm or more. Examples of such a foreign substance of the acrylic resin include a monomer and dust mixed by a polymerization operation.

  Moreover, when adding the acrylic elastic body particle | grains mentioned later to an acrylic resin film and aiming at the toughness improvement of a film, it is preferable to make small the refractive index difference of the acrylic elastic body particle and acrylic resin film to add. Furthermore, when obtaining an acrylic resin film by a solution casting method, it is preferable that the acrylic resin film after solvent drying and the cast base material have good peelability. When the peelability between the acrylic resin film and the cast substrate is poor, crazing is likely to occur in the acrylic resin film during peeling, and the haze value is likely to deteriorate. Moreover, it is preferable that the cast surface of a cast base material is smooth in order to suppress surface haze deterioration due to transfer. A preferable cast base material for obtaining an acrylic resin film by such a solution casting method will be described later. In addition, although the minimum of the haze value of an acrylic resin film is not specifically limited, It is thought about 0.1% practically.

The acrylic resin film of the present invention preferably has a volatile content of 1% or less, more preferably 0.7% or less, and further preferably 0.5% or less under the conditions described below. The volatile content of such a film is defined by the following method. Using a thermal mass measuring device, the thermal loss of the acrylic resin film is measured in a nitrogen atmosphere under the condition of a heating rate of 10 ° C./min, and the following formula is obtained from the mass at 35 ° C. and the mass at 200 ° C. be able to.
Volatiles (mass%) = ((mass at 35 ° C.−mass at 200 ° C.) / Mass at 35 ° C.) × 100.

  When an acrylic resin film is obtained by the solution casting method, the volatile matter may exceed 1% if the solvent is not sufficiently dried. This is a particular problem because it may deteriorate the adhesion. In addition, if the volatile component is contained in the acrylic resin film, the glass transition temperature of the acrylic resin film may decrease, and mechanical properties such as Young's modulus and breaking strength may decrease, which is not preferable. Examples of the solvent drying method include hot air jet, drum type, infrared ray, microwave (induction heating), electromagnetic induction heating, ultraviolet ray, and electron beam. The drying conditions are set appropriately depending on the drying method and the solvent to be used. However, when drying with a hot air jet method using acetone as a solvent, the drying temperature is in the range of 10 ° C to 200 ° C. It is preferable that In particular, when the temperature at the initial stage of drying exceeds the boiling point of the solvent used and is too high, foaming is likely to occur. Therefore, the initial drying temperature is preferably equal to or lower than the boiling point of the solvent used. The lower the volatile content of the acrylic resin film, the better. However, the lower limit is considered to be about 100 ppm in practice.

  The acrylic resin film of the present invention preferably contains acrylic elastic particles (B) in addition to the acrylic resin (A) in the resin from the viewpoint of improving toughness.

  The rubbery polymer constituting the acrylic elastic particles (B) has an acrylic component such as an ethyl acrylate unit or a butyl acrylate unit as an essential component, and other preferable components include a dimethylsiloxane unit and a phenylmethylsiloxane unit. Silicone component, styrene component such as styrene unit and α-methylstyrene unit, nitrile component such as acrylonitrile unit and methacrylonitrile unit, conjugated diene component such as butanediene unit and isoprene unit, urethane component or ethylene component, propylene component, isobutene Ingredients can be mentioned.

  Among these, those composed of an acrylic component, a silicone component, a styrene component, a nitrile component, and a conjugated diene component are preferable.

  A rubber elastic body composed of a combination of two or more of these components is also preferable. For example, a rubber elastic body composed of an acrylic component and a silicone component, a rubber elastic body composed of an acrylic component and a styrene component, acrylic Examples thereof include a rubber elastic body composed of a component and a conjugated diene component, a rubber elastic body composed of an acrylic component, a silicone component and a styrene component.

  In addition to these components, those containing a crosslinkable component such as a divinylbenzene unit, an allyl acrylate unit, or a butylene glycol diacrylate unit are also preferred.

  Of these, a combination of an alkyl acrylate unit and an aromatic vinyl unit is preferred. Alkyl acrylate units, especially butyl acrylate, are extremely effective in improving toughness, and by adjusting the refractive index of acrylic elastic particles (B) by copolymerizing aromatic vinyl units such as styrene. Can do. The copolymerization ratio of butyl acrylate and styrene is preferably 10 to 50% by mass of styrene with respect to 50 to 90% by mass of butyl acrylate, and more preferably 20 to 30% of styrene with respect to 70 to 80% by mass of butyl acrylate. % By mass.

  The refractive index of the acrylic elastic particles (B) is preferably adjusted so that the refractive index difference from the acrylic resin (A) is 0.01 or less. In order to satisfy such a refractive index condition, a method of adjusting each monomer composition ratio of the acrylic resin (A) and / or a rubbery polymer or monomer composition of the acrylic elastic particles (B) The difference in refractive index can be reduced by adjusting the ratio, and an acrylic resin film excellent in transparency can be obtained. Acrylic elastic particles having a small refractive index difference from acrylic resin (A) by copolymerizing aromatic vinyl units such as styrene with alkyl acrylate such as butyl acrylate, and adjusting the copolymerization ratio. Can be obtained.

  The average particle diameter of the acrylic elastic particles (B) is preferably 70 to 300 nm, and more preferably 100 to 200 nm. By setting the average particle size to 70 nm or more, it is possible to improve toughness and impact resistance, and by setting the average particle size to 300 nm or less, it is possible to suppress a decrease in heat resistance of the resin.

  The content of the acrylic elastic particles (B) with respect to the acrylic resin film is preferably 10 to 40% by mass, and more preferably 15 to 30% by mass. By setting the content of the acrylic elastic particles (B) to the acrylic resin film within the above range, it becomes a film having moderate flexibility, and a film excellent in workability such as winding property and slit property and heat resistance. Can be obtained.

  In addition, the acrylic resin film of the present invention includes polyethylene, polypropylene, polyamide, polyphenylene sulfide, polyether ether ketone, polyester, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyetherimide, etc., as long as the object of the present invention is not impaired. These thermoplastic resins, phenolic, melamine-based, polyester-based, silicone-based, and epoxy-based thermosetting resins may be contained. In addition, hindered phenol-based, benzotriazole-based, benzophenone-based, benzoate-based, and cyanoacrylate-based ultraviolet absorbers or antioxidants, lubricants or plasticizers such as higher fatty acids, acid esters, acid amides, and higher alcohols, Release agents such as montanic acid, its salt, its ester, its half ester, stearyl alcohol, stearamide and ethylene wax, anti-coloring agent such as phosphite and hypophosphite, halogen-based, phosphorus-based and silicone-based It may contain additives such as non-halogen flame retardants, nucleating agents, amine-based, sulfonic acid-based, polyether-based antistatic agents, pigments and other colorants. The content of these resins and additives other than the acrylic resin (A) with respect to the acrylic resin film is appropriately adjusted depending on the use, but the colorless transparency and optical isotropy that are the characteristics of the acrylic resin film of the present invention. It is preferably contained in a range that does not affect the content, and practically 10% by mass or less is considered preferable.

  The acrylic resin film of the present invention preferably has a glass transition temperature of 120 ° C. or higher from the viewpoint of heat resistance, more preferably 125 ° C. or higher, and further preferably 130 ° C. or higher. The glass transition temperature of such an acrylic resin film appropriately adjusts the content of the glutaric anhydride unit represented by the structural formula (1) relative to the acrylic resin (A) and the content of the acrylic elastic particles. Can be controlled. Moreover, since glass transition temperature may fall when there is much volatile matter of an acrylic resin film, it is so preferable that volatile matter is low. In addition, although the one where the upper limit of the glass transition temperature of an acrylic resin film is higher is preferable, it is preferable to set it as 160 degrees C or less from a viewpoint of workability.

