JPH0848791A - Polystyrene film and capacitor made thereof - Google Patents

Abstract

PURPOSE:To obtain a polystyrene film desirable as a dielectric film for a capacitor by using a specified polystyrene film having a specified ratio of the number of the ultrasuperficial carbon atoms to that of the ultrasuperficial oxygen atoms. CONSTITUTION:This film is one which is made of a syndiotactic styrene polymer and either of which surfaces has a ratio of the number of the ultrasuperficial carbon atoms to that of the ultrasuperficial oxygen atoms of 10% or above when determined by the X-ray photoelectron spectroscopy. A polystyrene film prepared by forming a surface layer comprising a resin composition (e.g. polyethylene or polypropylene) on at least either surface of a film of a syndiotactic styrene polymer is desirable. A polystyrene film prepared by surface-treating at least either surface of a film of a syndiotactic styrene polymer by the oxidation method is also desirable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polystyrene film and a capacitor using the same. More specifically, it is suitable as a dielectric film for a capacitor, and is suitable for running the film during the manufacturing of the capacitor or during the manufacturing of the capacitor. , Excellent in abrasion resistance, and moisture resistance under voltage load,
The present invention relates to a syndiotactic polystyrene film and a capacitor having improved self-healing property.

[0002]

2. Description of the Related Art A biaxially stretched film obtained by biaxially stretching and heat-fixing a resin composition containing a syndiotactic polystyrene-based polymer as a main component has excellent heat resistance and electric characteristics and is therefore developed as a dielectric for capacitors. (Japanese Patent Laid-Open No. 2-143851,
JP-A-3-124750 and JP-A-5-200858). Further, a capacitor having improved slipperiness in order to improve running performance and yield during manufacturing is known (JP-A-6-29146 and JP-A-6-29146).
80793).

[0003]

However, in these conventional syndiotactic polystyrene films,
Although abrasion resistance and running property were improved during the production of the film and during the production of the capacitor, the moisture resistance and self-healing property of the obtained capacitor under voltage load were not always satisfactory.

[0004]

The present invention provides a ratio of oxygen atoms to carbon atoms on the very surface of at least one surface of a film made of a styrene polymer having a syndiotactic structure, which is evaluated by X-ray photoelectron spectroscopy. Is 10% or more, which is a polystyrene film. Furthermore, a surface layer made of a resin composition is formed on at least one surface of a film made of a styrene polymer having a syndiotactic structure, and at least one of a film made of a styrene polymer having a syndiotactic structure is formed. The surface was surface-treated by an oxidation method, a surface layer made of a resin composition was formed on at least one surface of a film made of a styrene polymer having a syndiotactic structure, and the surface layer was surface-treated by an oxidation method. That is, the three-dimensional surface roughness SRa of at least one surface of the film made of a styrene polymer having a syndiotactic structure is 0.01 (μm) or more, and Sλa
(Μm) and the glass transition temperature satisfy the following relationship: 3 + 4 × (Tgc-Tgs) / Tgc ≤ Sλa ≤ 2
0 + 10 × (Tgc-Tgs) / Tgc where Tgc is the glass transition temperature of the syndiotactic polystyrene film layer Tgs is the glass transition temperature of the surface layer At least a film made of a styrene polymer having a syndiotactic structure A surface layer made of a resin composition is formed on one surface, and the thickness of the surface layer is 30% or less of the total thickness of the film, and the dielectric loss tangent (25
(° C, 1kHz) is 0.001 or less, which is suitable as a dielectric film for capacitors, which suppresses slipping off of lubricant during film production and during capacitor production, and has excellent runnability.
In addition, it is possible to obtain a syndiotactic polystyrene-based film having improved humidity resistance under voltage application and self-healing property. Further, a capacitor characterized by using a metallized syndiotactic polystyrene-based film in which a metal thin film layer is formed on at least one surface of such a syndiotactic polystyrene-based film has excellent electrical characteristics and moisture resistance under voltage load. And excellent self-healing property.

