JP7241532B2 - Capacitor film and manufacturing method thereof - Google Patents

Description

The present invention relates to a polypropylene film for capacitors.

Biaxially oriented polypropylene films are excellent in mechanical properties, heat resistance, chemical stability, insulating properties, etc., and are therefore widely used not only for packaging and tape applications but also as films for capacitors. Demand for films for capacitors is increasing mainly in the fields of automobiles and home appliances, and further miniaturization, higher capacity and higher reliability are desired. In particular, when using capacitors for high output, such as in hybrid and electric vehicles, a large amount of current flows through circuits such as transistors and capacitors, raising operating temperatures. Gender is also required.

Here, if the film is made thinner, it is possible to make the capacitor smaller and to increase the capacity, but because the withstand voltage at high temperatures drops significantly, it cannot be used as a capacitor film used at high output. .

Patent Document 1 discloses a film made of a composition containing polypropylene with high stereoregularity and a nucleating agent. In order to increase the dielectric breakdown voltage, it is effective to increase the stereoregularity of polypropylene. is described.

In Patent Document 2, not only the amount of eluted components at a predetermined temperature obtained by cross-fractionated chromatographic analysis (CFC) is specified, but also the molecular weight distribution is specified to adjust stretchability, dielectric breakdown voltage, etc. It describes a polypropylene that can be formed into a capacitor film having good physical properties.

Patent Literature 3 describes a polypropylene capable of obtaining a capacitor film having excellent durability such as dielectric breakdown voltage by specifying the amount of eluted components at a predetermined temperature obtained by cross fractional chromatography analysis (CFC). It is

Patent Document 4 describes a polypropylene having high stereoregularity and capable of obtaining a capacitor film having excellent withstand voltage by narrowing the half width of the elution peak obtained by cross fractional chromatography (CFC). ing.

Patent Documents 5 and 6 disclose a propylene homopolymer composition for a capacitor film comprising a metallocene-catalyzed polypropylene and a Ziegler-catalyzed polypropylene, and a capacitor film comprising the same.

JP-A-61-110906 JP-A-9-052917 JP-A-2005-089683 WO2010-087328 WO2016-017752 WO2016-017753

However, in the conventional techniques, as described below, the balance between stretchability (the stretching temperature range of the raw sheet is wide and the resulting capacitor film thickness is excellent in uniformity) and voltage resistance is inadequate. rice field.

In the technique described in Patent Document 1, even if the stereoregularity of polypropylene is improved and a nucleating agent is blended, it has a sufficient dielectric breakdown voltage, especially a high dielectric breakdown voltage in a harsh environment of high temperature and high frequency current. I haven't been able to get the film.

Patent Document 2 proposes a polypropylene for capacitor films in which the elution rate at 120° C. (CFC) is specified within a specific range, and states that if the CFC is less than the lower limit, the stretchability is poor, and if the upper limit is exceeded, the obtained dielectric breakdown voltage is lowered. are doing. However, in the technique described in Patent Document 2, there is a limit to compatibility between stretchability and dielectric breakdown voltage.

Patent Document 3 proposes a polypropylene for a capacitor film having a specified molecular weight distribution and a 110° C. elution rate (CFC), and proposes a film with excellent antiblocking properties, but does not describe the stretchability of the film. It has not been.

Patent Document 4 proposes a polypropylene suitable for a capacitor film, which has high stereoregularity, a small amount of elution at 90°C (CFC), a narrow elution distribution, and a xylene-soluble content within a predetermined range. However, no proposal has been made to achieve both the stretchability of polypropylene and the dielectric breakdown voltage of the obtained capacitor film.

In the techniques described in Patent Documents 5 and 6, a composition composed of polypropylene obtained with a metallocene catalyst and polypropylene obtained with a Ziegler-Natta catalyst is used to achieve both a stretching temperature range and a dielectric breakdown voltage, but still at high temperatures. There is a limit to the dielectric breakdown voltage at 100.degree. C., and no proposal for a uniform thin film has been made.

In view of the prior art as described above, the present invention has a high dielectric breakdown voltage in a severe environment of unprecedented levels of high temperature and high frequency current, and has a wide stretching temperature range during stretching molding and a film thickness. An object of the present invention is to provide a capacitor film with excellent uniformity.

The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, propylene having an unprecedented level of high stereoregularity is polymerized by combining a specific solid titanium catalyst component and a specific external donor. Furthermore, the propylene homopolymer that not only has high stereoregularity but also contains a predetermined amount or more of high-temperature elution components obtained by cross fractionation chromatography (CFC) has excellent stretchability (stretching temperature range, obtainable The inventors have found that the dielectric strength is extremely excellent while maintaining the uniformity of the film thickness, which is expected, and have completed the present invention. The present invention includes the following matters.

[1] A capacitor film having at least one resin layer containing a propylene homopolymer satisfying the following requirements (1) to (5):
(1) Melt flow rate (MFR) (ASTM D1238, 230° C., under 2.16 kg load) is 1 to 10 g/10 minutes;
(2) the pentad isotactic fraction measured by ¹³ C-NMR is 99.0% or more;
(3) The percentage of components eluting at temperatures above 124° C. by cross-fractionation chromatographic analysis (CFC) is 5 to 30% by mass;
(4) The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 4 to 20;
(5) The chlorine content is 2 mass ppm or less.
[2] The capacitor film according to [1], wherein the propylene homopolymer further satisfies the following requirement (6):
(6) The amount of n-decane soluble components at 23°C is 1.0% by mass or less.
[3] The capacitor film according to [1] or [2], which has a thickness of 1 to 50 μm.
[4] The capacitor film according to [1] or [2], which has a thickness of 1.5 to 30 μm.
[5] The method for producing a capacitor film according to any one of [1] to [4], wherein the raw sheet is stretched at a stretching surface ratio (longitudinal × horizontal surface ratio) of 30 to 80 times. A method of manufacturing a capacitor film comprising:

According to the present invention, it is possible to provide a capacitor film that is excellent in high-temperature withstand voltage property and stretchability (wide stretching temperature range during stretch molding and excellent uniformity of film thickness).

The present invention will be described in detail below.
A capacitor film according to the present invention is characterized by having at least one resin layer containing a propylene homopolymer, which will be described later.

[Propylene homopolymer]
The propylene homopolymer used in the present invention satisfies the following requirements (1) to (5).
<Requirement (1)>
The propylene homopolymer has an MFR (ASTM D1238, 230° C., under 2.16 kg load) of 1 to 10 g/10 min, preferably 2 to 6 g/10 min, more preferably 2.5 to 5 g/10 min. .

When the MFR is less than 1.0 g/10 minutes, it is difficult to form a raw film with an extruder, and the chuck may come off during stretching, making it impossible to obtain a desired stretched film. On the other hand, if the MFR exceeds 10.0 g/10 minutes, the productivity of the film is greatly reduced, such as frequent film breakage during stretching. In addition, MFR can adjust the hydrogenation amount at the time of polymerization of the propylene resin. The MFR can be determined by the method described in Examples below.

<Requirement (2)>
The mesopentad fraction (mmmm) of the propylene homopolymer determined by ¹³ C-NMR is 99.0% or more, preferably 99.1 to 100%, more preferably 99.2 to 100%.
When mmmm is 99.0% or more, high-temperature withstand voltage is excellent. Here, the mesopentad fraction indicates the existence ratio of the pentad isotactic structure in the molecular chain. rate. The mesopentad fraction can be determined by the method described in Examples below.

<Requirement (3)>
According to cross-fractionated chromatographic analysis (CFC) of the propylene homopolymer, the ratio of components eluting at a temperature above 124° C. is 5 to 30% by mass, preferably 7 to 20% by mass, more preferably 8 to 30% by mass. 15% by mass.
If the proportion of the component that elutes at a temperature exceeding 124°C is less than 5% by mass, the effect of improving the high-temperature voltage resistance cannot be obtained. . Within the predetermined range, the withstand voltage can be improved without impairing the stretchability, and the effect of the withstand voltage is small, especially at high temperatures.

