JP2863223B2 - Method for producing stretched film or sheet - Google Patents

Description

The present invention relates to a method for producing a stretched film or sheet,
More specifically, the present invention relates to a method for producing a stretched film or sheet of a styrene-based polymer having a syndiotactic structure without unevenness in thickness and with high productivity.

[Problems to be solved by conventional technology and invention]

In the production of biaxially stretched films, increasing productivity and reducing costs is an important issue as well as quality improvement, and therefore, the peripheral speed of the surface of a rotating cooling medium (such as a cooling roll) must be increased. It is known that improving the film forming speed is most effective.

On the other hand, it is known that productivity can be improved by using an electrostatically imprinted cast during the production of a polyester stretched film (Japanese Patent Application Laid-Open Nos. 50-136365 and 50/136365).
Nos. 139,722 and 51-70,269).

By the way, a styrenic polymer having a syndiotactic structure recently developed by the group of the present inventors (hereinafter referred to as SP).
Is sometimes referred to as S) is a polymer having excellent heat resistance, water resistance and electrical insulation, and having a small amount of oligomers.
Various applications are expected, and several SPS stretching methods have been proposed (JP-A-1-110122, JP-A-1-182346). However, this SPS is crystalline unlike a general atactic styrene-based polymer (aPS), and its crystallization temperature and crystallization temperature are higher than those of other crystalline resins (polypropylene, polyethylene terephthalate, nylon, etc.). Conventional methods have not always yielded satisfactory results due to differences in speed, viscosity, and the like.

In view of the above, the inventors of the present invention have conducted intensive studies in consideration of the crystallization speed and crystallization temperature of a styrene-based polymer having a syndiotactic structure in order to produce a stretched film having small thickness unevenness with high productivity.

[Means for solving the problem]

As a result, it has been found that when forming an SPS film, the above-mentioned problems can be solved by electrostatically casting an SPS having a constant melt viscosity at a specific temperature. The present invention has been completed based on such findings.

That is, the present invention has a syndiotactic structure,
And a melt viscosity at 300 ° C. and a shear rate of 200 / sec is 1 × 10 ² to 1
× 10 ⁶ Poise styrene polymer or a composition thereof is heated and melted and extruded into a sheet. Then, the obtained sheet is at least 30 ° C. lower than the crystallization temperature and 30 ° C. lower than the melting point.
An object of the present invention is to provide a method for producing a stretched film or sheet, wherein the sheet is cooled, solidified by electrostatic imprinting at a temperature not higher than 0 ° C., and then the sheet is stretched.

In the present invention, a styrene polymer having a syndiotactic structure is used as a main component of the material.
Here, the syndiotactic structure in the styrenic polymer having the syndiotactic structure refers to phenyl whose stereochemical structure is a syndiotactic structure, that is, a side chain with respect to a main chain formed from carbon-carbon bonds. Groups and substituted phenyl groups have a steric structure in which they are alternately located in opposite directions, and their tacticity is quantified by nuclear magnetic resonance ( ^13C -NMR) using isotope carbon. ¹³
Tacticity measured by the C-NMR method can be represented by the abundance ratio of a plurality of continuous structural units, for example, dyads for two, triads for three, and pentads for five. The styrenic polymer having a syndiotactic structure referred to in the present invention generally means a racemic diad of 75% or more, preferably 85% or more, or a racemic pentad of 30% or more, preferably 50% or more. Polystyrene with tacticity,
Poly (alkyl styrene), poly (halogenated styrene), poly (halogenated alkyl styrene), poly (alkoxy styrene), poly (vinyl benzoate), their hydrogenated polymers and mixtures thereof, or A copolymer as a component is referred to. Here, poly (alkylstyrene) includes poly (methylstyrene), poly (ethylstyrene), poly (isopropylstyrene), poly (tertiary butylstyrene), poly (phenylstyrene), poly (vinylnaphthalene), Examples include poly (vinyl styrene), and examples of poly (halogenated styrene) include poly (chlorostyrene), poly (bromostyrene), and poly (fluorostyrene). Examples of poly (halogenated alkylstyrene) include poly (chloromethylstyrene), and examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene). Further, as comonomer components of the copolymer containing these structural units, in addition to the above-mentioned styrene-based polymer monomers, ethylene, propylene, butene, hexene,
Examples include olefin monomers such as octene, diene monomers such as butadiene and isoprene, cyclic olefin monomers, cyclic diene monomers, and polar vinyl monomers such as methyl methacrylate, maleic anhydride, and acrylonitrile.

