JP2006183017A - Polypropylene and stretched film - Google Patents

Abstract

[PROBLEMS] To provide a well-stretchable polypropylene that has excellent electrical characteristics, in particular, a breakdown voltage, and enables a capacitor film to be thinned.
[1] Melt flow rate (MFR) is 0.5 to 30 g / 10 minutes, [2] Ash content is 30 ppm or less, chlorine content is 5 ppm or less, and [3] carbon number is 4 Polypropylene, wherein the α-olefin content is 0.05 to 5% by weight.
[Selection figure] None

Description

  The present invention relates to polypropylene having good stretchability and high withstand voltage, and a stretched film and a capacitor film.

  Polypropylene is used as a food packaging film, industrial film, industrial sheet, or the like because it has high mechanical strength, high electrical insulation, and excellent food hygiene and transparency.

In particular, a capacitor film used for an insulator of a capacitor is required to have a high breakdown voltage even if electric characteristics, particularly a breakdown voltage are important.
In addition, the capacitor film is becoming thinner due to an increase in capacitor capacity, and good stretchability is desired.

  Polypropylene containing a small amount of ethylene has good stretchability, but has problems such as a decrease in melting point and crystallinity and deterioration in breakdown voltage.

  An object of the present invention is to provide a well-stretchable polypropylene that is excellent in electrical characteristics, particularly in breakdown voltage, and capable of thinning a capacitor film.

The polypropylene of the present invention satisfies the following requirements [1] to [3] simultaneously.
[1] The melt flow rate (MFR) is 0.5 to 30 g / 10 min.
[2] Ash content is 30 ppm or less, and chlorine content is 5 ppm or less.
[3] The content of α-olefin having 4 or more carbon atoms is 0.05 to 5% by weight.

  The stretched film of the present invention is a film formed by stretching the polypropylene.

  Furthermore, the present invention relates to a capacitor film using the stretched film as a capacitor insulator.

  Since the polypropylene of the present invention is a copolymer of propylene of a specific ratio and an α-olefin having 4 or more carbon atoms, it improves the stretchability without impairing the crystallinity and rigidity, and has a capacitor film with excellent breakdown voltage. provide.

  The polypropylene of the present invention is a crystalline polypropylene resin, and is a copolymer of propylene and an α-olefin having 4 or more carbon atoms. The α-olefin content in the polypropylene resin is 5% by weight or less, preferably 3% by weight or less, more preferably 2% by weight or less.

  Since the α-olefin content is in this range, the stretchability is excellent while maintaining the crystallinity and rigidity of the film or the breakdown voltage characteristics.

  Preferred specific examples of the α-olefin include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and the like, and these can be used at the same time. Of these, 1-butene is preferably used.

  The polypropylene of the present invention has a melt flow rate (ASTM D-1238, 230 ° C., load 2.16 kg) of 0.5 to 30 g / 10 minutes, preferably 1 to 10 g / 10 minutes, and more preferably 1.5 to It is in the range of 5 g / 10 minutes. Since the melt flow rate is in this range, the formability of the sheet or film is excellent.

  The polypropylene of the present invention has no limitation on the molecular weight distribution measured by gel permeation chromatography, but if the Mw / Mn is 5.4 or more and the Mz / Mn is 20 or more, β crystals are sufficiently generated. .

  The polypropylene of the present invention preferably has an ash content of 30 ppm or less, more preferably 25 ppm or less. When the ash content is 30 ppm or less, the electric insulation as a capacitor film is excellent, and for this reason, it is suitably used as an insulator for a capacitor. Furthermore, when the chlorine content is 5 ppm or less, preferably 3 ppm or less, it is suitably used as a capacitor film because the characteristics of the capacitor parts are not impaired.

  Such a polypropylene having a low ash content and a low chlorine content can be produced by using a highly active catalyst, or by decomposing or removing the catalyst in the polymerized polypropylene.

  When a sheet or film is formed from the polypropylene of the present invention as a raw material, other polymers such as other resins or rubbers may be added to the polypropylene of the present invention within the range that does not impair the purpose of the present invention. It may be added. Examples of the other resin or rubber include poly α-olefins such as polyethylene, polybutene-1, polyisobutene, polypentene-1, and polymethylpentene-1, ethylene / propylene copolymers having a propylene content of less than 75% by weight, Ethylene or α-olefin / α-olefin copolymer such as ethylene / butene-1 copolymer, propylene / butene-1 copolymer having a propylene content of less than 75% by weight; propylene content of less than 75% by weight Ethylene such as ethylene / propylene / 5-ethylidene-2-norbornene copolymer or α-olefin / α-olefin / diene monomer copolymer; vinyl monomer / diene monomer such as styrene / butadiene random copolymer Random copolymer; Styrene / butadiene / styrene block copolymer Vinyl monomer / diene monomer / vinyl monomer block copolymer; hydrogenation (vinyl / diene monomer random copolymer) such as hydrogenation (styrene / butadiene random copolymer) Hydrogenation (vinyl monomer / diene monomer / vinyl monomer block copolymer) and the like such as hydrogenation (styrene / butadiene / styrene block copolymer).

