JP2011017761A - Method of manufacturing retardation film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a retardation film by longitudinal-roll-stretching a film consisting of amorphous thermoplastic resin by which the smooth film free from the breaking or stepwise surface defects (step unevenness) of the film due to the fusion to a pre-heating roll and the stretching ununiformity can be obtained.SOLUTION: In the method of manufacturing the retardation film which is for longitudinal-roll-stretching the film consisting of the amorphous thermoplastic resin by a roll stretching device having a plurality of pre-heating rolls, the preheating roll right before the stretching in the roll stretching device has a non-adhesion treated surface, and the preheating temperature is ≥(Tg-10°C) and ≤(Tg+5°C), where Tg is the glass transition point (°C) of the thermoplastic resin.

Description

  The present invention relates to a method for producing a retardation film in which a film made of an amorphous thermoplastic resin is longitudinally stretched.

  In recent years, the demand for visibility (brighter, easier to see, better contrast, higher viewing angle, etc.) has become stricter as the screen size and usage environment of liquid crystal display devices expand. However, since only the improvement of the liquid crystal cell body does not sufficiently satisfy the demand for improving the visibility, it largely depends on the performance improvement of an optical film such as a retardation film.

  Therefore, the optical film such as a retardation film has high transparency, low photoelasticity, heat resistance, light resistance, high surface hardness, high mechanical strength, large retardation, and small wavelength dependence of retardation, Characteristics such as small dependence of the phase difference on the incident angle are required. In recent years, the demand for visibility has become stricter as the screen size and usage environment of liquid crystal display devices (LCD) expand. However, since only the improvement of the liquid crystal cell main body cannot sufficiently satisfy the demand for improving the visibility, it largely depends on the performance improvement of the retardation film such as a retardation film.

  At present, amorphous thermoplastic resins are mainly used for retardation films because of their excellent optical properties, and birefringence can be controlled by stretching, so retardation films for liquid crystal display devices It is applied to such uses. In particular, acrylic resins represented by polymethyl methacrylate (PMMA) have excellent optical properties such as low light elastic modulus while having high light transmittance, mechanical strength, moldability and surface hardness. Therefore, it is suitable as a thermoplastic resin used for an optical film used in an apparatus that handles polarized light such as a retardation film. Then, the retardation film which made heat resistance and flexibility compatible by giving biaxial stretching to an acrylic resin film is disclosed (refer patent document 1 and patent document 2).

  In biaxial stretching, usually longitudinal stretching is performed and then lateral stretching is performed with a tenter. As longitudinal stretching techniques, oven longitudinal stretching and roll longitudinal stretching are known. Oven longitudinal stretching is a stretching technique in which stretching is performed while heating in a long stretching zone (oven). Roll longitudinal stretching is performed by preheating with a plurality of preheating rolls and then heating with a heater such as an IR heater. This is a stretching method of stretching between two different stretching rolls. When longitudinally stretching an optical film, oven longitudinal stretching, which is said to be easy to obtain an optically uniform film, is the mainstream. (See Patent Document 3 and Patent Document 4).

JP 2008-9378 A JP 2008-242426 A Japanese Patent Laid-Open No. 2001-21718 JP 2003-131033 A

  However, heating in the oven is inferior in heat conduction compared to roll longitudinal stretching that is conveyed while touching the preheating roll, so there is a disadvantage from the viewpoint of productivity and cost accompanying the price drop of display image devices in recent years. is there. In addition, since a film once stretched by oven longitudinal stretching is easy to tear in the flow direction of the film, an amorphous thermoplastic resin film having low flexibility such as an acrylic resin or a styrene resin may be stretched laterally. There was a problem that the vertical tearing of the steel became prominent and stable production was difficult.

  On the other hand, roll longitudinal stretching is advantageous in terms of equipment introduction because it does not require a large heat-retaining furnace or heating furnace. Furthermore, since the film is heated while being in contact with the preheating roll, heat conduction is preferable compared to heating in the oven, and the production speed can be increased. It is also advantageous for productivity and cost.

  However, in roll longitudinal stretching, there is a problem that it is difficult to obtain an optically uniform film. If the preheating temperature in the preheating roll is set low, it is necessary to increase the heating output just before stretching with an IR heater or the like, but the stretching point is not fixed by non-contact heating, and thus a uniform film is likely to occur. It was hard to get. In order to obtain a uniform film, it was considered to preheat to a temperature as high as possible with a preheating roll. However, as the glass transition temperature approaches, the adhesiveness of the amorphous thermoplastic resin film increases and the film melts into the roll. Adhesion occurred, and there was a problem that stepped surface defects (step unevenness) due to film breakage or adhesion to rolls occurred.

  The present invention has been made in view of the above-described problems, and provides a method for producing a retardation film that can be stably stretched in the longitudinal direction of a roll and that is smooth and has less unevenness of stretching and variation in retardation. Objective.

  In order to achieve the above object, the present inventors have made various studies on a method for producing a retardation film by roll-stretching a film made of an amorphous thermoplastic resin, and the present invention has been achieved.

  The method for producing a retardation film of the present invention is a method for producing a retardation film in which a film made of an amorphous thermoplastic resin is longitudinally stretched by a roll stretching apparatus having a plurality of preheating rolls, The preheating roll immediately before stretching is a preheating roll that has been subjected to non-adhesive treatment on the surface, and the preheating temperature is (Tg−10 ° C.) or more and (Tg + 5 ° C.) or less [where Tg is the glass transition temperature (° C.) of the thermoplastic resin. ].

  The preheating temperature is preferably (T1-20 ° C.) or more and T1 or less [where T1 is a stretching temperature (° C.)].

  After preheating with the preheating roll, it is preferable to perform longitudinal stretching after heating to the stretching temperature with at least one heater selected from an IR heater, a ceramic heater, and a hot air heater.

The amorphous thermoplastic resin preferably includes an acrylic polymer as a main component. The amorphous thermoplastic resin preferably includes an acrylic polymer having a ring structure in the main chain as a main component.

  By the production method of the present invention, it is possible to provide a retardation film that is smooth and has less unevenness of stretching and variations in retardation.

  In the following description, unless otherwise specified, “%” means “% by mass”, “parts” means “parts by mass”, and “A to B” representing a range means “A or more and B or less”. To do.

  The method for producing a retardation film of the present invention longitudinally stretches a film made of an amorphous thermoplastic resin.

[Amorphous thermoplastic resin]
The amorphous thermoplastic resin used in the production method of the present invention is not particularly limited as long as it is amorphous. However, acrylic resin, styrene resin, maleimide resin, cycloolefin resin, and cellulose resin are not particularly limited. Resin is preferred. Among them, cycloolefin resins, cellulose resins, acrylic resins having a lactone ring structure or a glutarimide structure generally have positive intrinsic birefringence. The ring structure, which is a structural unit contained in the resin having positive intrinsic birefringence, has an effect of imparting positive intrinsic birefringence to the amorphous thermoplastic resin.

  Intrinsic birefringence refers to the orientation axis from the refractive index n1 of light in a direction parallel to the direction (orientation axis) in which molecular chains are oriented in a layer (for example, a sheet or film) in which resin molecular chains are uniaxially oriented. A value obtained by subtracting the refractive index n2 of the light in the direction perpendicular to (ie, “n1-n2”). The sign of the intrinsic birefringence of the amorphous thermoplastic resin itself is determined by the balance between the action of the structural unit with respect to the intrinsic birefringence and the action of other structural units of the amorphous thermoplastic resin. The

  The amorphous thermoplastic resin may have a structural unit having an action of giving negative intrinsic birefringence to the resin. Styrenic resins and maleimide resins having a fanyl group in the side chain generally have negative intrinsic birefringence. An example of a structural unit having an effect of imparting negative intrinsic birefringence to an amorphous thermoplastic resin is a styrene unit or a phenylmaleimide unit.

  It is also possible to cause a structural unit having an effect of imparting positive intrinsic birefringence and a structural unit having an effect of imparting negative intrinsic birefringence to be present in the same polymer chain by copolymerization or the like. In this case, the degree of freedom in controlling the intrinsic birefringence in the amorphous thermoplastic resin is improved, and the use application of the retardation film in the present invention is expanded.

  When the amorphous thermoplastic resin is an acrylic resin, the acrylic resin is a resin having a (meth) acrylic acid ester unit as a structural unit, and a structural unit derived from a (meth) acrylic acid ester. You may have. The total of the proportion of the structural units derived from the (meth) acrylic acid ester unit and the derivative in the total structural units of the acrylic resin is usually 50% or more, preferably 60% or more, more preferably 70% or more. It is. In addition, when the main chain has a ring structure that is a derivative of a (meth) acrylic acid ester unit such as a lactone ring structure, the proportion of the (meth) acrylic acid ester unit and the (meth) acrylic acid unit in all the structural units, The sum total with the content rate of a ring structure should just be 50 weight% or more.

  (Meth) acrylic acid ester units are, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t- (meth) acrylic acid t- Butyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, (meth) acryl Dicyclopentanyl acid, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic acid 2, 3,4,5,6-pentahydroxyhexyl, 2,3,4,5-tetrahydro (meth) acrylic acid Shipenchiru is a structural unit derived from a monomer such as.