Among these, particularly preferred styrene polymers include polystyrene, poly (p-methylstyrene),
Poly (m-methylstyrene), poly (p-tert-butylstyrene), poly (p-chlorostyrene), poly (m-chlorostyrene), poly (p-fluorostyrene), hydrogenated polystyrene and their structural units And a copolymer containing

Although the molecular weight of the styrene-based polymer is not particularly limited, it has a weight average molecular weight of 60,000 or more and 3,000,000 or less, preferably 80,000 or more and 1,500,000 or less. Further, the molecular weight distribution is not limited in its width and may be any of various ones. Particularly preferred is a weight average molecular weight / number average molecular weight of 1.5 or more and 8 or less.

Furthermore, in the present invention, among these styrene-based polymers, the melt viscosity at a temperature of 300 ° C. and a shear rate of 200 / sec is 1 × 10 ²
１1 × 10 ⁶ poise, preferably 1 × 10 ^{2 to} 5 × 10 ⁵ poise.

When the melt viscosity at 300 ° C. and a shear rate of 200 / sec is less than 1 × 10 ² poise, the gap of the elastic modulus at the time of change from the molten state to the solidified state is large and the film can be formed stably. Becomes difficult. If it exceeds 1 × 10 ⁶ poise, melt fracture tends to occur during melt extrusion.

Styrene-based polymers having such a syndiotactic structure can be produced, for example, by using a titanium compound and a condensation product of water and a trialkylaluminum as a catalyst in an inert hydrocarbon solvent or in the absence of a solvent. (A monomer corresponding to the styrene-based polymer) (JP-A-62-187708). In addition, poly (halogenated alkylstyrene) can be obtained by the method described in JP-A-1-46912, and hydrogenated polymers thereof can be obtained by the method described in JP-A-1-178505.

The material used in the present invention, in addition to the above SPS,
In consideration of moldability, mechanical properties, surface properties, and the like, an antioxidant, an antistatic agent, a flame retardant, an inorganic filler, and other resins may be appropriately compounded as long as the object of the present invention is not impaired. it can.

Here, there are various resins as other resins. For example, the styrene-based polymer having an atactic structure, the styrene-based polymer having an isotactic structure, and polyphenylene ether are the styrene-based polymers having a syndiotactic structure. It is easy to be compatible with coalescence, is effective in controlling crystallization when preparing a preform for stretching, improves stretchability thereafter, easily controls stretching conditions, and provides a film with excellent mechanical properties. Obtainable. Among them, when a styrenic polymer having an atactic structure and / or an isotactic structure is contained, a styrene-based polymer having a syndiotactic structure is preferably used. The content ratio of these compatible resin components may be 70 to 1% by weight, particularly preferably 50 to 2% by weight. Here, when the content ratio of the compatible resin component is more than 70% by weight, heat resistance and the like, which are advantages of the styrene-based polymer having a syndiotactic structure, are not preferable. Examples of the incompatible resin include polyolefins such as polyethylene, polypropylene, polybutene and polypentene; polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polyamides such as nylon-6 and nylon 6,6; and polyphenylene sulfide. Such as polythioethers, polycarbonates, polyarylates, polysulfones, polyetheretherketones, polyethersulfones, polyimides, vinyl halide polymers such as Teflon, acrylic polymers such as polymethyl methacrylate, polyvinyl alcohol, etc. Except for the soluble resin, it corresponds to all, and further includes a crosslinked resin containing the above-mentioned compatible resin. Since these resins are incompatible with the syndiotactic-structured styrene-based polymer of the present invention, if they are contained in small amounts, they can be dispersed like islands in the syndiotactic-structured styrene-based polymer. , Give a good gloss after stretching,
It is effective for improving the surface slip property. The content ratio of these incompatible resin components is 50 for gloss.
~ 2% by weight, 0.001 ~
5% by weight is preferred. When the temperature used as a product is high, it is preferable to use a relatively heat-resistant incompatible resin.