  The acrylic resin film of the present invention preferably has a phase difference of 5 nm or less, more preferably 2 nm or less, with respect to light having a wavelength of 400 to 700 nm. When the phase difference with respect to light having a wavelength of 400 to 700 nm is 5 nm or less, it can be suitably used in applications requiring optical isotropy, such as polarizing plates and protective films for optical disks. In applications where optical isotropy is required, it is preferable that the phase difference with respect to light having a wavelength of 400 to 700 nm is smaller, but the lower limit is considered to be about 0.1 nm in practice. In order to obtain such an acrylic resin film having a low retardation, it is necessary not to introduce an additive or a copolymer component that expresses a retardation, or to reduce the melt or solution viscosity in the film-forming process or to reduce the draw ratio. It is effective to lower it.

  The acrylic resin film of the present invention preferably has a total light transmittance of 91% or more, and more preferably 92% or more. By setting the total light transmittance to 91% or more, the effect of improving the luminance can be obtained. The total light transmittance of such a film is measured by a method based on JIS-K7361-1-1996. In order to obtain an acrylic resin film having such a total light transmittance, it is necessary not to introduce an additive or copolymer component that absorbs visible light, or to reduce the refractive index of the acrylic resin (A). Is effective.

  The acrylic resin film of the present invention preferably has a Young's modulus in at least one direction of 1 GPa or more, and more preferably 2 GPa or more. It is particularly preferable that the Young's modulus in all directions is 2 GPa or more. It is preferable that the Young's modulus of the acrylic resin film is 1 GPa or more because film distortion due to stress during processing or use can be suppressed. The Young's modulus of such a film is measured by a method based on JIS-C2318. The upper limit of the Young's modulus of the acrylic resin film is not particularly limited, but in reality, it is considered to be about 5 GPa. In order to obtain an acrylic resin film having such a Young's modulus, the molecular weight of the acrylic resin (A), the content of glutaric anhydride units, the composition of the acrylic elastic particles (B), the particle diameter, the added amount, etc. are appropriately selected. Adjust it.

  In the acrylic resin film of the present invention, the elongation at break in at least one direction is preferably 10% or more, and more preferably 15% or more. It is preferable that the breaking elongation of the acrylic resin film is 10% or more because the film has appropriate flexibility, film breakage during film formation and processing is reduced, and workability such as slit property is improved. The elongation at break of such a film is measured by a method according to JIS-C2318. The upper limit of the elongation at break of the acrylic resin film is not particularly limited, but it is considered that it is practically about 50%. In order to obtain an acrylic resin film having such elongation at break, the molecular weight of acrylic resin (A), the content of glutaric anhydride units, the composition of acrylic elastic particles (B), the particle diameter, the added amount, the film It is advisable to appropriately adjust the dispersion state in the inside.

The acrylic resin film of the present invention preferably has a moisture absorption rate of 3% or less at 25 ° C. and a relative humidity of 75%, more preferably 2% or less, and even more preferably 1% or less. It is preferable for the acrylic resin film to have a moisture absorption rate of 3% or less because a change in characteristics due to a change in humidity during processing or use is suppressed. In order to obtain an acrylic resin film having such a moisture absorption rate, the molecular weight of the acrylic resin (A) and the content of glutaric anhydride units are not adjusted, and hydrophilic additives and copolymerization components are not introduced. It is effective to do. The moisture absorption rate of such a film is measured by the following method. First, about 0.5 g of film was sampled and heated for 3 hours at 105 to 120 ° C. for dehumidification, and then cooled to 25 ° C. so as not to absorb moisture, such as cooling by introducing nitrogen gas, and the film mass Is accurately weighed to the nearest 0.1 mg (the mass at this time is defined as W0). Next, the film is allowed to stand in an atmosphere of 25 ° C. and a relative humidity of 75% for 48 hours, and the subsequent mass is accurately weighed (the mass at this time is W1), and the moisture absorption rate is obtained by the following formula. . In addition, although the one where the moisture absorption rate of an acrylic resin film is low is preferable, realistically, a minimum is considered to be about 0.1%.
Moisture absorption rate (%) = ((W1-W0) / W0) × 100.

The acrylic resin film of the present invention preferably has a thermal expansion coefficient of 100 ppm / ° C. or less, more preferably 80 ppm / ° C. or less, in a temperature range of 25 ° C. to 80 ° C. In order to obtain an acrylic resin film having such a thermal expansion coefficient, the molecular weight of the acrylic resin (A), the content of the glutaric anhydride unit, the composition of the acrylic elastic particles (B), the particle diameter, the added amount, etc. It is good to adjust appropriately. It is preferable that the thermal expansion coefficient of the acrylic resin film at 25 ° C. to 80 ° C. is 100 ppm / ° C. or less because dimensional changes and characteristic changes due to temperature changes during processing or use are suppressed. The thermal expansion coefficient of such a film is measured in the temperature lowering process after the film is heated to 100 ° C. using a push rod type differential thermal dilatometer (TMA). The initial film length at a temperature of 25 ° C. and a relative humidity of 65% is L 0, the film length at a temperature T 1 (= 80 ° C.) is L 1, and the film length at a temperature T 2 (= 25 ° C.) is L 2. Obtain the coefficient of thermal expansion.
Thermal expansion coefficient (ppm / ° C.) = (((L1-L2) / L0) / (T1-T2)) × 10 ⁶ .

The acrylic resin film of the present invention preferably has a humidity expansion coefficient of 100 ppm /% RH or less, more preferably 80 ppm /% RH or less at an environmental temperature of 25 ° C. and a humidity range of 30% RH to 85% RH. In order to obtain an acrylic resin film having such a humidity expansion coefficient, the molecular weight of the acrylic resin (A), the content of glutaric anhydride units, the composition of the acrylic elastic particles, the particle diameter, the addition amount, and the like are appropriately adjusted. Good. It is preferable for the acrylic resin film to have a humidity expansion coefficient of 100 ppm /% RH or less at 25 ° C. and 30% RH to 85% RH because dimensional changes and characteristic changes due to changes in humidity during processing or use are suppressed. The humidity expansion coefficient of such a film is determined by setting the film in a constant temperature and humidity chamber, dehumidifying it to a constant humidity (30% RH) and holding it for 24 hours, and increasing the humidity ( 85% RH) and can be determined by measuring the film length after the film has been allowed to stand for 24 hours. The initial film length at a temperature of 25 ° C. and a relative humidity of 65% is L0, the film length after being allowed to stand for 24 hours at a humidified humidity M1 (= 85% RH) for 24 hours, and the humidity M2 after dehumidification (= The film length at 30% RH) is L2, and the humidity expansion coefficient is obtained by the following equation.
Humidity expansion coefficient (ppm /% RH) = {(L1-L2) / L0} / (M1-M2) × 10 ⁶ .

  It is preferable that the acrylic resin film of this invention exists in the range of 1-200 micrometers as film thickness. The film thickness should be adjusted as appropriate depending on the film properties, handling properties, target final thickness, etc., but if the film thickness is less than 1 μm, the yield may be deteriorated, such as tearing is likely to occur during film formation. When the thickness exceeds 200 μm, the transparency is lowered or the thickness of the member becomes too large. The thickness of the acrylic resin film is more preferably in the range of 5 to 150 μm, and further preferably in the range of 5 to 100 μm.

  Next, a method for producing the acrylic resin film of the present invention will be described.

  The acrylic resin (A) containing the glutaric anhydride unit represented by the structural formula (1) can basically be produced by the following method.

  An unsaturated carboxylic acid monomer represented by the following structural formula (3), an unsaturated carboxylic acid alkyl ester monomer represented by the following structural formula (4), and other vinyl monomer units. When it is contained, the vinyl monomer giving the unit is polymerized to obtain a copolymer (a).