  The acrylic resin may have two or more of these structural units as (meth) acrylic acid ester units. The acrylic resin preferably has a methyl methacrylate unit. In this case, the thermal stability of the film obtained by molding the acrylic resin is improved.

  The Tg of the acrylic resin is usually 110 ° C. or higher, preferably 115 ° C. or higher, more preferably 120 ° C. or higher, and further preferably 130 ° C. or higher. Note that Tg of polymethyl methacrylate (PMMA) which is a typical acrylic resin is 105 ° C.

  The acrylic resin may have a ring structure in the main chain. In this case, the Tg of the acrylic resin is increased, and the heat resistance of the resin molded product obtained from the composition is improved. Thus, a resin molded product obtained from an acrylic resin having a ring structure in the main chain, such as a film, is suitable for use as an optical member, such as being easy to arrange in the vicinity of a heat generating part such as a light source in an image display device. .

  Although the kind of ring structure is not specifically limited, For example, it is at least 1 sort (s) chosen from lactone ring structure, glutaric anhydride structure, glutarimide structure, N-substituted maleimide structure, and maleic anhydride structure.

  The following general formula (1) shows a glutaric anhydride structure and a glutarimide structure.

In the general formula (1), R ¹ and R ² are each independently a hydrogen atom or a methyl group, and X ¹ is an oxygen atom or a nitrogen atom. When X ¹ is an oxygen atom, R ³ does not exist, and when X ¹ is a nitrogen atom, R ³ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, or a phenyl group. It is.

When X ¹ is an oxygen atom, the ring structure represented by the general formula (1) is a glutaric anhydride structure. The glutaric anhydride structure can be formed, for example, by subjecting a copolymer of (meth) acrylic acid ester and (meth) acrylic acid to dealcoholization cyclocondensation in the molecule.

When X ¹ is a nitrogen atom, the ring structure represented by the general formula (1) is a glutarimide structure. The glutarimide structure can be formed, for example, by imidizing a (meth) acrylic acid ester polymer with an imidizing agent such as methylamine.

  The following general formula (2) shows a maleic anhydride structure and an N-substituted maleimide structure.

In the general formula (2), R ⁴ and R ⁵ are each independently a hydrogen atom or a methyl group, and X ² is an oxygen atom or a nitrogen atom. When X ² is an oxygen atom, R ⁶ is not present, and when X ² is a nitrogen atom, R ⁶ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, or a phenyl group. is there.

When X ² is an oxygen atom, the ring structure represented by the general formula (2) is a maleic anhydride structure. The maleic anhydride structure can be formed, for example, by copolymerizing maleic anhydride and (meth) acrylic acid ester.

When X ² is a nitrogen atom, the ring structure represented by the general formula (2) is an N-substituted maleimide structure. The N-substituted maleimide structure can be formed, for example, by polymerizing an N-substituted maleimide such as phenylmaleimide and a (meth) acrylic acid ester.

  In each method for forming the ring structure exemplified in the description of the general formulas (1) and (2), all polymers used for forming each ring structure have a (meth) acrylate unit as a single unit. The resin obtained by this method is an acrylic resin.

  The lactone ring structure that the acrylic resin may have in the main chain is not particularly limited, and may be, for example, a 4- to 8-membered ring. It is preferably a membered ring, more preferably a 6-membered ring. The lactone ring structure which is a 6-membered ring is, for example, the structure disclosed in Japanese Patent Application Laid-Open No. 2004-168882, but the lactone ring structure is high due to the high polymerization yield of the precursor and the cyclization condensation reaction of the precursor. A structure represented by the following general formula (3) is preferable because an acrylic resin having a ring content can be obtained and a polymer having a methyl methacrylate unit as a constituent unit can be used as a precursor.

In the general formula (3), R ⁷ , R ⁸ and R ⁹ are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The organic residue in the general formula (3) is, for example, an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, or a propyl group. An aromatic hydrocarbon group having 1 to 20 carbon atoms, such as a saturated aliphatic hydrocarbon group, a phenyl group, or a naphthyl group, and the alkyl group, the unsaturated aliphatic hydrocarbon group, and the aromatic hydrocarbon group are One or more hydrogen atoms may be substituted with at least one group selected from a hydroxyl group, a carboxyl group, an ether group, and an ester group.

  Although the content rate of the said ring structure except the lactone ring structure in acrylic resin is not specifically limited, For example, it is 5 to 90%, Preferably it is 10 to 70%, More preferably, it is 10 to 60%, Preferably it is 10 to 50%.

  When the acrylic resin has a lactone ring structure in the main chain, the content of the lactone ring structure in the resin is not particularly limited, but is, for example, 5 to 90%, preferably 10 to 80%, more preferably It is 10 to 70%, more preferably 20 to 60%.

  If the content of the ring structure in the acrylic resin becomes transiently small, the heat resistance of the film may be lowered, and the solvent resistance and surface hardness may be insufficient. On the other hand, when the above content rate increases transiently, the moldability and mechanical properties of the film deteriorate.

  The acrylic resin having a ring structure in the main chain can be produced by a known method. An acrylic resin whose ring structure is a glutaric anhydride structure or a glutarimide structure can be produced, for example, by the method described in WO2007 / 26659 or WO2005 / 108438. An acrylic resin whose ring structure is a maleic anhydride structure or an N-substituted maleimide structure can be produced, for example, by the method described in JP-A-57-153008 and JP-A-2007-31537. An acrylic resin whose ring structure is a lactone ring structure can be produced, for example, by the method described in JP-A-2006-96960, JP-A-2006-171464, or JP-A-2007-63541.

  The acrylic resin may have a structural unit other than the (meth) acrylic acid ester unit and the (meth) acrylic acid unit. Examples of such a structural unit include styrene, vinyltoluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile, methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, methyl 2- (hydroxyethyl) acrylate, acrylic acid , Methacrylic acid, 2- (hydroxymethyl) acrylic acid, 2- (hydroxyethyl) acrylic acid, methallyl alcohol, allyl alcohol, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1 -Butene, methyl vinyl ketone, N-vinyl Pyrrolidone, a structural unit derived from a monomer such as N- vinylcarbazole. The acrylic resin may have two or more of these structural units.

  The acrylic resin may have a UV-absorbing monomer as a constituent unit as long as heat resistance, physical properties, and optical properties are not impaired. Examples of the ultraviolet absorbing monomer include benzotriazole compounds, benzophenone compounds or triazine compounds and acrylic monomers having a polymerizable unsaturated group. Examples of benzotriazole compounds include 2- [2′-hydroxy-5 ′-(meth) acryloyloxymethylphenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(meth) acryloyloxyethyl. Phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(meth) acryloyloxypropylphenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(meth) acryloyloxyhexyl Phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3′-tert-butyl-5 ′-(meth) acryloyloxyethylphenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′ -(Β- (Meth) acryloyloxyethoxy) -3′-tert-butyl Enyl] -5-tert-butyl-2H-benzotriazole, 2- [2′-hydroxy-3′-methacrylaminomethyl-5 ′-(1 ″, 1 ″, 3 ″, 3 ″ -tetramethyl) butylphenyl ] -2H-benzotriazole and the like can be used. Examples of the benzophenone compounds include 2-hydroxy-4- [2- (meth) acryloyloxy] ethoxybenzophenone, 2-hydroxy-4- [2- (meth) acryloyloxy] butoxybenzophenone, 2,2 ′. -Dihydroxy-4- [2- (meth) acryloyloxy] ethoxybenzophenone, 2-hydroxy-4- [2- (meth) acryloyloxy] ethoxy-4 '-(2-hydroxyethoxy) benzophenone, and the like can be used. . Examples of the triazine compound include 4-diphenyl-6- [2-hydroxy-4- (2-acryloyloxyethoxy)]-s-triazine, 2,4-bis (2-methylphenyl) -6- [2-Hydroxy-4- (2-acryloyloxyethoxy)]-s-triazine, 2,4-bis (2-methoxyphenyl) -6- [2-hydroxy-4- (2-acryloyloxyethoxy)]- An s-triazine or the like can be used. When using such an ultraviolet-absorbing monomer, it is preferably copolymerized in an amount of 0.1 to 25% by weight, more preferably 1 to 15% by weight of all monomers. . If the content is small, the contribution to improving the weather resistance is low, and if the content is too large, the hot water resistance and solvent resistance may decrease or yellowing may occur.

  As the UV-stable monomer, a monomer having a polymerizable unsaturated group bonded to a hindered amine compound can be used, and specific examples include 4- (meth) acryloyloxy-2,2,6,6. -Tetramethylpiperidine, 4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- ( (Meth) acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2 , 2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4- (me ) Acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl -4-crotonoyloxy-2,2,6,6-tetramethylpiperidine and the like. When such an ultraviolet-stable monomer is used, it is preferably copolymerized in an amount of 0.1 to 25% by weight, more preferably 1 to 15% by weight of all monomers. . If the content is small, the contribution to improving the weather resistance is low, and if the content is too large, the hot water resistance and solvent resistance may decrease or yellowing may occur.

