JP2016000467A - Polystyrene-based film having rough surface and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a more inexpensive biaxially oriented syndiotactic polystyrene-based film having a rough surface.SOLUTION: The polystyrene-based film having a rough surface contains a syndiotactic polystyrene-based resin and a polycarbonate and is biaxially oriented. A method for producing the polystyrene-based film having a rough surface comprises the steps of: producing a precursor film containing the syndiotactic polystyrene-based resin and the polycarbonate; and simultaneously biaxially stretching the precursor film.

Description

  The present invention relates to a biaxially oriented syndiotactic polystyrene film having a rough surface.

  Syndiotactic polystyrene (SPS) -based resins are excellent in heat resistance and chemical resistance, and are thus used in various fields as molded articles and films. One such application is the use of SPS-based resins with low surface tension and low wettability to produce printed circuit boards, ceramic electronic components, semiconductor packages, and other various resin molded products. The use of a biaxially oriented SPS film has been studied as a release film for preventing fusion of a mold or a molding roll and a material to be molded.

  In such a release film, in order to impart a matte appearance to the surface of the molded product, the release film may be roughened and the surface irregularities may be transferred to the molded product. For example, Patent Documents 1 to 3 describe that a release film or a transfer film composed of a single layer film of an SPS resin or a multilayer film including an SPS resin layer is roughened.

JP2013-216777A JP 2013-215989 A JP 2011-094268 A

  As a method for roughening a biaxially oriented SPS film, a method is conventionally known in which a film is pressure-bonded to a metal roll engraved with a matte surface and the irregularities on the roll surface are transferred to the film surface. However, since a roughening step is required separately from the alignment step, there is room for improvement in terms of manufacturing cost.

  The present invention has been made in consideration of the above, and an object thereof is to provide a biaxially oriented SPS film having a rough surface at a lower cost.

  The polystyrene film having a rough surface of the present invention contains a syndiotactic polystyrene resin and a polycarbonate, and is biaxially oriented.

  Preferably, the glossiness of the polystyrene film having the rough surface is 90% or less. Here, the glossiness means 60-degree specular gloss, Gs (60 °) defined in JISZ8741: 1997. In addition, the average value of the value of the vertical direction (MD) and a horizontal direction (TD) is used for the glossiness in this invention.

  Preferably, the polystyrene film having the rough surface has a tensile elongation at room temperature of 5% or more. Here, the tensile elongation means the elongation when the sample is broken by the tensile test method described later. The tensile elongation is preferably 5% or more in both the machine direction (MD) and the transverse direction (TD).

  Preferably, the polystyrene film having the rough surface has a tensile elongation at 175 ° C. of 40% or more and 40% or more in each of the machine direction (MD) and the transverse direction (TD). Is preferred.

  Preferably, in the polystyrene film having the rough surface, the weight ratio of the syndiotactic polystyrene resin (a) to the polycarbonate (b) is (a) / (b) = 97/3 to 60/40. .

  Preferably, the polystyrene film having the rough surface further contains a styrene thermoplastic elastomer, and the weight ratio of the syndiotactic polystyrene resin (a) to the styrene thermoplastic elastomer (c) is (a). / (C) = 97 / 3-60 / 40, and the weight ratio of the syndiotactic polystyrene resin (a) to the total of the polycarbonate (b) and the styrene thermoplastic elastomer (c) is (a ) / (B + c) = 94/6 to 50/50.

  More preferably, the styrene thermoplastic elastomer is a hydrogenated styrene thermoplastic elastomer.

  The manufacturing method of the polystyrene-type film which has a rough surface of this invention has the process of manufacturing the precursor film containing a syndiotactic polystyrene-type resin and a polycarbonate, and the process of extending the said precursor film simultaneously biaxially.

  According to the present invention, a biaxially oriented syndiotactic polystyrene film having a rough surface can be used at a lower cost.

It is a figure for demonstrating the evaluation method when the polystyrene-type film which has the rough surface of this invention is used as a mold release film.

  The polystyrene film of this embodiment is a film whose surface is roughened by blending polycarbonate (PC) with syndiotactic polystyrene (SPS) resin and biaxially stretching.

  First, the composition of the film of this embodiment will be described.