The polystyrene-based polymer having stereoregular syndiotactic structure used in the present invention has a tacticity in which the side chain phenyl group or substituted phenyl group is quantified by a nuclear magnetic resonance method, which is a diad (constituent unit). 85% or more for 2) and 50 for pentad (5 units)
It is desirable that the structure has a syndiotactic structure of not less than%.

The polystyrene-based polymer includes polystyrene, poly (p-, m- or o-methylstyrene), poly (2,4-, 2,5-, 3,4- or 3,5-dimethylstyrene). ), Poly (alkylstyrene) such as poly (p-tert-butylstyrene), poly (p-, m- or o-chlorostyrene),
Poly (halogenated styrene) such as poly (p-, m- or o-bromostyrene), poly (p-, m- or o-fluorostyrene), poly (o-methyl-p-fluorostyrene), poly ( p-, m- or o-chloromethylstyrene) and other poly (halogen-substituted alkylstyrenes), poly (p-, m- or o-methoxystyrene), poly (p-, m- or o-ethoxystyrene), etc. Poly (alkoxystyrene), poly (p-, m-
Or poly (carboxyalkylstyrene) such as o-carboxymethylstyrene), poly (alkyletherstyrene) such as poly (p-vinylbenzylpropylether), poly (alkylsilylstyrene) such as poly (p-trimethylsilylstyrene), Examples include poly (vinylbenzyldimethoxyphosphide) and the like.

In the present invention, among the polystyrene polymers, polystyrene is particularly preferred. Also,
The polystyrene polymer having a syndiotactic structure used in the present invention is not necessarily a single compound, and if the syndiotacticity is within the above range, a polystyrene polymer having an atactic structure or an isotactic structure is used. It may be a mixture of, a copolymer and a mixture thereof.

The polystyrene-based polymer used in the present invention has a weight average molecular weight of 10,000 or more, more preferably 50,000 or more.
00 or more. If the weight average molecular weight is less than 10,000, it is not possible to obtain a film having excellent strength and elongation characteristics and heat resistance. The upper limit of the weight average molecular weight is not particularly limited, but if it is 1500,000 or more, breakage occurs due to an increase in stretching tension, which is not preferable.

Further, the syndiotactic polystyrene film of the present invention can be produced by a known method, for example, a sequential biaxial stretching method in which longitudinal stretching and transverse stretching are carried out in order, as well as lateral / longitudinal stretching.
A stretching method such as a longitudinal stretching method, a longitudinal / transverse / longitudinal stretching method, or a longitudinal / longitudinal / transverse stretching method can be adopted, and the stretching method is selected according to various characteristics such as required strength and dimensional stability. Further, heat setting treatment, vertical relaxation treatment, lateral relaxation treatment, etc. can be performed.

The syndiotactic polystyrene polymer used in the present invention may contain, if necessary, an appropriate amount of a known antioxidant, antistatic agent or the like. The blending amount is preferably 10% by weight or less with respect to 100% by weight of the syndiotactic polystyrene polymer. If it exceeds 10% by weight, breakage easily occurs during stretching, resulting in poor production stability.

The ratio of oxygen atoms to carbon atoms on the very surface of at least one surface of the film made of the styrene polymer having a syndiotactic structure of the present invention evaluated by X-ray photoelectron spectroscopy is 10% or more. Is preferred. More preferably, it is 15% or more. When the ratio of oxygen atoms to carbon atoms on the pole surface becomes smaller than 10%,
Moisture resistance and self-healing property under voltage load become poor, which is not preferable.

A method in which the ratio of oxygen atoms to carbon atoms on the very surface of at least one surface of the film made of the styrene polymer having a syndiotactic structure of the present invention is 10% or more evaluated by X-ray photoelectron spectroscopy. As the method, a method for forming a surface evaluation layer with a resin composition having a ratio of oxygen atoms to carbon atoms of 10% or more, a method for surface-treating the surface with an oxidation method, and an oxidation method for a surface layer formed with the resin composition And the like.