  The weight average molecular weight of the amorphous thermoplastic resin is, for example, in the range of 1,000 to 300,000, preferably in the range of 5,000 to 250,000, more preferably in the range of 10,000 to 200,000, and still more preferably in the range of 50,000 to 200,000. It is a range.

  The glass transition temperature of the amorphous thermoplastic resin is, for example, 100 ° C. or higher, preferably 110 ° C. or higher, more preferably 120 ° C. or higher, and further preferably 130 ° C. or higher. The upper limit of the glass transition temperature is preferably 200 ° C. or lower because molding processability becomes poor.

  The glass transition temperature in this invention can be calculated | required based on prescription | regulation of JISK7121. Specifically, using a differential scanning calorimeter (manufactured by Rigaku, DSC-8230), a sample of about 10 mg was heated from a normal temperature to 200 ° C. at a heating rate of 20 ° C./min in a nitrogen gas atmosphere. It calculated by the starting point method from the DSC curve. Α-alumina was used as a reference.

  The amorphous thermoplastic resin may contain other resins as long as the effects of the present invention are not impaired. The content of the additive is preferably 0% by mass to less than 50% by mass, more preferably 0 to 35% by mass, and still more preferably 0 to 10% by mass.

  Examples of the other resin components include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, and poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins. Acrylic polymers such as polymethyl methacrylate; styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyethylene terephthalate, polybutylene terephthalate Polyesters such as polyethylene naphthalate; biodegradable polyesters such as polylactic acid and polybutylene succinate; polycarbonates; polyamides such as nylon 6, nylon 66, and nylon 610; polyaceta Polyphenylene oxide; Polyphenylene sulfide; Polyether ether ketone; Polyether nitrile; Polysulfone; Polyether sulfone: Polyoxypentylene; Polyamideimide; Rubber such as ABS resin and ASA resin blended with polybutadiene rubber and acrylic rubber Polymer, etc. From the viewpoint of compatibility, a styrene-acrylonitrile copolymer is preferable. The rubbery polymer preferably has a graft portion having a composition compatible with the amorphous thermoplastic resin on the surface. The average particle diameter of the rubbery polymer is improved in transparency when formed into a film. In view of the above, it is preferably 100 nm or less, and more preferably 70 nm or less.

  Other resins having styrene as a structural unit such as styrene-acrylonitrile copolymer, ABS resin and ASA resin function as a phase difference adjusting agent, and reduce the positive intrinsic birefringence of amorphous thermoplastic resin. Alternatively, negative intrinsic birefringence can be imparted to the amorphous thermoplastic resin.

  The amorphous thermoplastic resin may contain an additive as long as the effects of the present invention are not impaired. The content of the additive is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, and still more preferably 0 to 5% by mass. Additives include, for example, ultraviolet absorbers; hindered phenol-based, phosphorus-based, sulfur-based and other antioxidants; anti-blocking agents; light-resistant stabilizers, weather-resistant stabilizers, heat stabilizers and other stabilizers; glass fibers, Reinforcing materials such as carbon fibers; near-infrared absorbers; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate and antimony oxide; antistatic agents such as anionic, cationic and nonionic surfactants; inorganic pigments And coloring agents such as organic pigments and dyes; organic fillers and inorganic fillers; resin modifiers; plasticizers;

  Examples of the ultraviolet absorber include benzophenone compounds, salicinate compounds, benzoate compounds, triazole compounds, and triazine compounds. Examples of the benzophenone compounds include 2,4-dihydroxybenzophenone, 4-n-octyloxy-2-hydroxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2-hydroxy-4-n-octyl. Examples thereof include oxybenzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 1,4-bis (4-benzoyl-3-hydroxyphenone) -butane and the like. Examples of the silicate compound include pt-butylphenyl silicate. Examples of the benzoate compound include 2,4-di-t-butylphenyl-3 ', 5'-di-t-butyl-4'-hydroxybenzoate. Examples of triazole compounds include 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (3 , 5-Di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol, 2-benzotriazol-2-yl-4,6-di-tert-butylphenol, 2- [5-chloro (2H) -benzotriazole- 2-yl] -4-methyl-6-tert-butylphenol, 2- (2H-benzotriazol-2-yl) -4,6-di-tert-butylphenol, 2- 2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) -4-methyl-6- (3,4) , 5,6-tetrahydrophthalimidylmethyl) phenol, methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 reaction product 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2- Hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 3- (2H-benzotriazol-2-yl ) -5- (1,1-dimethylethyl) -4-hydroxy -C7-9 side chain and straight chain alkyl esters. Further, triazine compounds include 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-). Ethoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-) Butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2- Hydroxy-4-hexyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5-tria 2,4-diphenyl-6- (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-benzyloxyphenyl)- 1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyethoxy) -1,3,5-triazine, 2,4-bis (2-hydroxy-4-butoxyphenyl) And -6- (2,4-dibutoxyphenyl) -1,3-5-triazine. Among them, 2,4-bis (2,4-dimethylphenyl) -6- [2-hydroxy-, which is highly compatible with amorphous thermoplastic resins, particularly acrylic resins, and has excellent absorption characteristics. An ultraviolet absorber having a 4- (3-alkyloxy-2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine skeleton (alkyloxy; a long-chain alkyloxy group such as octyloxy, nonyloxy, decyloxy, etc.) Can be mentioned. Examples of commercially available products include “Tinuvin 1577”, “Tinuvin 460” and “Tinuvin 477” (manufactured by Ciba Japan) as triazine-based UV absorbers, and “Adeka Stub LA-31” (manufactured by ADEKA) as triazole-based UV absorbers. It is done.

  These can be used alone or in combination of two or more. Moreover, it is also preferable to use together the method of copolymerizing the said ultraviolet absorptive monomer with an ultraviolet absorber. Although the compounding quantity of a ultraviolet-stable monomer ultraviolet absorber is not specifically limited, It is preferable that it is 0.01-25 mass% in the film containing an amorphous thermoplastic resin, More preferably, it is 0.05- 10% by mass. If the amount added is too small, the contribution to improving weather resistance is low, and if it is too large, the mechanical strength may be lowered or yellowing may be caused.

  A known antioxidant can be used as the antioxidant. Examples of phenolic antioxidants include n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, n-octadecyl-3- (3,5-di-t-butyl). -4-hydroxyphenyl) acetate, n-octadecyl-3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl-3,5-di-t-butyl-4-hydroxyphenylbenzoate, n-dodecyl 3,5-di-t-butyl-4-hydroxyphenylbenzoate, neododecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, dodecyl-β- (3,5-di- t-butyl-4-hydroxyphenyl) propionate, ethyl-α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate Octadecyl-α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl-α- (4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2- (n-octylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (n-octylthio) ethyl-3,5-di-t-butyl-4-hydroxyphenyl acetate, 2 -(N-octadecylthio) ethyl-3,5-di-t-butyl-4-hydroxyphenyl acetate, 2- (n-octadecylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-hydroxyethylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, diethyl glycol bis- (3,5 -Di-t-butyl-4-hydroxy-phenyl) propionate, 2- (n-octadecylthio) ethyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide-N, N -Bis- [ethylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], n-butylimino-N, N-bis- [ethylene-3- (3,5-di-t -Butyl-4-hydroxyphenyl) propionate], 2- (2-stearoyloxyethylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl- 7- (3-Methyl-5-tert-butyl-4-hydroxyphenyl) heptanoate, 1,2-propylene glycol bis- [3- (3,5 Di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], neopentyl glycol bis- [3- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), glycerin-1-n-octadecanoate- 2,3-bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), pentaerythritol tetrakis- [3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) Propionate], 1,1,1-trimethylolethanetris- [3- (3,5-di-tert-butyl-4-hydroxypheny ) Propionate], sorbitol hexa- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl-7- (3-methyl-5-tert-butyl-4-hydroxy Phenyl) propionate, 2-stearoyloxyethyl-7- (3-methyl-5-tert-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediol bis-[(3 ', 5'-di- t-butyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis- (3,5-di-t-butyl-4-hydroxyhydrocinnamate), 3,9-bis [1,1-dimethyl-2- [ [beta]-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-tetrao Saspiro [5,5] -undecane, 2,4-di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate and 2-t-butyl -6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate.

  Examples of the thioether-based antioxidant include pentaerythrityl tetrakis (3-laurylthiopropionate), dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl. -3,3'-thiodipropionate.

  Examples of phosphorus antioxidants include tris (2,4-di-t-butylphenyl) phosphite, 2-[[2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo [d. , F] [1,3,2] dioxaphosphin-6-yl] oxy] -N, N-bis [2-[[2,4,8,10-tetrakis (1,1 dimethylethyl) dibenzo [D, f] [1,3,2] dioxaphosphin-6-yl] oxy] -ethyl] ethanamine, diphenyltridecyl phosphite, triphenyl phosphite, 2,2-methylenebis (4,6- Di-t-butylphenyl) octyl phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite DOO, cyclic neopentanetetraylbis (2,6-di -t- butyl-4-methylphenyl) phosphite and the like.

