JP2008239742A - Thermoplastic resin film and production method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin film having high grade heat resistance, colorless transparency, optical isotropy, and handling property in processing. <P>SOLUTION: The thermoplastic resin film is obtained by a molten film forming method, comprises a film comprising a heat resistant copolymer (A) having a glutaric anhydride unit and a gum-containing polymer (B), and has a film thickness of 5-250 μm, a haze value of 1.0% or less and a surface roughness SRa of 40 nm or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a thermoplastic resin film excellent in transparency, toughness, and handling properties.

  Amorphous transparent resins typified by polycarbonate resins and polymethyl methacrylate resins are widely used in the electric and electronic fields. In particular, polycarbonate resin is used as a base material for recording media such as compact discs, but has a problem that the photoelastic coefficient is large and the birefringence is large. Polymethyl methacrylate resin, on the other hand, has low birefringence and excellent optical properties, but it is not sufficient in heat resistance and has problems when used in applications that require heat resistance such as laser write-once optical disks. is there.

  Therefore, with regard to improving the heat resistance of acrylic thermoplastic resins such as polymethyl methacrylate resin, heat resistance can be improved by improving the polymer skeleton and composition, such as copolymerization with acid anhydrides and maleimide compounds, and introduction of glutarimide structures. A method (for example, Patent Document 1) that aims to improve is disclosed. However, maleimide monomers are expensive and have low reactivity, and maleic anhydride has a problem of poor thermal stability, which satisfies the extremely high transparency and defect-free properties required for recent optical components. Was difficult.

  To solve these problems, a copolymer containing unsaturated carboxylic acid monomer units is heated in an extruder and cyclized to produce a copolymer containing glutaric anhydride-containing units. As a method for imparting heat resistance and further improving mechanical properties such as impact resistance, a method of adding a rubbery polymer to a copolymer containing a glutaric anhydride-containing unit is disclosed. (Patent Documents 2 to 4). However, in the methods disclosed in these patent documents, although mechanical properties such as impact resistance have been improved to some extent, a film having transparency cannot be obtained. Further, in Patent Document 5, in order to provide transparency, the refractive indexes of the graft copolymer and the matrix polymer are approximated, but only the resin composition is specified, and the draw resonance at the time of film forming is reduced. There is no description of the resulting transparency reduction or film surface properties.

  In Patent Document 6, there is a description of improving transparency in addition to improving the heat resistance of an acrylic thermoplastic resin film. However, Patent Document 6 discloses a so-called solution film forming method in which a polymer component is dissolved in a solvent to form a film. Since it is used, a process and cost for removing the solvent are required, and in terms of quality and physical properties, there are problems such as a bumping defect at the time of removing the solvent and a decrease in physical properties due to the residual solvent.

Moreover, in order to increase the transparency and defect-freeness of the acrylic thermoplastic resin film, it is effective to remove foreign substances contained in the acrylic thermoplastic resin by polymer filtration. Acrylic thermoplastic resin film has high melt viscosity and limited filtration accuracy, so as a method of lowering melt viscosity, change the polymer design such as lowering the molecular weight of the base polymer or adding a plasticizer, or Techniques such as increasing the processing temperature are carried out, but if the molecular weight is lowered, the toughness will be reduced, and it will be easy to break during film formation and unwinding, resulting in poor handling properties. In addition to lowering the toughness when the processing temperature is increased, the polymer is colored and the colorless transparency is deteriorated. Was Tsu.
“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 JP-A-60-67557 JP-A-4-277546 Japanese Patent Laid-Open No. 5-186659 JP 60-120734 A JP 2006-206881 A

  The object of the present invention is to solve the above-mentioned conventional problems, have excellent optical properties comparable to polymethyl methacrylate, have excellent heat resistance, transparency, optical isotropy, toughness, and handling properties. It is in providing the thermoplastic resin film which is excellent in.

The present invention for solving the above-described problems has the following features. That is, the present invention
(1) A thermoplastic resin film obtained by a melt film-forming method, (i) a heat-resistant copolymer (A) having a glutaric anhydride unit represented by the following general formula (1), and rubber A thermoplastic resin film comprising a containing polymer (B), having a thickness of 5 to 250 μm, a haze value of 1.0% or less, a surface roughness SRa of 40 nm or less, and a glass transition temperature of 120 ° C. or more.

(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.)
(2) The heat-resistant copolymer (A) is a copolymer having (i) a glutaric anhydride unit represented by the general formula (1) and (ii) an unsaturated carboxylic acid alkyl ester unit. The thermoplastic resin film according to (1) above.

  (3) In addition to the above units (i) and (ii), the heat resistant copolymer (A) further comprises (iii) an unsaturated carboxylic acid unit and / or (iv) a vinyl monomer unit. The thermoplastic resin film according to (1) or (2), which is a copolymer to be contained.

  (4) The thermoplastic resin film according to any one of (1) to (3), wherein an in-plane retardation of the film with respect to light having a wavelength of 590 nm is 5 nm or less.

  (5) The thermoplastic resin film according to (3) or (4), wherein the content of the unsaturated carboxylic acid unit (iii) is 0 to 1% by weight.

  (6) The heat according to any one of (1) to (5), comprising 10 to 90 parts by weight of the heat-resistant copolymer (A) and 90 to 10 parts by weight of the rubber-containing polymer (B). Plastic resin film.

  (7) The thermoplastic resin film according to any one of (1) to (6), wherein a difference in refractive index between the heat-resistant copolymer (A) and the rubber-containing polymer (B) is 0.02 or less. .

  (8) The rubber-containing polymer (B) is any one of the above (1) to (7), comprising a layer of the rubbery polymer (B-1) and a layer of the graft component (B-2). The thermoplastic resin film as described.

  (9) The rubber polymer (B-1) contains an acrylic acid alkyl ester unit and a substituted or unsubstituted styrene unit, and the graft component (B-2) is represented by the general formula (1). The thermoplastic resin film according to (8), which has a glutaric anhydride unit.

  (10) The thermoplastic resin film according to any one of (6) to (9), wherein the rubber-containing polymer (B) has a weight average particle diameter of 0.01 to 1 μm.

(11) When producing a thermoplastic resin film using a die, the lip gap of the die is adjusted so that the lip gap of the die and the average film thickness satisfy the following formula: The manufacturing method of the thermoplastic resin film in any one.
(Die lip gap (mm) / film average thickness (μm)) × 1,000 ≦ 20.0
(12) In the pipe located upstream of the die, provided is a diverting means for diverting the vicinity of the wall surface and the center portion of the thermoplastic resin flowing in the pipe, and the thermoplastic resin in the center portion is discharged from the die. The manufacturing method of the thermoplastic resin film as described in (11).
It is characterized by.

  As will be described below, according to the present invention, a thermoplastic resin film having high transparency and good handling properties can be obtained. Furthermore, the thermoplastic resin film obtained by the present invention is suitable for applications such as an optical disk, a display member, an optical lens, and a light guide plate for a liquid crystal backlight, taking advantage of excellent heat resistance and transparency.

  The thermoplastic resin film of the present invention comprises (i) a heat-resistant copolymer (A) having a glutaric anhydride unit represented by the following general formula (1), and a rubbery polymer (B). The film has a thickness of 5 to 250 μm, a haze value of 1.0% or less, and a surface roughness SRa of 40 nm or less.

(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.)
Here, the heat-resistant copolymer (A) preferably further contains (ii) an unsaturated carboxylic acid alkyl ester unit, and (iii) an unsaturated carboxylic acid unit and / or (iv) It is also preferable to have a vinyl monomer unit.

  In the present specification, the term “alkyl” includes both linear and branched.