Moreover, in Patent Documents 2 and 3, a polypropylene defined by the elution amount of CFC at 120° C. or 110° C. has been proposed. could not be explained by the elution amount of A possible reason for this is that the amount of elution at a low elution temperature was defined. As a result of the investigation in the present invention, it was concluded that the predominance of the withstand voltage of the capacitor film according to the present invention at high temperature can be explained by specifying the elution temperature of 124°C, which is higher than the conventional temperature.

The proportion of components eluted at temperatures above 124° C. can be determined by the method described in Examples below.
The proportion of components eluted at temperatures above 124° C. tends to increase with mmmm, but is not uniquely determined by mmmm alone. The reason for this is that mmmm is an index of the regularity of propylene penta-chains and is the average value of the local regularity of the molecular chain, whereas the proportion of components eluting at temperatures above 124 ° C. This is because it is an index of crystallinity that is influenced by the mmmm of the molecular chain, chain distribution, molecular weight, terminal structure, branched structure, etc., and the resulting structures are different. Therefore, even if the mmmm is the same, if the individual molecular chains differ in mmmm, chain distribution, molecular weight, terminal structure, branched structure, etc., the ratio of components eluted at temperatures above 124° C. will also differ.

Although it is not clear why the component that dissolves at a temperature exceeding 124°C has a large effect of improving the voltage resistance at high temperatures, if there is even one defect within a certain area of the stretched film made of polypropylene, dielectric breakdown will occur. Therefore, it can be interpreted that the component that dissolves at a temperature exceeding 124° C. has a large effect of reducing defects in the film. In addition, it is considered that the high-temperature withstand voltage property was able to be improved without impairing the stretchability because the ratio was small.

<Requirement (4)>
The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC of the propylene homopolymer is 4 to 20, preferably 5 to 15, more preferably 6 to 10. .
When Mw/Mn is 4 or more, the biaxially stretched film is excellent in stretchability, and a uniform film can be easily obtained. Also, when the Mw/Mn is 20 or less, the amount of low-molecular-weight components is small, and stickiness or the like is suppressed during molding, which is preferable in terms of moldability. That is, Mw/Mn within the above range is preferable from the viewpoint of the moldability and stretchability of the propylene-based polymer and the thickness uniformity of the resulting capacitor film. Mw/Mn can be determined by the method described in Examples below.

<Requirement (5)>
The chlorine content of the propylene homopolymer is 2 mass ppm or less, preferably 1.5 mass ppm or less, more preferably 1.2 mass ppm or less. When the chlorine content exceeds 2 ppm by mass, not only the voltage resistance of the resulting stretched film is lowered, but also the long-term capacitor properties are lowered. When the capacitor is used, the electric field increases locally in the vicinity of the chloride ions inside the film, which makes it easier for dielectric breakdown to occur, resulting in a decrease in withstand voltage. The chlorine content can be controlled within the above range by post-treating the polypropylene resin.

A propylene homopolymer satisfying the above requirements (1) to (5) can be obtained, for example, by polymerizing propylene in the presence of an olefin polymerization catalyst described below. The propylene homopolymer preferably satisfies the following requirement (6) in addition to the above requirements (1) to (5).

<Requirement (6)>
The content of n-decane soluble components in the propylene homopolymer at 23° C. is 1.0% by mass or less, preferably 0.8% by mass or less, and more preferably 0.5% by mass or less. When the amount of the decane-soluble component is within the above range, the high-crystalline component is sufficiently secured in the obtained capacitor film, and not only the high-temperature withstand voltage property is improved, but also the long-term withstand voltage property is maintained. Be expected.

<Catalyst for Olefin Polymerization>
The olefin polymerization catalyst used for producing the propylene homopolymer is not particularly limited as long as the propylene-based polymer can be obtained.
(i) a solid titanium catalyst component containing magnesium, titanium, a halogen and an electron donor and satisfying the following requirements (k1) to (k4);
(ii) an organosilicon compound component represented by the following formula (II);
(iii) a catalyst [A] containing an organometallic compound component containing an element belonging to Group 1, 2 or 13 of the periodic table, or
A catalyst [B] comprising a prepolymerized catalyst (p) obtained by prepolymerizing propylene with the catalyst [A], the organosilicon compound component (ii), and the organometallic compound component (iii)
is mentioned.
(k1) Titanium content is 2.5% by mass or less.
(k2) The electron donor content is 8 to 30% by mass.
(k3) The electron donor/titanium (mass ratio) is 7 or more.
(k4) Titanium is not substantially desorbed by hexane washing at room temperature.
^R1Si ( ^OR2 ) ₂ ( ^NR3R4 ) ⁽ II)
In formula (II), R ¹ represents a secondary or tertiary hydrocarbon group having 1 to 20 carbon atoms, R ² represents a hydrocarbon group having 1 to 4 carbon atoms, and R ³ represents a hydrocarbon group having 1 to 12 carbon atoms. is a hydrocarbon group or a hydrogen atom, and R ⁴ is a hydrocarbon group having 1 to 12 carbon atoms.
Each component constituting the olefin polymerization catalyst will be described below.

<<Solid titanium catalyst component (i)>>
The solid titanium catalyst component (i) is
(a) solid titanium containing magnesium, titanium, a halogen and an electron donor and from which hexane washing at room temperature does not eliminate titanium;
(b) an aromatic hydrocarbon;
(c) liquid titanium; and (d) an electron donor.

(a) Solid titanium The solid titanium (a) can be obtained by contacting a magnesium compound, a titanium compound, an electron donor (internal donor), and the like by various methods to prepare a known solid titanium catalyst component ( For example, it can be manufactured according to Japanese Unexamined Patent Publication No. 4-096911, Japanese Unexamined Patent Publication No. 58-83006, Japanese Unexamined Patent Publication No. 8-143580, etc.).

Preferably, the magnesium compound is used in a solid state. The solid-state magnesium compound may be the magnesium compound itself in a solid state, or an adduct with an electron donor. Examples of the magnesium compound include magnesium compounds described in JP-A-2004-2742, specifically magnesium chloride, ethoxymagnesium chloride, butoxymagnesium and the like. Examples of the electron donor include compounds capable of solubilizing magnesium compounds described in JP-A-2004-2742, specifically alcohols, aldehydes, amines, carboxylic acids and mixtures thereof. The amount of the magnesium compound and the electron donor to be used varies depending on their types, contact conditions, etc., but the amount of the magnesium compound to the liquid electron donor is 0.1 to 20 mol/liter, preferably 0.5 to 0.5 mol/liter. It can be used in an amount of 5 mol/liter.

Preferably, the titanium compound is used in a liquid state. Examples of such titanium compounds include tetravalent titanium compounds represented by the following formula (III).
Ti(OR ⁵ ) _g X _4-g (III)
In formula (III), ^R5 is a hydrocarbon group, X is a halogen atom, and 0≤g≤4.

Titanium tetrachloride is particularly preferable as the titanium compound. Moreover, you may use the said titanium compound in combination of 2 or more types.
Examples of the electron donor (internal donor) include compounds represented by the following formula (IV) (hereinafter also referred to as "compound (IV)").

In formula (IV), R represents a linear or branched alkyl group having 1 to 10 carbon atoms, preferably 2 to 8 carbon atoms, more preferably 3 to 6 carbon atoms; It represents a linear or branched alkyl group, and n represents an integer of 0-4. In the present invention, compounds in which n is 0 are preferred.

Examples of alkyl groups for R and R' are methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, pentyl, hexyl, heptyl. group, octyl group, nonyl group, decyl group, and the like.

Specific examples of the compound (IV) include dimethyl phthalate, methyl ethyl phthalate, diethyl phthalate, n-propyl phthalate, diisopropyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, and di-n-phthalate. Pentyl, dineopentyl phthalate, di-n-hexyl phthalate, di-n-heptyl phthalate, di(methylhexyl) phthalate, di(dimethylpentyl) phthalate, di(ethylpentyl) phthalate, di(2, 2,3-trimethylbutyl), di-n-octyl phthalate, and di-2-ethylhexyl phthalate. Among these, diisobutyl phthalate is particularly preferred.