When a stretched film or sheet having an easily roughened surface is desired, the surface smoothness can be adjusted by blending inorganic particles in the raw material or precipitating it during polymerization. Here, the inorganic fine particles are the IA group, II
Group A, Group IVA, Group VIA, Group VIA, Group VIII, Group IB, Group IIB, III
Oxides, hydroxides, sulfides, nitrides, halides, carbonates, sulfates, acetates, phosphates, phosphates,
Shows phosphites, organic carboxylate, silicate, titanate, borate and their hydrated compounds, composite compounds centered on them, and natural mineral particles.

Specifically, group IA element compounds such as lithium fluoride, borax (sodium borate hydrate), magnesium carbonate, magnesium phosphate, magnesium oxide (magnesia), magnesium chloride, magnesium acetate, magnesium fluoride,
Magnesium titanate, magnesium silicate, magnesium silicate hydrate (talc), calcium carbonate, calcium phosphate, calcium phosphite, calcium sulfate (gypsum), calcium acetate, calcium terephthalate, calcium hydroxide, calcium silicate, calcium fluoride, titanium Group IIA element compounds such as calcium phosphate, strontium titanate, barium carbonate, barium phosphate, barium sulfate, barium phosphite, titanium dioxide (titania), titanium monoxide,
Group IVA element compounds such as titanium nitride, zirconium dioxide (zirconia) and zirconium oxide; Group VIA element compounds such as molybdenum dioxide, molybdenum trioxide and molybdenum sulfide; Group VII A element compounds such as manganese chloride and manganese acetate; Group VIII element compounds such as cobalt chloride and cobalt acetate; Group IB element compounds such as cuprous iodide; Group IIB element compounds such as zinc oxide and zinc acetate; aluminum oxide (alumina); aluminum hydroxide; , Aluminosilicate (alumina silicate, kaolin, kaolinite) and other Group IIIB element compounds, silicon oxide (silica, silica gel), graphite, carbon, graphite, glass, etc.
IV Group B element compounds, particles of natural minerals such as kernalite, kainite, mica (mica, kinunmo), and virose ore.

The average particle diameter of the inorganic fine particles that can be used in the present invention is not particularly limited, but is preferably 0.01 to 3 μm, more preferably 0.01 to 1 μm, and the content in the composition is 0.001 to
It is 1% by weight, preferably 0.001 to 0.8% by weight.

These inorganic fine particles are contained in the final molded article (film or sheet), but the method of containing them is not limited. For example, a method of adding or precipitating the styrene-based monomer in an arbitrary step during the polymerization and a method of adding the styrene-based monomer in an arbitrary step of melt-extrusion may be mentioned. In order to effectively disperse these fine particles, a dispersant, a surfactant and the like may be used. For the purpose of controlling the melting specific resistance of the material, a Group IA element compound and a Group IIA element compound which can improve the conductivity of the material may be added.

In the present invention, a styrene-based polymer having the above-mentioned syndiotactic structure or a composition thereof (that is, a composition containing this styrene-based polymer (SPS)) is pelletized by a known means to obtain a material for extrusion. The pellets are extruded by an extruder to form a sheet. The thickness of the sheet in the present invention is 3 to 5000 μm, preferably 5 to 3000
μm, the stretched film obtained using the sheet material has a thickness of 0.1 to 1000 μm, preferably 0.3 to 700 μm. For example, the pellet is heated and melted and extruded into a sheet by an extruder having a T-die attached to the tip. The extruder used here may be either a single-screw extruder or a twin-screw extruder, and may or may not have a vent, but a single-screw in-line tandem type is preferred. Further, in this extruder, a gear pump may be used to stabilize the extruded amount, and an appropriate mesh may be used to control particles in the composition and remove impurities and foreign substances.