  The anti-blocking agent may be liquid, solid, or particulate as long as the anti-blocking agent, anti-blocking agent, slipping agent, lubricant, mold release agent, etc. express the slipperiness of the film. Particulate anti-blocking agent fine particles are preferred, and organic crosslinked polymer fine particles and inorganic fine particles can be used. The average particle diameter of the anti-blocking agent fine particles is preferably 0.01 to 30 μm, more preferably 0.05 to 10 μm, and still more preferably 0.1 to 5 μm. When the average particle size is less than 0.01 μm, the slipperiness is not sufficiently expressed, and when it exceeds 30 μm, fish eyes and the like are generated, the transparency of the film is not maintained, and the appearance may be poor. .

  The organic crosslinked polymer fine particles are not particularly limited, but monofunctional monomers such as methyl methacrylate and polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, and di (meth) acrylic. (Meth) acrylic crosslinked fine particles obtained by suspension polymerization of ethylene glycol acid (see Japanese Patent No. 4034157) and styrene monomers such as styrene, α-methylstyrene and divinylbenzene in the suspension polymerization (meth) Styrene- (meth) acrylic crosslinked fine particles obtained by copolymerization with acrylic monomers, or emulsion polymerization, soap-free emulsion polymerization, miniemulsion polymerization, dispersion polymerization, or seed polymerization of (meth) acrylic monomers or styrene monomers. (Meth) acrylic crosslinked particles obtained by Styrene - (meth) acrylic crosslinked fine particles.

  The inorganic fine particles are not particularly limited, and examples thereof include fine particles of fused silica, synthetic silica, zeolite, alumina, titania, and complex oxides thereof. The organic-inorganic composite fine particles are organic-inorganic composite fine particles composed of an organic portion and an inorganic portion. The ratio of the inorganic part is not particularly limited, but is preferably 0.5 to 90% by mass, more preferably 1 to 70% by mass, in terms of inorganic oxide, with respect to the mass of the organic / inorganic composite fine particles. %, More preferably in the range of 2 to 60% by mass. Inorganic oxide conversion indicating the proportion of the inorganic portion is expressed as a mass percentage obtained by measuring the mass before and after firing the organic / inorganic composite fine particles in an oxidizing atmosphere such as air at a high temperature (for example, 1000 ° C.). It is. If the proportion of the inorganic part of the organic-inorganic composite fine particles is less than the above range in terms of inorganic oxide, the organic-inorganic composite fine particles may become soft, which may be disadvantageous for the expression of slipperiness. If it exceeds the upper limit, it may be too hard and scratches may be caused on the film surface.

Such organic-inorganic composite fine particles are not particularly limited, but preferably an organic polymer skeleton described in JP-A-8-81561, and organic silicon in which a silicon atom is directly chemically bonded to at least one carbon atom in the organic polymer skeleton. An organic-inorganic composite fine particle containing 25 wt% or more of SiO ₂ constituting the polysiloxane skeleton, or a (meth) acryloxy group described in JP-A No. 2003-183337 Organic inorganic composite fine particles in which a vinyl polymer is contained in the structure of the inorganic fine particles made of polysiloxane fine particles having the above.

  The refractive index of the fine particles is preferably close to the refractive index of the amorphous thermoplastic resin in order to improve the transparency of the film. Specifically, the refractive index ratio is preferably 0.98 to 1.02, more preferably 0.99 to 1.01.

  The content of the antiblocking agent with respect to the amorphous thermoplastic resin is preferably 0.005 to 3% by mass, more preferably 0.01 to 2% by mass, and still more preferably 0.01 to 1% by mass. It is. When the content of the anti-blocking agent is less than 0.005% by mass, sufficient slipperiness cannot be obtained, and when it is more than 3% by mass, fish eyes and the like occur frequently on the film, resulting in poor appearance. .

  The timing for adding the additive to the amorphous thermoplastic resin is not particularly limited as long as the physical properties of the amorphous thermoplastic resin are not impaired. For example, an amorphous thermoplastic resin is added at a predetermined stage during production, or after an amorphous thermoplastic resin is produced, the amorphous thermoplastic resin and additives are heated and melted simultaneously. Kneading and kneading; heating and melting an amorphous thermoplastic resin and other components, adding an additive to the kneading; heating and melting the amorphous thermoplastic resin And a method of adding an additive or the like to knead there.

[Film made of amorphous thermoplastic resin]
The film comprising the amorphous thermoplastic resin of the present invention comprises the above amorphous thermoplastic resin.

  The thickness of the film made of an amorphous thermoplastic resin is, for example, 1 μm or more and less than 1000 μm, and preferably 10 μm or more and less than 350 μm. When the thickness is less than 1 μm, the strength as a film may be insufficient, and breakage or the like tends to occur when post-processing such as roll longitudinal stretching.

  The film made of an amorphous thermoplastic resin in the present invention is not particularly limited except that it is made of an amorphous thermoplastic resin, and can be produced by a known production method such as a solution casting method or a melt casting method. . A stretched film or a laminated film may be used.

  When trying to obtain a film using the solution casting method (solution casting method), the main component is an amorphous thermoplastic resin, an anti-blocking agent, and other polymers and other additives as required. It can be obtained by stirring and mixing the resin composition in a good solvent to make a uniform mixed solution, casting to a support film or drum and pre-drying until it has self-supporting property, then peeling off from the support film or drum and drying it can. Solvents used in the solution casting method (solution casting method) include, for example, chlorinated solvents such as chloroform and dichloromethane; aromatic solvents such as toluene, xylene, benzene, and mixed solvents thereof; methanol, ethanol, and isopropanol And alcohol solvents such as n-butanol and 2-butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl sulfoxide, dioxane, cyclohexanone, tetrahydrofuran, acetone, ethyl acetate, diethyl ether; These solvents may be used alone or in combination of two or more. Examples of the apparatus for performing the solution casting method (solution casting method) include a drum casting machine and a belt casting machine.

  As a specific example of the melt extrusion method, the kneader used for extrusion kneading is not particularly limited. For example, a known kneader such as a single screw extruder, a twin screw extruder, or a pressure kneader is used. Can be used. Alternatively, an amorphous thermoplastic resin and an additive as necessary may be added, and after pre-blending with a mixer such as an omni mixer, the resulting mixture may be extrusion kneaded from a kneader.

  Examples of the melt extrusion method include a T-die method and an inflation method, and the molding temperature at that time is preferably 200 to 350 ° C., more preferably 250 to 300 ° C., further preferably 255 to 300 ° C., particularly Preferably it is 260 to 300 degreeC.

  When the T-die method is used, a resin film wound into a roll can be obtained by attaching a T-die to the tip of the extruder and winding the film extruded from the T-die. At this time, it is also possible to control the temperature and speed of winding and to stretch (uniaxial stretching) in the extrusion direction of the film. Further, the film may be stretched in a direction perpendicular to the extrusion direction, and sequential biaxial stretching or simultaneous biaxial stretching may be performed.

  When an extruder is used for extrusion molding, the type is not particularly limited and may be uniaxial, biaxial, or multiaxial, but its L / D value is (L is the value of the extruder) In order to sufficiently plasticize the amorphous thermoplastic resin and obtain a good kneaded state, it is preferably 10 to 100, more preferably 15 to 80, in order to sufficiently plasticize the amorphous thermoplastic resin. Yes, more preferably 20 or more and 60 or less. When the L / D value is less than 10, the amorphous thermoplastic resin cannot be sufficiently plasticized and a good kneaded state may not be obtained. On the other hand, when the L / D value exceeds 100, the resin in the composition may be thermally decomposed due to excessive generation of shear heat with respect to the amorphous thermoplastic resin.

  In this case, the set temperature of the cylinder is preferably 200 ° C. or higher and 350 ° C. or lower, more preferably 250 ° C. or higher and 300 ° C. or lower. When the set temperature is less than 200 ° C., the melt viscosity of the amorphous thermoplastic resin becomes excessively high, and the productivity of the resin film decreases. On the other hand, if the set temperature exceeds 350 ° C., the resin in the amorphous thermoplastic resin may be thermally decomposed.

  When an extruder is used for extrusion molding, the shape is not particularly limited, but the extruder preferably has one or more open vent portions. By using such an extruder, the decomposition gas can be sucked from the open vent portion, and the amount of volatile components remaining in the obtained resin film can be reduced. In order to suck the decomposition gas from the open vent portion, for example, the open vent portion may be in a reduced pressure state, and the degree of pressure reduction is preferably in the range of 931 to 1.3 hPa as the pressure of the open vent portion, 798 A range of ˜13.3 hPa is more preferable. When the pressure in the open vent is higher than 931 hPa, volatile components or monomer components generated by the decomposition of the resin are likely to remain in the thermoplastic resin. On the other hand, it is industrially difficult to keep the pressure of the open vent part lower than 1.3 hPa.

