JP2001192555A - Polyphenylene sulfide resin composition and film using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polyphenylene sulfide films which solve the color specks when films are formed and improve the film-forming yield by stable when films are formed and also excel in fabricability in the condenser use. SOLUTION: Polyphenylene sulfide resin compositions comprise a polyphenylene sulfide resin and have a melt viscosity at 316 deg.C after heat treatment of 1,500 P to less than 6,000 P and, at the same time, a difference in melt viscosity between before and after heat treatment of less than 2,000 P, and the polyphenylane sulfide films are produced by using the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyphenylene sulfide resin composition having less color spots, and a polyphenylene sulfide film using the same.

[0002]

2. Description of the Related Art Polyphenylene sulfide films have extremely excellent properties in heat resistance, chemical resistance, electrical insulation, dielectric properties, mechanical properties, and the like. It is used for applications such as mold materials. It is known that polyphenylene sulfide is produced, for example, by the method described in JP-B-45-3368.

[0003] The color unevenness referred to in the present application is caused by partial coloration due to thermal degradation or crosslinking of a polymer and unevenness in viscosity due to thickening, and is a streak-like defect extending in the longitudinal direction of the film. .

[0004] In the vapor deposition process in the manufacturing process of a capacitor or the like, for example, in the vapor deposition process, the adhesion between the cooling roll and the color spot defect portion of the film is poor, so that the portion floats from the cooling roll and the film becomes wrinkled. Is to occur. For this reason, the yield decreases, and the deposition yield decreases. Further, due to this defect, the product rejection rate also increased in the film forming process, and the yield was reduced.

A defect similar in appearance to a color spot is a base streak. The die streaks are caused by stains on the die lip and scratches on the die lip due to gas generated during melt extrusion. The die streaks, like the color spots, cause wrinkles in the film at the time of, for example, vapor deposition processing.

Here, since the color spots occur before the die due to the denaturation of the polymer itself as described above, the generation mechanism is obviously different from that of the die streaks.

As an example of defining the polymer viscosity, a temperature 31
Polyphenylene sulfide having a melt index at 5.6 ° C. of 0.5 g / 10 min or more and 200 g / 10 min or less is heat-treated in an inert atmosphere having an oxygen partial pressure of 20 mmHg or less in a temperature range of 200 ° C. or more and a melting point or less. A method for producing polyphenylene sulfide, which is characterized in that it has been proposed (JP-A-5-125186).

[0008] When a film is formed using the polyphenylene sulfide obtained by this manufacturing method, there is an effect that occurrence of die defects is reduced. However, since the heat treatment is performed at a high temperature of 200 ° C. or higher, the polymers soften and adhere to each other to form a lump, and the feeding of the polymers to the extruder deteriorates. Further, the flatness of the film is deteriorated and the thickness is easily changed.
Further, a part of the polymer is thermally degraded or thermally crosslinked during the heat treatment to form a foreign substance, and the polymer is easily broken at the time of film formation. In particular, the film used for capacitor applications had a thickness of several μm, and the breakage due to the foreign matter significantly reduced the yield of film formation.

In addition, since heat treatment is performed at a high temperature, deterioration of the polymer and coloring and thickening due to thermal cross-linking have progressed, and the color spots noticed in the present invention have frequently occurred.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned deficiencies, that is, to eliminate color spots, improve the film formation yield by stable film formation, and to excel in processability in capacitor applications. To provide a polyphenylene sulfide film.

[0011]

Means for Solving the Problems The present inventors have found that the melt viscosity of a polyphenylene sulfide resin composition after heat treatment is not less than 1500 poise and less than 6000 poise, and the difference in melt viscosity of the resin composition before and after heat treatment is 2,000 poise. It has been found that when the ratio is less than the range, it is effective in suppressing color spots.

That is, the polyphenylene sulfide resin composition according to the present invention is a resin composition comprising polyphenylene sulfide, which has a melt viscosity of 31 after heat treatment.
It is characterized by being at least 1500 poise and less than 6000 poise at 6 ° C., and having a difference in melt viscosity before and after heat treatment of less than 2000 poise. In this polyphenylene sulfide resin composition, the color tone L value after heat treatment is preferably 65 or more.

