JP2006225494A - Polypropylene resin, and oriented film made from the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polypropylene oriented film excellent in breakdown strength as a capacitor film. <P>SOLUTION: A polypropylene resin composition is obtained by adding 0.1-10 pts.wt. of a fluorine resin (B) to 100 pts.wt. of a polypropylene resin (A) having an ash content of 30 ppm or less, a chlorine content of 3 ppm or less, a melt flow rate (ASTM D1238, 230°C, load 2.16 kg) of 0.1-10 g/10 min., a total amount of ethylene of 2 wt% or less, and an isotactic index (II) of 90% or more. The polypropylene resin composition is oriented in at least one direction to form the polypropylene oriented film. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polypropylene resin composition to which a fluororesin is added, and a polypropylene stretched film excellent in dielectric breakdown strength formed by stretching the polypropylene resin composition.

Polypropylene has excellent stretching characteristics, and can be formed into a uniform thin film. The polypropylene is widely used in various fields by taking advantage of the excellent characteristics. Moreover, since it has excellent electrical characteristics, it is widely used for capacitor insulating films. As polypropylene having excellent characteristics as a capacitor insulating film, studies such as improving stereoregularity have been made (for example, Patent Document 1).
JP-A-56-131922

In the field of capacitor insulating films, high dielectric breakdown voltage at high temperatures is required. Dielectric breakdown mainly occurs when charged particles carrying current collide with polypropylene molecules (atoms) upon receiving energy by application and break atomic bonds. A certain amount of electron density is required to break the atomic bond, but the electron density increases by repeating valence electrons from the atom (impact ionization) when the charged particle collides with the atom. . For this reason, until now, there has been almost no addition of other resins that can be the source of charged particles, reducing the catalyst residue as much as possible, and increasing the stereoregularity so that the bond portion is less likely to break down. Consideration such as increasing has been performed. However, in the reduction of the catalyst residue, it has already been considerably reduced to 30 ppm or less at present, and it is difficult to further reduce it. If the stereoregularity is too high, the stretchability is deteriorated, resulting in a problem that the dielectric breakdown voltage of the stretched film is lowered. We have now found that the dielectric breakdown strength of polypropylene is improved by adding a small amount of fluororesin to polypropylene. An object of the present invention is to provide a polypropylene stretched film for a capacitor having a high dielectric breakdown voltage by adding a fluorine-based resin to polypropylene.

(1) A polypropylene resin composition obtained by adding a fluorine resin (B) to a polypropylene resin (A) having an ash content of 30 ppm or less and a chlorine content of 3 ppm or less.
(2) The polypropylene resin composition according to claim 1, wherein 0.1 to 10 parts by weight of the fluorine resin (B) is added to 100 parts by weight of the polypropylene resin (A).
(3) Melt flow rate (ASTM D1238, 230 ° C., load 2.16 kg) of the polypropylene resin (A) is 0.1 to 10 g / 10 min, total ethylene amount is 2 wt% or less, isotactic index (II ) Is 90% or more, the polypropylene resin composition according to (1) or (2).
(4) The fluororesin (B) contains at least one selected from the group consisting of vinylidene fluoride resin, ethylene chloride trifluoride resin, tetrafluoroethylene resin, and hexafluoropropylene resin. The polypropylene resin composition as described in (1) or (2), which is characterized.

(5) A stretched polypropylene film obtained by stretching the polypropylene resin composition according to any one of (1) to (4) in at least one direction.
(6) The stretched polypropylene film according to (5), which is for use in a capacitor.

When a polypropylene stretched film obtained by stretching a polypropylene resin composition to which the fluororesin of the present invention is added is used as a capacitor insulating film, excellent dielectric breakdown strength can be obtained.

The melt flow rate of the polypropylene resin (A) used in the present invention (based on ASTM D1238, measured at a measurement temperature of 230 ° C. and a load of 2.16 kg) is in the range of 0.1 to 10 g / 10 minutes.
The ash content of the polypropylene resin (A) is preferably 30 ppm or less, and more preferably 20 ppm or less. The chlorine content of the polypropylene resin (A) is preferably 3 ppm or less, more preferably 2 ppm or less. If the ash content exceeds 30 ppm or the chlorine content exceeds 3 ppm, the dielectric breakdown strength may decrease due to an increase in the conductive component.

  The polypropylene resin (A) is a propylene homopolymer or a propylene-ethylene copolymer, and the total amount of ethylene contained in the polypropylene resin (A) is 2 wt% or less, and the polypropylene resin (A) The isotactic index (II) is 90% or more. If the total ethylene amount is more than 2 wt% or II is less than 90%, the dielectric breakdown strength may be reduced due to the decrease in crystallinity.