  When producing the retardation film of the present invention, it is preferable to incorporate a filtration step such as filtration with a polymer filter. By incorporating the filtration step, foreign substances present in the thermoplastic resin can be removed, so that defects in the appearance of the obtained film can be reduced. In addition, at the time of filtration by a polymer filter, a thermoplastic resin will be in a high temperature molten state. For this reason, when passing through the polymer filter, the thermoplastic resin deteriorates, gas components and colored deterioration products formed by the deterioration flow into the composition, and the resulting film has holes, flow patterns, and flows. Defects such as streaks may be observed. This defect is particularly easily observed during continuous molding of a resin film. For this reason, when molding an amorphous thermoplastic resin filtered through a polymer filter, the molding temperature reduces the melt viscosity of the thermoplastic resin and shortens the residence time of the thermoplastic resin in the polymer filter. For example, it is 255-350 degreeC, and 260-320 degreeC is preferable.

  The configuration of the polymer filter is not particularly limited, but a polymer filter in which a large number of leaf disk filters are arranged in a housing can be suitably used. The filter material of the leaf disk type filter may be any of a type in which a metal fiber nonwoven fabric is sintered, a type in which metal powder is sintered, a type in which several metal meshes are laminated, or a hybrid type in which they are combined. The sintered type is most preferred.

  The filtration accuracy by the polymer filter is not particularly limited, but is usually 15 μm or less, preferably 10 μm or less, more preferably 5 μm or less. When the filtration accuracy is 1 μm or less, the residence time of the amorphous thermoplastic resin becomes longer, so that the thermal deterioration of the composition increases, and the productivity of the resin film decreases. On the other hand, if the filtration accuracy exceeds 15 μm, it is difficult to remove foreign substances in the thermoplastic resin.

  The filtration area with respect to the amount of resin processed per hour in the polymer filter is not particularly limited, and can be appropriately set according to the amount of processing of the amorphous thermoplastic resin. The filtration area is, for example, 0.001 to 0.15 m2 / (kg / hour).

  The shape of the polymer filter is not particularly limited. For example, an inner flow type having a plurality of resin flow ports and a resin flow path in the center pole; the inner peripheral surface of the leaf disk filter at a plurality of vertices or faces And an external flow type having a resin flow path on the outer surface of the center pole. In particular, it is preferable to use an external flow type in which the resin stays are small.

  Although there is no restriction | limiting in particular in the residence time of the thermoplastic resin in a polymer filter, Preferably it is 20 minutes or less, More preferably, it is 10 minutes or less, More preferably, it is 5 minutes or less. Further, the filter inlet pressure and the filter outlet pressure during filtration are, for example, 3 to 15 MPa and 0.3 to 10 MPa, respectively, and the pressure loss (the pressure difference between the filter inlet pressure and the outlet pressure) is 1 MPa to 15 MPa. A range is preferred. When the pressure loss is 1 MPa or less, the flow path through which the thermoplastic resin passes through the filter tends to be biased, and the quality of the obtained resin film tends to deteriorate. On the other hand, when the pressure loss exceeds 15 MPa, the polymer filter is easily damaged.

  What is necessary is just to set suitably the temperature of the amorphous thermoplastic resin introduce | transduced into a polymer filter according to the melt viscosity, for example, it is 250-300 degreeC, Preferably it is 255-300 degreeC, More preferably, it is 260. ~ 300 ° C.

  The specific process of obtaining a resin film with few foreign substances and colored substances by filtration using a polymer filter is not particularly limited. For example, (1) a process in which an amorphous thermoplastic resin is formed and filtered in a clean environment, followed by molding of the thermoplastic resin in a clean environment, (2) a thermoplastic having foreign matter or colored matter A process in which a resin is filtered in a clean environment, and then a thermoplastic resin is molded in a clean environment. (3) A thermoplastic resin having foreign matter or colored substances is filtered and molded in a clean environment at the same time. Process, etc. You may perform the filtration process of the thermoplastic resin by a polymer filter in multiple times for each process.

  When filtering an amorphous thermoplastic resin with a polymer filter, it is preferable to install a gear pump between the extruder and the polymer filter to stabilize the pressure of the thermoplastic resin in the filter.

It is preferable that the amorphous thermoplastic resin is extruded as it is after the production to obtain a resin film. Since the thermal history can be reduced as compared with the case of molding the resin film by remelting the obtained pellet after pelletizing the thermoplastic resin, the thermal deterioration of the thermoplastic resin can be suppressed. Moreover, in this method, since mixing of the foreign material from an environment can be suppressed, it can suppress that a foreign material exists in the obtained resin film, or coloring of the obtained resin film. A gear pump and a polymer filter are preferably arranged between the extruder and the T die.
[Method for producing retardation film]
The method for producing a retardation film of the present invention is a method for producing a retardation film in which a film made of an amorphous thermoplastic resin is longitudinally stretched by a roll stretching apparatus having a plurality of preheating rolls, wherein the roll stretching apparatus includes: The preheating roll immediately before stretching is a preheating roll that has been subjected to non-adhesive treatment on the surface, and the preheating temperature is (Tg−10 ° C.) or more and (Tg + 5 ° C.) or less [where Tg is the glass transition temperature (° C.) of the thermoplastic resin. ].

  Here, the roll longitudinal stretching is a roll longitudinal stretching machine having a plurality of preheating rolls, while heating the film with a preheating roll set to a predetermined temperature and raising the film temperature to the predetermined temperature, This is a method of stretching in the stretching section provided between the rolls by increasing the roll rotation speed of the stretching rolls than the roll rotation speed of the preheating roll. Although it does not specifically limit, FIG. 1 shows a schematic view of a roll arrangement of a roll longitudinal stretching machine having a plurality of preheating rolls used in the present invention. As an arrangement of the stretching rolls, an arrangement as shown in FIG. 3 is possible in addition to FIG.

  The plurality of preheating rolls of the roll longitudinal stretching apparatus used in the present invention includes a preheating roll having a surface roughness Ra of 0.1 to 0.5 μm. The surface roughness Ra is more preferably 0.15 to 0.45 μm, still more preferably 0.2 to 0.4 μm. When the surface roughness of the preheating roll is less than 0.1 μm, wrinkles on the streaks due to adhesion of the film to the roll may occur in the optical film obtained after stretching, and when it exceeds 0.5 μm, it is obtained. The smoothness of the film surface may be impaired. In the present invention, the surface roughness Ra of the roll was measured in a 95 × 70 μm visual field with a laser microscope (VK-9700 manufactured by Keyence) in accordance with JIS B0601.

  The preheating roll having a surface roughness Ra of 0.1 to 0.5 μm is preferably a preheating roll immediately before stretching, and only the preheating roll immediately before stretching is a preheating roll having a surface roughness Ra of 0.1 to 0.5 μm. More preferably it is. Since the preheating roll having a surface roughness Ra of 0.1 to 0.5 μm is a preheating roll immediately before stretching, the preheating temperature can be set high and the output of the heater can be kept low.

  The preheating roll having a surface roughness Ra of 0.1 to 0.5 μm is preferably a roll subjected to non-adhesive treatment. Non-adhesive treatment prevents the amorphous thermoplastic resin film with increased adhesion near the glass transition temperature from fusing to the roll, and the stepped surface due to film breakage and adhesion to the roll It becomes possible to suppress the occurrence of defects (step unevenness). Examples of the non-adhesive treatment include Teflon impregnation in which a roll is impregnated with a fluororesin such as Teflon (registered trademark), and surface treatment of rolls such as ceramic coating and Teflon coating.

  In the method for producing an optical film of the present invention, the preheating temperature is preferably (Tg−10 ° C.) or more and (Tg + 5 ° C.) or less [where Tg is the glass transition temperature (° C.) of the thermoplastic resin]. More preferably, it is (Tg−5 ° C.) or more and (Tg + 5 ° C.) or less, and more preferably (Tg−3 ° C.) or more and (Tg + 3 ° C.) or less. In addition, the preheating temperature in this invention is a film temperature when leaving the preheating roll just before extending | stretching, and measured the film center part 1 point | piece using Sato Keiki Seisakusho's radiation thermometer and SK-8110.

  In the method for producing an optical film of the present invention, the preheating temperature is preferably (T1-20 ° C.) or more and T1 or less [where T1 is the stretching temperature (° C.)]. More preferably, it is (T1-20 ° C.) or more and (T1-5 ° C.) or less, and more preferably (T1-20 ° C.) or more (T1-10 ° C.). In addition, the extending | stretching temperature in this invention shows the film temperature of the extending | stretching area center part, and measured the film center part 1 point | piece using the Sato Keiki Seisakusho radiation thermometer and SK-8110. When the preheating temperature is less than (T1-20 ° C.), the gradient of the film surface temperature from the peeling point of the preheating roll to the heater heating part which is the stretching part is large, the difference in thermal expansion becomes large, and wrinkles are formed at the film end. When the preheating temperature exceeds 1, the film may be stretched on the preheating roll in a state where the stretching point is not fixed, and wrinkles may be generated.