Further, the polyphenylene sulfide film according to the present invention comprises a film produced using the above resin composition, and preferably has an average thickness of 10 μm.
Less than.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. In the present invention, polyphenylene sulfide is at least 80 mol% of repeating units,
Preferably, it refers to a polymer in which 90 mol% or more of the structural units represented by Chemical Formula 1 is used.

[0015]

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If the content of such a component is less than 20 mol%, the crystallinity and softening point of the polymer will be low, and the heat resistance, dimensional stability and mechanical properties of the resulting film will be impaired. If it is less than 20 mol% (preferably less than 10 mol%) of the repeating unit, a unit containing a copolymerizable sulfide bond may be contained. The method of copolymerizing the polymer may be random or block.

In the present invention, the polyphenylene sulfide resin composition refers to the above polyphenylene sulfide (preferably poly-p-phenylene sulfide)
Is 90% by weight or more. The remaining less than 10% by weight in the resin composition may be polymers other than polyphenylene sulfide and / or additives such as fillers, lubricants, coloring agents, ultraviolet absorbers, antistatic agents, antioxidants, and the like. . The resin composition has a viscosity at 316 ° C. after heat treatment of from 1500 poise to less than 6000 poise (preferably from 2000 poise to less than 4500 poise), and the difference in melt viscosity before and after heat treatment is 20 poise.
It is less than 00 poise (preferably less than 1000 poise). Further, it is preferable that the color tone L value of the resin composition after the heat treatment is 65 or more.

Here, the melt viscosity referred to in the present invention is a capillary rheometer which is 3 in accordance with JIS-K7199.
It is a viscosity measured under the conditions of 16 ° C. and a shear rate of 100 sec ⁻¹ . If the viscosity is less than 1500 poise, the crystallization rate of the polymer is increased, and the film is hardly stretched at the time of stretching due to crystallization of the polymer at the time of forming into a sheet with a die, so that breakage occurs frequently. Moreover, the heat resistance and mechanical strength of the obtained film are reduced, and the characteristics of the polyphenylene sulfide film are impaired.

On the other hand, if the viscosity is 6000 poise or more, the polymer viscosity is high and the polymer viscosity is not uniform when melt-extruded into a sheet. . In addition, the melt viscosity is 6
Even if it is less than 2,000 poise, if the difference in melt viscosity from the resin composition before the heat treatment becomes 2,000 poise or more, due to viscosity unevenness in the part where the viscosity has increased due to deterioration and crosslinking and the other part, Frequent color spots.

If the color tone L value of the resin composition is less than 65, the surface of the resin composition is colored yellow-brown or black, which causes the occurrence of color spots or crystallization of the surface. Otherwise, when the polymer is supplied to the extruder, the resin compositions stick to each other and the discharge becomes unstable. The color tone L value in the present invention is a measure of color brightness measured according to JIS-K7105.

The polyphenylene sulfide film of the present invention is an unstretched film, a uniaxially stretched film, or a biaxially stretched film obtained by melt-molding the above polyphenylene sulfide resin composition. Is preferred.

If the melt viscosity of the resin composition used in the present invention is 6000 poise or more or the difference between the melt viscosities before and after the heat treatment is 2,000 poise or more, color unevenness frequently occurs in the film. Occasionally, the film is wrinkled and reduces the deposition yield.

The polyphenylene sulfide film of the present invention can be produced as follows. First, as a polymerization method of polyphenylene sulfide, a method of reacting alkali sulfide and dihalobenzene in a polar solvent at high temperature and high pressure is used. In particular, it is preferable to react sodium sulfide with dichlorobenzene in an amide-based high-boiling solvent such as N-methylpyrrolidone. In order to adjust the degree of polymerization, it is most preferable to add a polymerization aid such as caustic alkali or an alkali metal carboxylate and react at a temperature of 230 to 280 ° C. The pressure and the polymerization time in the polymerization system are appropriately determined depending on the type and amount of the auxiliary agent used, the desired degree of polymerization, and the like. The polymer after polymerization is washed at a high temperature with a solvent having an affinity for polyphenylene sulfide such as N-methylpyrrolidone, washed with water, and dried to obtain a polyphenylene sulfide powder.