(However, R ⁵ represents hydrogen or an alkyl group having 1 to 5 carbon atoms.)

(However, R ⁶ represents hydrogen or an aliphatic or alicyclic hydrocarbon group having 1 to 5 carbon atoms, and R ⁷ represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms.)
The blending ratio of the monomers is such that the sum of the blended monomers is 100% by mass, and the unsaturated carboxylic acid monomer is preferably 15 to 45% by mass, more preferably 20 to 40 parts by mass. Moreover, 55-85 mass% is preferable, and, as for an unsaturated carboxylic-acid alkylester monomer, More preferably, it is 60-80 mass%.

  When the content of the unsaturated carboxylic acid monomer is 15 to 45% by mass, the content of the glutaric anhydride unit represented by the structural formula (1) when the copolymer (a) is heated. Is preferably in the range of 20 to 40% by mass, and can be an acrylic resin (A) excellent in heat resistance, colorless transparency, and retention stability.

  As a polymerization method for producing the copolymer (a), a known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization or the like basically by radical polymerization can be used, and there are fewer impurities. Particularly preferred are solution polymerization, bulk polymerization and suspension polymerization.

  The polymerization temperature for producing the copolymer (a) is preferably 95 ° C. or less, more preferably 85 ° C. or less, and still more preferably from the viewpoint of preventing the resin from being colored and having a good color tone. 75 ° C or lower. The lower limit of the polymerization temperature is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, from the viewpoint of productivity taking the polymerization rate into consideration. Further, for the purpose of improving the polymerization yield or the polymerization rate, the polymerization temperature may be raised according to the progress of the polymerization. In this case as well, the upper limit temperature is preferably controlled to 95 ° C. or lower throughout the process, and the polymerization initiation temperature is increased. Is preferably performed at a relatively low temperature of 75 ° C. or lower.

  The polymerization time for producing the copolymer (a) is preferably 1 to 6 hours, more preferably 1.5 to 3 hours from the viewpoint of production efficiency.

  Since the molecular weight of the acrylic resin (A) is determined by the molecular weight of the copolymer (a), as described above, when the acrylic resin (A) is within the preferable polymerization average molecular weight range (80,000 to 150,000), The molecular weight of the copolymer (a) is also preferably 80,000 to 150,000 in terms of mass average molecular weight.

  The molecular weight of the copolymer (a) is, for example, a radical polymerization initiator such as an azo compound or a peroxide, or a chain transfer agent such as an alkyl mercaptan, carbon tetrachloride, carbon tetrabromide, dimethylacetamide, dimethylformamide, triethylamine or the like. It can control by adjusting the addition amount. In particular, a method of adjusting the addition amount of alkyl mercaptan as a chain transfer agent can be preferably employed from the viewpoint of stability of polymerization and ease of handling.

  Examples of the alkyl mercaptan used here include n-octyl mercaptan, t-dodecyl mercaptan, n-dodecyl mercaptan, n-tetradecyl mercaptan, n-octadecyl mercaptan, and among them, t-dodecyl mercaptan, n-dodecyl. Mercaptans are preferably used.

  The addition amount of the alkyl mercaptan is preferably 0.2 to 5.0% by mass, more preferably 0.3 to 4.0% by mass, and still more preferably 0.4 to 100% by mass of the total of the monomers. It is -3.0 mass%.

  When the copolymer (a) is heated in the presence or absence of a suitable catalyst, the copolymer (a) is dehydrated from adjacent carboxyl groups of two unsaturated carboxylic acid units or adjacent to each other. The alcohol is eliminated from the unsaturated carboxylic acid unit and the unsaturated carboxylic acid alkyl ester unit to produce one unit of glutaric anhydride unit represented by the structural formula (1).

  Examples of the method for heating the copolymer (a) for dehydration and / or dealcoholization, that is, performing an intramolecular cyclization reaction, include a method using a heated extruder having a vent, an inert gas atmosphere or A method using an apparatus that can be heated and devolatilized under vacuum is preferable from the viewpoint of productivity.

  As a specific apparatus, for example, a single screw extruder equipped with a “unimelt” type screw, a twin screw extruder, a triaxial extruder, a continuous or batch kneader type kneader, etc. can be used. Use of a twin-screw extruder is preferable in terms of quality stability because it is easy to control continuous productivity, reaction temperature, time, and shear rate. The length / diameter ratio (L / D) of the screw of the extruder is preferably 40 or more. By setting the L / D to 40 or more, it is possible to secure a sufficient heating time for advancing the intramolecular cyclization reaction. The residual amount of saturated carboxylic acid units can be reduced, and a polymer with less generation of bubbles in the molded product due to re-advancement of the reaction during heat molding can be obtained, and deterioration of color tone during molding residence can be suppressed.

  Moreover, it is more preferable that the apparatus has a structure capable of introducing an inert gas such as nitrogen into them. When the intramolecular cyclization reaction by heating in the presence of oxygen tends to increase the yellowness of the resin, it is preferable to sufficiently replace the interior with an inert gas such as nitrogen. As a method for introducing an inert gas such as nitrogen into the twin screw extruder, for example, a method of connecting a pipe from the upper part and / or the lower part of the hopper and flowing an inert gas of about 10 to 100 L / min.

  The heating temperature for the intramolecular cyclization reaction is preferably 180 to 300 ° C, more preferably 200 to 280 ° C, from the viewpoint that the reaction proceeds smoothly.

  The heating time for the intramolecular cyclization reaction may be appropriately set according to the desired copolymer composition, but is usually preferably 1 to 60 minutes, more preferably 2 to 30 minutes, and even more preferably 3 to 20 minutes. It is.

  Moreover, when heating for the intramolecular cyclization reaction, it is also preferable to add one or more of an acidic catalyst, an alkaline catalyst, and a salt catalyst. Examples of the acidic catalyst include hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, phosphoric acid, phosphorous acid, phenylphosphonic acid, methyl phosphate, and the like. Examples of the basic catalyst include metal hydroxides, amines, imines, alkali metal derivatives, alkoxides and the like. Examples of the salt-based catalyst include acetic acid metal salt, stearic acid metal salt, metal carbonate salt, ammonium hydroxide salt and the like. Among them, a basic catalyst or a salt-based catalyst containing an alkali metal can be preferably used because it exhibits an excellent reaction promoting effect with a relatively small addition amount. Specifically, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, sodium methoxide, sodium ethoxide, sodium phenoxide, potassium methoxide, potassium ethoxide, alkoxide compounds such as potassium phenoxide, Examples thereof include organic carboxylates such as lithium acetate, sodium acetate, potassium acetate, and sodium stearate. Among them, sodium hydroxide, sodium methoxide, lithium acetate, and sodium acetate can be preferably used.

  The addition amount of these catalysts is preferably about 0.01 to 1% by mass with respect to 100% by mass of the copolymer (a). When it is 0.01% by mass or more, a catalytic function is exhibited, and when it is 1% by mass or less, coloring of the resin and a decrease in transparency can be prevented.

  When the acrylic resin (A) contains the acrylic elastic particles (B), an acrylic resin layer having a glass transition temperature of 60 ° C. or more is provided on the surface layer of the acrylic elastic particles (B) from the viewpoint of improving dispersibility. It is preferable to use acrylic elastic particles (B) obtained by graft copolymerization of vinyl monomers.