As a method of forming the surface layer with the resin composition, the syndiotactic polystyrene polymer and the resin composition for forming the surface are melted and bonded at the inside of the die or at the opening of the die, laminated, extruded from the die and rapidly cooled. A method of stretching after forming an amorphous sheet, extruding a syndiotactic polystyrene-based polymer from a die and quenching, and then coating the surface forming resin composition on the obtained amorphous sheet or uniaxially stretched film Method of stretching,
Examples include a method in which individually stretched films are adhered and laminated.

The resin laminated on the syndiotactic polystyrene of the present invention includes polyolefin resins such as polyethylene, polypropylene and polybutene, polyethylene terephthalate, polyethylene isophthalate, polyethylene-2,6-terenaphthalate and polybutylene terephthalate. Polyester polymer, nylon 6,
Examples thereof include polyamide polymers such as nylon 66, nylon 12, nylon 4, polyhexamethylene adipamide, polyphenylene oxide, polycarbonate, polyarylate, polyether sulfone, and polyphenylene sulfide. The resin may be a mixture, a copolymer or a mixture thereof. Here, when the ratio of oxygen atoms to carbon atoms on the pole surface evaluated by X-ray photoelectron spectroscopy of the formed surface layer is less than 10%, it is necessary to increase the ratio of oxygen atoms by oxidation treatment or the like. .

In the present invention, it is preferable that at least one surface of the film made of the styrene polymer having a syndiotactic structure is surface-treated by an oxidation method. Examples of the surface treatment method by the oxidation method include corona discharge treatment, chromium oxidation treatment, flame treatment, flame plasma treatment, hot air treatment, ozone / ultraviolet irradiation treatment and the like. Among these treatments, the one subjected to flame plasma treatment is most preferable because it has good moisture resistance and self-healing property under voltage load.

The three-dimensional surface roughness Sλa and SR
a is adjusted by the film forming conditions, the protrusion forming agent, the lamination, and the like. The type and amount of the protrusion-forming agent are not particularly limited as long as the three-dimensional surface roughness Sλa, SRa falls within a predetermined range, and examples thereof include metals such as silica, titanium dioxide, talc, kaolinite, and zeolite. Examples include addition of oxides, salts of metals such as calcium carbonate, calcium phosphate and barium sulfate, particles of an organic polymer such as silicone resin and crosslinked polystyrene, and the like.
These fine particles may be used alone or in combination of two or more, but the average particle size of the fine particles used is 0.01 μm or more and 2.0 μm or less, and particularly, 0.
The thickness is preferably 05 μm or more and 1.5 μm or less, and the degree of variation in particle size (ratio between standard deviation and average particle size) is preferably 25% or less. The addition amount is preferably 0.005% by weight or more and 2.0% by weight or less, particularly 0.1% by weight or more and 1.0% by weight, based on 100% by weight of the syndiotactic polystyrene polymer.
The following are preferred.

The three-dimensional surface roughness SRa and Sλa of the surface layer formed on the syndiotactic polystyrene-based film of the present invention depends on the glass transition temperature of the film of the surface layer, and thus the three-dimensional surface roughness SRa and Sλa It was found that the optimum range for suppressing falling and making the product excellent in running property is different, and it is necessary to be within the following range. SRa ≥0.01 3 + 4 x (Tgc-Tgs) / Tgc ≤ Sλa ≤20 + 10 x (Tgc-Tgs)
/ Tgc where Tgc is the glass transition temperature of the syndiotactic polystyrene film layer Tgs is the glass transition temperature SRa of the surface layer outside of this range, which results in poor running properties and rolls during film production and capacitor production. This is not preferable because it causes defects such as wrinkles and scratches.
When Sλa is less than 3 + 4 × (Tgc-Tgs) / Tgc, the running property becomes poor. Furthermore, Sλa is 20 + 10 × (T
When it is larger than gc-Tgs) / Tgc, it is not preferable because white powder is generated due to the scraping of the protrusions, resulting in poor wear resistance.

In the present invention, the thickness of the surface layer is preferably 30% or less of the thickness of the entire film. If the thickness is more than 30%, the electrical properties such as capacitance and temperature of dielectric loss tangent, frequency characteristics, and heat resistance become poor, which is not preferable.
The lower limit of the thickness is not particularly limited, but 0.005 μm
If the thickness is thinner, it is difficult to obtain the effect of improving the self-healing property, which is not preferable.