The extrusion conditions are not particularly limited and may be appropriately selected according to various situations. Preferably, the temperature is selected in a range from the melting point of the molding material to a temperature 30 ° C. higher than the decomposition temperature. For example, in the case of a composition containing inorganic fine particles in a styrene homopolymer having a syndiotactic structure, 265 to 3
50 ° C. is preferred. If the temperature is lower than the melting point, the whole is not melted, so that it is difficult to extrude. If the temperature exceeds 30 ° C. higher than the decomposition temperature, foaming, coloring, and off-flavor due to decomposition are not preferred. Further, the shear stress of the T-die die is 5 × 10 ⁶ dyne /
cm ² or less is preferable from the viewpoint of preventing a melt fracture chart.

In the present specification, the decomposition temperature refers to a temperature at which the weight reduction rate measured by a thermobalance becomes 1%.

Next, in the present invention, the sheet material extruded as described above is subjected to electrostatic imprinting. The method of applying electrostatic imprinting is not particularly limited, but usually, a method of providing a wire or knife-shaped electrode to deposit an electrostatic charge on one surface of a sheet-like material is used. A grounded DC high voltage generator is usually connected to this electrode, and a grounded DC roller is also used for a cooling roll described later. These positional relationships, when centering on a sheet-like material, a cooling roll on one side,
It is preferable to arrange an electrode on the opposite side.

The applied voltage used for electrostatic imprinting is usually 2 to 30 kV,
It is preferably 3 to 20 kV, particularly preferably 5 to 13 kV.
At this time, if the voltage is too low, the effect of electrostatic imprinting cannot be obtained, and if the voltage is too high, the film surface tends to be roughened due to dielectric breakdown.

Here, in the present invention, the temperature of the sheet during the electrostatic imprinting is set to a temperature (Tc−30 ° C.) lower than the crystallization temperature (Tc) by 30 ° C. or more, and 30 ° C. lower than the melting point (Tm). High (Tm + 30
C) or lower, preferably the crystallization temperature (Tc) to (Tm), particularly preferably the crystallization temperature (Tc) to a temperature 10 ° C lower than the melting point (Tm-10 ° C), and the T-die and the electrostatic Adjust the position, atmosphere, etc. of the loading electrode. If the temperature of the sheet at this time is lower than (Tc−30 ° C.), crystallization is likely to occur,
As a result, the elasticity of the sheet-like material increases, and it becomes difficult to adhere to the cooling roll. As a result, thickness unevenness easily occurs. On the other hand, when the temperature exceeds (Tm + 30 ° C.), the viscosity becomes low and the charged sheet is easily deformed, which may cause uneven thickness.

In this specification, the melting point and the crystallization temperature are the temperature of the peak of the melting point peak and the peak of the crystallization peak that appear when the material before extrusion is raised and lowered at 20 ° C./min in a differential scanning calorimeter, respectively. Say

The sheet material electrostatically imprinted in this way is preferably cooled and solidified by a cooling roll. The temperature of the cooling roll is preferably 0 ° C. or higher, and preferably 30 ° C. or higher than the glass transition temperature, and particularly preferably 20 ° C. or higher and adjusted to the glass transition temperature or lower. If the cooling roll temperature exceeds a temperature 30 ° C. higher than the glass transition temperature, the sheet-like material becomes difficult to separate from the cooling roll after cooling, and it is difficult and uneconomical to reduce the temperature to less than 0 ° C. in terms of an apparatus configuration. In addition, the temperature of the cooling roll is controlled by PID control,
It is preferable that the surface of the cooling roll has a mirror finish of 2S or more. The cooling rate can be appropriately selected within the range of 200 to 3 ° C./sec. Further, it is desirable that each of the above-described apparatuses for heating and melting, extrusion, electrostatic application, and cooling be designed and manufactured so as to minimize vibrations in order to minimize thickness unevenness.