  In the so-called core-shell type acrylic elastic particles (B) provided with an acrylic resin layer having a glass transition temperature of 60 ° C. or higher on the surface layer, as an acrylic resin having a glass transition temperature of 60 ° C. or higher constituting the shell portion of the outer layer, Those containing an unsaturated carboxylic acid alkyl ester unit or an unsaturated carboxylic acid unit are preferred. When such core-shell type acrylic elastic particles (B) are added to the copolymer (a) and heated, the affinity with the matrix resin is good and the dispersibility is improved. In addition, due to heating, the intramolecular cyclization reaction proceeds even in the shell portion, and the composition of the shell portion and the matrix resin becomes the same, so that a decrease in transparency of the acrylic resin film can be suppressed.

  As a monomer used as a raw material of the unsaturated carboxylic acid alkyl ester unit, (meth) acrylic acid alkyl ester is preferable, and methyl (meth) acrylate is more preferably used.

  Moreover, as a monomer used as the raw material of an unsaturated carboxylic acid-type unit, (meth) acrylic acid is preferable and methacrylic acid is more preferably used.

  The mass ratio of the core portion to the shell portion of the core-shell type acrylic elastic particles (B) is preferably 50 to 90 mass%, more preferably 60 to 80 mass%.

  Typical core-shell type acrylic elastic particles (B) include, for example, “Metablene” manufactured by Mitsubishi Rayon Co., Ltd., “Kane Ace” manufactured by Kaneka Chemical Co., Ltd., “Paraloid” manufactured by Kureha Chemical Industry Co., Ltd. “Acryloid”, “Staffyroid” manufactured by Ganz Kasei Kogyo Co., Ltd., “Parapet SA” manufactured by Kuraray Co., Ltd. and the like may be used, and these may be used alone or in combination of two or more.

  In the graft copolymerization type acrylic elastomer particles (B) obtained by graft copolymerization with a vinyl monomer, the vinyl monomer may be an unsaturated carboxylic acid ester monomer having a vinyl group, It can be selected from unsaturated carboxylic acid monomers having a vinyl group, aromatic vinyl monomers and the like. Also, other vinyl monomers may be copolymerized in accordance with the compatibility with the rubbery polymer or matrix resin constituting the acrylic elastic particles (B).

  The amount of the vinyl monomer to be imparted to the acrylic elastic particles (B) is a mass ratio of the rubber polymer to the vinyl monomer (rubber polymer: vinyl monomer). 80): (20-90) is preferable, (20-70): (30-80) is more preferable, and (30-60): (40-70) is more preferable. By setting the vinyl monomer in the range of 20 to 90% by mass, elastic particles having moderate flexibility can be obtained.

  The graft copolymer type acrylic elastic particles (B) may contain a component derived from a vinyl monomer that is not graft copolymerized, but from the viewpoint of impact strength, the graft ratio is 10 to 100. % Is preferred. Here, the graft ratio is a mass ratio of a graft copolymerized vinyl monomer provided to the rubber polymer. Further, the intrinsic viscosity of the ungrafted copolymer is not particularly limited, but a methyl ethyl ketone solvent having an intrinsic viscosity of 0.1 to 0.6 dl / g measured at 30 ° C. has an impact strength and moldability. It is preferable from the viewpoint of balance.

  As a method for obtaining the graft copolymer type acrylic elastic particles (B), polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be used.

  Regarding the particle diameter of the core-shell type or graft copolymer type acrylic elastic particles (B), the cross-section observation using a transmission electron microscope, etc. is performed for rubber polymers excluding the shell part and the graft copolymer part. It can be measured by the method. The content of the core-shell type or graft copolymer type acrylic elastic particles (B) can be measured from the amount of insoluble components after the acrylic resin is dissolved in a solvent such as acetone.

  As a method of blending the acrylic elastic particles (B) and other additives into the acrylic resin (A) or a precursor thereof, for example, after blending the acrylic resin (A) and other additive components in advance, usually 200 to 350 A method of uniformly melting and kneading with a single-screw or twin-screw extruder at ° C can be used.

  In addition, the acrylic elastic particles (B) and other additives are added to the copolymer (a), which is the precursor of the acrylic resin (A), and simultaneously with the intramolecular cyclization reaction using a twin screw extruder or the like. Further, blending by melt kneading of the acrylic elastic particles (B) and other additives can be performed.

  In the melt-kneading, a cyclization reaction of unsaturated carboxylic acid monomer units such as a shell portion imparted to the acrylic elastic particles (B) and unsaturated carboxylic acid alkyl ester monomer units can be performed simultaneously.

  Next, the method for producing the acrylic resin film of the present invention will be described.

  The acrylic resin film of the present invention can be produced by a melt film-forming method such as a T-die method, a calendar method, an inflation method, or a cutting method, or a solution film-forming method such as a cast method on a polymer film, a cast method on a metal belt, or a casting drum method. The film may be formed by any method, but the film formation by the solution film formation method is preferable in terms of excellent defect-freeness, optical isotropy, and thickness unevenness accuracy.

  Further, the solution film forming method includes a dry-wet method, a dry method, a wet method, etc., and any method may be used to form a film. Here, the dry-wet method will be described as an example.

  The acrylic resin (A) obtained by the above-described method can be dissolved in a solvent such as acetone, tetrahydrofuran, methyl ethyl ketone, dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, and used as a film forming stock solution. These solvents are good solvents excellent in the solubility of the acrylic resin (A), and may be used alone or in combination of two or more. When the acrylic resin (A) is prepared by solution polymerization, the polymerization solution may be used as a film-forming stock solution as it is, or the once-isolated acrylic resin (A) may be dissolved in the solvent to form a film-forming stock solution. Good. In addition, an inorganic and / or organic additive such as a release agent, an antioxidant, a heat stabilizer, an ultraviolet absorber, and a nucleating agent is added to the above-mentioned film forming stock solution as long as the object of the present invention is not impaired. May be.

  In addition to the above good solvent, the solvent for the acrylic resin (A) is a poor solvent inferior in solubility of the acrylic resin (A), for example, a hydrocarbon solvent such as cyclohexane, benzene, toluene, xylene, styrene, cyclopentane, etc. Halogenated hydrocarbon solvents such as methylene chloride, ethylene chloride, chloroform, alcohol solvents such as methanol, ethanol, isopropyl alcohol, n-butanol, tert-butyl alcohol, ether solvents such as dimethyl ether, diethyl ether, butyl ether, One or two or more selected from ester solvents such as methyl acetate, ethyl acetate, and acetic acid-n-butyl, polyhydric alcohol solvents such as ethyl cellosolve, cellosolve acetate, and tert-butyl cellosolve can be used. . By mixing the above poor solvent with the solvent of the film forming stock solution, the poor solvent having low affinity with the polymer is easily volatilized from the film in the solution film forming drying step, and the drying efficiency can be increased. Depending on the poor solvent, it is effective because it may exhibit a function as an antifoaming agent that suppresses foaming caused by rapid solvent drying in the drying step.

  The mixing ratio of the good solvent and the poor solvent is appropriately adjusted depending on the concentration of the acrylic resin (A), the type of the good solvent or the poor solvent, and the mass ratio of the good solvent and the poor solvent ( The good solvent: poor solvent is preferably in the range of (50-100) :( 0-50), and more preferably in the range of (70-100) :( 0-30). If the amount of the poor solvent is too large, the solubility may be lowered and the polymer may be precipitated, or the stability of the film-forming stock solution may be deteriorated.

  Although the density | concentration of the acrylic resin (A) in film forming undiluted | stock solution is suitably adjusted with the kind of said solvent, it is preferable to exist in the range of 5-40 mass%, and within the range of 10-30 mass%. It is more preferable that When the concentration of the acrylic resin (A) is less than 5% by mass, the solution viscosity is low, and the flatness of the film deteriorates due to the convection of the solution at the initial stage of drying of the solution casting, and it takes a long time to dry the solvent. This is not preferable because the properties are lowered. On the other hand, if the concentration of the acrylic resin (A) exceeds 40% by mass, the solution viscosity is high, handling properties are deteriorated, and problems such as difficulty in high-precision filtration occur, which is not preferable.