The addition amount of the fluororesin (B) used in the present invention is 0.1 to 10 parts by weight, preferably 0.2 to 10 parts by weight, more preferably 100 parts by weight of the polypropylene resin (A). Preferably it is 1-10 weight part. As the fluorine-based resin (B), any resin that is generally obtained by polymerizing a fluorine atom-containing monomer may be used, but vinylidene fluoride resin, chloroethylene fluoride resin, tetrafluoroethylene resin, hexafluoride resin. It preferably contains at least one selected from the group consisting of propylene resins.
Furthermore, you may add stabilizers, such as antioxidant and a hydrochloric acid absorber, to the polypropylene resin composition in this invention in the range which does not impair the effect of this invention.

  In order to obtain the polypropylene resin (A) of the present invention, a solid titanium catalyst component containing titanium, magnesium, halogen and an internally added electron donating compound and a group I, II or III of the periodic table are selected. It is desirable to use polypropylene obtained by polymerizing propylene in the presence of a polymerization catalyst comprising an organometallic compound containing a metal and an externally added electron donating compound.

  More specifically, as the polymerization catalyst, a catalyst usually used for industrially producing polypropylene is used. For example, a titanium trichloride or titanium tetrachloride supported on a carrier such as magnesium halide and an organoaluminum compound are used. Among them, it is desirable to use a catalyst having a particularly high activity and a low amount of titanium component.

  Since the polypropylene used in the present invention is used for a capacitor insulating film, when the amount of polymer obtained per unit amount of the catalyst is low, it is necessary to perform post-treatment to remove the catalyst residue. Even when the catalyst activity is high and the amount of polymer obtained is large, it is desirable to perform post-treatment to remove the catalyst residue. As a post-treatment method, the polypropylene obtained by polymerization is washed with liquid propylene, butane, hexane, heptane or the like. At this time, water, alcohol compounds, ketone compounds, ether compounds, ester compounds, amine compounds, organic acid compounds, inorganic acid compounds, etc. may be added to solubilize catalyst components such as titanium and magnesium to facilitate extraction. Done. It is also preferable to wash with a polar compound such as water or alcohol.

  Furthermore, a particularly preferred polypropylene resin (A) can be obtained by dehalogenating the polypropylene obtained by the above polymerization method.

  Among the dehalogenation treatments, dehalogenation treatment using an epoxy compound is particularly preferable. Here, as the epoxy compound, alkylene oxide such as ethylene oxide, propylene oxide, butene oxide, and cyclohexene oxide, glycidyl alcohol, glycidyl acid, glycidyl ester, and the like are preferably used. When the polymer is dechlorinated using these epoxy compounds, it is very effective to use a compound having an OH group equal to or more than that of the epoxy compound. Examples of the compound having an OH group include water and alcohol compounds.

In order to produce the polypropylene resin composition used in the present invention, a raw material polypropylene resin, a fluorine resin, and other additives as necessary are mixed with a ribbon blender, a tumbler blender, a Henschel blender, or the like.
The mixed raw material polypropylene-based resin, fluorine-based resin, and other additive materials added as necessary can then be melt-kneaded to obtain a polypropylene-based resin composition. The melt-kneading equipment includes kneaders, Banbury mixers, Brabenders, single-screw extruders, twin-screw extruders and other kneading machines, twin-screw surface renewal machines, double-shaft multi-disk devices and other horizontal stirrers or double helical ribbons. A vertical stirrer such as a stirrer can be employed.
The heating temperature at the time of melt kneading is 170 to 270 ° C, preferably 180 to 240 ° C. Melting and kneading in this temperature range is preferable because the raw material polypropylene resin is sufficiently melted and mixed with the fluorine resin, and the properties of the resulting polypropylene resin composition are not changed. The melt kneading time is generally 10 seconds to 5 minutes, preferably 30 seconds to 60 seconds.

  There is no restriction | limiting in particular as a method of extending | stretching the polypropylene resin composition in this invention at least to one direction, and the method of manufacturing a normal polypropylene stretched film can be used.

As such a method, for example, a sheet having a thickness of 500 μm is first prepared at 250 ° C. using a two-layer T die having a diameter of 30 mm. The sheet thus obtained is preheated at 154 ° C. for 1 minute, and then stretched 5 times in the longitudinal direction and 7 times in the transverse direction at a stretching speed of 6 m / s at 154 ° C. to obtain a film having a thickness of 15 μm. The method is mentioned.
The polypropylene stretched film thus obtained is excellent in dielectric breakdown strength and can be preferably used for, for example, a capacitor application. When used for capacitor applications, it is desirable that the value of the dielectric breakdown voltage of the polypropylene stretched film is at least 600 V / μm.