In the present invention, an electron donor other than the compound (IV) may be used as the electron donor (internal donor). Other electron donors include, for example, compounds having two or more ether bonds existing via a plurality of atoms (hereinafter also referred to as "polyether compounds").

Examples of the polyether compound include compounds in which the atoms present between ether bonds are carbon, silicon, oxygen, nitrogen, sulfur, phosphorus, boron, or two or more atoms selected from these. . Among these, preferred are compounds in which relatively bulky substituents are bonded to atoms between ether bonds and atoms present between two or more ether bonds contain a plurality of carbon atoms. For example, a polyether compound represented by the following formula (3) is preferred.

In the above formula (3), m is an integer of 1-10, preferably an integer of 3-10, more preferably an integer of 3-5. R ¹¹ , R ¹² , R ³¹ to R ³⁶ are each independently a hydrogen atom or at least one selected from carbon, hydrogen, oxygen, fluorine, chlorine, bromine, iodine, nitrogen, sulfur, phosphorus, boron and silicon. It is a substituent having a seed element. R ¹¹ and R ¹² are each independently preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms. R ³¹ to R ³⁶ are each independently preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms.

Specific examples of R ¹¹ and R ¹² include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, isopentyl, neopentyl, hexyl, heptyl, octyl, 2 -ethylhexyl group, decyl group, cyclopentyl group and cyclohexyl group. Among these, ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl group are preferred. Specific examples of R ³¹ to R ³⁶ include hydrogen atom, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl group. Among these, a hydrogen atom and a methyl group are preferred. Optional R ¹¹ , R ¹² , R ³¹ to R ³⁶ (preferably R ¹¹ and R ¹² ) may jointly form a ring other than a benzene ring, and the main chain contains an atom other than carbon. It may be

Specific examples of the polyether compound include 2,2-dicyclohexyl-1,3-dimethoxypropane, 2,2-diethyl-1,3-dimethoxypropane, 2,2-dipropyl-1,3-dimethoxypropane, 2 , 2-dibutyl-1,3-dimethoxypropane, 2-methyl-2-propyl-1,3-dimethoxypropane, 2-methyl-2-ethyl-1,3-dimethoxypropane, 2-methyl-2-isopropyl- 1,3-dimethoxypropane, 2-methyl-2-cyclohexyl-1,3-dimethoxypropane, 2,2-bis(2-cyclohexylethyl)-1,3-dimethoxypropane, 2-methyl-2-isobutyl-1 , 3-dimethoxypropane, 2-methyl-2-(2-ethylhexyl)-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-bis(cyclohexylmethyl)-1, 3-dimethoxypropane, 2,2-diisobutyl-1,3-diethoxypropane, 2,2-diisobutyl-1,3-dibutoxypropane, 2-isobutyl-2-isopropyl-1,3-dimethoxypropane, 2, 2-di-s-butyl-1,3-dimethoxypropane, 2,2-di-t-butyl-1,3-dimethoxypropane, 2,2-dineopentyl-1,3-dimethoxypropane, 2-isopropyl-2 -isopentyl-1,3-dimethoxypropane, 2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane, 2,3-dicyclohexyl-1,4-diethoxybutane, 2,3-diisopropyl-1,4- Diethoxybutane, 2,4-diisopropyl-1,5-dimethoxypentane, 2,4-diisobutyl-1,5-dimethoxypentane, 2,4-diisoamyl-1,5-dimethoxypentane, 3-methoxymethyltetrahydrofuran, 3 -methoxymethyldioxane, 1,2-diisobutoxypropane, 1,2-diisobutoxyethane, 1,3-diisoamyloxyethane, 1,3-diisoamyloxypropane, 1,3-diisoneopentyloxy Ethane, 1,3-dineopentyloxypropane, 2,2-tetramethylene-1,3-dimethoxypropane, 2,2-pentamethylene-1,3-dimethoxypropane, 2,2-hexamethylene-1,3 -dimethoxypropane, 1,2-bis(methoxymethyl)cyclohexane, 2-cyclohexyl-2-ethoxymethyl-1,3-di Ethoxypropane, 2-cyclohexyl-2-methoxymethyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxycyclohexane, 2-isopropyl-2-isoamyl-1,3-dimethoxycyclohexane, 2-cyclohexyl -2-methoxymethyl-1,3-dimethoxycyclohexane, 2-isopropyl-2-methoxymethyl-1,3-dimethoxycyclohexane, 2-isobutyl-2-methoxymethyl-1,3-dimethoxycyclohexane, 2-cyclohexyl-2 -ethoxymethyl-1,3-diethoxycyclohexane, 2-cyclohexyl-2-ethoxymethyl-1,3-dimethoxycyclohexane, 2-isopropyl-2-ethoxymethyl-1,3-diethoxycyclohexane, 2-isopropyl-2 -ethoxymethyl-1,3-dimethoxycyclohexane, 2-isobutyl-2-ethoxymethyl-1,3-diethoxycyclohexane, 2-isobutyl-2-ethoxymethyl-1,3-dimethoxycyclohexane and the like can be exemplified. .

Among these, 1,3-diethers are preferred, and 2-isopropyl-2-isobutyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl- More preferred are 1,3-dimethoxypropane, 2,2-dicyclohexyl-1,3-dimethoxypropane and 2,2-bis(cyclohexylmethyl)1,3-dimethoxypropane. One of these compounds may be used, or two or more thereof may be used in combination.

Preparation of Solid Titanium (a) The solid titanium (a) can be prepared by contacting the magnesium compound, the titanium compound, and the electron donor. At this time, it is preferable to use a magnesium compound in a solid state suspended in a hydrocarbon solvent. Further, when these components are brought into contact, the liquid form of the titanium compound may be used once to produce the solid (1), and the obtained solid (1) is further brought into contact with the liquid form of the titanium compound. to form a solid (2). Further, it is preferable to prepare the solid titanium (a) after washing the solid (1) or (2) with a hydrocarbon solvent as necessary.

The contact of each component as described above is usually carried out at a temperature of -70°C to +200°C, preferably -50°C to +150°C, more preferably -30°C to +130°C. The amount of each component used in preparing the solid titanium (a) varies depending on the preparation method and cannot be generally defined. In an amount of 0.1 to 5 mol, the titanium compound can be used in an amount of 0.01 to 1000 mol, preferably 0.1 to 200 mol.

In the present invention, the solid material (1) or (2) thus obtained can be used as it is as solid titanium (i), but this solid material is washed with a hydrocarbon solvent at 0 to 150°C. is preferred.

Examples of the hydrocarbon solvent include aliphatic hydrocarbon solvents such as hexane, heptane, octane, nonane, decane, and cetane; non-halogen aromatic hydrocarbon solvents such as toluene, xylene, and benzene; A hydrocarbon solvent or the like is used. Among these, aliphatic hydrocarbon solvents and halogen-free aromatic hydrocarbon solvents are preferably used.

When washing the solids, the hydrocarbon solvent is used in an amount of usually 10-500 ml, preferably 20-100 ml, per 1 g of the solids. The solid titanium (a) thus obtained contains magnesium, titanium, halogen and an electron donor. The solid titanium (a) preferably has an electron donor/titanium (mass ratio) of 6 or less.
The solid titanium (a) obtained in this manner does not desorb titanium by washing with hexane at room temperature.

(b) Aromatic hydrocarbon Examples of the aromatic hydrocarbon (b) used in contact with the solid titanium (a) include benzene, toluene, xylene, ethylbenzene, and halogen-containing hydrocarbons thereof. . Among these, xylene (especially para-xylene) is preferred. By bringing the solid titanium (a) into contact with such an aromatic hydrocarbon (b), so-called "surplus titanium compounds" that produce low stereoregularity components by-products can be reduced.

(c) Liquid Titanium As the liquid titanium (c) used for contact with the solid titanium (a), the same titanium compounds as those used in preparing the solid titanium (a) can be mentioned. can. Among them, titanium tetrahalides are preferred, and titanium tetrachloride is particularly preferred.