Next, the cooled and solidified sheet (preformed body)
, Especially uniaxially or biaxially. In the case of biaxial stretching, the film may be stretched simultaneously in the machine direction and the transverse direction, but may be sequentially stretched in any order. The stretching may be performed in one step or may be performed in multiple steps.

Here, there are various stretching methods such as a method using a tenter, a method of stretching between rolls, a method of rolling, and the like.
These may be appropriately selected or combined and applied. In particular, after stretching between rolls in the machine direction (MD),
It is preferred that the film is stretched in D) by a tenter and, if necessary, further stretched.

The stretching temperature may be generally set between the glass transition temperature and the melting point of the preform, but when performing sequential stretching or multi-stage stretching, the first stage is performed between the glass transition temperature and the crystallization temperature, The latter stage is preferably performed between the glass transition temperature and the melting point. The stretching speed is usually 1 × 10 to 1 × 10 ⁵
% / Min, preferably 1 × 10 ³ to 1 × 10 ⁵ % / min.

The stretching ratio is 2 in both the machine direction (MD) and the transverse direction (TD).
Times or more, and the area stretch ratio is preferably 6 times or more.

In the stretched film obtained by stretching under the conditions as described above,
Further, when dimensional stability at high temperatures, heat resistance, and strength balance in the film plane are required, heat setting is effective for reducing the coefficient of linear expansion. The heat setting can be carried out by a commonly used method. However, the stretched film is stretched, relaxed or restricted in a contracted state, and has a glass transition temperature to a melting point of the film, preferably 100 ° C. lower than the melting point. What is necessary is just to hold | maintain in the temperature range just before a melting point from the temperature for 0.5 to 120 seconds. The heat setting can be performed twice or more with the conditions changed within the above range. The heat fixing may be performed in an atmosphere of an inert gas such as an argon gas or a nitrogen gas.

[Examples] Next, the present invention will be described in more detail based on examples and comparative examples.

Made of glass having an inner volume of 500ml substituted (Preparation contact product of trimethylaluminum and water) argon Reference Example, copper sulfate pentahydrate _{(CuSO 4 · 5H 2 O)} 17.8g (71 mmol), and toluene 200ml 24 ml (250 mmol) of trimethylaluminum was added and reacted at 40 ° C. for 8 hours. Thereafter, toluene was further distilled off from the solution obtained by removing the solid portion under reduced pressure at room temperature to obtain 6.7 g of a contact product. Its molecular weight measured by freezing point depression method was 610.

Production Example 1 (Production of styrene-based polymer) In a reaction vessel having an inner volume of 2 were placed purified styrene 1, 5 mmol of the contact product obtained in Reference Example 1 as aluminum atoms, 5 mmol of triisobutylaluminum, and pentamethylcyclohexane. Pentadienyl titanium trimethoxide
A polymerization reaction was carried out at 90 ° C. for 5 hours using 0.025 mmol. After completion of the reaction, the product was decomposed with a methanol solution of sodium hydroxide to decompose the catalyst component, washed repeatedly with methanol, and dried to obtain 308 g of a polymer.

The weight average molecular weight of this polymer measured by gel permeation chromatography at 135 ° C. using 1,2,4-trichlorobenzene as a solvent was 389,000, and the weight average molecular weight / number average molecular weight was 2.64. Was. Further, the polymer was confirmed to be a polystyrene having a syndiotactic structure by the melting point and ¹³ C-NMR measurement. The melt viscosity of this polymer at 300 ° C. and 200 / sec was 1 × 10 ⁴ poise.