The dielectric loss tangent (25 ° C., 1 kHz) of the styrene polymer film having a syndiotactic structure in the present invention is preferably 0.001 or less. When the dielectric loss tangent (25 ° C, 1kHz) was greater than 0.001, the good electrical properties of the film made of syndiotactic polystyrene polymer were affected by the properties of the resin of the laminated surface layers. Therefore, it is not preferable because it will be damaged.

Further, in the present invention, the capacitor using the metallized syndiotactic polystyrene film in which a metal thin film layer is formed on at least one surface of these polystyrene film is suppressed from slipping off of lubricant in the capacitor manufacturing process, In addition, since the running property is excellent, variations in the characteristics of the obtained capacitor are reduced and the yield is improved. Moreover, the obtained capacitor has improved moisture resistance and self-healing property under voltage load.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The evaluation method of the film is shown below.

(1) Three-dimensional surface roughness Sλa, SRa The surface of the film was measured using a stylus-type three-dimensional surface roughness meter (SE-3AK, Kosaka Laboratory Ltd.) with a needle radius of 2 μm and a load.
Cutoff value of 0 in the longitudinal direction of the film under the condition of 30 mg.
25 mm, measuring length 1 mm, 2 μm pitch
It is divided into 500 points and the height of each point is calculated by 3D roughness analyzer (SP
A-11). The same operation as above was continuously performed 150 times in the width direction of the film at intervals of 2 μm, that is, over 0.3 mm in the width direction of the film, and the data was taken into the analyzer. Next, Sλa and SRa were obtained using an analyzer.

(2) Glass transition temperature Using THERMOFLEX DSC-8230 manufactured by Rigaku Denki Co., Ltd.
The temperature rising rate was 20 ° C./min, and the sample weight was 5 mg.

(3) Oxygen atom-to-carbon atom ratio (O / C ratio) on the pole surface measured by X-ray photoelectron spectroscopy The oxygen atom-to-carbon atom ratio was calculated by using Shimadzu ESCA-850 The ratio of carbon atoms and oxygen atoms existing on the pole surface was evaluated by using -Kα ray (1254ev). Ratio (%) of oxygen atoms to carbon atoms on the extreme surface of the surface layer = (oxygen atom / carbon atom) × 100.

(4) Dielectric loss tangent Yokogawa / Hewlett Packard Co. 4192A LF
Using IMPEDANCE ANALYZER, the dielectric loss tangent at 25 ° C and 1kHz was evaluated.

(5) Running property and abrasion resistance of film The film is formed into a tape slit into a narrow width, rubbed on a metal guide roll, and run at high speed for a long time. The magnitude of the tension and the amount of white powder generated on the surface of the guide roll were evaluated and ranked on a scale of 5 as shown below. (A) Runnability 1st class; high tension (very many scratches) 2nd class; slightly high tension (many scratches) 3rd class; medium tension (slightly scratches) 4th class; tension slightly small (almost no scratches) 5th class; Low tension (no scratches) (b) Scratch resistance 1st class: White powder is very much generated 2nd class: White powder is often generated 3rd class: White powder is slightly generated 4th class: White powder is almost not generated 5 Grade: No white powder

(6) Moisture resistance under voltage load A capacitor of 100 V (DC) voltage is applied in an atmosphere of 60 ° C. and 95% RH and aged for 1000 hours to determine the rate of change in capacitance by Yokogawa / Hewlett-Packard. Co., Ltd. 4192A LF
It measured using IMPEDANCE ANALYZER. This is ΔC /
It is shown in C (%), and the smaller the rate of change in capacitance, the better the moisture resistance. Here, C is the capacitance before aging, and ΔC is the value obtained by subtracting the capacitance after aging from the capacitance before aging. The judgment is 5 as shown below.
Graded and ranked. 1st grade; -20> ΔC / C 2nd grade; -10> ΔC / C ≧ −20 3rd grade; −5> ΔC / C ≧ −10 4th grade; 0> ΔC / C ≧ −5 5th grade; ΔC / C ≧ 0