  The SPS resin is a styrene polymer having a syndiotactic structure. The syndiotactic structure is a syndiotactic structure, that is, a three-dimensional structure in which phenyl groups or substituted phenyl groups that are side chains with respect to the main chain formed from carbon-carbon bonds are alternately located in opposite directions. Means structure.

The degree of tacticity (tacticity) of the SPS resin can be quantified by a nuclear magnetic resonance method ( ¹³ C-NMR method) using isotope carbon. The tacticity of the SPS resin measured by the ¹³ C-NMR method is a chain composed of several monomer units, for example, a dyad for two, a triad for three, a pentad for five. It can be shown by the proportion of the syndiotactic steric configuration (racemic dyad etc.). The SPS resin in the present invention is usually 75% or more, preferably 85% or more, racemic triad, 60% or more, preferably 75% or more, or 30% or more, preferably 50%, racemic pentad. It is a styrenic polymer having the above syndiotacticity.

  The types of styrenic polymers as SPS resins include polystyrene, poly (alkyl styrene), poly (halogenated styrene), poly (halogenated alkyl styrene), poly (alkoxy styrene), poly (vinyl benzoate), These hydrogenated polymers and the like and mixtures thereof, or copolymers containing these as main components can be mentioned. Poly (alkyl styrene) includes poly (methyl styrene), poly (ethyl styrene), poly (isopropyl styrene), poly (tertiary butyl styrene), poly (phenyl styrene), poly (vinyl naphthalene), poly (vinyl styrene) ) And the like. Examples of poly (halogenated styrene) include poly (chlorostyrene), poly (bromostyrene), poly (fluorostyrene), and the like. Examples of poly (halogenated alkylstyrene) include poly (chloromethylstyrene). Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene).

  The weight average molecular weight of the SPS resin constituting the plastic film according to the present invention is 10,000 to 3,000,000, preferably 30,000 to 1,500,000, particularly preferably 50,000 to 500,000. It is. The glass transition temperature of the SPS resin is 60 to 140 ° C, preferably 70 to 130 ° C. The melting point of the SPS resin is 200 to 320 ° C, preferably 220 to 280 ° C. In this specification, values measured according to JISK7121 are used for the glass transition temperature and melting point of the resin.

  As the polycarbonate (PC), various commercially available products can be used. The blending amount of PC is preferably such that the weight ratio of the SPS resin and PC is SPS / PC = 97/3 to 60/40, and 97/3 to 65/35, 97/3 to 70/30, More preferably, it is 97 / 3-80 / 20. If the amount of PC is too small, a sufficiently roughened film cannot be obtained. On the other hand, when there are too many compounding quantities of PC, characteristics, such as heat resistance, chemical resistance, and low surface tension which are the characteristics of SPS type resin, will fall.

  The film of the present invention may contain a polystyrene-based thermoplastic elastomer (TPS). TPS is a thermoplastic elastomer (TPE) in which the hard segment is made of polystyrene, which makes it difficult to cause appearance defects when blended into an SPS film.

  By blending TPS, the flexibility of the film can be improved. Specifically, by blending TPS, the tensile elastic modulus at 175 ° C. can be reduced. Since blending PC with SPS tends to increase the tensile modulus at high temperatures, reducing the tensile modulus at 175 ° C. by blending TPS is particularly useful when the film of this embodiment is used as a release film. It is valid.

  It is preferable to use a hydrogenated TPS. Thereby, the heat resistance of TPS is improved, and it is possible to prevent an unexpected reaction from occurring in the SPS resin melting / extrusion process performed at a high temperature. As hydrogenated TPS, polystyrene-poly (ethylene / butylene) -polystyrene (TPS-SEBS), polystyrene-poly (ethylene / propylene) -polystyrene (TPS-SEPS), polystyrene-poly (ethylene-ethylene / propylene) -polystyrene. Various types having different soft segments such as (TPS-SEEPS) and polystyrene-poly (ethylene / propylene) -polystyrene (TPS-SEP) can be used.

  When blending TPS, the blending amount is preferably such that the weight ratio of the SPS resin to TPS is SPS / TPS = 97 / 3-60 / 40, and 97 / 3-65 / 35, 97/3. It is more preferable to set to 70/30, 97/3 to 80/20. If the amount of TPS is too small, the flexibility cannot be sufficiently improved. On the other hand, when there are too many compounding quantities of TPS, characteristics, such as heat resistance, chemical resistance, and low surface tension which are the characteristics of SPS type resin, will fall.