The thus obtained resin powder is blended with, for example, an inorganic or organic additive using a Henschel mixer or the like, and supplied to an extruder (preferably an extruder having one or more vent holes) to supply 290-360. The mixture is melt-kneaded at a temperature of ° C. and extruded from a suitable die to obtain a polyphenylene sulfide resin composition.

At this time, the resin composition preferably has a melt viscosity at 316 ° C. of not less than 1500 poise and less than 6000 poise (more preferably, not less than 1500 poise and 5 poise).
(Less than 800 poise, more preferably 2000 poise or more and less than 4500 poise). If the melt viscosity of the resin composition is 6000 poise or more, the polymer will be degraded and crosslinked in the subsequent heat treatment step, so that the melt viscosity cannot be controlled within the target range of the present invention. The melt viscosity of the resin composition is appropriately determined by the ratio of the monomers, the temperature during polymerization, the pressure, the amount of the polymerization aid, the amount of the crosslinking agent such as trihalobenzene added, the melt extrusion temperature, and the like.

Crystallizing the recovered polyphenylene sulfide resin composition to stabilize the supply to the extruder;
The heat treatment of the resin composition is performed to remove volatile impurities, and the heat treatment is preferably performed under the following conditions in order to control the melt viscosity and color tone L value of interest within the range of the present invention.

The heat treatment is performed under a reduced pressure of less than 20 mmHg (more preferably 0 to 5 mmHg) or under an inert gas atmosphere at less than 200 ° C. (more preferably 140 ° C.).
To 190 ° C.) with stirring by a mixer for 30 hours or less (preferably 5 to 20 hours).

Here, the oxygen partial pressure during the heat treatment was 20 mm.
If the temperature exceeds Hg or the heat treatment temperature is 200 ° C. or more, deterioration and crosslinking of the polymer are promoted, so that the difference in melt viscosity before and after heat treatment and the color tone L value, which are of interest, fall outside the range of the present invention. Further, since the deteriorated product becomes foreign matter in the film, the film frequently breaks, and the polymer softens during the heat treatment and fuses with each other, so that the supply to the melt extruder becomes unstable.

If the total heat treatment time is within the above range, the resin composition may be subjected to heat treatment, then gradually cooled, returned to room temperature, and heat-treated again to perform drying in multiple stages. Here, if the heat treatment temperature is 200 ° C. or more or the oxygen partial pressure is 20 mmHg or more, the object of the present invention cannot be achieved because oxidative crosslinking of the polymer proceeds.

The resin composition heat-treated or multi-step heat-treated under the above conditions is supplied to a melt extruder, and melted at a temperature equal to or higher than the melting point of the resin composition (preferably 290 to 360 ° C.) to form a slit. And then quenched by casting on a rotating metal drum to obtain an unstretched, non-oriented film.

In order to form a biaxially stretched film, the unstretched film obtained above can be subjected to a known method such as a sequential biaxial stretching method or a simultaneous biaxial stretching method. It is preferable to use a so-called sequential biaxial stretching method in which the film is stretched in the width direction by a tenter after stretching. The stretching conditions are preferably performed at a temperature of 85 to 110 ° C., and each stretching is performed at a magnification of 1.5 to 4.5 times.

Next, the stretched film thus obtained is subjected to a heat treatment at a fixed length or under a limited shrinkage of 1.5% or less. The heat treatment is performed at 200 ° C. to 290 ° C. for 1 to 50 seconds (preferably at 230 ° C. to 285 ° C. for 3 to 20 seconds). After the heat treatment, a treatment such as annealing may be performed.

[Method for Measuring Physical Properties and Method for Evaluating Effect] Next, the method for evaluating characteristics and the criteria for evaluation used in the description of the present invention will be described. (1) Melt viscosity The melt viscosity of the resin composition and the film was measured according to JIS-K71.
The measurement was performed using a capillary rheometer under the following conditions in accordance with 99. Temperature: 316 ° C Shear rate: 100 sec ^-1 Barrel diameter: 9.55 mm Capillary length: 10 mm Capillary diameter: 1 mm

(2) Color Tone The color tone of the resin composition was measured according to JIS-K7105.