(7) Self-healing property (SH property) A polystyrene film having a thickness of 600 Å vapor-deposited on one side is cut into a square with a side of 1 cm, two pieces are stacked, and further sandwiched between rubber plates with a side of 2 cm. A load of 2 kg was applied. In this state, a voltage was applied to the vapor-deposited film to cause dielectric breakdown, and the presence or absence of self-healing property was evaluated with 20 samples. 1st grade: No self-healing ability 2nd grade: Almost no self-healing ability 3rd grade: May not have self-healing ability 4th grade: Almost self-healing ability 5th grade: All self-healing ability

(8) Temperature characteristics Yokogawa / Hewlett-Packard Co. 4192A LF
The IMPEDANCE ANALYZER was used to evaluate the dielectric loss tangent at 150 ° C and 1 kHz. The dielectric loss tangent was evaluated and ranked in 5 stages as shown below. 1st grade; 0.05 or more; 2nd grade; 0.01 to 0.05 3rd grade; 0.005 to 0.01 4th grade; 0.001 to 0.005 5th grade; less than 0.001

Example 1 Comparative Example 1 Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.1 μm, variation = 20%)
Polyethylene terephthalate containing 30% by weight (IV = 0.
62) 0.5 to 9.5% of polymer chips added with 4.0 parts by weight of resin and polymer chips not added with the protrusion-forming agent.
After mixing at a ratio of 100 μm, dry, melt at 300 ° C, and
It was extruded from a T-die with a lip gap of m, adhered to a 40 ° C. cooling roll by an electrostatic loading method, and then cooled and solidified to obtain a 44 μm amorphous sheet. The amorphous sheet is first preheated to 100 ° C. by a roll, further heated by using four infrared heaters with a surface temperature of 700 ° C., stretched 2.0 times in the machine direction at a film temperature of 139 ° C., and further stretched at 125 ° C. in the machine direction. Was stretched 1.8 times. Then, the film was preheated to 120 ° C with a tenter and stretched in the transverse direction at a stretching temperature of 120 ° C by 2.0 times, and further stretched to 150 ° C.
After stretching 1.6 times in the transverse direction at ℃, it was heat set at 260 ℃.
The thickness of the obtained polystyrene film was 4 μm. Furthermore, both surfaces are 100 m / min (Example 1), 200 m / min.
Flame plasma treatment was performed at a treatment rate of minutes (Comparative Example 1). Aluminum was vapor-deposited on the coated surface of the obtained film by 500 Å to fabricate a roll-type film capacitor. The film and capacitor characteristics are shown in Table 1.

Examples 2 and 3 Comparative Example 2 (a) Preparation of aqueous polyester solution Bayronal MD1200 (manufactured by Toyobo Co., Ltd.) 20 parts by weight (solid content 25%) Water 36 parts by weight Isopropyl alcohol 36 parts by weight Benzyl alcohol 8 parts by weight

(B) Production of Laminated Film Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.1 μm, variation = 20%)
Polyethylene terephthalate containing 30% by weight (IV = 0.
62) A polymer chip containing 4.0 parts by weight of resin and a polymer chip containing no protrusion-forming agent in a ratio of 0.2 to 9.8
(Comparative Example 1), 0.5 to 9.5 (Example 1), 1 to 9 (Example 2), mixed, dried and melted at 300 ° C.
Extruded from T-die with 200 μm lip gap, 40 ℃
It adheres to the cooling roll of the
An amorphous sheet of μm was obtained. The amorphous sheet is first preheated to 100 ° C. by a roll and further heated by using four infrared heaters with a surface temperature of 700 ° C.
Stretched 2.0 times in the machine direction at 9 ° C and then 1.25 in the machine direction at 125 ° C.
It was stretched 8 times. The coating solution obtained in (a) above was applied to both surfaces of the uniaxially stretched film by a bar coating method. The film is then preheated to 120 ° C with a tenter and stretched in the transverse direction.
The film was stretched 2.0 times at 120 ° C, then 1.6 times transversely at 150 ° C, and then heat set at 260 ° C. The total thickness of the obtained laminated film is 4 μm, and the total thickness of the surface layers is 0.1 μm.
The coating film was uniform. Aluminum was vapor-deposited on the coated surface of the obtained film by 500 Å to fabricate a roll-type film capacitor. Film and capacitor characteristics are shown in Table 1.
Shown in