  In order to improve the film defect and haze value of the film-forming stock solution, it is preferable to remove foreign substances by filtration. Examples of the filter used for such filtration include a wire mesh, sintered metal, porous ceramic, glass, a filter made of a polymer such as polypropylene resin and polyethylene resin, or a filter made by combining two or more of the above materials. .

  The filtration accuracy of this membrane-forming stock solution is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. It is preferable to reduce the filtration accuracy of the membrane-forming stock solution, but if it is too small, the filter may be clogged, or the filtration pressure will increase and the filter may be damaged, so the lower limit is 0.1 μm. The degree is considered appropriate.

  The film-forming stock solution prepared as described above is extruded from a die onto a cast substrate such as a polymer film, a drum, or an endless belt to form a thin film, and then the solvent is scattered from the thin film until the thin film has self-supporting properties. dry.

  The cast substrate may be any of the above polymer film, drum, endless belt, etc., but since the peelability between the acrylic resin film after drying and the cast substrate is good, the polymer film is used as the cast substrate. It is preferable to do. The polymer film cast substrate is not particularly limited as long as it is resistant to the solvent of the film forming stock solution. For example, polyethylene terephthalate film, polyethylene naphthalate film, polypropylene film, polyethylene film, polyphenylene sulfide film, aramid film Among these, a polyethylene terephthalate film having an excellent balance of rigidity, thickness unevenness, defect-free property, cost, and the like is preferable.

  Furthermore, when a film in which a resin layer for enhancing the releasability is disposed on the polyethylene terephthalate film is used as a cast substrate, the releasability between the acrylic resin film after drying and the cast substrate is improved, and at the time of peeling The resulting craze is suppressed and the haze value is reduced, which is preferable. The peelability between the acrylic resin film and the cast substrate is good when the solvent remains in the film in the middle of drying because the solvent is present at the interface between the film and the substrate. In a state where almost no solvent remains in the finished film, the film and the substrate are easily bonded to each other, and the peelability is deteriorated. For this reason, when the solvent drying of the acrylic resin film is sufficiently performed on the base film, it is effective to use the base film provided with the resin layer for improving the peelability.

  Such a resin layer for improving the peelability should be appropriately adjusted depending on the composition of the acrylic resin (A). For example, the resin layer is formed of an acrylic resin or a polyvinyl alcohol resin having an alkyl group in the side chain. It is preferable. Such an acrylic resin or polyvinyl alcohol resin having an alkyl group in the side chain can be obtained by copolymerization with an acrylic monomer having an alkyl group in the side chain. The acrylic monomer having an alkyl group in the side chain preferably has an alkyl group having 12 to 25 carbon atoms in the side chain, and the copolymerization ratio with the acrylic resin or polyvinyl alcohol resin is 35 to 85% by weight. 60 to 80% by weight is preferable from the viewpoint of blocking resistance and copolymerization.

  The acrylic monomer having such an alkyl group in the side chain is not particularly limited as long as it satisfies the above requirements. For example, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, acrylic acid Pentadecyl, hexadecyl acrylate, heptadecyl acrylate, octadecyl acrylate, nonadecyl acrylate, eicosyl acrylate, henecosyl acrylate, docosyl acrylate, tricosyl acrylate, tetracosyl acrylate, pentacosyl acrylate, dodecyl methacrylate, eicosyl methacrylate, An alkyl group-containing acrylic monomer such as pencosyl methacrylate can be used.

  As for the thickness of the resin layer for improving the said peelability, 5-5000 nm is preferable, 10-1000 nm is more preferable, 30-500 nm is further more preferable. If the thickness of the resin layer for improving the peelability is too thin, it may cause a peeling failure, and if the resin layer is too thick, the expected peeling effect cannot be obtained.

  Moreover, in order to improve the said peelability, it is preferable to add an antistatic agent in the resin layer because dust adhering to the cast substrate can be suppressed and film defects can be reduced.

  50-200 micrometers is preferable and, as for the polymer film thickness as a cast base material, 100-150 micrometers is more preferable. When the thickness of the substrate is less than 50 μm, the rigidity of the film is low, and it is not preferable because problems such as wrinkling during casting or drying tend to deteriorate the flatness of the film. On the other hand, when the thickness of the substrate exceeds 200 μm, it is not economical, and problems such as difficulty in transferring heat to the cast polymer are not preferable.

  The stock solution is cast on a cast substrate and dried using a bar coater, a die coater or the like. The drying temperature of the film-forming stock solution is preferably within a range of 10 to 200 ° C, and more preferably within a range of 20 to 180 ° C. In particular, when an acrylic resin film is obtained by solution casting, since foaming occurs due to rapid solvent drying, it is preferable to perform solvent drying by increasing the drying temperature stepwise or continuously.

  The stepwise or continuous drying temperature and time should be appropriately adjusted depending on the boiling point of the solvent used, the viscosity of the film forming stock solution, the glass transition temperature of the polymer, the drying method, etc. It is preferable to dry at a temperature 20 to 40 ° C. lower than the boiling point of the solvent used in the film-forming stock solution. The next secondary drying temperature is preferably dried at a temperature 0 to 50 ° C. lower than the glass transition temperature of the polymer. The final drying temperature is preferably 0 to 50 ° C. higher than the glass transition temperature of the polymer. When the drying temperature at each stage is low, the solvent drying takes time and the productivity is deteriorated. When the drying temperature is high, foaming occurs and the film defects are likely to increase. In particular, if the final drying temperature is too higher than the glass transition temperature of the polymer, the flatness of the film deteriorates, which is not preferable. Moreover, it is preferable to perform the solvent drying time of each drying step in about 1 to 120 minutes.

  The solvent drying method may be a single-sided drying method that is performed on the cast film until final drying, or the acrylic resin film exhibiting self-supporting property and the cast base material are once peeled off during drying. Either of the both sides drying which dries only an acrylic resin film may be sufficient.

  The acrylic resin film may be stretched during solvent drying or after drying. The stretching temperature is preferably within the range of ± 30 ° C. of the glass transition temperature of the polymer. Further, the draw ratio is preferably in the range of 1.2 to 9, more preferably in the range of 2 to 6, in terms of the ability to stably form a film having excellent mechanical properties. The area magnification is defined as a value obtained by dividing the film area after stretching by the area of the film before stretching.

  The acrylic resin film of the present invention may be a single layer film or a laminated film. In the case of making a laminated film, for example, laminating in a die, laminating in a composite pipe, or once forming a single layer A method of forming another layer on the top may be used.

  The present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto.

  The physical properties were measured and the effects were evaluated according to the following methods.

(1) Composition of each component Acetone is added to the acrylic resin film used as the base material of the acrylic resin film, and the mixture is refluxed for 4 hours. The solution is centrifuged at 9,000 rpm for 30 minutes to obtain an acetone soluble component and an acetone insoluble component. Separated. The acetone-soluble component was dried under reduced pressure at 60 ° C. for 5 hours, and each component unit was quantified to obtain each component composition of the acrylic resin (A).
Quantification of each component unit was performed by a proton nuclear magnetic resonance ( ¹ H-NMR) method.
^{In the 1} H-NMR method, for example, in the case of a copolymer consisting of a glutaric anhydride unit, methacrylic acid, and methyl methacrylate, the spectral assignment in a dimethyl sulfoxide heavy solvent is 0.5 to 1.5 ppm peak. Is hydrogen of α-methyl group of methacrylic acid, methyl methacrylate and glutaric anhydride ring compound, peak of 1.6 to 2.1 ppm is hydrogen of methylene group of polymer main chain, peak of 3.5 ppm is methyl methacrylate The carboxylic acid ester (—COOCH ₃ ) of hydrogen, the peak at 12.4 ppm can determine the copolymer composition from the carboxylic acid hydrogen of methacrylic acid and the integral ratio of the spectrum. In addition to the above, in the case of a copolymer containing styrene as another copolymer component, hydrogen of an aromatic ring of styrene is seen at 6.5 to 7.5 ppm, and the copolymer is similarly obtained from the spectral ratio. The composition can be determined.