  The method for producing the heat-resistant copolymer (A) described above in the present invention is not particularly limited, but the unsaturated carboxylic acid alkyl ester monomer that gives the glutaric anhydride unit (i) by the subsequent heating step. A copolymer, an unsaturated carboxylic acid monomer and / or a vinyl monomer to form a precursor, and then heating the precursor in the presence or absence of a suitable catalyst to remove alcohols and It can be produced by carrying out an intramolecular cyclization reaction by dehydration. In this case, typically, the carboxyl group of the unsaturated carboxylic acid unit (iii) of 2 units is dehydrated by heating the precursor polymer, or unsaturated with the adjacent unsaturated carboxylic acid unit (iii). One unit of the glutaric anhydride unit (i) is produced by elimination of the alcohol from the carboxylic acid alkyl ester unit (ii).

  Although there is no restriction | limiting in particular as an unsaturated carboxylic-acid alkylester type monomer used in this case, As a preferable example, the monomer represented by following General formula (4) can be mentioned.

(However, R ³ represents hydrogen or an alkyl group having 1 to 5 carbon atoms, R ⁴ is an aliphatic or alicyclic hydrocarbon group having 1 to 6 carbon atoms, or a number of 1 or more and not more than carbon atoms. (A C1-C6 aliphatic or alicyclic hydrocarbon group substituted with a hydroxyl group or a halogen is shown.)
Among these, an acrylate ester and / or a methacrylic ester having an aliphatic or alicyclic hydrocarbon group having 1 to 6 carbon atoms or the hydrocarbon group having a substituent is particularly preferable. The unsaturated carboxylic acid alkyl ester monomer represented by the general formula (4) gives an unsaturated carboxylic acid alkyl ester unit having a structure represented by the following general formula (2) when copolymerized.

  Preferable specific examples of the unsaturated carboxylic acid alkyl ester monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, ( T-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate , (Meth) acrylic acid 3-hydroxypropyl, (meth) acrylic acid 2,3,4,5,6-pentahydroxyhexyl and (meth) acrylic acid 2,3,4,5-tetrahydroxypentyl Of these, methyl methacrylate is most preferably used. These can be used alone or in combination of two or more thereof.

  Moreover, there is no restriction | limiting in particular as an unsaturated carboxylic acid monomer, As preferable unsaturated carboxylic acid monomer, following General formula (5)

(However, R ⁵ represents hydrogen or an alkyl group having 1 to 5 carbon atoms.)
In particular, acrylic acid and methacrylic acid are preferred, and methacrylic acid is more preferred from the viewpoint of excellent thermal stability. These can be used alone or in combination. The unsaturated carboxylic acid monomer represented by the general formula (5) gives an unsaturated carboxylic acid unit (3) having a structure represented by the following general formula (3) when copolymerized.

  Furthermore, in the production of the heat resistant copolymer (A) used in the present invention, a vinyl monomer may be used as long as the effects of the present invention are not impaired. The vinyl monomer gives the other vinyl monomer units (iv) described above when copolymerized. Preferable specific examples of the vinyl monomer include aromatic vinyl monomers such as styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, and pt-butylstyrene. Monomer, vinyl cyanide monomer such as acrylonitrile, methacrylonitrile, ethacrylonitrile, allyl glycidyl ether, styrene-p-glycidyl ether, p-glycidyl styrene, maleic anhydride, itaconic anhydride, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, acrylamide, methacrylamide, N-methylacrylamide, butoxymethylacrylamide, N-propylmethacrylamide, aminoethyl acrylate, propylamino acrylate Chill, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, phenylaminoethyl methacrylate, cyclohexylaminoethyl methacrylate, N-vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine, p-amino Mention may be made of styrene, 2-isopropenyl-oxazoline, 2-vinyl-oxazoline, 2-acryloyl-oxazoline and 2-styryl-oxazoline. From the viewpoint of transparency and optical isotropy, a monomer containing no aromatic ring can be used more preferably. These may be used alone or in combination of two or more.

  (Ii) (iii) The method for copolymerizing the monomer of (iv) is not particularly limited, and various polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization by radical polymerization are used. Can do.

  The preferred proportion of the monomer mixture used in the production of these precursor polymers is that the monomer mixture is 100% by weight, and the unsaturated carboxylic acid alkyl ester monomer is preferably 30 to 95% by weight, more preferably 30-90% by weight, most preferably 30-85% by weight, unsaturated carboxylic acid monomer 7-70% by weight, more preferably 10-50% by weight, most preferably 15-40% by weight, vinyl monomer The body is preferably in the range of 10% by weight or less, ie in the range of 0-10% by weight.

When the amount of the unsaturated carboxylic acid monomer is less than 7% by weight, the amount of the cyclized reaction product produced by heating the precursor polymer is decreased, and therefore the heat resistance improvement effect of the copolymer tends to be reduced. On the other hand, when the amount of the unsaturated carboxylic acid monomer is 70% by weight or more, there is a tendency that a large amount of highly reactive unsaturated carboxylic acid units remain after the cyclization reaction by heating of the precursor polymer. Molding can be difficult because reversible bonds can form.
A proton nuclear magnetic resonance ( ¹ H-NMR) measuring machine is used for quantification of each copolymer component in the thermoplastic resin film and heat-resistant copolymer (A) of the present invention. ^{In the 1} H-NMR method, the copolymer composition can be determined from the integral ratio of the spectrum. For example, in the case of a copolymer consisting of a glutaric anhydride-containing unit, a methacrylic acid unit, and a methyl methacrylate unit, the spectral assignment measured in dimethyl sulfoxide heavy solvent is 0.5 to 1.5 ppm peak. Α-methyl group hydrogen 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 hydrogen of the carboxylic acid ester (—COOCH ₃ ), the peak at 12.4 ppm is the hydrogen of the carboxylic acid of methacrylic acid. 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.

  Although the manufacturing method of the heat resistant copolymer (A) in this invention does not have a restriction | limiting in particular, The method of performing a cyclization reaction by passing an original copolymer through an extruder with a vent and carrying out heat volatilization is used preferably. be able to. Furthermore, it is preferable to use an extruder having two or more vents as a method for reducing the amount of highly reactive unsaturated carboxylic acid unit of the copolymer. As a particularly preferred apparatus, for example, a single-screw extruder, a twin-screw or three-screw extruder equipped with a “unimelt” type screw, a continuous or batch kneader type kneader, or the like can be used.

  In addition, when the intramolecular cyclization reaction by heating in the presence of oxygen tends to deteriorate the yellowness, it is preferable to sufficiently substitute the inside of the system with an inert gas such as nitrogen. Examples of a method for introducing an inert gas such as nitrogen into the machine include a method of connecting a pipe of an inert gas stream of about 10 to 100 liters / minute from the upper part and / or the lower part of the hopper.

  The temperature for heating and devolatilizing is not particularly limited as long as the intramolecular cyclization reaction is caused by dehydration and / or dealcoholization, but is preferably in the range of 180 to 300 ° C, more preferably in the range of 200 to 280 ° C.

  Moreover, the time for heating and devolatilization can be appropriately set according to the desired copolymer composition, but usually about 1 to 20 minutes is appropriate. In order to secure a sufficient heating time for advancing the intramolecular cyclization reaction using an extruder, the length / diameter ratio (L / D) of the extruder screw is preferably 40 or more. . When an extruder with a short L / D is used, a large amount of unreacted unsaturated carboxylic acid units remain, and when it is melted again and formed into a film or processed, the reaction proceeds again, generating die lines and bubbles. Leads to.