(3) Film Thickness The average thickness of the film was measured at 30 points in the width direction according to JIS-C2151, and averaged.

(4) Number of color spots After cleaning the lip of the base, the polyphenylene sulfide resin composition was extruded at a temperature of 320 ° C. and an extruded amount of 50.
kg / hour, die lip width 600 mm, die lip gap 1 mm, and formed into a sheet on a metal drum rotating at 20 m / min with a lip gap of 1 mm, and visually observed the number of color spots in the width direction of the film according to the following criteria. evaluated. ：: no occurrence △: one or more and less than three occurrences ×: three or more occurrences

(4) Vapor deposition property A vapor deposition machine having a cooling roll is 500 mm wide and 2 μm thick.
The shape of the deposited film after aluminum was deposited on the film was observed and evaluated according to the following criteria. The deposition conditions are
The speed was 100 m / min, the film tension before and after the cooling roll was 3 kg / mm ^2, and the surface temperature of the cooling roll was −30 ° C. The pattern of vapor deposition was vapor-deposited in a stripe shape in which vapor-deposited portions having a width of 9 mm and non-vapor-deposited portions having a width of 1 mm were alternately repeated. ：: no wrinkles in the film, no problem in subsequent processes. Δ: little wrinkles in the film, but no problem in subsequent processes. X: strong wrinkles in the film, obstructing subsequent processes. Coming level

(5) Film-forming stability The resin composition was extruded at a temperature of 320 ° C. and the extruded amount was 50 k.
g / hour, base lip width 600 mm, base lip gap 1
It was formed into a sheet on a metal drum rotating at 20 m / min in mm. The obtained unstretched film was stretched 3.5 times in the longitudinal direction and 3.3 times in the width direction at 99 ° C.
For 3 seconds to form a biaxially stretched film. Extrusion stability at that time, tearing during film formation and variation in film thickness were evaluated according to the following criteria. ：: There is no change in the extrusion amount at the time of extrusion, and there is no hindrance to tearing and variation in film thickness. Δ: Extrusion amount fluctuates during extrusion and does not affect tearing during film formation, but film thickness fluctuation is slightly large. X: Extrusion amount frequently fluctuates during extrusion, foreign matter flows out, and the like, breakage during film formation and film thickness fluctuation are large, and the film formation yield is drastically reduced.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Example 1 A poly-p-phenylene sulfide powder (T1881) manufactured by Toray Industries, Inc. was washed twice with N-methyl-2-pyrrolidone. Further, after blending 1.0% by weight of calcium carbonate particles having an average particle size of 1 μm with the poly-p-phenylene sulfide powder using a Henschel mixer, the mixture was supplied to a twin-screw extruder having a hole diameter of 30 mm, and was heated at a temperature of 320 ° C. to a diameter of 2 mm. Was extruded from a circular die, cooled with water, and then cut into a length of 3 mm with a cutter. The obtained poly-p-phenylene sulfide resin composition has a shear rate of 316 ° C. and a shear rate of 10.
The melt viscosity at 0 sec ^-1 was 3570 poise.

The resulting poly-p-phenylene sulfide resin composition was heat-treated at 160 ° C. for 15 hours while stirring with a mixer under a reduced pressure of oxygen partial pressure of 1 mmHg. 316 of the obtained polyphenylene sulfide resin composition
The melt viscosity at 100 ° C. and a shear rate of 100 sec ⁻¹ is 3860.
Poise and color tone L value were 69.9.

The resin composition was extruded at a temperature of 320 ° C. with an extruder having a hole diameter of 40 mm, and formed into a sheet with a die having a width of 600 mm and a lip gap of 1 mm.
Was cast on a metal drum controlled at a temperature of, to obtain an unstretched film.