(d) Electron donor Examples of the electron donor (d) used in contact with the solid titanium (a) are the same as those exemplified for the electron donor (internal donor) described above. can. Among them, it is preferable to use the same electron donor as used in the preparation of the solid titanium (a).

<<Method for preparing solid titanium catalyst component (i)>>
Solid titanium (a), aromatic hydrocarbon (b), liquid titanium (c) and electron donor (d) are contacted at a temperature of usually 110 to 160° C., preferably 115 to 150° C. for 1 minute. to 10 hours, preferably 10 minutes to 5 hours.

In this contact, the aromatic hydrocarbon (b) is generally used in an amount of 1-10000 ml, preferably 5-5000 ml, more preferably 10-1000 ml, per 1 g of solid titanium (a). Liquid titanium (c) is usually used in an amount of 0.1 to 50 ml, preferably 0.2 to 20 ml, particularly preferably 0.3 to 10 ml, per 100 ml of aromatic hydrocarbon (b). The electron donor (d) is generally used in an amount of 0.01-10 ml, preferably 0.02-5 ml, particularly preferably 0.03-3 ml, per 100 ml of the aromatic hydrocarbon (b).

The contact order of solid titanium (a), aromatic hydrocarbon (b), liquid titanium (c) and electron donor (d) is not particularly limited, and they can be contacted simultaneously or sequentially.
Solid titanium (a), aromatic hydrocarbon (b), liquid titanium (c) and electron donor (d) are preferably brought into contact with stirring under an inert gas atmosphere. For example, in a sufficiently nitrogen-substituted glass flask equipped with a stirrer, a slurry of solid titanium (a), aromatic hydrocarbon (b), liquid titanium (c) and electron donor (d) is added at the above temperature. , the stirrer is stirred at a rotation speed of 100 to 1000 rpm, preferably 200 to 800 rpm, for the above time to obtain the solid titanium (a), the aromatic hydrocarbon (b), the liquid titanium (c) and the electron donor ( d) is preferably brought into contact.

After contact, the solid titanium (a) and the aromatic hydrocarbon (b) can be separated by filtration.
By contacting the solid titanium (a) with the aromatic hydrocarbon (b), a solid titanium catalyst component (i) having a lower titanium content than the solid titanium (a) is obtained. Specifically, a solid titanium catalyst component (i) having a titanium content of 25% by mass or more, preferably 30 to 95% by mass, and more preferably 40 to 90% by mass less than that of solid titanium (a) is obtained.

The solid titanium catalyst component (i) obtained as described above contains magnesium, titanium, a halogen and an electron donor, and satisfies the following requirements (k1) to (k4), preferably the following requirement (k5): further satisfies

(k1) The titanium content of the solid titanium catalyst component (i) is 2.5% by mass or less, preferably 2.2 to 0.1% by mass, more preferably 2.0 to 0.2% by mass, particularly preferably is 1.8-0.3% by weight, most preferably 1.5-0.4% by weight.
(k2) The content of the electron donor is 8 to 30% by mass, preferably 9 to 25% by mass, more preferably 10 to 20% by mass.
(k3) electron donor/titanium (mass ratio) is 7 or more, preferably 7.5 to 35, more preferably 8 to 30, particularly preferably 8.5 to 25.
(k4) The solid titanium catalyst component (i) does not substantially desorb titanium by washing with hexane at room temperature. The washing of the solid titanium catalyst component (i) with hexane means that 1 g of the solid titanium catalyst component (i) is usually washed with 10 to 500 ml, preferably 20 to 100 ml of hexane for 5 minutes. say. Room temperature is 15 to 25°C. Further, "substantially no desorption of titanium" means that the concentration of titanium in the hexane washing liquid is 0.1 g/liter or less.
(k5) The solid titanium catalyst component (i) has an average particle size of 5 to 70 μm, preferably 7 to 65 μm, more preferably 8 to 60 μm, particularly preferably 10 to 55 μm.

Here, the amounts of magnesium, halogen, titanium, and electron donor are respectively mass % per unit mass of the solid titanium catalyst component (i), and magnesium, halogen, and titanium are determined by plasma emission spectrometry (ICP method). , the electron donor is quantified by gas chromatography. Also, the average particle size of the catalyst is measured by a centrifugal sedimentation method using decalin solvent.

When the solid titanium catalyst component (i) as described above is used as a catalyst component for olefin polymerization, it is possible to polymerize propylene with high activity, and the amount of polypropylene with low stereoregularity produced is small. Polypropylene can be produced stably.

<<Organosilicon compound component (ii)>>
The organosilicon compound component (ii) constituting the olefin polymerization catalyst of the present invention is represented by the following formula (II).
^R1Si ( ^OR2 ) ₂ ( ^NR3R4 ) ⁽ II)
In formula (II), R ¹ represents a secondary or tertiary hydrocarbon group having 1 to 20 carbon atoms, R ² represents a hydrocarbon group having 1 to 4 carbon atoms, and R ³ represents a hydrocarbon group having 1 to 12 carbon atoms. is a hydrocarbon group or a hydrogen atom, and R ⁴ is a hydrocarbon group having 1 to 12 carbon atoms.

Examples of R ¹ include alicyclic hydrocarbon groups such as cyclobutyl, cyclopentyl, cyclopentenyl, cyclopentadienyl, cyclohexyl, cyclohexynyl, and substituted groups.

Examples of R ¹ include hydrocarbon groups in which the carbon adjacent to Si is a secondary carbon, i-propyl group, s-butyl group, s-amyl group, α-methylbenzyl group and the like. Hydrocarbon groups in which the adjacent carbon is a tertiary carbon include a tert-butyl group, a tert-amyl group, an α,α'-dimethylbenzyl group and an admantyl group.

Among these, a cyclopentyl group and a cyclobutyl group are preferred, and a cyclopentyl group is particularly preferred.
Examples of R ² include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, ter-butyl group, sec-butyl group, n-pentyl group, iso- pentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group and the like. Among these, a methyl group and an ethyl group are particularly preferred.

Examples of R ³ include hydrogen, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, ter-butyl group, sec-butyl group, n-pentyl group, iso-pentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, octyl group and the like. Among these, an ethyl group is particularly preferred.

Examples of R ⁴ include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, ter-butyl group, sec-butyl group, n-pentyl group, iso- pentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, octyl group and the like. Among these, an ethyl group is particularly preferred.

Specific examples of the organosilicon compound represented by formula (II) include cyclopentyldiethylaminodimethoxysilane, cyclopentenyldiethylaminodimethoxysilane, cyclopentadienyldiethylaminodimethoxysilane, cyclohexyldiethylaminodimethoxysilane, isopropyldiethylaminodimethoxysilane, and tert-butyldiethylamino. dimethoxysilane and the like.

Among the organosilicon compounds represented by the formula (II), cyclopentyldiethylaminodimethoxysilane is preferred from the viewpoint of high stereoregularity, particularly a long meso chain length and high-temperature elution ratio in cross fractional chromatography (CFC). is preferred.

The organosilicon compound component (ii) described above may be used alone or in combination of two or more.
By using the solid titanium catalyst component (i) and the organosilicon compound component (ii) in combination, it is possible to obtain a propylene-based polymer having an unprecedented level of stereoregularity.

<<organometallic compound component (iii)>>
The organometallic compound component (iii) constituting the olefin polymerization catalyst of the present invention is an organometallic compound containing a metal belonging to Group 1, Group 2 or Group 13 of the periodic table. complex alkyl compounds of group metals and aluminum, organic metal compounds of group 2 metals, and the like. Two or more kinds of the organometallic compound component (iii) may be used in combination.

Organoaluminum Compound The organoaluminum compound is represented, for example, by the following formula.
R ^a _n AlX _3-n
In the formula, R ^a is a hydrocarbon group having 1-12 carbon atoms, X is halogen or hydrogen, and n is 1-3.

R ^a is a hydrocarbon group having 1 to 12 carbon atoms, such as an alkyl group, a cycloalkyl group or an aryl group, specifically methyl, ethyl, n-propyl, isopropyl, isobutyl, pentyl, hexyl, Octyl, cyclopentyl, cyclohexyl, phenyl, tolyl and the like.