  As a catalyst for accelerating the cyclization reaction to glutaric anhydride when the original copolymer is heated by the above method or the like, one or more of acid, alkali, and salt compound is added to 0.1 part by weight of 100 parts by weight of the original polymer. It is preferable to add 01 to 1 part by weight. These acids, alkalis, and salt compounds are not particularly limited, and examples of the acid catalyst include hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, phosphoric acid, phosphorous acid, phenylphosphonic acid, and methyl phosphate. Examples of the basic catalyst include metal hydroxides, amines, imines, alkali metal derivatives, alkoxides, ammonium hydroxide salts and the like. Furthermore, examples of the salt catalyst include acetic acid metal salts, stearic acid metal salts, metal carbonate salts, and the like, and particularly hydrated salts are preferably used. However, it is necessary to add the catalyst in such a range that the color of the catalyst does not adversely affect the coloring of the heat-resistant copolymer (A) and the transparency is not lowered. Especially, since the compound containing an alkali metal shows the outstanding reaction-promoting effect with a comparatively small addition amount, it can be used preferably. Specifically, hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, alkoxide compounds such as sodium methoxide, sodium ethoxide, sodium phenoxide, potassium methoxide, potassium ethoxide, and potassium phenoxide, lithium acetate , Organic carboxylates such as sodium acetate, potassium acetate, sodium stearate and the like, and sodium hydroxide, sodium methoxide, lithium acetate, sodium acetate and the like can be preferably used.

  The heat-resistant copolymer (A) of the present invention preferably has a glass transition temperature (Tg) of 120 ° C. or higher, and particularly preferably 130 ° C. or higher from the viewpoint of heat resistance. Setting the glass transition temperature of the copolymer to 120 ° C. or higher can be achieved by controlling the amount of glutaric anhydride units (i) in the copolymer to about 10% by weight or higher. In addition, although the upper limit of a glass transition point is not specifically limited, Usually, it is about 170 degreeC.

  The glutaric anhydride unit (i) contained in 100% by weight of the heat resistant copolymer (A) in the present invention is preferably 5 to 60% by weight, most preferably 15 to 15% in the heat resistant copolymer (A). 50% by weight. When the glutaric anhydride unit is less than 5% by weight, the heat resistance improving effect tends to be small. The unsaturated carboxylic acid alkyl ester unit (ii) is preferably 30 to 95% by weight, more preferably 30 to 90% by weight, and most preferably 30 to 85% by weight. The unsaturated carboxylic acid unit (iii) is 0 to 10% by weight, more preferably 0 to 3% by weight, and particularly preferably 0 to 1% by weight. When the unsaturated carboxylic acid unit is 10% by weight or more, a non-thermo-reversible bond may be generated, which may make molding difficult. Furthermore, when other vinyl monomer units are included, vinyl monomer units that do not contain an aromatic ring are preferred. When aromatic vinyl monomer units such as styrene are high, colorless transparency, optical properties, Since there is a tendency for the isotropic and handling properties to decrease, the content is more preferably 0 to 10% by weight.

(However, in the above, the total of each unit (i) (ii) (iii) (iv) is 100% by weight.)
The heat-resistant copolymer (A) of the present invention preferably has a weight average molecular weight of 30,000 to 150,000. The heat-resistant copolymer (A) having such a molecular weight can be achieved by previously controlling the weight average molecular weight to 30,000 to 150,000 at the time of producing the original copolymer.

  Regarding the molecular weight control method of the original copolymer, for example, the addition amount of radical polymerization initiators such as azo compounds and peroxides, or alkyl mercaptan, carbon tetrachloride, carbon tetrabromide, dimethylacetamide, dimethylformamide, triethylamine It can be controlled by the amount of chain transfer agent added. In particular, a method of controlling the amount of alkyl mercaptan added as a chain transfer agent can be preferably used from the viewpoint of stability of polymerization, ease of handling, and the like.

  Examples of the alkyl mercaptan include n-octyl mercaptan, t-dodecyl mercaptan, n-dodecyl mercaptan, n-tetradecyl mercaptan, n-octadecyl mercaptan and the like, among which t-dodecyl mercaptan and n-dodecyl mercaptan are preferable. Used.

The addition amount of these alkyl mercaptans is not particularly limited as long as it is controlled to a specific molecular weight of the present invention, and the addition amount differs depending on the monomer species to be copolymerized, but usually the total amount of the monomer mixture. It is 0.3-5.0 weight part with respect to 100 weight part, Preferably it is 0.9-4.0 weight part, More preferably, it is 1.0-3.0 weight part. For example, when t-dodecyl mercaptan is used, the range of 1.0 to 3.0 parts by weight is particularly effective, and when n-dodecyl mercaptan is used, 0.6 to 2.0 parts by weight. The range of is particularly effective.
The thermoplastic resin film in the present invention greatly impairs the excellent properties of the heat-resistant copolymer (A) by incorporating the rubber-containing polymer (B) into the heat-resistant copolymer (A). And excellent toughness and handling properties can be imparted.

  The rubbery polymer (B) is preferably composed of a layer of the rubbery polymer (B-1) and a layer of the graft component (B-2).

  The kind of rubber polymer (B-1) is not specifically limited, What is necessary is just to be comprised from the polymer component which has rubber elasticity. For example, rubber composed of a polymer obtained by polymerizing an acrylic component, a silicone component, a styrene component, a nitrile component, a conjugated diene component, a urethane component, an ethylene component, a propylene component, an isobutene component, and the like can be given. Preferred rubbers include, for example, acrylic components such as ethyl acrylate units and butyl acrylate units, silicone components such as dimethylsiloxane units and phenylmethylsiloxane units, styrene components such as styrene units and α-methylstyrene units, acrylonitrile units, It is a rubber composed of a nitrile component such as a methacrylonitrile unit and a conjugated diene component such as a butanediene unit or an isoprene unit. A rubber composed of a combination of two or more of these components is also preferred. For example, rubber composed of acrylic components such as ethyl acrylate units and butyl acrylate units and silicone components such as dimethylsiloxane units and phenylmethylsiloxane units, acrylic components such as ethyl acrylate units and butyl acrylate units, and styrene units Rubber composed of styrene components such as styrene units and α-methylstyrene units, rubber composed of acrylic components such as ethyl acrylate units and butyl acrylate units, and conjugated diene components such as butanediene units and isoprene units, and acrylic Examples include acrylic components such as ethyl acid units and butyl acrylate units, silicone components such as dimethylsiloxane units and phenylmethylsiloxane units, and rubbers composed of styrene components such as styrene units and α-methylstyrene units. I can get lost. Of these, a rubber containing an acrylic acid alkyl ester unit and a substituted or unsubstituted styrene unit is most preferable in terms of transparency and mechanical properties. In addition to these components, a rubber obtained by crosslinking a copolymer composed of a crosslinking component such as a divinylbenzene unit, an allyl acrylate unit, or a butylene glycol diacrylate unit is also preferable.

  The types of the graft component (B-2) are unsaturated carboxylic acid alkyl ester units, unsaturated carboxylic acid units, unsaturated glycidyl group-containing units, aliphatic vinyl units, aromatic vinyl units, vinyl cyanide units, maleimide units, Examples thereof include at least one selected from a polymer containing an unsaturated dicarboxylic acid unit, an unsaturated dicarboxylic anhydride unit, and other vinyl units. Among them, at least one selected from an unsaturated carboxylic acid alkyl ester unit, an unsaturated carboxylic acid unit, an unsaturated glycidyl group-containing unit, and an unsaturated dicarboxylic anhydride unit is preferable, and an unsaturated carboxylic acid alkyl is particularly preferable. It is a polymer containing an ester unit and an unsaturated carboxylic acid unit.