Production Example 2 (Production of styrene-based polymer) In a reaction vessel having an inner volume of 2, purified styrene 1, 10 mmol of the contact product obtained in Reference Example 1 as aluminum atoms, 60 mmol of triisobutylaluminum, pentamethylcyclo Pentadienyl titanium trimethoxide
The polymerization reaction was carried out at 90 ° C. for 1 hour using 0.075 mmol. After completion of the reaction, the product was decomposed with a methanol solution of sodium hydroxide to decompose the catalyst component, washed repeatedly with methanol, and dried to obtain 268 g of a polymer.

The weight average molecular weight of this polymer was measured by gel permeation chromatography at 135 ° C. using 1,2,4-trichlorobenzene as a solvent and found to be 180,000, and the ratio of weight average molecular weight / number average molecular weight was 2.53. Was. Further, the polymer was confirmed to be a polystyrene having a syndiotactic structure by the melting point and ¹³ C-NMR measurement. The melt viscosity of this polymer at 300 ° C. and 200 / sec was 2 × 10 ³ poise.

Production Example 3 (Production of styrene polymer) 100 ml of toluene was placed in a reaction vessel having an internal volume of 500 ml, and Reference Example 1
20 mmol, 10 mmol of trimethylaluminum, 0.05 mmol of cyclopentadienyltitanium trichloride and 100 ml of purified styrene were added to the catalyst product obtained in the above as an aluminum atom, and a polymerization reaction was carried out at 60 ° C. for 3 hours. After completion of the reaction, the product was decomposed with a methanol solution of sodium hydroxide to decompose a catalyst component, washed repeatedly with methanol, and dried to obtain 7.1 g of a polymer.

The weight average molecular weight of this polymer was 47,400 as measured by gel permeation chromatography at 135 ° C. using 1,2,4-trichlorobenzene as a solvent,
The weight average molecular weight / number average molecular weight was 3.43. Further, the polymer was confirmed to be a polystyrene having a syndiotactic structure by the melting point and ¹³ C-NMR measurement. The melt viscosity of the polymer at 300 ° C. and 200 / sec was 28 poise.

Example 1 The styrene-based polymer obtained in Production Example 1 was sufficiently dried, and then formed into pellets using an extruder. The melting point, crystallization temperature, and glass transition temperature of the pellets were 272 ° C, 23
0 ° C, 99 ° C.

The pellets were melt-extruded at 330 ° C. using an apparatus having a T-die attached to the tip of a seismic type, single-screw tandem type extruder. A wire electrode was placed at a position where the temperature of the melt-extruded sheet became 250 ° C., and the imprint voltage was set to 10 kV, and the sheet was imprinted electrostatically immediately before contact with the cooling roll. The charged sheet-like material having a thickness of 110 μm was passed through two cooling rolls adjusted to a temperature of 40 ° C. and wound up.

Here, while adjusting the speeds of the cooling roll and the winding roll, samples having different take-up speeds were manufactured by 10 m each. From the samples having different take-up speeds, arbitrarily cut out five-point raw materials, and successively biaxially stretched three times at 110 ° C. and 3000% / min with a table tenter to remove the thickness unevenness of the obtained film of about 12 μm. The evaluation was performed by measuring the thickness of ten films. The maximum take-off speed at which the thickness unevenness was 4% or less was 120 m / min. The sheet thickness at this time was 150 μm, and the film thickness after biaxial stretching was 16 μm.
m.

Comparative Example 1 The same operation as in Example 1 was performed except that the electrostatic imprinting was not performed, but a film having thickness unevenness of 4% or less could not be obtained.

Comparative Example 2 The same operation as in Example 1 was performed, except that an air knife was used instead of the electrostatic imprint. As a result, the maximum take-off speed at which the thickness unevenness of the film after biaxial stretching was 4% or less was 40 m / min.

Comparative Example 3 The same operation as in Example 1 was performed, except that the melting temperature and the electrode position were adjusted so that the temperature of the electrostatically charged part was 320 ° C. As a result, the thickness unevenness of the film after biaxial stretching was 4%.
The following maximum take-off speed was 50 m / min.