Moreover, the compound shown by the following formula can also be mentioned as said organoaluminum compound.
R ^a _n AlY _3-n
In the formula, R ^a is the same as above, Y is —OR ^b group, —OSiR ^c ₃ group, —OAlR ^d ₂ group, —NR ^e ₂ group, —SiR ^f ₃ group or —N(R ^g )AlR ^h ₂ groups, n is 1 to 2, R ^b , R ^c , R ^d and R ^h are methyl group, ethyl group, isopropyl group, isobutyl group, cyclohexyl group, phenyl group, etc., and R ^e is Hydrogen, methyl group, ethyl group, isopropyl group, phenyl group, trimethylsilyl group and the like, and R ^f and R ^g are methyl group, ethyl group and the like.

Specific examples of such organoaluminum compounds include the following compounds.
A compound represented by R ^a _n Al(OR ^b ) _3-n , such as dimethylaluminum methoxide, diethylaluminum ethoxide, diisobutylaluminum methoxide, and the like.
Compounds represented by R ^a _n Al(OSiR ^c ) _3-n , such as Et ₂ Al(OSiMe ₃ ), (iso-Bu) ₂ Al(OSiMe ₃ ), (iso-Bu) ₂ Al(OSiEt ₃ ) Such.
^RanAl ( ^OAlRd2 ) _{3-nEt2AlOAlEt2 ,} (iso-Bu) _2AlOAl ( _iso -Bu) ₂ and _the like _.
Among the above organoaluminum compounds, an organoaluminum compound represented by R ^a ₃ Al is preferably used.

<Method for Producing Olefin Polymerization Catalyst>
The olefin polymerization catalyst can be produced by a method comprising the step of contacting the solid titanium catalyst component (i), the organosilicon compound component (ii), and the organometallic compound component (iii). .

In the present invention, when forming the olefin polymerization catalyst from each of these components (i), (ii) and (iii), other components can be used as necessary.
In the present invention, the prepolymerization catalyst (p) may be formed from each component as described above. The prepolymerization catalyst (p) is formed by prepolymerizing propylene in the presence of the components (i), (ii) and (iii) described above and other optional components. Such a prepolymerization catalyst (p) usually forms an olefin polymerization catalyst together with the organosilicon compound (ii) and the organometallic compound (iii), but only the prepolymerization catalyst (p) is used as an olefin polymerization catalyst. sometimes it is possible.

<Method for Producing Propylene Homopolymer>
In the method for producing a propylene homopolymer, propylene is polymerized in the presence of the olefin polymerization catalyst described above.
When propylene is polymerized, in addition to propylene, a small amount of other olefins other than propylene or a small amount of diene compound may coexist in the polymerization system within a range that does not impair the quality of the capacitor film according to the present invention. Random copolymers may be produced. Such olefins other than propylene include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 3-methyl- Examples include olefins having 2 to 8 carbon atoms such as 1-butene. Among these, ethylene is preferred. In the case of random copolymers, the content of comonomers other than propylene is preferably 6 mol % or less, more preferably 3 mol % or less.

In the present invention, polymerization can be carried out by either a liquid phase polymerization method such as solution polymerization or suspension polymerization, or a gas phase polymerization method. When the polymerization takes the reaction form of slurry polymerization, an inert organic solvent can be used as the reaction solvent, and an olefin that is liquid at the reaction temperature can also be used.

Specific examples of inert organic solvents include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons; aromatic hydrocarbons; Hydrogen, or a contact product thereof can be mentioned. Among these, it is particularly preferable to use aliphatic hydrocarbons.

In the polymerization, the solid titanium catalyst component (i) or the prepolymerization catalyst (p) is usually used in an amount of about 1×10 ⁻⁵ to 1 millimole, preferably about 1×1 millimole in terms of titanium atoms per liter of polymerization volume. It is used in amounts of 10 ^-4 to 0.1 mmol.

The organosilicon compound (ii) is generally used in an amount of about 0.001 mol to 10 mol, preferably 0.01 mol to 5 mol, per 1 mol of the metal atom in the organometallic compound (iii).
The organometallic compound (iii) is used in an amount such that the metal atom in the compound (iii) is usually about 1 to 2000 mol, preferably about 2 to 500 mol, per 1 mol of the titanium atom in the polymerization system. be done.

If the prepolymerization catalyst (p) is used during this polymerization, the organosilicon compound (ii) and/or the organometallic compound (iii) may not need to be added. When the olefin polymerization catalyst is formed from the prepolymerized catalyst (p), component (ii) and component (iii), each of these components (ii) and (iii) can be used in amounts as described above.

If hydrogen is used during polymerization, the molecular weight of the propylene polymer to be obtained can be adjusted, and a polymer with a large MFR can be obtained.
In the present invention, the polymerization is usually carried out at a temperature of about 20-150° C., preferably about 50-100° C., and under a pressure of normal pressure to 100 kg/cm ² , preferably about 2-50 kg/cm ² . .
In the present invention, polymerization can be carried out in any of batch, semi-continuous and continuous processes. Furthermore, the polymerization can be carried out in two or more stages by changing the reaction conditions.

<Additive>
The propylene homopolymer for a capacitor film of the present invention contains a weather stabilizer, a heat stabilizer, an antistatic agent, an antislip agent, an antiblocking agent, an antifogging agent, a nucleating agent, Additives such as lubricants, pigments, dyes, plasticizers, antioxidants, hydrochloric acid absorbers, and antioxidants may be added. Preferably, while adding various additives such as various antioxidants (Irganox 1010, BHT (dibutylhydroxytoluene), Irgafos 168, etc.) and calcium stearate, it is blended by melt extrusion in the range of 180 to 280 ° C. is an example.

[Capacitor film]
A capacitor film according to the present invention is obtained by stretching a raw sheet obtained from the above propylene homopolymer. The thickness of the capacitor film according to the invention is preferably 1-50 μm, more preferably 1.5-30 μm, even more preferably 1.5-20 μm, particularly preferably 2-15 μm. When the thickness is 1 μm or more, film breakage is less likely to occur, and the productivity of the film is improved. On the other hand, when the thickness is 50 μm or less, the film can be made lightweight and excellent in flexibility.

<Manufacturing method of capacitor film>
The capacitor film according to the present invention can be obtained, for example, by producing a raw sheet and then stretching it. The method for producing a capacitor film of the present invention preferably includes a step of stretching a raw sheet at a stretching area ratio (longitudinal×horizontal area ratio) of 30 to 80 times. In the method for producing a capacitor film according to the present invention, the stretching temperature range is wide and the capacitor film according to the present invention can be produced even if there is temperature unevenness in the furnace. A more specific manufacturing method of the capacitor film of the present invention is as follows.

The propylene homopolymer is supplied from a hopper to an extruder, heated and melted at preferably 170 to 300° C., more preferably 200 to 260° C., and melt extruded through a T-die. Thereafter, this is preferably cooled and solidified on a metal chill roll at 70 to 120° C. to obtain an unstretched raw sheet. The thickness of the original sheet is not particularly limited, but is preferably 60 to 800 μm, more preferably 80 to 400 μm. If the original sheet has a thickness of less than 60 μm, it may break during stretching. On the other hand, if the thickness exceeds 800 μm, a thin film cannot be obtained, which may not be suitable as a capacitor film.

A capacitor film can be produced by stretching the raw sheet. The stretching method includes a uniaxial stretching method and a biaxial stretching method, and the biaxial stretching method is preferable. The biaxial stretching method includes a sequential biaxial stretching method in which the film is uniaxially stretched in the machine direction and then in a direction perpendicular to the machine direction; An axial stretching method and the like can be mentioned. Specifically, a tenter method, a sequential biaxial stretching method such as a tubular film method, and a simultaneous biaxial stretching method can be used.