  In the method for producing an optical film of the present invention, it is possible to longitudinally stretch without heating after preheating with the preheating roll, but stretching with at least one heating heater selected from IR heaters, ceramic heaters, and hot air heaters. It is preferable to perform longitudinal stretching after heating to temperature. By heating with a heater, the stretching points are fixed by concentrating the heating points of the film, and uneven stretching can be reduced.

  The total number of preheating rolls in the roll longitudinal stretching apparatus used in the present invention is preferably 5 or more. When the number is less than 5, the heating effect is reduced, so that the film cannot be sufficiently preheated. Although it is possible to increase the roll diameter and roll temperature to increase the heating effect, it is not possible to escape the thermal expansion of the film due to heating, and wrinkles are generated and wrinkles are ruptured. Since it becomes easy, it is not preferable.

  When the distance between the center of the preheating roll (low speed roll) immediately before stretching and the center of the stretching roll (high speed roll) is the stretching section length A and the film width before longitudinal stretching is B, A / B is 0.05 or more and 0.5 or less. It is preferable that When it is smaller than 0.05, the length of the stretching section becomes too short with respect to the width of the film, and it is necessary to reduce the diameter of the stretching roll. In this case, since strength such as deflection of the roll is insufficient, uniform stretching cannot be performed. When the ratio is larger than 0.5, the influence of neck-in in the longitudinal stretching is exerted to the film center portion, which is disadvantageous for the retardation in the width direction and the uniformity of the thickness. More preferably, it is 0.1 or more and 0.45 or less.

  Further, transverse stretching may be applied after the roll longitudinal stretching of the present invention. For the transverse stretching, a tenter transverse stretching machine constituted by a clip traveling device for transverse stretching and an oven is preferably used. The clip travel device grips and conveys the lateral end portion of the film with the clip, and at the same time opens the guide rail of the clip travel device to extend the distance between the left and right two rows of clips. In addition, the simultaneous biaxial stretching machine which gave the expansion / contraction function of the clip also to the flow direction of the film may be used. The oven heats the film to a temperature at which the film can be stretched, and after the stretching, heat-treats the film as necessary, and then cools it.

  The thickness of the retardation film produced according to the present invention is, for example, 1 μm or more and less than 1000 μm, preferably 5 μm or more and less than 350 μm, more preferably 10 μm or more and less than 100 μm. When the thickness is less than 1 μm, the strength as a film may be insufficient, and breakage or the like is likely to occur during post-processing.

  The retardation film produced by the present invention has a high light transmittance. When the film has a thickness of 100 μm, the total light transmittance is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more.

  The retardation film produced according to the present invention is less colored, and the b value per 250 μm thickness is preferably 0.5 or less, more preferably 0.3 or less.

  The retardation film produced according to the present invention preferably has a haze of 5% or less, more preferably 3% or less. If the haze exceeds 5%, the transmittance is lowered and may not be suitable for optical applications.

  Various functional coating layers may be formed on the surface of the retardation film produced according to the present invention, if necessary. Functional coating layers include, for example, antistatic layers, adhesive layers, adhesive layers, easy adhesion layers, antiglare (non-glare) layers, antifouling layers such as photocatalyst layers, antireflection layers, hard coat layers, and UV shielding layers. Layers, heat ray shielding layers, electromagnetic wave shielding layers, gas barrier layers, and the like.

  The use of the retardation film produced according to the present invention is not particularly limited, but is used for displays such as liquid crystal displays, plasma displays, organic EL displays, field emission displays, rear projection televisions, quarter wavelength plates, 1/2 Suitable for wave plates, viewing angle control films, optical compensation films, etc. In particular, it is suitably used as a retardation film having a positive retardation or a negative retardation used in liquid crystal display devices such as VA, IPS, TN, and OCB modes.

<Measurement method>
The physical properties in the present invention are measured by the following method. The same method was used in the examples and comparative examples.
(Lactone ring content)
First, the dealcoholization reaction rate (lactone cyclization rate) is based on the weight loss that occurs when all hydroxyl groups are dealcoholated as methanol from the polymer composition obtained by polymerization, and weight loss starts in dynamic TG measurement. It calculated | required from the weight reduction by the dealcoholization reaction to 300 degreeC before decomposition | disassembly of a polymer starts from 150 degreeC before.

That is, in the dynamic TG measurement of the polymer having a lactone ring structure, the weight reduction rate between 150 ° C. and 300 ° C. is measured, and the obtained actual weight reduction rate is defined as (X). On the other hand, from the composition of the polymer, all the hydroxyl groups contained in the polymer composition are involved in the formation of the lactone ring, so that it becomes an alcohol and is dealcoholized. (Y) is the weight loss rate calculated on the assumption that the% dealcoholization reaction has occurred. The theoretical weight reduction rate (Y) is more specifically the molar ratio of raw material monomers having a structure (hydroxyl group) involved in the dealcoholization reaction in the polymer, that is, the raw material unit in the polymer composition. It can be calculated from the content of the monomer. These values (X, Y) are calculated from the dealcoholization formula:
1- (actual weight reduction rate (X) / theoretical weight reduction rate (Y))
Substituting into, the value is obtained and expressed in% to obtain the dealcoholization reaction rate.

Next, assuming that the lactone cyclization reaction was performed by the amount corresponding to the dealcoholization reaction rate, the content ratio (wt%) of the following formula lactone ring = B × A × MR / Mm
(In the formula, B is the weight content ratio of the raw material monomer structural unit having a structure (hydroxyl group) involved in lactone cyclization in the polymer before lactone cyclization, and MR is the lactone ring structural unit to be generated. Mm is the molecular weight of the raw material monomer having a structure (hydroxyl group) involved in lactone cyclization, and A is the dealcoholization reaction rate)
Thus, the lactone ring content ratio can be calculated.
(Weight average molecular weight)
The weight average molecular weight of the polymer was determined by polystyrene conversion of GPC (GPC system manufactured by Tosoh Corporation, chloroform solvent).
(Glass-transition temperature)
The glass transition temperature (Tg) of each sample was determined in accordance with JIS K7121 regulations. Specifically, using a differential scanning calorimeter (manufactured by Rigaku, DSC-8230), a sample of about 10 mg was heated from a normal temperature to 200 ° C. at a heating rate of 20 ° C./min in a nitrogen gas atmosphere. It calculated by the starting point method from the DSC curve. Α-alumina was used as a reference.
(Melt flow rate)
The melt flow rate was measured at a test temperature of 240 ° C. and a load of 10 kg based on JIS K7210.
(Film thickness)
Measurement was performed using a Digimatic Micrometer (manufactured by Mitutoyo Corporation).
(Film temperature)
One point of the film center portion was measured using a radiation thermometer, SK-8110, manufactured by Sato Keiki Seisakusho. In the present specification, the preheating temperature is the film temperature when leaving the preheating roll immediately before stretching, and the stretching temperature is the film temperature at the center of the stretching section.
(Phase difference)
The in-plane retardation value (R0) of the film at a wavelength of 589 nm was measured using KOBRA-WR manufactured by Oji Scientific Instruments. In addition, the average value and variation of the retardation in the stretching direction were calculated by measuring the central retardation at 20 points at intervals of 5 mm using a 10 cm long film. On the other hand, the average value and dispersion of the retardation in the width direction were calculated by measuring 40 points of phase difference of 20 cm width from the center of the film to 10 cm on both sides at intervals of 5 mm.
(Surface roughness)
Based on JIS B0601, Ra and Rz in a 95 * 70 micrometer visual field were measured with the laser microscope (VK-9700 by Keyence).
(Slip test)
Measured with reference to JIS K7125. Place a surface-treated sample plate on a plate-like heater that can be heated to a set temperature, place a 30 x 70 mm film with an auxiliary plate attached in the short direction, and place a weight on the film. (100 g) was placed as a weight for fixing the film. Then, a thread was attached to the auxiliary plate, and a cup was attached to the tip of the thread that passed through the pulley. A weight was placed in the cup, and the weight load when the film placed on the test piece started to move was measured. (See Figure 1)

EXAMPLES The present invention will be described in further detail below with reference to examples, but the present invention is not limited thereto.
[Production Example 1]
A 1 m2 reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe is charged with 204 kg of methyl methacrylate (MMA), 51 kg of methyl 2- (hydroxymethyl) acrylate (MHMA), and 249 kg of toluene. Then, while the temperature was raised to 105 ° C. while refluxing nitrogen and refluxed, 281 g of tertiary amyl peroxyisononanoate (manufactured by Atofina Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator. While a solution comprising a polymerization initiator and 5.4 kg of toluene was added dropwise over 2 hours, solution polymerization was performed under reflux (about 105 to 110 ° C.), followed by further aging for 4 hours.

  To the obtained polymer solution, 255 g of stearyl phosphate / distearyl phosphate mixture (manufactured by Sakai Chemicals, trade name: Phoslex A-18) was added and cyclized under reflux (about 90 to 110 ° C.) for 5 hours. A condensation reaction was performed.