  Even when TPS is blended, the weight ratio of the SPS resin and the total of PC and TPS is preferably SPS / (PC + TPS) = 50/50 or more, and more preferably 60/40 or more. It is particularly preferably 75/25 or more. This is because characteristics such as heat resistance, chemical resistance, and low surface tension, which are characteristics of the SPS resin, are not deteriorated.

  Each of the SPS resin, PC, and TPS contained in the film of the present embodiment may be a mixture of two or more different types of resins.

  Moreover, you may contain resin other than the above in the range which does not have a practical bad influence on the heat resistance, chemical resistance, low surface tension, etc. which are the characteristics of an SPS type film. Even in that case, the content ratio of the SPS resin to the total polymer component in the plastic film is preferably 50% by weight or more, more preferably 60% by weight or more, and particularly preferably 75% by weight or more. preferable.

  In addition to the above-described polymers, the film of the present embodiment has an antioxidant, an ultraviolet absorber, a light stabilizer, a lubricant, an antistatic agent, an inorganic filler, a colorant, a crystal nucleating agent, a difficulty, and the like. You may contain additives, such as a flame retardant.

  Next, the characteristics of the film of this embodiment will be described.

  The thickness of the film is preferably 5 to 300 μm because it can be used for many applications and can be easily manufactured and handled. Moreover, when using the film of this embodiment as a release film, it is preferable to set it as 10-100 micrometers. The thickness of the biaxially stretched film used as a release film is typically 50 μm.

  The degree of roughening of the film can be represented by 60 ° specular gloss, Gs (60 °) defined in JISZ8741: 1997. As an index of the degree of roughening, a measurement value relating to the surface shape such as arithmetic average roughness Ra can be used, but as described later, the degree of matte tone felt visually is better when using glossiness. Can be represented.

  The glossiness required for the film is determined according to the application, and is preferably 90% or less so as not to feel “light” on the surface of the molded product when used as a film surface or a release film. Further, in order to give a matte appearance to the surface of the molded product when used as a release film, it is preferably 60% or less, more preferably 35% or less, and 30% or less. Is particularly preferred.

  The tensile elongation of the film is preferably 5% or more at room temperature, more preferably 10% or more, and particularly preferably 15% or more. The tensile elongation at room temperature is particularly related to the handleability of the film. If the tensile elongation at room temperature is too small, the film is easily damaged during handling. Therefore, it is preferable that a larger product has a higher tensile elongation.

  When the film of the present embodiment is used as a release film, the tensile elongation of the film is preferably 40% or more, more preferably 60% or more, and particularly preferably 80% at 175 ° C. That's it. Further, in each of the vertical direction (MD) and the horizontal direction (TD), each is 40% or more, more preferably 60% or more, and particularly preferably 80% or more. If the tensile elongation at 175 ° C. is too small, it cannot sufficiently follow the unevenness of the mold or the like. It is required that the tensile elongation at 175 ° C. is larger as the unevenness of the mold or the like becomes deeper.

  The tensile elongation of the film can be determined by a tensile test. In this specification, the tensile elongation means the elongation at break when a test piece having a shape defined in ASTM D1708-6a is pulled at a speed of 200 mm / min.

  When the film of this embodiment is used as a release film, the wettability is preferably 40 mN / m or less, more preferably 38 mN / m or less, and particularly preferably 35 mN / m or less. The low wettability of the film of this embodiment is due to the characteristics of the SPS resin. The wettability of the SPS resin is typically 32 to 33 mN / m. The wettability can be measured by a method defined in JIS K6768: 1999.

  Further, when the film of the present embodiment is used as a release film, the absolute value of the thermal shrinkage at 175 ° C. is preferably 15% or less, more preferably 10% or less, and particularly preferably 8% or less. is there. The absolute value of the heat shrinkage rate is preferably within the above range in both the MD direction and the TD direction. Further, the difference between the MD direction and the TD direction of the heat shrinkage rate is not particularly problematic if the absolute value in each direction is in the above range, but the smaller the difference is, the easier the setting of the molding process conditions is It is preferable because of its merit. The absolute value of the difference between the MD direction and the TD direction of the heat shrinkage rate is more preferably 8% or less.