Comparative Example 3 Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.1 μm, variation = 20%)
0.5 to 9.5 by weight ratio of polymer chip added with 3.0 parts by weight of polymer chip and polymer chip without addition of protrusion-forming agent.
Example 1 was repeated except that the mixture was mixed and used. 50 aluminum on the coated surface of the obtained film
A roll-type film capacitor was prototyped by vapor deposition. The film and capacitor characteristics are shown in Table 1.

Examples 4 and 5 Comparative Example 4 Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.1 μm, variation = 20%)
Was mixed with 3.0 parts by weight of a polymer chip and a polymer chip to which a protrusion-forming agent was not added at a weight ratio of 1: 9, and polyethylene terephthalate (IV = 0.62) containing no protrusion-forming agent as a surface layer. ) Are fed to separate extruders, melted, joined in a T-die so that polyethylene terephthalate forms both surface layers, extruded from the T-die with a 200 μm lip gap, and chilled to a 40 ° C chill roll. Adhesion, cooling and solidification by the electrophotographic loading method gave an amorphous laminated sheet of 44 μm. Here, the total thickness of the surface layers was set to 5 μm (Example 3), 11 μm (Example 4), and 14 μm (Comparative Example 3). The amorphous sheet was first preheated to 100 ° C by a roll and the surface temperature 70
It is further heated by using four infrared heaters at 0 ℃ and stretched 2.0 times in the machine direction at a film temperature of 139 ℃.
It was stretched 1.8 times in the machine direction at 125 ° C. The coating solution obtained in (a) above was applied to both surfaces of the uniaxially stretched film by a bar coating method. Then, the film was preheated to 120 ° C with a tenter and stretched in the transverse direction at a stretching temperature of 120 ° C by 2.0 times, and further stretched to 150 ° C.
After stretching 1.6 times in the transverse direction at ℃, it was heat set at 260 ℃.
The total thickness of the obtained laminated film was 4 μm. Aluminum was vapor-deposited on the coated surface of the obtained film by 500 Å to fabricate a roll-type film capacitor. The film and capacitor characteristics are shown in Table 1.

Example 6 Comparative Example 5 Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.1 μm, variation = 20%)
Was added to the polymer chips to which 3.0 parts by weight of the polymer was added, and the polymer chips to which the protrusion-forming agent was not added were mixed at a weight ratio of 1: 9, and polyethylene-2,6- Telenaphthalate (Example 5) and polyphenylene sulfide (Comparative Example 4) were fed to separate extruders and melted, and polyethylene-2,6-terenaphthalate or polyphenylene sulfide formed both surface layers in a T-die. And extruded from a T-die with a 200 μm lip gap,
It was brought into close contact with a 40 ° C cooling roll by the electrostatic loading method and solidified by cooling to obtain an amorphous laminated sheet of 44 μm. Here, the total thickness of the surface layers was set to 1.0 μm. The amorphous sheet is first preheated to 100 ℃ with a roll and the surface temperature is 700
Further heating by using 4 infrared heaters at ℃,
The film was stretched 2.0 times in the machine direction at a film temperature of 139 ℃ and then 125
It was stretched 1.8 times in the machine direction at ℃. The film is then preheated to 120 ° C in a tenter and stretched in the transverse direction at a temperature of 120 ° C to 2.0 ° C.
After stretching twice and then stretching 1.6 times in the transverse direction at 150 ℃, 26
It was heat-set at 0 ° C. The total thickness of the obtained laminated film was 4 μm. Aluminum was vapor-deposited on the coated surface of the obtained film by 500 Å to fabricate a roll-type film capacitor. Table 1 shows the film and capacitor characteristics.