In the tenter method, for example, the following method can be used. The molten sheet melted and extruded from the T-die is solidified by cooling rolls, preheated if necessary, and then introduced into the stretching zone. The sheet is then stretched 3 to 9 times in the machine direction (longitudinal direction) at a temperature of 120 to 160° C., and stretched in the direction perpendicular to the machine direction (transverse direction) by 5 to 11 times at a temperature of 150 to 190° C. . The total areal drawing ratio is 30 to 80 times, preferably 35 to 75 times, more preferably 35 to 70 times, and still more preferably 35 to 50 times. If the stretched areal ratio is less than 30 times, it may be difficult to obtain the desired strength and thickness accuracy. In addition, when the stretching areal ratio exceeds 80 times, breakage tends to occur during stretching, and productivity may be poor.

Also, if necessary, the biaxially stretched film can be heat-set at 160 to 190°C. As a result, a capacitor film having improved thermal dimensional stability, abrasion resistance, etc. can be obtained.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. Methods for measuring various physical properties described in Examples are as follows.

<Mesopentad fraction (mmmm (noise removal method))>
1. Measurement conditions Apparatus: Bruker Biospin AVANCE III cryo-500 type nuclear magnetic resonance apparatus Measurement nucleus: ¹³ C (125 MHz)
Measurement mode: Single pulse proton broadband decoupling Pulse width: 45° (5.00 microseconds)
Repeat time: 5.5 seconds Accumulation times: 256 times Measurement solvent: o-dichlorobenzene/heavy benzene (80/20% by volume) mixed solvent Sample concentration: 50 mg/0.6 mL
Measurement temperature: 120°C
Chemical shift standard: 21.59 ppm (mesopentad methyl peak shifts)

2. Calculation Method The mesopentad fraction (mmmm, %), which is one of the indicators of the stereoregularity of a polymer and used to investigate its microtacticity, is the peak intensity of the ¹³ C-NMR spectrum obtained under the measurement conditions of 1 above. Calculated from the ratio.

Here, in the case of polypropylene having an unprecedentedly high level of stereoregularity, such as the object to be measured in the present invention, if the rmmr, mmrm, rmrr, rmrm, and mrrr regions are included in the integral value, the integral of "noise" It is considered that there is a problem that the degree of influence on the value increases, and S2 in the general calculation method is overestimated, that is, mmmm (%) is underestimated. Prog. Polym. Sci. 26 (2001), 443-533 also, in the case of polypropylene having a stereoregularity of 95% or more, if certain requirements are satisfied, the integral values of the rmmr, mmrm, rmrr, rmrm, and mrrr regions are , is theoretically reported to be 0.1% or less in total, suggesting that it leads to overestimation of S2 in a general calculation method.

Therefore, in the present invention, it is calculated according to the following (Equation 1). The rmmr, mmrm, rmrr, rmrm, mrrr regions were excluded from the calculations as suggested in Prog. Polym. Sci. 26 (2001), 443-533. Hereinafter, the calculation method in this specification is referred to as the "noise removal method".
mmmm (noise removal method) (%) = S1/S2*100 (Formula 1)
S1 = (peak containing mmmm, mmmr)-(n-propyl end)-(n-butyl end)-mrrm*2
S2 = S1 + mmmr + mmrr + mrrm + rrrr
= S1 + 5 * mrrm + rrrr

In calculating with the above (Equation 1), as an example, assignments were made as follows. The mmmm peak overlaps the mmmr, (n-propyl end) and (n-butyl end) peaks.
Peak including mmmm and mmmr: Peak area from 21.2 to 22.0 ppm mmmr = mrrm * 2
mmrr = mrrm * 2
mrrm: peak area from 19.5 to 19.7 ppm rrrr: peak area from 20.0 to 20.2 ppm n-propyl end: (A1 + A3)/2
A1: peak area of 14.2 ppm A3: peak area of 39.4 ppm n-butyl end: peak area of 36.7 ppm

<Cross Fractionation Chromatographic Analysis (CFC)>
In cross-fractionation chromatograph analysis (CFC), the ratio of components eluted at temperatures above 124 ° C. is obtained by temperature-rising fractionation measurement under the following conditions, subtracting the ratio of components eluted at temperatures below 124 ° C. from 100%. calculated by
Apparatus: Polymer Char CFC2 type cross fractionation chromatograph Detector: Polymer Char IR4 type infrared spectrophotometer (built-in)
Mobile phase: o-dichlorobenzene, BHT added Flow rate: 1.0 mL/min
Sample concentration: 90 mg/30 mL
Injection volume: 0.5 mL
Dissolution conditions: 145°C, 30min
Stabilization conditions: 135°C, 30min
Temperature drop rate: 1.0 mL/min
Elution division: -20°C to 0°C in 10°C increments, 0°C to 80°C in 5°C increments,
80°C to 104°C in 3°C increments, 104 to 126°C in 2°C increments Elution time: 3min

<Molecular weight distribution>
The Mw/Mn value, which is an index of molecular weight distribution, was obtained by analyzing the chromatogram measured under the following conditions by a known method.
Apparatus: Gel permeation chromatograph Alliance GPC2000 type manufactured by Waters Column: TSKgel GMH6-HT x2 + TSKgel GMH6-HTL x2 manufactured by Tosoh
Mobile phase: o-dichlorobenzene (containing 0.025% BHT)
Flow rate: 1.0ml/min
Temperature: 140°C
Column calibration: Tosoh monodisperse polystyrene Sample concentration: 0.15% (w / v)
Injection volume: 0.4 ml

<Melt flow rate (MFR)>
According to ASTM D1238E, the measurement temperature was 230° C. and the load was 2.16 kg.

<Amount of soluble component in decane>
About 6 grams of a propylene-based polymer (this mass is expressed as b (grams) in the following formula), 500 ml of decane, and a small amount of a heat stabilizer soluble in decane are placed in a glass measurement container, and a nitrogen atmosphere is placed. Then, while stirring with a stirrer, the temperature was raised to 150°C over 2 hours to dissolve the propylene polymer, maintained at 150°C for 2 hours, and then gradually cooled to 23°C over 8 hours. The obtained liquid containing the precipitate of the propylene polymer was filtered under reduced pressure through a 25G-4 standard glass filter manufactured by Iwata Glass Co., Ltd. A 100 ml portion of the filtrate was collected and dried under reduced pressure to obtain a portion of the decane-soluble component. This mass was expressed as a (gram) in the following formula. After this operation, the amount of decane solubles was determined by the following formula.
Decane soluble component content (% by mass) = 100 x (500 x a) / (100 x b)

<Chlorine content>
0.8 g of the sample was burned at 400-900° C. under an argon/oxygen stream using a Mitsubishi Kasei combustion apparatus. After that, the combustion gas was captured with ultrapure water, and the sample solution after concentration was treated with a DIONEX-DX300 type ion chromatography device (trade name, manufactured by Nippon Dioneck Co., Ltd.) and an anion column AS4A-SC (trade name, Dionek Co., Ltd.). ) was used to determine the chlorine content.

<Withstand voltage (BDV)>
The BDV of the obtained stretched film was measured according to JIS-C2330. The dielectric breakdown voltage of the biaxially stretched film was measured at 120°C and 140°C. The withstand voltage (BDV, V/μm) was calculated by dividing the dielectric breakdown voltage by the film thickness.

<Stretchability>
The stretching temperature range was measured by changing the preheating temperature in the biaxial stretching of the film and measuring the temperature range in which stretching is possible. The uniformity of the thickness of the stretched film was determined by the presence or absence of interference fringes. When interference fringes occurred in the stretched film, the uniformity of the film thickness was low, and was marked with x.

[Example 1]
<Preparation of solid titanium (a-1)>
After sufficiently purging a high-speed stirring device with an internal volume of 2 liters (manufactured by Tokushu Kika Kogyo Co., Ltd.) with nitrogen, 700 ml of refined kerosene, 10 g of magnesium chloride, 24.2 g of ethanol and sorbitan distearate (manufactured by Kao Atlas Co., Ltd.) were added to the device. 3 g of Emsol 320") were charged. The system was heated under stirring and stirred for 30 minutes at 120° C. and 800 rpm. Under high-speed stirring, using a Teflon (registered trademark) tube with an inner diameter of 5 mm, the liquid was transferred to a 2-liter glass flask (equipped with a stirrer) filled with 1 liter of purified kerosene previously cooled to -10°C. The resulting solid was filtered and thoroughly washed with purified n-hexane to obtain a solid adduct in which 1 mol of magnesium chloride was coordinated with 2.8 mol of ethanol.