  In this specification, the thermal shrinkage rate at 175 ° C. is the thermal shrinkage rate in each direction of the MD direction and the TD direction when the test piece (150 mm × 150 mm) is left for 30 minutes at an ambient temperature of 175 ° C. Is measured by the method described below. As for the value of the heat shrinkage rate, a positive value means shrinkage, and a negative value means expansion.

  Next, the manufacturing method of the film of this embodiment is demonstrated.

  The film of the present embodiment is prepared by melting and kneading the above resin-containing composition to produce a precursor film (raw film before stretching), and then performing a biaxial stretching process on the obtained precursor film. Can be manufactured.

  A well-known method can be employ | adopted for the manufacturing method of a precursor film. For example, a mixture composed of desired components may be melted and kneaded with an extruder, the kneaded material is extruded from a T die, and then cooled.

  The biaxial stretching step is a step of performing stretching in the biaxial direction of the film, and then optionally heat setting. By this biaxial stretching step, the SPS resin is crystallized, the glass transition temperature of the film is increased, and the mechanical strength is improved. Moreover, the film of this embodiment is roughened by the biaxial stretching process.

  Biaxial stretching is performed in the MD direction and TD direction of the film. The stretching method includes a sequential biaxial stretching method and a simultaneous biaxial stretching method, but it is preferable to use the simultaneous biaxial stretching method because the heat-resistant dimensional stability and tensile elongation can be further improved. For example, according to the simultaneous biaxial stretching method, the difference between the MD direction and the TD direction of the absolute value of the heat shrinkage rate can be easily reduced to 8% or less. When performing biaxial stretching, conditions suitable for obtaining a desired coefficient of thermal expansion and the like can be selected for the stretching ratio, stretching temperature, and stretching speed.

  The heat setting is a process for fixing the orientation of the polymer molecules by holding the stretched film at a temperature equal to or higher than the stretching temperature. The heat treatment temperature, time, and relaxation rate can be selected as appropriate conditions for obtaining a desired heat shrinkage rate and the like.

  In the production of the film of this embodiment, another roughening step may be performed after the stretching step. For example, after the stretching step, the surface may be pressure-bonded to a sculpted roll. Thereby, in addition to the surface unevenness | corrugation by biaxial stretching, the unevenness | corrugation which provides larger unevenness, for example, larger Ra can be provided to the film surface.

  Hereinafter, the present invention will be described more specifically with reference to examples.

  A precursor film was obtained by melting and extruding SPS alone or a full compound obtained by previously kneading a resin other than SPS and SPS at 280 ° C. using an extruder with a T-die attached to the tip. . This precursor film was simultaneously biaxially stretched in the machine direction (MD) and the transverse direction (TD) at 110 ° C. at a stretch rate of about 500% / min. After stretching, relaxation treatment was performed at 210 ° C. at 0.95 times in the machine direction (MD) and 0.95 times in the transverse direction (TD) to obtain a simultaneous biaxially stretched SPS resin film having a thickness of about 50 μm. The glass transition temperature of the film after stretching was 170 ° C. or higher in all the comparative examples and examples.

Table 1 shows the manufacturing conditions and the glossiness of the obtained film. The resin used is as follows.
SPS: trade name “Zarek 142ZE”, Idemitsu Kosan Co., Ltd. Glass transition temperature 95 ° C, melting point 247 ° C
PC (E): Trade name “Iupilon E-2000”, Mitsubishi Engineering Plastics Corporation. The melt volume rate (MVR) = ^5cm 3/10 minutes. MVR is a value measured at a measurement temperature of 300 ° C. and a measurement load of 1.20 kgf based on ISO-1133 (hereinafter the same).
PC (S): Trade name “Iupilon S-3000”, Mitsubishi Engineering Plastics Corporation. MVR = 14 cm < ³ > / 10 minutes.
· PC (K): trade name "Panlite K-1300, Teijin Limited .MVR = 2.8cm ^3/10 minutes.
・ HDPE: Trade name “Hi-Zex 7000F”, Prime Polymer Co., Ltd. ・ PP: Trade name “Prime Polypro F113G”, Prime Polymer Co., Ltd. ・ PET: Trade name “MA-2103”, Unitika Ltd. ・ PBT: Trade name “Nova Duran 5020 ", Mitsubishi Engineering Plastics Co., Ltd. PMMA: Trade name" Acrypet MD ", Mitsubishi Rayon Co., Ltd. PA6: Trade name" UBE nylon 1030B ", Ube Industries, Ltd.