In addition to the ¹ H-NMR method, each component unit can be quantified by infrared spectroscopy. In this method, glutaric anhydride units are characterized by absorption at 1800 cm ⁻¹ and 1760 cm ⁻¹ , and can be distinguished from units derived from vinyl carboxylic acids and units derived from vinyl carboxylic acid alkyl esters.

(2) Mass average molecular weight (absolute molecular weight)
Gel permeation chromatograph equipped with a DAWN-DSP type multi-angle light scattering photometer (manufactured by Wyatt Technology) using dimethylformamide as a solvent (pump: model 515, manufactured by Waters, column: TSK-gel-GMHXL, Tosoh Corporation) ).

(3) Glass transition temperature (Tg)
Using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer), the measurement was performed at a temperature increase rate of 20 ° C./min in a nitrogen atmosphere. The glass transition temperature is determined according to the method for determining the midpoint glass transition temperature in 9.3 of JIS-K7121, a straight line equidistant from the extended straight line of each baseline of the measurement chart in the vertical axis direction, and glass The temperature at the point where the curve of the step-like change part of the transition intersects was taken.

(4) Volatile content of acrylic resin film Using a thermal mass measuring device (TGA-50H) manufactured by Shimadzu Corporation and an analyzer thermal analyzer (TA-50) in combination with a personal computer for data processing. Measurements were made. About 7 mg of an acrylic resin film was set in a furnace, the inside of the furnace was placed in a nitrogen atmosphere, and the film was heated from room temperature to 220 ° C. at a temperature rising rate of 10 ° C./min. From the obtained thermal mass curve, the volatile content of the acrylic resin film was determined by the following formula.
Volatiles (mass%) = ((mass at 35 ° C.−mass at 200 ° C.) / Mass at 35 ° C.) × 100.

(5) Haze value and total light transmittance The haze value (%) and total light transmittance (%) at 23 ° C. were measured using a direct reading haze meter manufactured by Toyo Seiki Co., Ltd.

(6) Tensile Young's modulus and elongation at break of acrylic resin film The film was measured under the following conditions using an automatic measuring device “Tensilon AMF / RTA-100” manufactured by Orientec Co., Ltd.
Sample size: width 10mm, length 150mm
Chuck distance 50mm
Tensile speed: 300 mm / min Measurement environment: 23 ° C., 65% RH, tensile Young's modulus was determined from the tangent of the rising portion of the load-elongation curve obtained under atmospheric pressure. Also, elongation obtained by multiplying the length obtained by subtracting the chuck distance from the length at the time of film break by the chuck distance was multiplied by 100.

(7) Moisture absorption rate of acrylic resin film About 0.5 g of acrylic resin film is sampled and heated for 3 hours at 105 to 120 ° C. for dehumidification. The temperature was lowered to 25 ° C. and the film mass was measured (the mass at this time is defined as W0). Next, the film was allowed to stand for 48 hours in an atmosphere of 25 ° C. and a relative humidity of 75%. Thereafter, the mass was measured (the mass at this time is W1), and the moisture absorption rate was determined by the following equation.
Moisture absorption rate (%) = ((W1-W0) / W0) × 100.

(8) Thermal expansion coefficient of acrylic resin film Using a thermal / stress / strain measuring device TMA / SS6000 manufactured by Seiko Instruments Inc., the thermal expansion coefficient at 25 to 80 ° C. was measured under the following measurement conditions.
Sample size: 15mm length, 4mm width
Temperature range: 25-150 ° C
Temperature increase rate: 5 ° C / min Temperature decrease rate: 5 ° C / min Load: 3g
Measurement environment: 65% RH, coefficient of thermal expansion under atmospheric pressure was measured in the temperature lowering process after the film was heated to 100 ° C. An initial film length L0 (= 15 mm) at a temperature of 25 ° C. and a relative humidity of 65%, a film length at a temperature of 80 ° C. as L1, a film length at a temperature of 25 ° C. as L2, and a coefficient of thermal expansion is obtained by the following formula. It was.
Thermal expansion coefficient (ppm / ° C.) = (((L1-L2) / L0) / (80-25)) × 10 ⁶
(9) Humidity expansion coefficient of acrylic resin film A tape elongation test device manufactured by Okura Industry Co., Ltd. was installed in a constant temperature and humidity chamber, a retardation film was set in this device, and humidity was maintained at a constant temperature and a constant load. The amount of retardation film elongation when changing was measured.
Sample size: Length 200mm, width 10mm
Temperature: 25 ° C
Humidity conditions: (Step 1) 30% RH, hold for 24 hours
(Step 2) 85% RH, 24-hour retention humidity increase rate: 0.37% RH / min (target humidity arrival time: 2 hours 30 minutes)
Load: 11.6g
The humidity expansion coefficient was determined by measuring the length of the film dehumidified in Step 1 (25 ° C., 30% RH, maintained for 24 hours), and then increasing the humidity at a rate of 0.37% RH / min. The film length after absorbing moisture at 25 ° C. and 85% RH for 24 hours was determined by measurement. The initial film length L0 (= 200 mm) at a temperature of 25 ° C. and a relative humidity of 65%, the film length after standing for 24 hours at a humidity of about 85% RH is L1, and the film length at a humidity of about 30% RH is L2. As a result, the humidity expansion coefficient was determined by the following equation.
Humidity expansion coefficient (ppm /% RH) = (((L1-L2) / L0) / (85-30)) × 10 ⁶
(10) Phase difference Measured using an automatic birefringence meter (KOBRA-21ADH) manufactured by Oji Scientific Co., Ltd. In the chromatic dispersion measurement mode, the phase difference is measured in a phase difference for a light beam having a wavelength of 480.4 nm, a phase difference for a light beam having a wavelength of 548.3 nm, a phase difference for a light beam having a wavelength of 628.2 nm, and a position for a light beam having a wavelength of 752.7 nm. The phase difference is measured, and each of a to d in the Cauchy wavelength dispersion formula (R (λ) = a + b / λ ² + c / λ ⁴ + d / λ ⁶ ) is calculated from the phase difference (R) and the measured wavelength (λ) at each wavelength. The coefficient was determined and determined by substituting the wavelength of 550 nm (λ = 550) into the Cauchy wavelength dispersion formula.

(11) Film defects The acrylic resin film after film formation was visually confirmed whether or not defects with a diameter of about 0.5 mm or more existed, and evaluated according to the following criteria.
◯: No defects are observed Δ: Defects are slightly observed ×: Defects are observed on the entire surface

[Example 1]
(1) Preparation of acrylic resin (a) First, a methyl methacrylate / acrylamide copolymer suspending agent was prepared at the following ratio.
Methyl methacrylate: 20% by mass
Acrylamide: 80% by mass
Potassium persulfate: 0.3% by mass
Ion exchange water: 1500% by mass
Charge the above methyl methacrylate / acrylamide copolymer suspension into the reactor, and replace the reactor with nitrogen gas while maintaining the temperature at 70 ° C. until the monomer is completely converted into a polymer. A suspension was obtained.
Next, a solution in which 0.05% by mass of the above suspending agent was dissolved in 165% by mass of ion-exchanged water was supplied to a stainless steel autoclave equipped with a baffle having a capacity of 5 liters and a foudra type stirring blade, and the system was filled with nitrogen gas. It stirred at 400 rpm, replacing.
Next, a mixture having the following composition was added while stirring the reaction system.
Methacrylic acid: 27% by mass
Methyl methacrylate: 73% by mass
t-dodecyl mercaptan: 1.2% by mass
2,2′-Azobisisobutyronitrile: 0.4% by mass
After the above mixture was added, the temperature was raised to 70 ° C., and the time when the internal temperature reached 70 ° C. was set as the polymerization start time, and the polymerization was continued for 180 minutes.
Thereafter, the reaction system was cooled, the polymer was separated, washed and dried in accordance with a normal method to obtain a bead-shaped acrylic resin (a). The degree of polymerization of this acrylic resin (a) was 98%, and the mass average molecular weight was 130,000.