Example 7 Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.1 μm, variation = 20%)
Polymer chip added with 3.0 parts by weight of the polymer, a polymer chip not added with the protrusion-forming agent in a weight ratio of 1: 9, and polypropylene without the protrusion-forming agent as the surface layer are separately extruded. Supply to the machine,
Melted and joined in a T-die so that polypropylene forms both surface layers, extruded from a T-die with a 200 μm lip gap, adhered to a 40 ° C chill roll by an electrostatic loading method, cooled and solidified, An amorphous laminated sheet of 44 μm was obtained.
Here, the total thickness of the surface layers was set to 1.0 μm. The amorphous sheet is first preheated to 100 ° C. by a roll, further heated by using four infrared heaters with a surface temperature of 700 ° C., stretched 2.0 times in the machine direction at a film temperature of 139 ° C., and further stretched in the machine direction at 125 ° C. Was stretched 1.8 times. The film was then preheated to 120 ° C. with a tenter, stretched 2.0 times in the transverse direction at a stretching temperature of 120 ° C., further stretched 1.6 times in the transverse direction at 150 ° C., and then heat set at 260 ° C. The total thickness of the obtained laminated film was 4 μm. Further, the surface formed of polypropylene was subjected to flame plasma treatment at a treatment speed of 100 m / min. Aluminum was vapor-deposited on the coated surface of the obtained film by 500 Å to fabricate a roll-type film capacitor. Table 1 shows the film and capacitor characteristics.

[0037]

[Table 1] From Table 1, the films obtained in Examples 1 to 6 are excellent in the running property and the abrasion resistance of the film during the production of the film and during the production of the capacitor, and the moisture resistance under the voltage load and the self-healing property are improved. They were syndiotactic polystyrene films and capacitors.

[0038]

As described above, according to the present invention, by adopting the constitution as set forth in the claims, the film has excellent running property and abrasion resistance at the time of manufacturing a film or a capacitor. Further, a syndiotactic polystyrene film and a capacitor having improved moisture resistance under voltage application and self-healing property are provided. Therefore, the industrial value of the present invention is great.

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Claims (8)

[Claims] 1. A ratio of oxygen atoms to carbon atoms on the very surface of at least one surface of a film made of a styrene-based polymer having a syndiotactic structure, which is evaluated by X-ray photoelectron spectroscopy, is 10% or more. Characteristic polystyrene film. 2. The polystyrene film according to claim 1, wherein a surface layer made of a resin composition is formed on at least one surface of a film made of a styrene polymer having a syndiotactic structure. 3. The polystyrene film according to claim 1, wherein at least one surface of the film made of a styrene polymer having a syndiotactic structure is surface-treated by an oxidation method. 4. A surface layer made of a resin composition is formed on at least one surface of a film made of a styrene polymer having a syndiotactic structure, and the surface layer is surface-treated by an oxidation method. The polystyrene film according to claim 1. 5. A three-dimensional surface roughness SRa of at least one surface of a film made of a styrene polymer having a syndiotactic structure is 0.01 (μm) or more, and Sλa
The polystyrene film according to claim 1, wherein (μm) and the glass transition temperature satisfy the following relationship. 3 + 4 x (Tgc-Tgs) / Tgc ≤ Sλa ≤ 20 + 10 x (Tgc-Tgs)
/ Tgc where Tgc is the glass transition temperature of the syndiotactic polystyrene film layer Tgs is the glass transition temperature of the surface layer 6. A surface layer made of a resin composition is formed on at least one surface of a film made of a styrene polymer having a syndiotactic structure, and the thickness of the surface layer is 30% or less of the total thickness of the film. The polystyrene film according to claim 2, wherein the polystyrene film is present. 7. The dielectric loss tangent (25 ° C., 1 kHz) of the film is 0.
The polystyrene-based film according to claim 1, which is 001 or less. 8. A capacitor using a metallized syndiotactic polystyrene film having a metal thin film layer formed on at least one surface of the syndiotactic polystyrene film according to claim 1.