Comparative Example 4 The same operation as in Example 1 was performed except that the melting temperature and the electrode position were adjusted so that the temperature of the electrostatic imprinting part was 180 ° C., but a film having thickness unevenness of 4% or less was obtained. I couldn't do that.

Comparative Example 5 The same operation as in Example 1 was performed except that the SPS obtained in Production Example 3 was used, but no conditions were found to obtain a sheet having a thickness unevenness of 4% or less.

Examples 2 to 4 The temperature, the imprinting voltage, and the thickness of the raw sheet of the electrostatic imprinting portion were set to the first values.
The same operation as in Example 1 was performed, except for the points shown in the table. Table 1 shows the maximum take-off speeds of the obtained films in which the thickness unevenness is 4% or less.

Example 5 In Production Example 1, silica fine particles (Aerosil TT-600 manufactured by Degussa, average particle size: 40 mμ) in a purified styrene monomer.
Was uniformly dispersed in 0.5 parts by weight to obtain a styrene-based polymer. The melting point, crystallization temperature and glass transition temperature of pellets prepared from this polymer composition were 273 ° C, 233 ° C, and 10 ° C, respectively.
It was 0 ° C. The same operation as in Example 1 was performed using this material. The maximum take-off speed at which the thickness unevenness of the obtained film was 4% or less was 120 m / min.

Example 6 After a material containing inorganic fine particles was prepared in the same manner as in Example 5, this was mixed with atactic polystyrene (trade name: HH30).
E, Idemitsu Petrochemical Co., Ltd.) was melt-kneaded with a twin-screw extruder to prepare pellets. The atactic polystyrene content in the pellets was 10% by weight. The melting point, crystallization temperature, and glass transition temperature of these pellets were 270 ° C,
220 ° C, 101 ° C. The same operation as in Example 1 was performed using this material. 4% unevenness in thickness of the obtained film
The maximum take-off speed, below, was 110 m / min.

Example 7 In Example 5, a p-methylstyrene monomer was added to a purified styrene monomer to obtain pellets of a styrene copolymer composition having a p-methylstyrene content of 9 mol%. The melting point, crystallization temperature, and glass transition temperature of the pellets were 244 ° C, 218 ° C, and 101 ° C, respectively. The same operation as in Example 1 was performed using this material. The maximum take-off speed at which the thickness unevenness of the obtained film was 4% or less was 120 m / min.

Example 8 The same operation as in Example 1 was performed except that the material of Production Example 2 was used. The maximum take-off speed at which the thickness unevenness of the obtained film was 4% or less was 90 m / min.

Example 9 Instead of atactic polystyrene, polyphenylene ether (PPO, manufactured by Aldrich, catalog No. 18178)
Except that -1) was used, the procedure was the same as that of Example 6.

Table 1 summarizes the main conditions and results (productivity: maximum take-off speed) of each of the above Examples and Comparative Examples.

[Effects of the Invention] As described above, according to the present invention, a sheet or film made of a styrene-based polymer having a syndiotactic structure or a composition thereof has excellent thickness uniformity with thickness unevenness of 4% or less. Can be manufactured with high productivity.

Therefore, the method of the present invention is expected to be effectively used as a method for efficiently obtaining various industrial films such as magnetic tapes, photographic films, FPCs, and condenser films.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B29C 47/00-47/96 C08F 12/08

Claims (1)

(57) [Claims] (1) having a syndiotactic structure, and
A styrene polymer having a melt viscosity of 1 × 10 ² to 1 × 10 ⁶ poise or a composition thereof at a shear rate of 200 ° C./200° C. is heated and melted and extruded into a sheet. Manufacturing a stretched film or sheet, wherein the material is electrostatically charged at a temperature 30 ° C. lower than the crystallization temperature and 30 ° C. or lower than the melting point and cooled and solidified, and then the sheet is stretched. Method.