Then, the above solid adduct (45 millimoles in terms of magnesium atom) was suspended in 20 ml of decane, and the entire amount was introduced into 195 ml of titanium tetrachloride maintained at -20°C with stirring. The mixture was heated to 80° C. over 5 hours, and 1.8 ml (6.2 mmol) of diisobutyl phthalate was added. Subsequently, the temperature was raised to 110° C. and the mixture was stirred for 1.5 hours.

After completion of the reaction for 1.5 hours, the solid portion was collected by hot filtration and washed with decane at 100° C. and hexane at room temperature until titanium was no longer detected in the filtrate. Thus, solid titanium (a-1) containing 3.8% by mass of titanium, 16% by mass of magnesium, 18.2% by mass of diisobutyl phthalate, and 1.1% by mass of ethanol residues was obtained. Obtained.

<Preparation of solid titanium catalyst component (i-1)>
6.8 g of the obtained solid titanium (a-1), 113 ml of paraxylene, 11 ml of decane, 2.5 ml (23 mmol) of titanium tetrachloride and diisobutylphthalate were placed in a 200 ml glass reactor sufficiently purged with nitrogen. - 0.34 ml (1.2 mmol) was added. The temperature in the reactor was raised to 130° C., and the mixture was stirred at that temperature for 1 hour for contact treatment, and then the solid portion was collected by hot filtration. This solid portion was resuspended in 101 ml of paraxylene and 1.7 ml (15 mmol) of titanium tetrachloride and 0.22 ml (0.8 mmol) of diisobutyl phthalate were added.

Then, the temperature was raised to 130° C., and the mixture was stirred for 1 hour while maintaining the temperature to react. After completion of the reaction, solid-liquid separation was performed again by hot filtration, and the obtained solid portion was washed with decane at 100° C. and hexane at room temperature until the p-xylene in the catalyst was reduced to 1% by mass or less. Thus, a solid titanium catalyst component (i-1) containing 1.3% by mass of titanium, 20% by mass of magnesium and 13.8% by mass of diisobutyl phthalate was obtained.

<Preparation of prepolymerized catalyst (p-1)>
Into a nitrogen-purged 200 ml glass reactor, 50 ml of hexane, 2.5 mmol of triethylaluminum, 0.5 mmol of cyclopentyldiethylaminodimethoxysilane, and the solid titanium catalyst component (i-1) obtained above were added to titanium atoms. After charging 0.25 millimoles in conversion, propylene was supplied at a rate of 1.47 liters/hour for 1 hour while maintaining the temperature in the system at 20°C. By this operation, a prepolymerized catalyst (p-1) in which 3 g of propylene was prepolymerized per 1 g of the solid titanium catalyst component (i-1) was obtained.

<Main polymerization>
An autoclave having an inner volume of 2 liters was charged with 500 g of propylene and 3.5 liters of hydrogen, and the temperature in the system was raised to 60°C. Thereafter, 1.4 millimoles of triethylaluminum, 0.7 millimoles of cyclopentyldiethylaminodimethoxysilane and 0.0028 millimoles of the prepolymerized catalyst (p-1) obtained above in terms of titanium atoms were added to initiate polymerization. . Polymerization was carried out for 1 hour while the temperature in the system was maintained at 70°C. The polymerization was then stopped by adding ethanol and purging the unreacted propylene to obtain 248 g of polypropylene.

A similar operation was performed multiple times to obtain a total of 5 kg of polypropylene. 0.6 g of pure water and 5.4 ml of propylene oxide were added to 1 kg of the obtained polypropylene, and dechlorination was performed at 90° C. for 2 hours, followed by vacuum drying at 80° C. to obtain polypropylene powder. got Table 1 shows the results of evaluating the physical properties of the obtained polypropylene.

<Combination and Granulation of Additives>
Next, 0.2 parts by mass of 3,5-di-tert-butyl-4-hydroxytoluene as an antioxidant and tetrakis[methylene- 0.2 parts by mass of 3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane and 0.01 parts by mass of calcium stearate as a neutralizing agent were mixed and dry-blended. Thereafter, using a Laboplastomill single-screw extruder D2025 (L/D=25) manufactured by Toyo Seiki Seisakusho Co., Ltd. as a granulator, the mixture was melt-kneaded at a resin temperature of 230° C. and pelletized.

<Forming of original sheet>
The obtained pellets of the propylene homopolymer composition were melted at 230°C with a 25 mmφ T-die sheet molding machine (manufactured by Plastic Engineering Laboratory Co., Ltd.), extruded, and pulled by a single cooling roll maintained at 60°C. It was cooled at a speed of 1.0 m/min to obtain a raw sheet with a thickness of 150 μm.

<Production of stretched film>
The raw sheet thus obtained was cut into a size of 85 mm×85 mm and biaxially stretched under the following conditions to obtain a biaxially stretched film (capacitor film) having a thickness of 4 μm. The thickness was adjusted by changing the preheating temperature. The resulting film was evaluated for withstand voltage (BDV) and stretchability according to the methods described above. Table 1 shows the results.

<Stretching conditions>
Stretching device: KAROIV (trade name, manufactured by Bruckner)
Preheating temperature: 145-160°C
Preheating time: 60 seconds Stretch ratio: sequential biaxial stretching of 5 times in the longitudinal direction (machine direction) × 9 times in the transverse direction (stretching ratio: 45 times)
Stretching speed: 6m/min

[Example 2]
In the main polymerization of Example 1, 3.5 to 3 liters of hydrogen was charged, 1.4 to 0.7 mmol of triethylaluminum was added, and 0.7 to 0.14 mmol of cyclopentyldiethylaminodimethoxysilane was added. Polypropylene was produced in the same manner as in Example 1, except that it was changed to Table 1 shows the results of evaluating the physical properties of the obtained polypropylene.

Further, blending and granulation of additives, molding of raw film, preparation of stretched film and evaluation thereof were performed in the same manner as in Example 1 except that the obtained polypropylene was used. Table 1 shows the results.

[Example 3]
In the main polymerization of Example 1, 3.5 to 3 liters of hydrogen was charged, 1.4 to 0.5 mmol of triethylaluminum was added, and 0.7 to 0.1 mmol of cyclopentyldiethylaminodimethoxysilane was added. , and the prepolymerization catalyst (p-1) was changed from 0.0028 millimoles to 0.002 millimoles in terms of titanium atoms. Table 1 shows the results of evaluating the physical properties of the obtained polypropylene.

Further, blending and granulation of additives, molding of raw film, preparation of stretched film and evaluation thereof were performed in the same manner as in Example 1 except that the obtained polypropylene was used. Table 1 shows the results.

[Example 4]
In a 30 ml glass container containing 7 ml of heptane, 0.35 mmol of triethylaluminum, 0.07 mmol of cyclopentyldiethylaminodimethoxysilane, and the solid titanium catalyst component (i-1) obtained in Example 1 were added in terms of titanium atoms. was charged at 0.0028 mmol and contacted at 20° C. for 10 minutes to prepare an olefin polymerization catalyst. Then, the olefin polymerization catalyst was charged into an autoclave having an inner volume of 2 liters containing 500 g of propylene, and polymerization was carried out at 20° C. for 10 minutes. The temperature was raised to 70° C. and polymerization was carried out for 1 hour. Polymerization was then stopped by adding ethanol and 312 g of polypropylene was obtained by purging unreacted propylene.

A similar operation was performed multiple times to obtain a total of 5 kg of polypropylene. 0.6 g of pure water and 5.4 ml of propylene oxide were added to 1 kg of the obtained polypropylene, and dechlorination was performed at 90° C. for 2 hours, followed by vacuum drying at 80° C. to obtain polypropylene powder. got Table 1 shows the results of evaluating the physical properties of the obtained polypropylene.