The obtained unstretched film was stretched 3.5 times in the longitudinal direction and 3.3 times in the width direction by the successive biaxial stretching method. The stretching temperature was 99 ° C. in both the longitudinal and width directions. In the heat treatment zone following the tenter stretched further in the width direction,
Heat treatment was performed at 60 ° C. The relaxation rate in the width direction was 6%. The average thickness of this biaxially stretched film is 2 μm
No color spots occurred during film formation, and no wrinkles occurred during vapor deposition. Table 1 summarizes the properties of the obtained film.

Example 2 A poly-p-phenylene sulfide resin composition was obtained in the same manner as in Example 1. 130 ° C. the resin composition,
Heat treatment was performed for 6 hours while stirring with a mixer under a reduced pressure of oxygen partial pressure of 1 mmHg. The obtained polyphenylene sulfide resin composition was subjected to a shear rate of 316 ° C. and a shear rate of 100 sec ^−1.
Was 3630 poise and the color tone L value was 72.2. . The resin composition was cast as in Example 1,
The film was stretched to obtain a biaxially stretched film. No color spots occurred during film formation. Table 1 summarizes the properties of the obtained film.

Example 3 A poly-p-phenylene sulfide resin composition was obtained in the same manner as in Example 1. 195 ° C,
Heat treatment was performed for 15 hours while stirring with a mixer under a reduced pressure of oxygen partial pressure of 1 mmHg. 316 ° C., shear rate 100 sec of the obtained polyphenylene sulfide resin composition
The melt viscosity at ^-1 was 5530 poise and the color tone L value was 67.3.
Met. The resin composition was cast as in Example 1,
The film was stretched to obtain a biaxially stretched film. During the film formation, two color spots were generated in the width direction of the film. In addition, the film produced several weak wrinkles during the deposition.
Table 1 summarizes the properties of the obtained film.

Example 4 A poly-p-phenylene sulfide resin composition was obtained in the same manner as in Example 1. 160 ° C. the resin composition,
After heat-treating for 7 hours while stirring with a mixer under a reduced pressure of oxygen partial pressure of 1 mmHg, the obtained resin composition was gradually cooled to room temperature and again heat-treated under the same conditions. The melt viscosity of the heat-treated resin composition at 316 ° C. and a shear rate of 100 sec ⁻¹ was 3,700 poise, and the color tone L value was 71.5. The resin composition was cast and stretched in the same manner as in Example 1 to obtain a biaxially stretched film. No color spots occurred during the film formation, and the film did not wrinkle during the vapor deposition. Table 1 summarizes the properties of the obtained film.

Comparative Example 1 A poly-p-phenylene sulfide resin composition was obtained in the same manner as in Example 1. 210 ° C. the resin composition,
Heat treatment was performed for 10 hours while stirring with a mixer under a reduced pressure of oxygen partial pressure of 1 mmHg. 316 ° C., shear rate 100 sec of the obtained polyphenylene sulfide resin composition
The melt viscosity at ^-1 was 6630 poise and the color tone L value was 64.5.
Met. The resin composition was cast as in Example 1,
The film was stretched to obtain a biaxially stretched film. During the film formation, four color spots occurred in the width direction of the film. This film had strong wrinkles during deposition.
Further, there was a fluctuation in filtration pressure during film formation, and a slight fluctuation in thickness was observed.

Comparative Example 2 A poly-p-phenylene sulfide resin composition was obtained in the same manner as in Example 1. 240 ° C.,
Heat treatment was performed for 7 hours while stirring with a mixer under a reduced pressure of oxygen partial pressure of 1 mmHg. The obtained polyphenylene sulfide resin composition was subjected to a shear rate of 316 ° C. and a shear rate of 100 sec ^−1.
Was 6930 poise and color tone L value was 63.2. The resin composition was cast and stretched in the same manner as in Example 1 to obtain a biaxially stretched film. The melt viscosity of the biaxially stretched film at 316 ° C. and a shear rate of 100 sec ⁻¹ was 7,130 poise. During the film formation, seven color spots occurred in the width direction of the film. This film had strong wrinkles during deposition. In addition, the film had strong wrinkles during vapor deposition. Further, fluctuations in the filtration pressure occurred during the film formation, and a large amount of foreign matters flowed out, causing frequent tearing and poor flatness of the obtained film. The properties of the obtained film are summarized in Table 1.