  When the graft component (B-2) is a polymer containing an unsaturated carboxylic acid alkyl ester unit and an unsaturated carboxylic acid unit, heating is performed as in the production of the heat-resistant copolymer (A) described above. It was found that the intramolecular cyclization reaction proceeds to produce a glutaric anhydride unit represented by the general formula (1). Accordingly, the rubber component-containing polymer (B) having a polymer containing an unsaturated carboxylic acid alkyl ester unit and an unsaturated carboxylic acid unit is blended with the heat-resistant copolymer (A) in the graft component (B-2). Then, the rubber-containing polymer (B) containing the glutaric anhydride unit represented by the general formula (1) in the graft component (B-2) is obtained by heating and kneading. As a result, the rubber-containing polymer (B) can be satisfactorily dispersed in the heat-resistant copolymer (A) to be a continuous phase (matrix phase) without agglomeration, and the thermoplasticity of the present invention. It is possible to develop a high degree of transparency as well as improving the handleability of the resin film.

  As a preferable example of the rubber-containing polymer (B) of the present invention, the rubber-like polymer (B-1) is a butyl acrylate / styrene copolymer, and the graft component (B-2) is methyl methacrylate / above. The rubbery polymer (B-1) is a butyl acrylate / styrene copolymer, which is a copolymer composed of a glutaric anhydride-containing unit represented by the general formula (1), and a graft component (B-2 ) Is methyl methacrylate / glutaric anhydride-containing unit represented by the above general formula (1) / methacrylic acid copolymer, rubber polymer (B-1) is dimethylsiloxane / butyl acrylate copolymer A polymer in which the graft component (B-2) is a methyl methacrylate polymer, a rubbery polymer (B-1) is a butanediene / styrene copolymer, and a graft component (B-2) is a methyl methacrylate polymer. Coalesce Shall, rubbery polymer (B-1) is acrylic acid butyl copolymer, graft component (B-2) can be cited such as a methyl methacrylate polymer. Here, “/” indicates copolymerization. Furthermore, a rubbery polymer (B-1) or a graft component (B-2), or a polymer in which both layers contain a glycidyl methacrylate unit is also a preferred example. Among them, the rubbery polymer (B-1) is a butyl acrylate / styrene polymer, and the graft component (B-2) is methyl methacrylate / glutaric anhydride-containing unit represented by the general formula (1). Or a rubbery polymer (B-1) is a butyl acrylate / styrene copolymer, and a graft component (B-2) is methyl methacrylate / the above general formula (1) What is represented by the glutaric anhydride-containing unit / methacrylic acid polymer can approximate the refractive index of the heat-resistant copolymer (A) that is the continuous phase (matrix phase), and the heat-resistant copolymer. A good dispersion state can be obtained in the polymer (A), and high transparency can be exhibited.

  The refractive index difference here means that the thermoplastic resin film of the present invention is sufficiently dissolved in a solvent in which the heat-resistant copolymer (A) is soluble, and then the resulting cloudy solution is subjected to an operation such as centrifugation. By separating the solvent-soluble part and the insoluble part, the soluble part (solvent containing the heat-resistant copolymer (A)) and the insoluble part (rubber-containing polymer (B)) are purified, respectively. It means the one obtained by measuring the refractive index (23 ° C., 550 nm wavelength) of each solid content and determining the difference.

  The difference in refractive index between the heat-resistant copolymer (A) and the rubber-containing polymer (B) is preferably 0.02 or less, more preferably 0.01 or less. In order to satisfy such a refractive index condition, the composition ratio of each monomer unit of the heat-resistant copolymer (A) is adjusted, and in addition to this, the rubber material constituting the rubber-containing polymer (B) This can be achieved by adjusting the monomer unit composition ratio of the polymer (B-1) and the graft component (B-2).

  The weight average particle diameter of the rubber-containing polymer (B) of the present invention is preferably 0.01 μm or more from the handling point of the thermoplastic resin film obtained, and preferably 1 μm or less from the viewpoint of transparency. Is 0.02 μm or more and 500 μm or less, particularly preferably 0.05 μm or more and 200 μm or less.

  The rubber-containing polymer (B) in the present invention contains 10 to 80% by weight of the rubbery polymer, preferably 30 to 75% by weight, more preferably 50 to 70% by weight. 90) to 20% by weight, preferably 70 to 25% by weight, more preferably 50 to 30% by weight. That is, the graft ratio is more preferably 40 to 100%. Here, the graft ratio is a weight ratio of the grafted monomer mixture to the rubbery polymer. When the ratio of the rubbery polymer (B-1) is less than the above range or exceeds the above range, handling properties and surface appearance may be deteriorated.

  The production method for graft polymerization of the graft component (B-2) to the rubber polymer (B-1) in the present invention is not particularly limited, and known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. It can be obtained by a polymerization method.

  The thermoplastic resin film of the present invention can be formed by a melt film forming method. As the melt film forming method, there are an inflation method, a die method, a calendar method, a cutting method and the like, and the die method can be particularly preferably employed. The die method can be classified into a straight die method, a cross head die method, a flat die method, and a special die method depending on the shape of the die, and the flat die method can be particularly preferably employed.

For the melt film forming method, an extruder type melt extruder equipped with a single screw or a twin screw can be used. The L / D of the screw is preferably 25 to 120 in order to prevent coloring. The melt extrusion temperature is preferably 150 to 350 ° C, more preferably 200 to 300 ° C. The melt shear rate, 1,000 s ^-1 or 5,000 S ^-1 or less. Moreover, when melt-kneading using a melt-extrusion apparatus, it is preferable to perform melt-kneading under a reduced pressure using a vent or nitrogen stream from a viewpoint of coloring suppression.

  Resin melted by a melt extrusion apparatus or the like is measured by a gear pump and then continuously sent to a die. The die has only to be designed so that the molten resin does not stay therein, and any type of commonly used T-type manifold die, coat hanger die, and fish tail die may be used in the flat die method.

  The molten resin extruded from the die into a sheet can be cooled and solidified on a cooling medium such as a drum to obtain a film. At this time, it is preferable to increase adhesion to a cooling medium such as a drum by an electrostatic application method, an air chamber method, an air knife method, a vacuum nozzle method, a touch roll method, or the like. In particular, the touch roll method is preferable for obtaining a transparent film with little thickness unevenness.

  Such a method for increasing the adhesion may be performed on the entire surface of the molten resin sheet, or may be performed partially. Moreover, the method of raising these contact | adherence may be performed by single, or you may combine multiple.

  As a method for producing the thermoplastic resin film in the present invention, for example, in the pipe located upstream of the die, provided with a diversion means for diverting the vicinity of the wall surface and the central part of the thermoplastic resin flowing in the pipe, For example, a method of discharging the thermoplastic resin in the central portion from the die can be employed. In particular, by providing the diverting means immediately before the resin flows into the die, the obtained thermoplastic resin film becomes a product formed by a resin with a very small amount of resin staying on the wall surface and with little staying in the center, and the object of the present invention A thermoplastic resin film having excellent transparency can be obtained.

  The resin in the vicinity of the shunted wall surface (residual wall surface resin) is preferably discharged to the outside of the system or collected at both ends of the film when joined in the die, and both end portions may be cut and removed in the step before winding. As the diversion means for diverting, a barrier for diversion is provided in the pipe, but the shape is not particularly limited, and examples thereof include a rectangle, a trapezoid, an ellipse, a cone, and a triangle. When a rectangular or trapezoidal barrier is used, it is more preferable to further combine a triangle, a semicircle, and a parabola on the upstream side of the barrier in order to prevent the resin from staying. Further, in order to clearly separate the resin staying on the wall surface flowing in the vicinity of the tube wall and the resin having a short residence time flowing in the center portion, it is more preferable to use a double tube provided with a partition wall inside the barrier.

  The partial flow rate indicating the ratio of the resin staying on the wall surface having a long residence time flowing near the pipe wall of the pipe and the resin having a short residence time flowing in the center is not particularly limited, but in order to obtain high transparency and In consideration of production efficiency, the ratio of the resin staying on the wall surface / resin having a short stay is preferably 10/90 wt% to 30/70 wt%, more preferably 15/85 wt% to 25/75 wt%. is there. When the ratio of the resin staying on the wall surface having a long residence time is less than 10% by weight, the transparency of the film is lowered, or the width of the film to be cut and removed is narrow, and tearing easily occurs. When the ratio of the resin staying on the wall surface having a long residence time exceeds 30% by weight, the production efficiency is lowered and the cost is increased. Each shape and each dimension are not particularly limited, but it is designed so that the above diversion ratio can be obtained depending on the viscosity and flow rate of the resin.