(2) Preparation of acrylic elastic particles The following composition was added as an initial adjustment solution in a glass container (capacity 5 liters) with a cooler.
Deionized water: 120% by mass
Potassium carbonate: 0.5% by mass
Dioctyl sulfosuccinate: 0.5% by mass
Potassium persulfate: 0.005% by mass
While stirring the initial adjustment solution under a nitrogen atmosphere, the following composition was added and reacted at 70 ° C. for 30 minutes to obtain a rubbery polymer.
Butyl acrylate: 53% by mass
Styrene: 17% by mass
Allyl methacrylate (crosslinking agent): 1% by mass
The following composition was continuously added at 70 ° C. for 90 minutes while stirring, and after the addition was completed, the mixture was further maintained for 90 minutes to form a shell layer.
Methyl methacrylate: 21% by mass
Methacrylic acid: 9% by mass
Potassium persulfate: 0.005% by mass
The polymer latex was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered and dried to obtain core-shell type acrylic elastic particles. The average particle size of the rubbery polymer portion of the acrylic elastic particles measured with an electron microscope was 140 nm.

(3) Preparation of acrylic resin composition (a-1) 80% by mass of acrylic resin (a) obtained in (1) above, 20% by mass of core-shell type acrylic elastic particles obtained in (2) above, and additives as NaOCH ₃ was blended 0.2 weight percent, using a Japan steel Works Co. biaxial extruder TEX30 (L / D = 44.5) , while the nitrogen from the hopper section is purged with an amount of 10L / min, a screw An intramolecular cyclization reaction was performed at a rotational speed of 100 rpm, a raw material supply rate of 5 kg / hour, and a cylinder temperature of 290 ° C. to obtain a pellet-shaped acrylic resin composition (a-1).
In this acrylic resin composition (a-1), the glutaric anhydride unit was 30% by mass, the methyl methacrylate unit was 69% by mass, and the methacrylic acid unit was 1% by mass. The glass transition temperature Tg was 128 ° C.

(4) Preparation of film-forming stock solution The acrylic resin composition (a-1) obtained in (3) above was dried at 80 ° C. for 8 hours using a vacuum dryer to remove moisture. Next, 25% by mass of the dried acrylic resin composition (a-1) and 75% by mass of methyl ethyl ketone were added to a separable flask equipped with a condenser, and 8 hours at 150 rpm and 50 ° C. using a double helical ribbon stirring blade. And a polymer solution having a polymer concentration of 25% was obtained.
Subsequently, the polymer solution was subjected to pressure filtration with a sintered metal filter having a filtration accuracy of 1 μm to obtain a membrane forming stock solution.

(5) Solution film formation of acrylic resin film PET film having a thickness of 100 μm (hereinafter referred to as a base material) fixed to a glass plate having a thickness of 1.5 mm with a double-sided tape using a bakery applicator manufactured by Nippon Cedars Service Co., Ltd. The film-forming stock solution obtained in (4) above was cast so that the film thickness after drying was 80 μm. Next, solvent drying was performed using a hot air oven under the following drying conditions.
Initial drying: 50 ° C / 10 minutes Secondary drying: 80 ° C / 10 minutes Third drying: 120 ° C / 20 minutes Fourth drying: 140 ° C / 20 minutes Final drying: 170 ° C / 40 minutes It peeled from A and obtained the acrylic resin film.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects. Moreover, the characteristic value of the said acrylic resin film is shown below.
Tensile Young's modulus: 2.3 GPa
Elongation at break: 15%
Moisture absorption: 1.1%
Thermal expansion coefficient: 87 ppm / ° C
Humidity expansion coefficient: 54 ppm /% RH.

[Example 2]
A PET film (hereinafter referred to as “base material B”) in which an alkyl acrylate resin layer having the following copolymer composition was disposed to a thickness of 50 nm was used as a cast base material, and the final drying condition was 170 ° C./60 minutes. Except that, an acrylic resin film was obtained in the same manner as in Example 1.
Methyl methacrylate 40% by mass
60% by weight of dodecyl methacrylate
Acrylic acid 1% by mass
Anionic reactive emulsifier 2% by mass
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects.

[Example 3]
Use a PET film (hereinafter referred to as substrate C) in which a polyvinyl alcohol resin having an alkyl group in the side chain (K256 manufactured by Chukyo Yushi Co., Ltd.) is disposed to have a resin layer thickness of 50 nm is used as a cast substrate. Except for this, an acrylic resin film was obtained in the same manner as in Example 2.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects.

[Example 4]
An acrylic resin film was obtained in the same manner as in Example 2 except that acetone was used as the solvent for the stock solution.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects.

[Examples 5 to 11]
An acrylic resin film was obtained in the same manner as in Example 2 except that the solvent composition of the film-forming stock solution was a mixed solvent composed of a good solvent and a poor solvent in Table 1.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects.

[Example 12]
The blending ratio of the acrylic resin composition (a) obtained by the same method as in Example 1 and the core-shell type acrylic elastic particles was as follows, and a twin screw extruder was used in the same manner as in Example 1. An intramolecular cyclization reaction was performed to obtain a pellet-shaped acrylic resin composition (a-2).
Acrylic resin (a) 50% by mass
Core-shell type acrylic elastic particles 50% by mass
In this acrylic resin composition (a-2), the glutaric anhydride unit was 32% by mass, the methyl methacrylate unit was 65% by mass, and the methacrylic acid unit was 3% by mass. The glass transition temperature was 113 ° C.
Next, the acrylic resin composition (a-2) 25% by mass and methyl ethyl ketone 75% by mass were mixed in the same manner as in the method for preparing the film-forming stock solution of Example 1 to obtain a polymer solution having a polymer concentration of 25%.
Next, an acrylic resin film was obtained in the same manner as in the solution casting method for the acrylic resin film of Example 2 using the substrate B.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects.

[Example 13]
The blending ratio of the acrylic resin composition (a) obtained by the same method as in Example 1 and the core-shell type acrylic elastic particles was as follows, and a twin screw extruder was used in the same manner as in Example 1. An intramolecular cyclization reaction was performed to obtain a pellet-shaped acrylic resin composition (a-3).
Acrylic resin (a) 60% by mass
Core-shell type acrylic elastic particles 40% by mass
In this acrylic resin (a-3), the glutaric anhydride unit was 32% by mass, the methyl methacrylate unit was 65% by mass, and the methacrylic acid unit was 3% by mass. The glass transition temperature was 118 ° C.
Next, the acrylic resin composition (a-3) 25% by mass and methyl ethyl ketone 75% by mass were mixed in the same manner as in the method for preparing the film-forming stock solution of Example 1 to obtain a polymer solution having a polymer concentration of 25%.
Next, an acrylic resin film was obtained in the same manner as in the solution casting method for the acrylic resin film of Example 2 using the substrate B.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects.