  Subsequently, the polymer solution obtained by the cyclization condensation reaction was subjected to a vent having a barrel temperature of 250 ° C., a rotation speed of 150 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent of 1 and a forevent of 4 It is introduced into a type screw twin screw extruder (Φ = 42 mm, L / D = 42) at a processing rate of 15 kg / hour in terms of the amount of resin, subjected to cyclization condensation reaction and devolatilization in the extruder, and then extruded. Thus, a transparent pellet was obtained.

Next, using a single screw extruder of L / D = 36 consisting of a full flight type screw having a mixing portion of Φ50 mm and multi-flight structure, 90 parts of heat-resistant acrylic resin pellets, AS resin (Stylac AS783 manufactured by Asahi Kasei Chemicals) 10 Part and 0.04 part of zinc acetate were melt-extruded at a cylinder set temperature of 270 ° C. at a processing rate of 50 kg / hour to prepare resin pellets (1A). The obtained resin pellet (1A) had a mass average molecular weight of 132,000, a lactone ring content of 28.5%, a glass transition temperature of 125 ° C., and a refractive index of 1.506.
[Production Example 2]
A 1 m2 reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe is charged with 204 kg of methyl methacrylate (MMA), 51 kg of methyl 2- (hydroxymethyl) acrylate (MHMA), and 249 kg of toluene. Then, while the temperature was raised to 105 ° C. while refluxing nitrogen and refluxed, 281 g of tertiary amyl peroxyisononanoate (manufactured by Atofina Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator. While a solution comprising a polymerization initiator and 5.4 kg of toluene was added dropwise over 2 hours, solution polymerization was performed under reflux (about 105 to 110 ° C.), followed by further aging for 4 hours.

  To the obtained polymer solution, 255 g of stearyl phosphate / distearyl phosphate mixture (manufactured by Sakai Chemicals, trade name: Phoslex A-18) was added and cyclized under reflux (about 90 to 110 ° C.) for 5 hours. A condensation reaction was performed.

  Subsequently, the polymer solution obtained by the cyclization condensation reaction was subjected to a vent having a barrel temperature of 250 ° C., a rotation speed of 150 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent of 1 and a forevent of 4 It is introduced into a type screw twin screw extruder (Φ = 42 mm, L / D = 42) at a processing rate of 15 kg / hour in terms of the amount of resin, subjected to cyclization condensation reaction and devolatilization in the extruder, and then extruded. Thus, a transparent pellet was obtained.

Next, 66 parts of heat-resistant acrylic resin pellets, AS resin (Styrac AS783 manufactured by Asahi Kasei Chemicals Corporation) 34 using a single screw extruder of L / D = 36 consisting of a full flight type screw having a mixing part of Φ50 mm and multi-flight structure. Part and 0.04 part of zinc acetate were melt-extruded at a processing speed of 50 kg / hour at a cylinder set temperature of 270 ° C. to prepare resin pellets (2A). The obtained resin pellet (2A) had a mass average molecular weight of 135,000, a glass transition temperature of 121 ° C., and a melt flow rate of 14.9 g / 10 min.
[Production Example 3]
A 1 m2 reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe is charged with 204 kg of methyl methacrylate (MMA), 51 kg of methyl 2- (hydroxymethyl) acrylate (MHMA), and 249 kg of toluene. Then, while the temperature was raised to 105 ° C. while refluxing nitrogen and refluxed, 281 g of tertiary amyl peroxyisononanoate (manufactured by Atofina Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator. While a solution comprising a polymerization initiator and 5.4 kg of toluene was added dropwise over 2 hours, solution polymerization was performed under reflux (about 105 to 110 ° C.), followed by further aging for 4 hours.
To the obtained polymer solution, 255 g of stearyl phosphate / distearyl phosphate mixture (manufactured by Sakai Chemicals, trade name: Phoslex A-18) was added and cyclized under reflux (about 90 to 110 ° C.) for 5 hours. A condensation reaction was performed.

  Subsequently, the polymer solution obtained by the cyclization condensation reaction was subjected to a vent having a barrel temperature of 250 ° C., a rotation speed of 150 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent of 1 and a forevent of 4 It is introduced into a type screw twin screw extruder (Φ = 42 mm, L / D = 42) at a processing rate of 15 kg / hour in terms of the amount of resin, subjected to cyclization condensation reaction and devolatilization in the extruder, and then extruded. As a result, a transparent pellet (3A) was obtained.

The obtained resin pellet (3A) had a mass average molecular weight of 132,000, a lactone ring content ratio of 28.5%, and a glass transition temperature of 129 ° C.
[Production Example 4]
In a 1 m2 reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, nitrogen gas introduction pipe, 150 kg of methyl methacrylate (MMA), 75 kg of 2- (hydroxymethyl) methyl acrylate (MHMA), n-butyl methacrylate (BMA) 25 kg and 250 kg of toluene were charged. While introducing nitrogen gas into the reaction vessel, the temperature was raised to 105 ° C. and refluxed. As a polymerization initiator, 0.15 kg of t-amyl peroxyisononanoate (manufactured by Arkema Yoshitomi Corp., Luperox 570) was added. At the same time as the addition, an initiator solution consisting of 0.30 kg of t-amylperoxyisonononanoate (manufactured by Arkema Yoshitomi Corp., Luperox 570) and 3.5 kg of toluene was added dropwise over 6 hours under reflux (about 105 The solution was polymerized at a temperature of from C. to 111.degree. C. and aged over 2 hours after the initiator solution was dropped.

  The weight average molecular weight of the obtained polymer (4A) was 195000, and the polymerization reaction rate was 96.2%. The content of the structural unit of MHMA in the polymer (4A) is 30.2% by mass, the content of the MMA structural unit is 59.9% by mass, and the content of the BMA structural unit is 9.9% by mass. %Met.

  To the obtained polymer solution, 0.250 kg of an octyl phosphate / dioctyl phosphate mixture (manufactured by Sakai Chemical Co., Phoslex A-8) is added as a cyclization catalyst, and the mixture is refluxed at about 85 to 105 ° C. for 2 hours. The polycondensation reaction (reaction in which the polymer is subjected to intramolecular dealcoholization reaction to form a lactone ring structure in the polymer molecule) was performed.

Next, the obtained polymer solution was heated to 220 ° C. through a heat exchanger, barrel temperature 250 ° C., rotation speed 170 rpm, degree of vacuum 13.3 hPa to 400 hPa (10 mmHg to 300 mmHg), one rear vent, Introduced into a vent type screw twin screw extruder (φ = 42 mm, L / D = 42) with a fore vent number of 4 at a processing rate of 15 kg / hour in terms of resin amount, and the cyclocondensation reaction and desorption were carried out in the extruder. Volatile treatment was performed. At that time, 9.8 parts by mass of zinc octylate (manufactured by Nippon Kagaku Sangyo Co., Ltd., Nikka Octix Zinc 18%), Irganox 1010, C.I. A solution consisting of 8 parts by mass, 0.8 parts by mass of Adeka Stub AO-412S manufactured by Asahi Denka Kogyo Co., Ltd., and 88.6 parts by mass of toluene was poured at a rate of 0.46 kg / hour. By the devolatilization operation, a transparent resin pellet (4B) was obtained. The obtained resin pellet (4B) had a weight average molecular weight of 128,000, a glass transition temperature of 133 ° C., and a melt flow rate of 12.4 g / 10 min.
Example 1
The resin pellet (1A) obtained in Production Example 1 is melt-extruded at a temperature of 282 ° C. to form a 240 μm-thick unstretched film, and a roll stretching apparatus including seven preheating rolls and a heating IR heater continuously. A longitudinal uniaxial stretching was performed.

  Pre-rolling roll just before stretching uses a roll (surface roughness Ra: 0.25 μm, test piece slip test (130 ° C.): 37 g) whose surface is impregnated with Teflon (Teflock manufactured by Otec Co., Ltd.) to prevent film sticking. did.

  After preheating to a preheating temperature of 125 ° C., the film was heated with an IR heater to a film temperature of 140 ° C. and stretched 1.8 times to obtain a film having a thickness of 130 μm.

The surface roughness Rz of the obtained film was 2.05 μm. The results are shown in Table 1.
(Example 2)
Example except that a roll (surface roughness Ra: 0.30 μm, test piece slip test (130 ° C.): 50 g) having a ceramic coating (OAT manufactured by Nippon Coating Industry Co., Ltd.) on the surface of the preheating roll immediately before stretching is used. The film was formed and stretched by the same method as 1 to obtain a film having a thickness of 130 μm.

The film obtained had a surface roughness Rz of 2.38 μm. The results are shown in Table 1.
(Comparative Example 1)
Example 1 with the exception of using a roll (surface roughness Ra: 0.03 μm, test piece slidability test (130 ° C.): 200 g) obtained by subjecting the surface of the preheating roll immediately before stretching to hard chrome plating (manufactured by Otec). The film was formed and stretched in the same manner, but the film stuck to the surface of the preheating roll, and the film repeatedly adhered and peeled on the surface of the preheating roll, so that stable stretching could not be performed. For this reason, the obtained film had many wrinkles on the streaks, and the surface roughness Rz of the film was 15.06 μm. The results are shown in Table 1.
(Example 3)
The resin pellet (2A) obtained in Production Example 2 is melt-extruded at a temperature of 282 ° C. to form an unstretched film having a thickness of 240 μm, and the roll stretching apparatus is provided with seven preheating rolls and an IR heater for heating continuously. A longitudinal uniaxial stretching was performed.