Comparative Example 3 A poly-p-phenylene sulfide resin composition was obtained in the same manner as in Example 1. 160 ° C. the resin composition,
Heat treatment was performed for 35 hours while stirring with a mixer under a reduced pressure of oxygen partial pressure of 1 mmHg. 316 ° C., shear rate 100 sec of the obtained polyphenylene sulfide resin composition
The melt viscosity at ^-1 was 6430 poise and the color tone L value was 63.4.
Met. The resin composition was cast as in Example 1,
The film was stretched to obtain a biaxially stretched film. At the time of film formation, four color spots were generated in the width direction, and strong wrinkles were generated at the time of vapor deposition. Further, there was a change in filtration pressure during film formation, and a slight change in thickness was observed.

Comparative Example 4 A poly-p-phenylene sulfide resin composition was obtained in the same manner as in Example 1. 160 ° C. the resin composition,
Heat treatment was performed for 10 hours while stirring with a mixer under a reduced pressure of oxygen partial pressure of 25 mmHg. 316 ° C., shear rate 100 sec of the obtained polyphenylene sulfide resin composition
The melt viscosity at c ^-1 was 6,980 poise, and the color tone L value was 62.
It was 2. The resin composition was cast and stretched in the same manner as in Example 1 to obtain a biaxially stretched film. Nine color spots were generated in the width direction during the film formation, and strong wrinkles were generated in the film during the deposition. Further, during film formation, a large amount of foreign matters flowed out during film formation, and tearing frequently occurred.

Comparative Example 5 E as a polyphenylene sulfide powder manufactured by Toray Industries, Inc.
Using 2481, a poly-p-phenylene sulfide resin composition was obtained in the same manner as in Example 1. The resulting poly
The melt viscosity of the p-phenylene sulfide resin composition at 316 ° C. and a shear rate of 100 sec ⁻¹ was 1,180 poise. The resin composition was heated at 160 ° C. and an oxygen partial pressure of 1 mmH
The mixture was heat-treated for 15 hours while stirring with a mixer under a reduced pressure of g. The melt viscosity of the obtained polyphenylene sulfide resin composition at 316 ° C. and a shear rate of 100 sec ⁻¹ was 1380 poise, and the color tone L value was 70.2. The resin composition was cast and stretched in the same manner as in Example 1 to obtain a biaxially stretched film. No color spots occurred during film formation, but crystallization of the film progressed during forming into a sheet on a metal drum, and tearing frequently occurred during stretching.

Comparative Example 6 As a polyphenylene sulfide powder, E manufactured by Toray Industries, Inc.
Using 2481, a poly-p-phenylene sulfide resin composition was obtained in the same manner as in Example 1. The resulting poly
The melt viscosity of the p-phenylene sulfide resin composition at 316 ° C. and a shear rate of 100 sec ⁻¹ was 1,180 poise. The resin composition was heated at 200 ° C. and an oxygen partial pressure of 10 mm.
Heat treatment was performed for 15 hours while stirring with a mixer under a reduced pressure of Hg. The obtained polyphenylene sulfide resin composition had a melt viscosity at 316 ° C. and a shear rate of 100 sec ⁻¹ of 3450 poise, and a color tone L value of 62.8. The resin composition was cast and stretched in the same manner as in Example 1 to obtain a biaxially stretched film. Nine color spots were generated in the width direction at the time of film formation, and strong wrinkles were generated at the time of vapor deposition. In addition, many outflows of foreign substances during film formation frequently resulted in tearing.