  The appearance of the precursor film is confirmed by visual inspection, and “○” indicates that there are no defects that cause problems in practice, “△” indicates that defects are scattered, and “×” indicates that most defects are defects. It was. The gloss of the film after stretching was 60 ° specular gloss, Gs (60 °) as defined in JISZ8741: 1997, and was measured using a gloss meter (Unigloss 60, Konica Minolta, Inc.).

  In Examples 1 to 12 in which PC is blended with SPS, the glossiness is lower than that of Comparative Example 1 consisting only of SPS. In particular, in Examples 1 to 6 and Examples 8 to 12, the glossiness was in the range of 13 to 35%, and it was easily confirmed that a matte tone was imparted by visual observation. In Comparative Examples 5 and 7, the glossiness was low, but the appearance was defective at the stage of the precursor film. In these comparative examples, it is considered that the dispersion of the blended resin component was not uniform, and the glossiness was low due to the presence of defects such as aggregates, microprojections, and micropores.

  Next, Table 2 shows the surface roughness and glossiness of Comparative Example 1 and Examples 3, 4, 5, and 8. In the table, "Unstretched film" is a precursor film after melting / extrusion and before stretching, "Stretched film" is a film after stretching and heat setting, and "Molded product" is an epoxy resin plate with the stretched film as a release film. The product to be molded when heat-press molding, “post-molding film” is the film after use as the release film, “post-heating film at 175 ° C.” is the film after holding the stretched film at 175 ° C. for 5 minutes , About the data. The surface roughness is an arithmetic average roughness Ra, a maximum height Ry, a ten-point average roughness Rz, and an average interval Sm of irregularities as defined in JIS B0601: 1994. The surface roughness was measured using a surface roughness measuring instrument (Handy Surf, Tokyo Seimitsu Co., Ltd.).

In the evaluation, a hot press molded product of an epoxy resin plate was prepared as follows. As shown in FIG. 1, when the epoxy resin flake 1 was hot press-molded with the upper and lower molds 2, 3, a film 4 was interposed between the flake 1 and the molds 2, 3. The film 4 was held and fixed outside the mold. During pressing, the approach of the dies 2 and 3 was limited by the spacer 5. After the press molding, the molded body was taken out and immediately the film 4 was peeled off from the molded body. The press conditions were as follows: the temperature of the molds 2 and 3 was 175 ° C .; the press pressure was 100 kgf / cm ² ; the press clearance was 1 mm; and the press time was 3 minutes.

  From Table 2, it can be seen that the film of the example maintains a low glossiness even after molding or after holding at 175 ° C. Moreover, the glossiness of the molded product is low, and it can be seen that the surface irregularities of the film are accurately transferred to the molding target.

  From Table 2, it can be seen that in the film or molded product of the example with low glossiness, Ra, Ry and Rz are large and Sm is small as compared with Comparative Example 1. However, the difference between the individual parameters is not very large. For example, Ra of the film of an Example is 0.17-0.30 micrometers, and the difference with Ra (0.1 micrometer) of the film of the comparative example 1 is not so large. Therefore, it is not easy to judge the degree of matte tone using the measured value of the surface roughness as an index. Further, the degree of matte tone that can be perceived visually has a good correlation with the numerical value of glossiness. Therefore, it is considered that the glossiness is the most suitable as an index of the degree of roughening of the film of the embodiment.

  Next, an example in which PC and TPS are blended with SPS will be described. A full compound in which SPS, PC, and TPS were previously kneaded was prepared, and thereafter a film was prepared in the same manner as the above-described film not containing TPS.

Table 3 shows the manufacturing conditions and the glossiness of the obtained film. The TPS used is as follows.
-TPS (S): TPS-SEEPS, trade name "Septon 4055", Kuraray Co., Ltd. TPS (D): TPS-SEBS, trade name "Dynaron 8903P", JSR Corporation-TPS (T): TPS-SEBS, Product name “Tuftec H1041”, Asahi Kasei Corporation

  In Examples 13 to 17 in which PC and TPS were blended with SPS, the glossiness was in the range of 12 to 22%, and it was easily confirmed that a matte tone was imparted visually. In addition, the glossiness of the molded product when the epoxy resin plate is hot-press molded using the stretched film of Examples 13 to 17 as a release film is low, and the surface irregularities of the film are accurately transferred to the molded body. I understand that.