  In the melt film-forming method by the flat die method, a predetermined film thickness can be obtained by adjusting the extrusion temperature, the take-up speed during take-up, the lip gap of the die, and the like. The film thickness is preferably in the range of 5 to 250 μm. 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 5 μm, the yield may deteriorate, for example, the film may be easily broken during film formation. When the thickness exceeds 250 μm, the transparency may decrease or the thickness of the member may become too large. The thickness of the thermoplastic resin film is more preferably in the range of 10 to 150 μm, and still more preferably in the range of 20 to 100 μm.

  As a method of adjusting the extrusion temperature at the time of melt film formation and the take-up speed at the time of take-up, the extrusion temperature is set to a temperature that is 100 ° C. to 150 ° C. higher than the glass transition temperature of the copolymer that is a component of the thermoplastic resin film. The ratio of the lip gap to the film average thickness, that is, the value represented by the die lip gap (mm) / film average thickness (μm) × 1,000 is preferably 20 or less, more preferably 15 or less. It is preferable to take over. The time from the extrusion from the die to the contact with the cooling medium such as a drum is 0.05 second or more and 1 second or less, preferably 0.15 second or more and 0.6 second or less. Further, the surface temperature of the cooling medium such as a drum is preferably a glass transition temperature of the copolymer constituting the thermoplastic resin film, preferably 40 ° C. or more lower than the glass transition temperature. If the temperature is lower than or equal to ° C., condensation tends to occur, which may cause film defects. By melt-extrusion under such conditions, a thermoplastic resin film that is excellent in transparency and handling properties of the object of the present invention and hardly causes optical anisotropy can be obtained.

  The color tone b value of the thermoplastic resin film can be adjusted to 0.5 or less by adjusting the extrusion temperature, the diversion ratio and the extrusion residence time. The extrusion residence time is preferably within 120 minutes, more preferably within 90 minutes.

  By adjusting the ratio of the resin composition, the extrusion temperature, the diversion ratio, the extrusion residence time, and the lip gap of the die and the average film thickness, the haze value of the thermoplastic resin film is adjusted to 1.0% or less. Can do. That is, for example, the extrusion temperature is lowered, the resin staying on the wall surface in the diversion ratio is diverted by 10% by weight or more, the ratio between the lip gap of the die and the average film thickness, that is, the lip gap (mm) / average film thickness ( It is effective to set the value represented by (μm) × 1,000 to 20 or less.

  Further, by adjusting the ratio of the resin composition, the extrusion temperature, the diversion ratio, the extrusion residence time, and the lip gap of the die and the average film thickness, the surface roughness SRa of the thermoplastic resin film is set to 40 nm or less. The thickness can be preferably 30 nm or less, more preferably 20 nm or less. In order to reduce the surface roughness, for example, the extrusion temperature is lowered, the resin staying on the wall surface in a diversion ratio is diverted by 10% by weight or more, the ratio between the lip gap of the die and the average film thickness, that is, the die lip gap ( mm) / average film thickness (μm) × 1,000 is effectively 20 or less. In terms of optical characteristics, the surface roughness SRa is preferably small, but from the viewpoint of handling, SRa is preferably 1 nm or more, and more preferably 3 nm or more.

  In the thermoplastic resin film of the present invention, the in-plane retardation with respect to light having a wavelength of 590 nm is preferably 5 nm or less, and more preferably 2 nm or less. When the phase difference with respect to a light beam having a wavelength of 590 nm is 5 nm or less, it can be suitably used in applications requiring optical isotropy such as a polarizing plate and a protective film for an optical disk. In order to obtain such a low retardation acrylic resin film, it is effective not to introduce an additive or a copolymer component that exhibits a retardation. A smaller in-plane retardation is preferable, but the lower limit is considered to be about 0.1 nm in practice.

  The thermoplastic resin film of the present invention preferably has a thickness direction retardation (Rth) with respect to a light beam having a wavelength of 590 nm of −10 to 10 nm, preferably −8 to 8 nm, more preferably −5 to 5 nm. When the absolute value of the thickness direction retardation (Rth) is 10 nm or less, it can be suitably used in applications requiring optical isotropy, such as polarizing plates and protective films for optical disks. Although it is preferable that the absolute value of the thickness direction retardation (Rth) is small, the lower limit is considered to be about 0.1 nm in practice.

  The thermoplastic resin film of the present invention is excellent in heat resistance, transparency and optical properties, but the impact strength is dramatically improved by adding an impact modifier such as an elastic polymer to the thermoplastic resin film of the present invention. It is also possible. By selecting an impact modifier having a small difference in refractive index from the copolymer of the present invention, it is possible to improve impact resistance while maintaining transparency. When such an impact modifier is added, its content can be appropriately selected in light of each application and is not limited at all, but is usually about 5 to 45 parts by weight with respect to 100 parts by weight of the resin.

  Furthermore, the thermoplastic resin film of the present invention includes hindered phenol-based, benzotriazole-based, benzophenone-based, benzoate-based and cyanoacrylate-based UV absorbers and antioxidants, higher fatty acids, acid esters, and acid amides, Lubricants and plasticizers such as higher alcohols, montanic acid and salts thereof, esters thereof, half esters thereof, mold release agents such as stearyl alcohol, stellar amide and ethylene wax, and coloration prevention such as phosphites and hypophosphites Contains additives such as additives, halogen-based flame retardants, phosphorus-based and silicone-based non-halogen-based flame retardants, nucleating agents, amine-based, sulfonic acid-based, polyether-based antistatic agents, pigments and other colorants. May be. When these additives are added, the content can be appropriately selected in light of each application.

  The thermoplastic film of the present invention is provided with an antistatic layer or an easy-adhesion layer by coating on the surface depending on the purpose of use, a hard coat layer made of an ultraviolet curable resin, a triangular prism layer, a microlens array, etc. Use a metal deposited layer, a transparent conductive layer by sputtering, or laminated with other optically isotropic films, optical functional films such as polarizers and retardation films, glass substrates, etc. via an adhesive layer Can do.

  Hereinafter, the present invention will be described more specifically based on examples. In addition, this invention is not limited to the following Example. Prior to the description of each example, various physical property measurement methods employed in the example will be described.

(1) Weight average molecular weight (absolute molecular weight)
Gel permeation chromatograph (pump: 515 type, manufactured by Waters) equipped with a DAWN-DSP type multi-angle light scattering photometer (manufactured by Wyatt Technology) using dimethylformamide as a solvent for the heat-resistant copolymer (A) Column: TSK-gel-GMHXL, manufactured by Tosoh Corporation). The standard curve was used for the calibration curve, and the retention time was fitted with a cubic curve.

(2) Refractive Index Difference After adding 200 ml of acetone to 1 g of the thermoplastic resin film of the present invention and refluxing in a 70 ° C. hot water bath for 4 hours, this solution was treated with 9,000 r. p. m. Centrifuge for 40 minutes. After centrifugation, the insoluble matter was filtered to separate it into an acetone-soluble matter (A component) and an insoluble matter (B component). The insoluble matter (component B) is dried at 60 ° C. for 5 hours, and the acetone-soluble matter (component A) is concentrated with a rotary evaporator, and the precipitate is dried at 60 ° C. for 5 hours. Solids were obtained respectively. Each solid material is press-molded at 250 ° C. to form a film with a thickness of 0.1 mm, and the refractive index at 23 ° C. and 550 nm wavelength is measured using an Abbe refractometer (DR-M2 manufactured by Atago Co., Ltd.). did. The absolute value of the difference between the refractive index of the acetone soluble component (component A) and the refractive index of the insoluble component (component B) was taken as the refractive index difference.
(3) Each component composition The film was melt | dissolved in acetone, this solution was centrifuged at 9,000 rpm for 30 minutes, and it isolate | separated into the acetone soluble component and the acetone insoluble component. The acetone-soluble component was dried under reduced pressure at 60 ° C. for 5 hours, and each component unit was quantified to identify each component composition of the acrylic resin.