Comparative Example 7 120 kg of sodium sulfide / 9 hydrate was added to an autoclave.
2.8 kg of sodium hydroxide, 73 sodium benzoate
Kg and 160 kg of N-methyl-2-pyrrolidone were charged, heated to 200 ° C. while stirring in a nitrogen atmosphere, and dehydrated. P-Dichlorobenzene 7 was added to the residual mixture.
3.5 kg and 1,2,4-trichlorobenzene
8 kg, and N-methyl-2-pyrrolidone was added to 4 kg.
Add 0Kg and pressurize with nitrogen at 260 ° C and 0.4MPa.
Stirred for hours. The reaction product was washed twice with N-methyl-2-pyrrolidone to obtain a poly-p-phenylene sulfide powder. The poly-p- obtained by repeating the polymerization three times
A poly-p-phenylene sulfide resin composition was obtained from 132 kg of phenylene sulfide powder in the same manner as in Example 1. The melt viscosity of the obtained poly-p-phenylene sulfide resin composition at 316 ° C. and a shear rate of 100 sec ⁻¹ was 8,100 poise. The resin composition is
The mixture was heat-treated at 60 ° C. under a reduced pressure of 1 mmHg of oxygen for 15 hours while stirring with a mixer. The obtained polyphenylene sulfide resin composition has a shear rate of 10 at 316 ° C.
The melt viscosity at 0 sec ^-1 was 8310 poise, and the color tone L value was 69.7. The resin composition was cast and stretched in the same manner as in Example 1 to obtain a biaxially stretched film. Eleven color spots were generated in the width direction at the time of film formation, and strong wrinkles were generated at the time of vapor deposition.

[0053]

[Table 1]

From Table 1, it can be seen that the film using the resin composition of the present invention having a melt viscosity after heat treatment of 2,000 poise or more and less than 6000 poise and having a difference in melt viscosity before and after heat treatment of less than 2,000 poise is smaller than a conventional film. It can be seen that not only the occurrence of color spots is small and stable film formation can be performed, but also the film formation yield is improved, and also that the film is hardly wrinkled at the time of vapor deposition in the process of manufacturing a capacitor or the like.

On the other hand, in Comparative Examples 1 and 2, heat treatment was performed at a temperature of 200 ° C. or more, and in Comparative Example 3, the heat treatment time was 35 minutes.
In Comparative Example 4, the oxygen partial pressure during the heat treatment was 25
The measurement was carried out at a pressure of mmHg, and the melt viscosity and the difference in melt viscosity referred to in the present invention were all large, and the color tone L value was less than 65, so that the object of the present invention could not be achieved. In Comparative Example 5, the degree of polymerization and the degree of cross-linking of the polyphenylene sulfide powder were changed, and the melt viscosity was set to 2000 poise or less.
Although the color unevenness of the obtained film was good, the crystallization rate was high and the film was frequently broken in the stretching step, so that the stable film formation as the object of the present invention could not be achieved. Comparative Example 6 was obtained by heat-treating the same resin composition as Comparative Example 5 at a high temperature of 200 ° C. or more.
Because of 0 poise or more, color spots occurred frequently. In Comparative Example 7, a polymer having a high viscosity was prepared, and the difference in melt viscosity before and after the heat treatment was less than 2000 poise.
Since the viscosity was not less than 00 poise, the viscosity was not equalized during extrusion molding, and color spots frequently occurred.

[0056]

According to the present invention, since the above-mentioned structure is employed, color spots are extremely small, and tears during film formation are reduced, so that not only the film formation yield is remarkably improved, but also the use of capacitors and the like. Deposition problems were reduced.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Ikuo Hagiwara F-term (reference) 4F071 AA61 AF06Y AF29Y AF34 AH12 4F210 AA34C AA34D AB16 AG01 QA02 QC06 QG01 QG18 QW12 4J002 CN011 FD010 FD070 FD090 FD100 FD170

Claims (4)

[Claims] 1. A resin composition comprising polyphenylene sulfide has a melt viscosity after heat treatment of 1 at 316 ° C.
500 poise or more and less than 6000 poise, and
A polyphenylene sulfide resin composition having a difference in melt viscosity before and after heat treatment of less than 2000 poise. 2. The polyphenylene sulfide resin composition according to claim 1, wherein the color tone L value after heat treatment is 65 or more. 3. A polyphenylene sulfide film produced using the polyphenylene sulfide according to claim 1 or 2. 4. The method according to claim 3, wherein the average thickness is less than 10 μm.
The polyphenylene sulfide film according to the above.