  Next, Table 4 shows the wettability, heat shrinkage rate, and tensile properties of the comparative examples and examples.

  In Table 4, the wettability was measured in accordance with JISK6768: 1999.

  The thermal contraction rate was measured as follows. Two straight lines having a length of 100 mm were drawn on a test piece (film; 150 mm × 150 mm) so as to be parallel to the MD direction and the TD direction, respectively, and to cross each other at the midpoint. This test piece was left in a standard state (temperature 23 ° C. × humidity 50%) for 2 hours, and then the length of the straight line before the test was measured. Subsequently, the substrate was left standing in a suspended state in which a corner was supported in a hot air circulation oven set at 175 ° C. for 30 minutes, then taken out and cooled to a standard state for 2 hours. Thereafter, the length of the straight line in each direction was measured, the amount of change from the length before the test was determined, and the thermal shrinkage rate was determined as the ratio of the amount of change to the length before the test.

  Tensile properties were measured as follows. A test piece having a shape defined in ASTM D1708-6a (the length of the gripping part is 16 mm) is prepared, and using a tensile tester (Autograph “AG-10kNIS MO”, Shimadzu Corporation), 200 mm / min. Done at speed. The test was performed three times for each of the MD direction and the TD direction, and the average was taken. The test at room temperature was performed in a laboratory room temperature of 23 ° C. The test at 175 ° C. was carried out in a thermostatic chamber set at 175 ° C., and the test piece was held via an aluminum foil in order to prevent the film from sticking to the grip (chuck) of the test apparatus. The tensile elongation is the elongation when the sample breaks.

  From Table 4, it turns out that the softness | flexibility of a film is improving by mix | blending TPS. This is particularly preferable for use as a release film in order to transfer the unevenness of the molding die surface to the material to be molded with high accuracy and transfer the matte surface of the film surface to the material to be molded with high accuracy.

  The present invention is not limited to the above-described embodiments and examples, and various modifications can be made within the scope of the technical idea.

  The polystyrene film having a rough surface of the present invention is particularly useful as a release film for molding an epoxy resin printed board or the like, but its application is not limited to this. In addition to the above-described use as a release film, it is useful for various applications that require a rough surface. Also, when used as a release film, the type of plastic constituting the material to be molded is not particularly limited. For example, epoxy resin, phenol resin, melamine resin, urea resin, alkyd resin, polyimide resin, polyester resin, polyurethane It can be used for molding of resin, acrylic resin and the like.

Claims (8)

Containing syndiotactic polystyrene resin and polycarbonate,
Biaxially oriented,
Polystyrene film having a rough surface. Glossiness is 90% or less,
A polystyrene-based film having the rough surface according to claim 1. The tensile elongation at room temperature is 5% or more,
A polystyrene-based film having the rough surface according to claim 1. The tensile elongation at 175 ° C. is 40% or more in each of the machine direction (MD) and the transverse direction (TD).
The polystyrene-type film which has a rough surface as described in any one of Claims 1-3. The weight ratio of the syndiotactic polystyrene resin (a) and the polycarbonate (b) is (a) / (b) = 97 / 3-60 / 40,
The polystyrene-type film which has a rough surface as described in any one of Claims 1-4. It further contains a styrenic thermoplastic elastomer,
The weight ratio of the syndiotactic polystyrene resin (a) and the styrene thermoplastic elastomer (c) is (a) / (c) = 97 / 3-60 / 40,
The weight ratio of the syndiotactic polystyrene resin (a) to the total of the polycarbonate (b) and the styrene thermoplastic elastomer (c) is (a) / (b + c) = 94/6 to 50/50. ,
The polystyrene-type film which has a rough surface as described in any one of Claims 1-5. The styrenic thermoplastic elastomer is a hydrogenated styrenic thermoplastic elastomer,
A polystyrene-based film having the rough surface according to claim 6. Producing a precursor film containing a syndiotactic polystyrene-based resin and a polycarbonate;
And simultaneously biaxially stretching the precursor film,
A method for producing a polystyrene film having a rough surface.

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