  Pre-rolling roll just before stretching uses a roll (surface roughness Ra: 0.25 μm, test piece slip test (130 ° C.): 37 g) whose surface is impregnated with Teflon (Teflock manufactured by Otec Co., Ltd.) to prevent film sticking. did.

  After preheating so that the preheating temperature becomes 120 ° C., the film was heated by an IR heater to a film temperature of 138 ° C. and stretched 1.8 times to obtain a film having a thickness of 131 μm.

The surface roughness Rz of the obtained film was 2.63 μm, the average value of the in-plane retardation in the stretching direction was −84.5 nm, the variation was ± 2.1 nm, and the average of the measured values in the width direction was − 84.3 nm and variation was ± 2.0 nm. The results are shown in Table 1.
Example 4
Example except that a roll (surface roughness Ra: 0.30 μm, test piece slip test (130 ° C.): 50 g) having a ceramic coating (OAT manufactured by Nippon Coating Industry Co., Ltd.) on the surface of the preheating roll immediately before stretching is used. The film was formed and stretched in the same manner as in No. 3 to obtain a film having a thickness of 131 μm.

The surface roughness Rz of the obtained film was 2.69 μm, the average value of the in-plane retardation measured in the stretching direction was −85.7 nm, the variation was ± 1.9 nm, and the average measured value in the width direction was − The variation was 85.5 nm and the variation was ± 1.9 nm. The results are shown in Table 1.
(Comparative Example 2)
Example 3 with the exception of using a roll (surface roughness Ra: 0.03 μm, test piece slip test (130 ° C.): 200 g) with the surface of the preheating roll immediately before stretching being hard chrome plated (manufactured by Otec). The film was formed and stretched in the same manner, but the film stuck to the surface of the preheating roll, and the film repeatedly adhered and peeled on the surface of the preheating roll, so that stable stretching could not be performed. For this reason, the obtained film had many wrinkles on the streaks, and the surface roughness Rz of the film was 10.06 μm. The results are shown in Table 1.
(Example 5)
The film was formed and stretched in the same manner as in Example 3 except that the preheating temperature was 110 ° C.

The surface roughness Rz of the obtained film was 4.36 μm, the average value of the in-plane retardation measured in the stretching direction was −83.4 nm, the variation was ± 4.8 nm, and the average measured value in the width direction was 83. 0.8 nm and variation was ± 5.4 nm. The results are shown in Table 1.
(Example 6)
The film was formed and stretched in the same manner as in Example 3 except that the preheating temperature was 127 ° C.

The surface roughness Rz of the obtained film was 4.16 μm, the average value of the in-plane retardation in the stretching direction was −86.5 nm, the variation was ± 5.1 nm, and the average of the measured values in the width direction was − The variation was 86.8 nm and the variation was ± 5.7 nm. The results are shown in Table 1.
(Example 7)
The resin pellet (3A) obtained in Production Example 3 is melt-extruded at a temperature of 275 ° C. to form an unstretched film having a thickness of 240 μm, and the roll stretching apparatus is provided with seven preheating rolls and an IR heater for heating continuously. A longitudinal uniaxial stretching was performed.

  Pre-rolling roll just before stretching uses a roll (surface roughness Ra: 0.25 μm, test piece slip test (130 ° C.): 37 g) whose surface is impregnated with Teflon (Teflock manufactured by Otec Co., Ltd.) to prevent film sticking. did.

  After preheating to a preheating temperature of 130 ° C., the film was heated with an IR heater to a film temperature of 140 ° C. and stretched 1.8 times to obtain a film having a thickness of 130 μm.

The surface roughness Rz of the obtained film was 2.57 μm, the average measured value of the in-plane retardation in the stretching direction was 64.5 nm, the variation was ± 1.8 nm, and the average measured value in the width direction was 64.nm. The variation was 8 nm and the variation was ± 1.4 nm. The results are shown in Table 1.
(Comparative Example 3)
Example 7 with the exception of using a roll (surface roughness Ra: 0.03 μm, test piece slidability test (130 ° C.): 200 g) obtained by subjecting the surface of the preheating roll immediately before stretching to hard chrome plating (manufactured by Otec). The film was formed and stretched in the same manner, but the film stuck to the surface of the preheating roll, and the film repeatedly adhered and peeled on the surface of the preheating roll, so that stable stretching could not be performed. Therefore, the obtained film had many wrinkles on the stripes, and the surface roughness Rz of the film was 13.52 μm. The results are shown in Table 1.
(Comparative Example 4)
Except for heating with an IR heater to a film temperature of 155 ° C., film formation and stretching were performed in the same manner as in Example 7 to obtain a retardation film having a thickness of 131 μm.

The surface roughness Rz of the obtained film was 4.72 μm, the average value of the in-plane retardation measured in the stretching direction was 63.8 nm, the variation was ± 8.1 nm, and the average measured value in the width direction was 65. The variation was 2 nm and ± 6.3 nm. The results are shown in Table 1.
(Example 8)
The resin pellet (4B) obtained in Production Example 4 is melt-extruded at a temperature of 280 ° C. to form a 240 μm-thick unstretched film, and a roll stretching apparatus including seven preheating rolls and a heating IR heater continuously. A longitudinal uniaxial stretching was performed.

  The preheating roll immediately before stretching is a roll (surface roughness Ra: 0.30 μm, test piece slip test (130 ° C.): 50 g) whose surface is ceramic coated (OAT manufactured by Nippon Coating Industry Co., Ltd.) to prevent film sticking. used.

  After preheating to a preheating temperature of 130 ° C., the film was heated with an IR heater to a film temperature of 140 ° C. and stretched 1.8 times to obtain a film having a thickness of 130 μm.

The surface roughness Rz of the obtained film was 2.72 μm, the average value of the in-plane retardation measured in the stretching direction was 90.7 nm, the variation was ± 1.9 nm, and the average measured value in the width direction was 91. 0 nm and variation were ± 1.6 nm. The results are shown in Table 1.
Example 9
Except for preheating so that the preheating temperature becomes 120 ° C., film formation and stretching were performed in the same manner as in Example 8 to obtain a retardation film having a thickness of 130 μm.

The surface roughness Rz of the obtained film was 4.18 μm, and when the in-plane retardation was measured, the average of the measured values in the stretching direction was 64.3 nm, the variation was ± 4.6 nm, and the average of the measured values in the width direction Was 65.1 nm, and the variation was ± 3.7 nm. The results are shown in Table 1.
(Comparative Example 5)
A film having a thickness of 129 μm was obtained by performing film formation and stretching in the same manner as in Example 8 except that the film temperature was 128 ° C. by heating with an IR heater.

  The surface roughness Rz of the obtained film was 5.32 μm, the average value of the in-plane retardation measured in the stretching direction was 66.9 nm, the variation was ± 7.1 nm, and the average measured value in the width direction was 65. The variation was 2 nm and ± 5.9 nm. The results are shown in Table 1.

It is an example of the schematic of the roll longitudinal drawing machine used with the manufacturing method of this invention. It is an example of the outline of the roll longitudinal stretch which can be used with the manufacturing method of this invention. It is an example of the outline of the roll longitudinal stretch which can be used with the manufacturing method of this invention. It is the schematic of a slipperiness test.

1: Preheating roll immediately before stretching 2: Stretching roll 3: Nip roll 4: Heating heater 5: Film 6: Preheating roll 7: Cooling roll 8: Test piece 9: Weight (100 g)
10: Film 11: Clip 12: Octopus thread 13: Weight for evaluation 14: Plastic cup 15: Stopper 16: Panel heater (heating)

Claims (5)

  A method for producing a retardation film in which a film made of an amorphous thermoplastic resin is longitudinally stretched by a roll stretching apparatus having a plurality of preheating rolls, wherein the preheating roll immediately before stretching of the roll stretching apparatus is non-adhesive treated on the surface A method for producing a retardation film, wherein the preheating temperature is (Tg−10 ° C.) or more and (Tg + 5 ° C.) or less [where Tg is the glass transition temperature (° C.) of the thermoplastic resin].   The method for producing a retardation film according to claim 1, wherein the preheating temperature is (T1-20 ° C.) or more and T1 or less (where T1 is a stretching temperature (° C.)).   3. The production of a retardation film according to claim 1, wherein the film is pre-heated by the pre-heating roll, and then is stretched longitudinally after being heated to a stretching temperature by at least one heater selected from an IR heater, a ceramic heater, and a hot air heater. Method.   The method for producing a retardation film according to claim 1, wherein the amorphous thermoplastic resin contains an acrylic polymer as a main component.   The method for producing a retardation film according to claim 1, wherein the amorphous thermoplastic resin contains an acrylic polymer having a ring structure in the main chain as a main component.

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