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 the aromatic ring of styrene is seen at 6.5 to 7.5 ppm, and the copolymer composition is similarly determined from the spectral ratio. Can be determined.

  The weight average particle diameter of the rubbery polymer is the sodium alginate method described in “Rubber Age, Vol. 88, p. 484-490 (1960), by E. Schmidt, PH B. Biddison”, that is, the concentration of sodium alginate. By using the fact that the diameter of the polybutadiene particles to be creamed differs depending on the particle size, it can be measured by a method of determining the particle size of 50% cumulative weight fraction from the weight proportion of cream and the cumulative weight fraction of sodium alginate concentration.

(4) Graft rate 200 ml of acetone was added to a predetermined amount (m; about 1 g) of the copolymer grafted on the rubbery polymer, and the mixture was refluxed in a hot water bath at 70 ° C. for 3 hours. p. m. After centrifugation at (10,000 G) for 40 minutes, the insoluble matter is filtered, this insoluble matter is dried under reduced pressure at 60 ° C. for 5 hours, and the weight (n) is measured. The graft ratio is calculated from the following formula. Here, L is the ratio (%) of the rubbery polymer charged at the time of graft copolymerization.
Graft ratio (% by weight) = {[(n) − (m) × L] / [(m) × L]} × 100
(5) Glass transition temperature (Tg)
About 5 mg of the thermoplastic resin film was taken and measured at a temperature increase rate of 20 ° C./min in a nitrogen atmosphere using a differential scanning calorimeter (RDC220 type manufactured by Seiko Denshi Kogyo Co., Ltd.). The method for determining the glass transition temperature follows the method for determining the midpoint glass transition temperature in Section 9.3 of JIS-K-7121 (1987), and is equidistant from the extended straight line of each baseline of the measurement chart in the vertical axis direction. The temperature was the point at which a straight line and the curve of the step-like change part of the glass transition intersect.

(6) Haze Based on JIS-K-7105 (1981), the haze value (%) at 23 ° C. was measured using a haze meter manufactured by Suga Test Instruments Co., Ltd. Haze meter model: HZ-1, system: single beam system, measurement light: C light, light source unit: pinhole system, light receiving unit: integrating sphere system.

(7) Color tone Color tone of each film based on JIS Z 8722 (2000) using a spectroscopic color difference meter (SE-2000 manufactured by Nippon Denshoku Industries Co., Ltd., light source halogen lamp 12V4A, 0 ° to -45 ° spectroscopic method) (B value) was measured by the transmission method. The measurement was performed in an atmosphere at a temperature of 23 ° C. and a humidity of 65%. Measurement was carried out by selecting five arbitrary positions on the film, and the average value was adopted.

(8) Surface roughness (SRa)
Based on JIS-B-0601 (2001), using an optical stylus type three-dimensional roughness meter ET-30HK (manufactured by Kosaka Laboratory Co., Ltd.), measuring length 0.5 mm, measuring number 80, cut-off 0 .25 mm, feed pitch 5 μm, stylus load 10 mg, speed 100 μm / sec. In addition, it measured 3 times and used the average value.

(9) In-plane retardation and thickness direction retardation Ellipsometer (KOBRA-WPR) and phase difference measuring apparatus KOBRA-RE (KOBRA-WR software) Ver. 1.21 was used. Measurement is performed in a single N calculation mode of incident angle dependence measurement, using a low phase difference measurement method, with the slow axis as the tilted central axis and an incident angle of 40 ° (wavelength 590 nm). A phase difference and a thickness direction retardation (Rth) were obtained. The R0 value, which is the phase difference at an incident angle of 0 °, was used as the in-plane phase difference. Further, the measurement was performed on a sample stored for 24 hours in a desiccator, and the average value of N = 5 times was defined as an in-plane retardation and a thickness direction retardation (Rth).

(10) Elongation at break The measurement was performed under the following conditions using an automatic measuring device for film strong elongation “Tensilon AMF / RTA-100” manufactured by Orientec Co., Ltd.

Sample size: width 10mm, length 150mm
Distance between chucks: 100mm
Tensile speed: 200 mm / min Measurement environment: 23 ° C., 65% RH, under atmospheric pressure The breaking elongation is obtained by dividing the length at the time of film rupture by subtracting the distance between chucks by the distance between chucks and multiplying by 100. The elongation value was used.

(11) Folding resistance MIT (handling index)
As an index indicating the handling property, the number of times in the bending strength test was used, and the evaluation was performed according to the following criteria. The test was performed using MIT-D (manufactured by Toyo Seiki Co., Ltd.) at a temperature of 23 ° C. and a relative humidity of 65%. The test piece was 10 mm in width, φ = 2.0 mm, and the load was 0.83 kg / mm ² , and the number of refractions until breakage was measured.

Handling property ○: Number of refractions 1,000 times or more Handling property ×: 未 満 Less than 1,000 times (12) Film defects Visual confirmation of the presence of defects with a diameter of about 0.5 mm or more for the thermoplastic resin film after film formation And evaluated according to the following criteria.

○: No defects are observed ×: Defects are observed <Reference Example (1) Production of Heat Resistant Copolymer (A)>
(1) Production of heat-resistant copolymers (A-1-1) and (A-1-2) containing glutaric anhydride units (A-1-1)
In a stainless steel autoclave having a capacity of 20 liters and equipped with a baffle and a foudra-type stirring blade, methyl acrylate / acrylamide copolymer (weight ratio 20/80, disclosed in Example 1 of JP-B-45-24151) as a suspending agent. ) A solution in which 0.05 part by weight was dissolved in 165 parts by weight of ion-exchanged water was stirred at 400 rpm, and the system was replaced with nitrogen gas. Next, a reaction system of the following mixed substances was added with stirring, and the temperature was raised to 60 ° C. to initiate suspension polymerization.

Methacrylic acid 50 parts by weight Methyl methacrylate 50 parts by weight t-dodecyl mercaptan (chain transfer agent) 0.3 part by weight 2,2′-azobisisobutyronitrile (polymerization initiator) 0.4 part by weight Over 15 minutes After raising the reaction temperature to 65 ° C, the temperature was raised to 100 ° C over 50 minutes. Thereafter, the reaction system was cooled, the polymer was separated, washed, and dried in accordance with ordinary methods to obtain a bead-shaped vinyl copolymer (prepolymer (A-1-0)). As a result of measuring the amount of residual monomers by gas chromatography, the residual monomers were 0.7 parts by weight of methacrylic acid and 0.8 parts by weight of methyl methacrylate. The weight average molecular weight was 70,000.

This bead-like vinyl copolymer (A-1-0) is supplied from the hopper port of a vented co-rotating twin-screw extruder (PCM-30, manufactured by Ikekai Tekko Co., Ltd.) having a screw diameter of 30 mm and an L / D of 25. Then, it was melt-extruded at a resin temperature of 250 ° C. and a screw rotation speed of 100 rpm to obtain a copolymer (A-1-1) containing pellet-like glutaric anhydride units. With respect to the obtained (A-1-1), a ¹ H-NMR spectrum was measured, and the attribution of the spectrum was 0 to 0.8 ppm. The peaks of methacrylic acid, methyl methacrylate and glutaric anhydride ring compounds were α- Hydrogen of methyl group, 0.8 to 1.6 ppm peak is water of methylene group of polymer main chain, 3.0 ppm peak is hydrogen of carboxylic acid ester of methyl methacrylate (—COOCH ₃ ), 11.9 ppm peak Was hydrogen of carboxylic acid of methacrylic acid. As a result of calculating the composition of each copolymer unit from the integral ratio of the spectrum, it was as follows.