[Example 14]
100 mass% of the acrylic resin composition (a) obtained by the same method as in Example 1 above was subjected to an intramolecular cyclization reaction using a twin screw extruder in the same manner as in Example 1 to produce a pellet-shaped acrylic. A resin composition (a-4) was obtained.
In this acrylic resin composition (a-4), the glutaric anhydride unit was 30% by mass, the methyl methacrylate unit was 68% by mass, and the methacrylic acid unit was 2% by mass. The glass transition temperature was 138 ° C.
Next, the acrylic resin composition (a-4) 25 mass% and methyl ethyl ketone 75 mass% were mixed in the same manner as in the method for preparing the film-forming stock solution of Example 1 to obtain a polymer solution having a polymer concentration of 25%.
Next, an acrylic resin film was obtained in the same manner as in the solution casting method for the acrylic resin film of Example 2 using the substrate B.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects.

[Example 15]
The blending ratio of the acrylic resin composition (a) obtained by the same method as in Example 1 and the core-shell type acrylic elastic particles was as follows, and a twin screw extruder was used in the same manner as in Example 1. An intramolecular cyclization reaction was performed to obtain a pellet-shaped acrylic resin composition (a-5).
Acrylic resin (a) 90% by mass
Core-shell type acrylic elastic particles 10% by mass
In this acrylic resin composition (a-5), the glutaric anhydride unit was 32% by mass, the methyl methacrylate unit was 65% by mass, and the methacrylic acid unit was 3% by mass. The glass transition temperature was 133 ° C.
Next, the acrylic resin composition (a-5) (25% by mass) and methyl ethyl ketone (75% by mass) were mixed in the same manner as in the method for preparing the film-forming stock solution of Example 1 to obtain a polymer solution having a polymer concentration of 25%.
Next, an acrylic resin film was obtained in the same manner as in the solution casting method for the acrylic resin film of Example 2 using the substrate B.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects.

[Comparative Example 1]
An acrylic resin film was obtained in the same manner as in Example 1 except that the final drying condition was 170 ° C./60 minutes.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, total light transmittance, retardation at a wavelength of 550 nm, and film defects.
The peelability between the acrylic resin film and the cast substrate was not good, and the haze value was deteriorated.

[Comparative Example 2]
An acrylic resin film was obtained in the same manner as in Example 1 except that the final drying condition was 150 ° C./30 minutes.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, total light transmittance, retardation at a wavelength of 550 nm, and film defects.
Since final drying was not sufficient, the volatile content in the acrylic resin film increased.

[Comparative Example 3]
An acrylic resin film was obtained in the same manner as in Example 1 except that the drying conditions of the acrylic resin film were as follows.
Initial drying: 50 ° C./1 minute Secondary drying: 100 ° C./1 minute Tertiary drying: 120 ° C./20 minutes Fourth drying: 140 ° C./20 minutes Final drying: 170 ° C./40 minutes Composition of the acrylic resin film, etc. Table 1 shows the evaluation results of volatile matter, haze value, total light transmittance, retardation at a wavelength of 550 nm, and film defects.
Due to the rapid drying, foaming occurred and the film defect deteriorated.

[Comparative Example 4]
An acrylic resin film was obtained in the same manner as in Example 2 except that the solvent of the film-forming stock solution was 70% by mass of acetone and 30% by mass of N-butanol.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, total light transmittance, retardation at a wavelength of 550 nm, and film defects. The film forming stock solution was stable while maintaining transparency, but the film was devitrified during film formation, and the haze value and total light transmittance were deteriorated.

[Comparative Example 5]
80% by mass of polymethyl methacrylate resin (Sumitomo Chemical "Sumipex" MG5) and 20% by mass of acrylic rubber (Mitsubishi Rayon "Metabrene" W-341) are blended. Nippon Steel's twin screw extruder TEX30 (L /D=44.5), while purging nitrogen from the hopper at a rate of 10 L / min, kneading at a screw speed of 100 rpm, a raw material supply rate of 5 kg / hour, and a cylinder temperature of 240, and a pellet-like acrylic resin A composition (a-6) was obtained.
In this acrylic resin composition (a-6), the glutaric anhydride unit was 0% by mass, the methyl methacrylate unit was 100% by mass, and the methacrylic acid unit was 0% by mass. The glass transition temperature was 92 ° C.
Next, in the same manner as in the method for preparing the film-forming stock solution of Example 1, 25% by mass of the acrylic resin composition (a-6) and 75% by mass of methyl ethyl ketone were mixed to obtain a polymer solution having a polymer concentration of 25%.
Next, an acrylic resin film was obtained in the same manner as in the solution casting method for the acrylic resin film of Example 2 using the substrate B.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects.

[Comparative Example 6]
A polymethyl methacrylate resin (“SUMIPEX” MG5 manufactured by Sumitomo Chemical Co., Ltd.) was used as it was to prepare an acrylic resin composition (a-7). In this acrylic resin composition (a-7), the glutaric anhydride unit was 0% by mass, the methyl methacrylate unit was 100% by mass, and the methacrylic acid unit was 0% by mass. The glass transition temperature was 102 ° C.
Next, the acrylic resin composition (a-7) 25% by mass and methyl ethyl ketone 75% by mass were mixed in the same manner as in the method for preparing the film-forming stock solution of Example 1 to obtain a polymer solution having a polymer concentration of 25%.
Next, an acrylic resin film was obtained in the same manner as in the solution casting method for the acrylic resin film of Example 2 using the substrate B.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects.

[Comparative Example 7]
Using the acrylic resin composition (a-4) obtained in Example 14, an acrylic resin film was obtained in the same manner as in Comparative Example 2 except that the substrate B was used.
Table 1 shows the composition and the like of the acrylic resin film, and Table 2 shows the evaluation results of volatile matter, haze value, glass transition temperature, total light transmittance, retardation at a wavelength of 550 nm, and film defects.

The acrylic resin film obtained in the present invention is excellent in heat resistance, transparency, defect-free properties, impact resistance, toughness, optical isotropy, etc., so a liquid crystal display, a flat panel display, a light guide plate of a plasma display, a Fresnel lens, Optical components such as polarizing plates, polarizing plate protective films, retardation films, light diffusion films, viewing angle widening films, reflective films, antireflection films, antiglare films, brightness enhancement films, conductive films for touch panels, cameras, VTRs , Such as viewfinders such as projection TV, filters, prisms, and Fresnel lenses, optical recording / protection films for optical discs (VD, CD, DVD, MD, LD, etc.), optical switches, optical connectors, etc. Optical communication related parts,
It can be used for parts such as various covers, various terminal boards, printed wiring boards, speakers, microscopes, binoculars, cameras and watches.

Claims (8)

An acrylic resin film comprising an acrylic resin containing a glutaric anhydride unit represented by the following structural formula (1), having a haze value of 1% or less and a volatile content of 1% or less.

(In the above ^formula, R 1, ^{R 2} represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)   The acrylic resin film of Claim 1 which contains 10-40 mass% of acrylic elastic body particles.   The acrylic resin film according to claim 1, wherein the glass transition temperature is 120 ° C. or higher.   The acrylic resin film according to any one of claims 1 to 3, wherein a phase difference with respect to a light beam having a wavelength of 400 to 700 nm is 5 nm or less.   The optical filter using the acrylic resin film in any one of Claims 1-4.   A method for producing an acrylic resin film, in which an acrylic resin solution dissolved in a mixed solvent of a good solvent and a poor solvent is cast on a base film and dried.   The method for producing an acrylic resin film according to claim 6, wherein the good solvent contains at least one solvent selected from the group consisting of acetone, tetrahydrofuran, methyl ethyl ketone, and N-methyl-2-pyrrolidone.   The acrylic resin solution is cast on a resin layer containing an acrylic resin or polyvinyl alcohol resin having an alkyl group in a side chain provided on at least one surface of the base film instead of the base film. Or the manufacturing method of the acrylic resin film of 7.