Further, blending and granulation of additives, molding of raw film, preparation of stretched film and evaluation thereof were performed in the same manner as in Example 1 except that the obtained polypropylene was used. Table 1 shows the results.

[Comparative Example 1]
In Example 4, 0.35 to 0.25 millimoles of triethylaluminum was added, and 0.7 millimoles of cyclopentyldiethylaminodimethoxysilane and 0.05 millimoles of dicyclopentyldimethoxysilane were added to the silane compound. Same as Example 4 except that the solid titanium catalyst component (i-1) was changed from 0.0028 mmol to 0.002 mmol in terms of titanium atoms, and the charged hydrogen was changed from 3 liters to 2.5 liters. Then, polypropylene was produced. Table 1 shows the results of evaluating the physical properties of the obtained polypropylene.

Further, blending and granulation of additives, molding of raw film, preparation of stretched film and evaluation thereof were performed in the same manner as in Example 1 except that the obtained polypropylene was used. Table 1 shows the results.

[Comparative Example 2]
<Preparation of solid titanium (a-2)>
After a high-speed stirring device with an internal volume of 2 liters (manufactured by Tokushu Kika Kogyo Co., Ltd. (TK Homomixer M)) was sufficiently purged with nitrogen, 700 ml of purified decane, 10 g of commercially available magnesium chloride, 24.2 g of ethanol, and Rhedol SP- (trade name) were added to this device. 3 g of S20 (sorbitan distearate manufactured by Kao Corporation) was added, and the temperature of the reaction system was raised while stirring the suspension, and the suspension was stirred at 120° C. and 800 rpm for 30 minutes. Next, 1 liter of purified decane previously cooled to −10° C. was added to this suspension using a Teflon (registered trademark) tube with an inner diameter of 5 mm while stirring at high speed so as not to generate precipitates. Transferred to a 2 liter glass flask with stirrer. The solid produced by the liquid transfer was filtered and thoroughly washed with purified n-heptane to obtain a solid adduct in which 2.8 mol of ethanol was coordinated with 1 mol of magnesium chloride.

This solid adduct was suspended in decane, and 23 mmol of the solid adduct in terms of magnesium atom was introduced into 100 ml of titanium tetrachloride maintained at -20°C with stirring to form a mixed solution. got The mixture was heated to 80° C. over 5 hours, and when the temperature reached 80° C., diisobutyl 3,6-dimethylcyclohexane-1,2-dicarboxylate (mixture of cis and trans isomers) was added to the solid adduct. was added in an amount of 0.085 mol with respect to 1 mol of magnesium atom of , and the temperature was raised to 110° C. in 40 minutes. When the temperature reaches 110° C., diisobutyl cyclohexane 1,2-dicarboxylate (mixture of cis and trans isomers) is further added in an amount of 0.0625 mol per 1 mol of magnesium atom in the solid adduct, and the temperature is lowered. These were reacted by holding at 110° C. for 90 minutes with stirring.

After completion of the reaction for 90 minutes, the solid portion was collected by hot filtration, resuspended in 100 ml of titanium tetrachloride, and stirred for 45 minutes when the temperature was raised to 110°C. These were reacted by holding while holding. After completion of the reaction for 45 minutes, the solid portion was collected again by hot filtration and thoroughly washed with decane and heptane at 100° C. until free titanium compounds were no longer detected in the washing liquid.

The solid titanium (a-2) prepared by the above procedure was stored as a decane suspension, and part of it was dried for the purpose of examining the catalyst composition. The composition of the solid titanium (a-2) thus obtained was 3.2% by mass of titanium, 17% by mass of magnesium, 57% by mass of chlorine, and 10% by mass of diisobutyl 3,6-dimethylcyclohexane-1,2-dicarboxylate. .6% by weight, 8.9% by weight of diisobutyl cyclohexane 1,2-dicarboxylate and 0.6% by weight of ethyl alcohol residues.

<Main polymerization>
0.5 millimoles of triethylaluminum, 0.1 millimoles of cyclopentyldiethylaminodimethoxysilane, and 0.004 of the solid titanium (a-2) obtained above in terms of titanium atoms were added to a 30-ml glass container containing 7 ml of heptane. An olefin polymerization catalyst was prepared by charging millimoles and contacting them at 20° C. for 10 minutes.

Next, the above olefin polymerization catalyst was charged into an autoclave having an inner volume of 2 liters charged with 500 g of propylene, and polymerization was carried out at 20° C. for 10 minutes. The internal temperature was raised to 70° C. and polymerization was carried out for 1 hour. The polymerization was then terminated by adding ethanol and purging unreacted propylene to obtain 156 g of polypropylene.

A similar operation was performed multiple times to obtain a total of 5 kg of polypropylene. 0.6 g of pure water and 5.4 ml of propylene oxide were added to 1 kg of the obtained polypropylene, and dechlorination was performed at 90° C. for 2 hours, followed by vacuum drying at 80° C. to obtain polypropylene powder. got Table 1 shows the results of evaluating the physical properties of the obtained polypropylene.

Further, blending and granulation of additives, molding of raw film, preparation of stretched film and evaluation thereof were performed in the same manner as in Example 1 except that the obtained polypropylene was used. Table 1 shows the results.

[Comparative Example 3]
Polypropylene was prepared according to PP-2 used in Example 2 of JP-A-2011-256278. Table 1 shows the results of evaluating the physical properties of the obtained polypropylene.

Further, blending and granulation of additives, molding of raw film, preparation of stretched film and evaluation thereof were performed in the same manner as in Example 1 except that the obtained polypropylene was used. Table 1 shows the results.

[Comparative Example 4]
Polypropylene was prepared according to Production Example 5 (PP5) of International Publication WO2016/017752. Table 1 shows the results of evaluating the physical properties of the obtained polypropylene.

Further, blending and granulation of additives, molding of raw film, preparation of stretched film and evaluation thereof were performed in the same manner as in Example 1 except that the obtained polypropylene was used. Table 1 shows the results.

As is clear from Table 1 above, the films of Examples 1 to 4 of the present invention have high dielectric breakdown voltages at high temperatures. On the other hand, the films of Comparative Examples 1 to 4 do not satisfy the requirements of the present invention, and thus the intended performance is not exhibited.

Since the capacitor film according to the present invention is excellent in high-temperature withstand voltage property and film thickness uniformity, even if the stretching temperature range is wide in the film production method and the temperature in the furnace is uneven, the capacitor film according to the present invention can be used. Since the capacitor film can be produced, the industrial value of the capacitor film including one resin layer containing the propylene homopolymer according to the present invention and the method for producing the same is extremely high.

Claims (5)

A capacitor film having at least one resin layer containing a propylene homopolymer satisfying the following requirements (1) to (5):
(1) Melt flow rate (MFR) (ASTM D1238, 230° C., under 2.16 kg load) is 1 to 10 g/10 minutes;
(2) The pentad isotactic fraction mmmm (noise elimination method) calculated according to the following formula 1 from the peak intensity ratio of the spectrum measured using ¹³ C-NMR is 99.0% or more;
(3) The percentage of components eluting at temperatures above 124° C. by cross-fractionation chromatographic analysis (CFC) is 5 to 30% by mass;
(4) The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 4 to 20;
(5) The chlorine content is 2 mass ppm or less.
mmmm (noise removal method) (%) = S1/S2*100 (Formula 1)
S1 = (peak containing mmmm, mmmr)-(n-propyl end)-(n-butyl end)-mrrm*2
S2 = S1 + mmmr + mmrr + mrrm + rrrr
= S1 + 5 * mrrm + rrrr The capacitor film of claim 1, wherein the propylene homopolymer further satisfies requirement (6) below:
(6) The amount of n-decane soluble components at 23°C is 1.0% by mass or less. 3. The capacitor film according to claim 1, wherein the thickness of the film is 1-50 μm. 3. The capacitor film according to claim 1, wherein the thickness of the film is 1.5-30 μm. 5. The method for manufacturing the capacitor film according to any one of claims 1 to 4, which comprises a step of stretching the original sheet at a stretching surface ratio (longitudinal×horizontal surface ratio) of 30 to 80 times. manufacturing method.