Methacrylic acid unit: 2.0% by weight
Methyl methacrylate unit: 51.5% by weight
Glutaric anhydride unit: 46.5% by weight
(A-1-2)
(A-1-1) is supplied again from the hopper port of a vented co-rotating twin screw extruder (PCM-30, manufactured by Ikegai Iron Works) with a screw diameter of 30 mm and an L / D of 25, and a resin temperature of 250 ° C. It was melt-extruded at a screw rotational speed of 100 rpm to obtain a copolymer (A-1-2) containing pellet-shaped glutar anhydride units. The composition of each copolymer unit (A-1-2) calculated from the integration ratio of the ¹ H-NMR spectrum was as follows.

Methacrylic acid unit: 0.1% by weight
Methyl methacrylate unit: 50.0% by weight
Glutaric anhydride unit: 49.9% by weight
(2) Production of copolymers (A-2-1) and (A-2-2) containing glutaric anhydride units (A-2-1)
In the same manner as in (A-1-0), the monomer composition was changed to 20 parts by weight of methacrylic acid and 80 parts by weight of methyl methacrylate to obtain a bead-shaped vinyl polymer (A-2-0). As a result of measuring the amount of residual monomers by gas chromatography, the residual monomers were 0.2 parts by weight of methacrylic acid and 0.7 parts by weight of methyl methacrylate. The weight average molecular weight was 130,000. This vinyl copolymer was melt-kneaded by the same method to obtain a copolymer (A-2-1) containing pellet-like glutaric anhydride units. The composition of each copolymer unit (A-2-1) calculated from the integral ratio of the ¹ H-NMR spectrum was as follows.

Methacrylic acid unit: 1.3% by weight
Methyl methacrylate unit: 81.0% by weight
Glutaric anhydride unit: 17.7% by weight
(A-2-2)
The above (A-2-1) is supplied again from the hopper port of a vented co-rotating twin-screw extruder (PCM-30 manufactured by Ikekai Tekko Co., Ltd.) having a screw diameter of 30 mm and an L / D of 25, and a resin temperature of 250 The copolymer (A-2-2) containing pellet-like glutar anhydride units was obtained by melt extrusion at 0 ° C. and a screw rotation speed of 100 rpm. The composition of each copolymer unit (A-2-2) calculated from the integration ratio of the ¹ H-NMR spectrum was as follows.

Methacrylic acid unit: 0.1% by weight
Methyl methacrylate unit: 79.8% by weight
Glutaric anhydride unit: 20.1% by weight
(3) Production of copolymer (A-3-1) containing glutar anhydride unit (A-3-1)
In the same manner as in (A-1-0), the monomer composition was changed to 30 parts by weight of methacrylic acid and 70 parts by weight of methyl methacrylate to obtain a bead-shaped vinyl polymer (A-3-0). As a result of measuring the amount of residual monomers by gas chromatography, the residual monomers were 0.3 parts by weight of methacrylic acid and 0.7 parts by weight of methyl methacrylate. The weight average molecular weight was 90,000. This vinyl copolymer was melt-kneaded by the same method to obtain a copolymer (A-3-1) containing pellet-like glutaric anhydride units. The composition of each copolymer unit of (A-3-1), calculated from the integration ratio of the ¹ H-NMR spectrum, was as follows.

Methacrylic acid unit: 0.1% by weight
Methyl methacrylate unit: 69.8% by weight
Glutaric anhydride unit: 30.1% by weight
(A-4-1)
In the same manner as (A-1-0), the monomer composition was 15 parts by weight of methacrylic acid, 75 parts by weight of methyl methacrylate, 10 parts by weight of styrene, and 1.5 parts by weight of n-dodecyl mercaptan. It changed and obtained the bead-like vinyl polymer (A-4-0). As a result of measuring the amount of residual monomer by gas chromatography, the residual monomer was 0.6 part by weight of methacrylic acid and 1.0 part by weight of methyl methacrylate. The weight average molecular weight was 100,000. This vinyl copolymer was melt-kneaded by the same method to obtain a copolymer (A-4-1) containing pellet-like glutaric anhydride units. The composition of each copolymer unit of (A-4-1) calculated from the integral ratio of the ¹ H-NMR spectrum was as follows.

Methacrylic acid unit: 2.0% by weight
Methyl methacrylate unit: 73.0% by weight
Glutaric anhydride unit: 16.0% by weight
Styrene unit: 9.0% by weight
Table 1 summarizes the composition of each copolymer component of each heat-resistant copolymer (A) obtained.

<Reference Example (2) Production of Rubber-Containing Polymer (B)>
(B-1-1)
In a glass container with a condenser (capacity 5 liters), charged with 120 parts by weight of deionized water, 0.5 parts by weight of potassium carbonate, 0.5 parts by weight of dioctyl sulfosuccinate, 0.005 parts by weight of potassium persulfate, and a nitrogen atmosphere After stirring below, 53 parts by weight of butyl acrylate, 17 parts by weight of styrene, and 1 part by weight of allyl methacrylate (crosslinking agent) were charged. These mixtures were reacted at 70 ° C. for 30 minutes to obtain a rubbery polymer. Next, a mixture of 15.5 parts by weight of methyl methacrylate, 14.5 parts by weight of methacrylic acid, and 0.005 parts by weight of potassium persulfate was continuously added over 90 minutes, and the mixture was further maintained for 90 minutes. Polymerized. The polymer latex was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered, and dried to obtain a rubbery polymer (B-1-1). The graft ratio of this rubber-containing polymer (B-1-1) was 41% by weight. The number average particle diameter of the polymer particles measured with an electron microscope was 0.16 μm.

(B-1-2)
A rubber-containing polymer (B-1) was prepared in the same manner as in the above (B-1-1) except that the charged mixture composition of the graft component was changed to 30 parts by weight of methyl methacrylate and 0.005 parts by weight of potassium persulfate. -2) was obtained. The graft ratio of this rubber-containing polymer (B-1-2) was 48% by weight. The number average particle diameter of the polymer particles measured with an electron microscope was 0.25 μm.

(B-1-3)
A rubber-containing polymer (B-) was prepared in the same manner as (B-1-1) except that the charged mixture composition of the graft component was changed to 21.0 parts by weight of methyl methacrylate and 9.0 parts by weight of methacrylic acid. 1-3) was obtained. The graft ratio of this rubber-containing polymer (B-1-3) was 43% by weight. The number average particle diameter of the polymer particles measured with an electron microscope was 0.15 μm.

(B-2-1)
Polybutadiene latex (number average particle size 0.3 μm) 50 parts by weight (solid content conversion)
Sodium formaldehyde sulfoxylate 0.4 part by weight Sodium ethylenediaminetetraacetate 0.1 part by weight Ferrous sulfate 0.01 part by weight Sodium phosphate 0.1 part by weight Pure water 200 part by weight The above substances are charged in a polymerization vessel, After purging with nitrogen, the temperature was raised to 65 ° C. with stirring. A polymerization mixture comprising 36.0 parts by weight of methyl methacrylate, 11.5 parts by weight of styrene, 2.5 parts by weight of acrylonitrile and 0.3 part by weight of t-dodecyl mercaptan was started when the internal temperature reached 65 ° C. It was continuously added dropwise over 5 hours. In parallel, an aqueous solution consisting of 0.25 parts by weight of cumene hydroperoxide, 2.5 parts by weight of sodium laurate as an emulsifier and 25 parts by weight of pure water was continuously added dropwise over 5 hours, and held for another hour after completion of the addition. To complete the reaction. The obtained graft copolymer latex was coagulated with 1.5% sulfuric acid, then neutralized with caustic soda, washed, filtered and dried to obtain a powdery rubbery polymer (B-2-1). Obtained. The graft ratio of this rubber-containing polymer (B-2-1) was 47% by weight.