〔Example〕
The dielectric breakdown voltage (V / μm) was measured at 23 ° C. or 80 ° C. according to JIS-2330.

  As a method for quantifying the ash content, first, a 100 g sample is put in a magnetic crucible, and the sample is burned, and then the carbon produced in the electric furnace is completely burned at 800 ° C. After that, the weight of the remaining ash was obtained and calculated by the weight percentage with respect to the sample.

  As a method for measuring the isotactic index (II), first, a 1 g sample is put into a Soxhlet extractor and extracted with boiling n-heptane for 10 hours. Next, this sample was washed with acetone and then dried at 120 ° C. for 6 hours, and then its weight was determined and calculated by the weight percentage with respect to the initial sample amount.

As a method for quantifying the chlorine content, an ion chromatographic method was used in which the sample was burned in a mixed gas stream of argon gas and oxygen gas, and then the generated chlorine ions were quantified by ion chromatography.

  Polypropylene resin A, which is a propylene homopolymer having an MFR of 3 g / 10 min, II of 98%, an ash content of 17 ppm, and a chlorine content of 1 ppm, is added to a fluororesin (3M Dynamer FX-5911X; vinylidene fluoride resin, A polypropylene resin composition to which 0.2 phr of a mixture of a tetrafluoroethylene resin and a hexafluoropropylene resin) was added to a sheet having a thickness of 500 μm at 250 ° C. using a 30 mmφ two-layer T die. The obtained sheet was preheated at 154 ° C. for 1 minute using a biaxial stretching machine (KARO IV) manufactured by Bruckner, and then stretched 5 times in the longitudinal direction and 7 times in the transverse direction at a stretching speed of 6 m / s at 154 ° C. And a biaxially stretched film having a thickness of 15 μm was prepared.

  The dielectric breakdown voltage at 23 ° C. and 80 ° C. of the biaxially stretched film obtained by the above method was measured. The results are shown in Table 1.

  A polypropylene resin composition obtained by adding 0.5 phr of a fluororesin (3M Dynamer FX-5911X) to the polypropylene resin A used in Example 1 was prepared in the same manner as in Example 1, but with a thickness of 15 μm. An axial stretched film was prepared, and the dielectric breakdown voltage of this biaxially stretched film at 23 ° C. and 80 ° C. was measured. The results are shown in Table 1.

  A polypropylene resin composition obtained by adding 1.0 phr of a fluororesin (3M Dynamer FX-5911X) to the polypropylene resin A used in Example 1 was prepared in the same manner as in Example 1, but with a thickness of 15 μm. An axial stretched film was prepared, and the dielectric breakdown voltage of this biaxially stretched film at 23 ° C. and 80 ° C. was measured. The results are shown in Table 1.

[Comparative Example 1]
A biaxially stretched film having a thickness of 15 μm was prepared in the same manner as in Example 1 without adding a fluororesin to the polypropylene resin A used in Example 1, and this biaxially stretched film was subjected to 23 ° C. and The breakdown voltage at 80 ° C. was measured. The results are shown in Table 1.

In the polypropylene resin composition to which the fluororesin was added, a polypropylene stretched film having a high dielectric breakdown strength could be obtained as compared with the case where the fluororesin was not added. Moreover, the dielectric breakdown strength increased as the amount of fluorine resin added increased.

Claims (6)

A polypropylene resin composition comprising a fluorine resin (B) added to a polypropylene resin (A) having an ash content of 30 ppm or less and a chlorine content of 3 ppm or less.
The polypropylene resin composition according to claim 1, wherein 0.1 to 10 parts by weight of the fluororesin (B) is added to 100 parts by weight of the polypropylene resin (A).
The polypropylene resin (A) has a melt flow rate (ASTM D1238, 230 ° C., load 2.16 kg) of 0.1 to 10 g / 10 minutes, a total ethylene amount of 2 wt% or less, and an isotactic index (II) of 90. The polypropylene resin composition according to claim 1 or 2, which is at least%.
The fluororesin (B) contains at least one selected from the group consisting of vinylidene fluoride resin, chloroethylene trifluoride resin, tetrafluoroethylene resin, and hexafluoropropylene resin. The polypropylene resin composition according to claim 1 or 2.
A polypropylene stretched film obtained by stretching the polypropylene resin composition according to claim 1 in at least one direction.
The stretched polypropylene film according to claim 5, which is for use in a capacitor.