(B-3-1)
(B-1-1) The rubbery polymer was added in the same manner as (B-1-1) except that the composition of the charged mixture of the rubber-like polymer was 28 parts by weight of butyl acrylate and 42 parts by weight of styrene. A polymer (B-3-1) was obtained. The graft ratio of this rubber-containing polymer (B-3-1) was 50% by weight. The number average particle diameter of the polymer particles measured with an electron microscope was 0.15 μm.

<Reference Example (3) Production of Chip for Melt Film Formation>
The heat-resistant polymer (A) obtained in Reference Example (1) and the rubbery polymer (B) obtained in Reference Example (2) were blended at the composition ratio shown in Table 3, and biaxial Using an extruder (TEX30 (manufactured by Nippon Steel Co., Ltd., L / D = 44.5)), kneading was performed at a screw rotation speed of 150 rpm and a cylinder temperature of 280 ° C. to obtain a chip for melting film formation.

(Examples 1-5, Comparative Examples 1-3)
(4) Film formation (Example 1)
The molten film-forming chip (C-1) was dried under reduced pressure at 80 ° C. for 8 hours, then extruded at 260 ° C. using a vented φ65 mm single screw extruder, and the discharge rate was made constant by a gear pump, and then a 25 μm cut filter was attached. A flat die (set temperature) with a lip gap of 0.6 mm is provided with a flow divider immediately before the die, the ratio of the partial flow rate of the resin staying on the wall and the resin having a short residence time at the center is 15/85% by weight. 260 ° C.). After discharging, the sheet-like molten resin (130 ° C.) is cooled so that both surfaces of the sheet-like molten resin are completely brought into close contact with each other, and then the end portion including the resin staying on the wall surface is cut to a thickness of 100 μm. A thermoplastic resin film was obtained. The residence time until the molten resin was discharged from the die was 80 minutes. The shunt is a double pipe, and among the resin staying on the wall flowing between the inner partition wall and the outer wall, the wall staying on the wall that tries to flow into the surface layer of the product center flows into both ends of the sheet. The inner partition wall and the outer wall were provided.

(Examples 2 to 6)
The thermoplastic resin films shown in Tables 4 and 5 were obtained in the same manner as in Example 1 except that the melt film-forming chip, thickness, draft ratio, and fractional flow ratio were changed.

(Comparative Example 1)
The molten film-forming chip (C-1) was dried under reduced pressure at 80 ° C. for 8 hours, then extruded at 260 ° C. using a vented φ65 mm single screw extruder, and the discharge rate was made constant by a gear pump, and then a 25 μm cut filter was attached. It was discharged from a flat die (set temperature 260 ° C.) having a lip gap of 0.6 mm without using a flow divider. After discharging, the sheet-like molten resin was cooled in such a manner that the both surfaces of the sheet-like molten resin were completely brought into close contact with a stainless steel cooling roll (130 ° C.) having a surface finish of 1 S, and a thermoplastic resin film having a thickness of 100 μm was obtained. The residence time until the molten resin was discharged from the die was 80 minutes.

(Comparative Examples 2-3, 5-6)
The thermoplastic resin films shown in Tables 4 and 5 were obtained in the same manner as in Comparative Example 1 except that the melt-forming chip, thickness, and draft ratio were changed.

(Comparative Example 4)
The molten film-forming chip (C-4) was dried under reduced pressure at 80 ° C. for 8 hours, dissolved in methyl ethyl ketone so as to have a solid concentration of 30% by weight, and filtered using a 2 μm cut filter. This solution was cast on a PET film through a die having a lip gap of 0.5 mm using a gear pump, and heat-treated at 60 ° C., 110 ° C., and 170 ° C. for 30 minutes in a hot air oven to obtain a thermoplastic resin film.

  The evaluation results of each thermoplastic resin film are shown in Tables 1 to 5.

  From the examples and comparative examples in Table 5, the following is clear. The thermoplastic resin film of the present invention is improved in transparency and color tone as compared with the case where the diverting means is not performed. Furthermore, the thermoplastic resin film of the present invention has a high elongation at break and a large number of bending refractions, indicating that it has good handling properties during unwinding. In Comparative Example 4, transparency and color tone are improved, but the quality is impaired due to bumping defects that occur when the remaining solvent is volatilized. In Comparative Examples 5 and 6, since the difference in refractive index between the heat-resistant copolymer and the rubber-containing polymer is large, not only the transparency is greatly reduced, but also the elongation at break and folding resistance are deteriorated. I understand that. As described above, since the highly transparent thermoplastic resin film of the present invention is excellent in transparency, heat resistance and handling properties, it is preferably used as a material for optical disks, display members, optical lenses, and light guide plates for liquid crystal backlights. Can do.

Claims (12)

A thermoplastic resin film obtained by a melt film-forming method, wherein (i) a heat-resistant copolymer (A) having a glutaric anhydride unit represented by the following general formula (1), and a rubber-containing polymer (B), a thermoplastic resin film having a thickness of 5 to 250 μm, a haze value of 1.0% or less, a surface roughness SRa of 40 nm or less, and a glass transition temperature of 120 ° C. or more.

(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 heat-resistant copolymer (A) is a copolymer having (i) a glutaric anhydride unit represented by the general formula (1) and (ii) an unsaturated carboxylic acid alkyl ester unit. The thermoplastic resin film described in 1. In addition to the units (i) and (ii) above, the heat resistant copolymer (A) further comprises (iii) an unsaturated carboxylic acid unit and / or (iv) a vinyl monomer unit. The thermoplastic resin film according to claim 1 or 2, which is a polymer. The thermoplastic resin film according to any one of claims 1 to 3, wherein an in-plane retardation of the film with respect to a light beam having a wavelength of 590 nm is 5 nm or less. The thermoplastic resin film according to claim 3 or 4, wherein the content of the unsaturated carboxylic acid unit (iii) is 0 to 1% by weight. The thermoplastic resin film according to any one of claims 1 to 5, comprising 10 to 90 parts by weight of the heat-resistant copolymer (A) and 90 to 10 parts by weight of the rubber-containing polymer (B). The thermoplastic resin film according to any one of claims 1 to 6, wherein a difference in refractive index between the heat-resistant copolymer (A) and the rubber-containing polymer (B) is 0.02 or less. The thermoplastic resin film according to any one of claims 1 to 7, wherein the rubber-containing polymer (B) comprises a rubber polymer (B-1) layer and a graft component (B-2) layer. . The rubber polymer (B-1) contains an acrylic acid alkyl ester unit and a substituted or unsubstituted styrene unit, and the graft component (B-2) is represented by the general formula (1). The thermoplastic resin film according to claim 8, comprising an acid anhydride unit. The thermoplastic resin film according to any one of claims 6 to 9, wherein the rubber-containing polymer (B) has a weight average particle diameter of 0.01 to 1 µm. The heat according to any one of claims 1 to 10, wherein when producing a thermoplastic resin film using a die, the lip gap of the die is adjusted so that the lip gap of the die and the average film thickness satisfy the following formula. A method for producing a plastic resin film.
(Die lip gap (mm) / film average thickness (μm)) × 1,000 ≦ 20.0 12. A diversion means for diverting a portion near the wall surface of the thermoplastic resin flowing in the pipe and the center portion is provided in the pipe located upstream of the die, and the thermoplastic resin in the center portion is discharged from the die. The manufacturing method of the thermoplastic resin film of description.