  The amount of other polymer added varies depending on the type of resin to be added or the type of rubber and may be in a range that does not impair the object of the present invention as described above, but is usually about 5 wt. Part or less.

  In addition, when forming a sheet or film from the polypropylene of the present invention as a raw material, the polypropylene of the present invention is optionally provided with stabilizers such as antioxidants, ultraviolet absorbers, metal soaps, hydrochloric acid absorbers, lubricants, plastics. You may add additives, such as an agent, a flame retardant, and an antistatic agent, in the range which does not impair the objective of this invention.

  Various known methods can be employed to form a capacitor film from the polypropylene of the present invention. For example, there are a method of stretching from a T die to a sheet by an extrusion tenter, a method of extrusion from a circular die and tubular stretching.

  Although the thickness of the obtained sheet | seat is not limited, It is 0.1-3 mm normally, It is desirable that it is 0.2-1 mm normally. The polypropylene sheet of the present invention can be further stretched as necessary to obtain a stretched film. The raw sheet for a capacitor film using the polypropylene of the present invention is stretched and used as a capacitor film. Stretching can be performed by a known method such as stretching roll and / or tenter stretching or tubular stretching, usually by reheating the film to a temperature between 100 ° C. and melting point. In the case of biaxial stretching, the draw ratio is about 3 to 8 times in length and about 3 to 11 times in width. By this stretching treatment, a film having excellent mechanical strength and withstand voltage characteristics can be produced.

  EXAMPLES Next, although this invention is demonstrated in detail based on an Example, this invention is not limited to this Example. The measuring method of the physical property in an Example is as follows.

1) Melt flow rate (MFR )
Measurement was performed at 230 ° C. and a load of 2.16 kg by the method of ASTM D-1238. Nitrogen was not introduced into the cylinder, and the pellets were charged directly into the cylinder and melted.

2) The ash content pellet was put into a crucible and completely burned, and the crucible was ashed in an electric furnace at 800 ° C. for 2 hours. The ash remaining in the crucible was measured to determine the ash content (ppm).

3) Chlorine content 0.8 g of polypropylene was burned at 400-900 ° C. in an argon / oxygen stream with a burner manufactured by Mitsubishi Kasei Co., Ltd., and the sample liquid after collecting and concentrating the combustion gas with ultrapure water was collected. The measurement was performed using an anion column AS4A-SC (manufactured by Dioness) using a Dionex-DX300 ion chromatograph measuring apparatus manufactured by Nippon Dioneck Co., Ltd.

4) Melting point (Tm)
Using Perkin Elmer DSC-7, 7 mg of the sample was heated to 230 ° C. at 10 ° C./min, held at 230 ° C. for 10 minutes, cooled to 50 ° C. at 10 ° C./min, and again at 10 ° C./min. It was determined from the endothermic curve when the temperature was raised.

5) Young's modulus The film was cut in accordance with JISK6781, and a tensile test was performed with a distance between chucks of 80 mm to obtain an apparent Young's modulus. The tensile speed was 50 mm / min.

6) Crystallinity of film The obtained film was measured by wide-angle X-ray diffraction.

Measuring device: Rigaku RINT2500
X-ray source: CuKα, output: 50 kV, 300 mA

7) Stretching stress Measured using a KAROIV stress meter manufactured by Bruckner.

  Next, the present invention will be described with reference to typical examples.

1) Production of polypropylene
[Preparation of solid titanium catalyst component (a)]
In a glass container having an internal volume of 10 liters, 952 g of anhydrous magnesium chloride (further pulverized one), 4420 ml of decane and 3906 g of 2-ethylhexyl alcohol were heated at 130 ° C. for 2 hours to obtain a homogeneous solution. To this solution, 213 g of phthalic anhydride was added, and further stirred and mixed at 130 ° C. for 1 hour to dissolve phthalic anhydride.

  The homogeneous solution thus obtained was cooled to 23 ° C. and allowed to stand for 10 hours, and then 750 ml of the supernatant was extracted from the homogeneous solution at a position of 10 cm from the liquid surface at 50 ml / min. The magnesium chloride solution was added dropwise to 2000 ml of titanium tetrachloride at −20 ° C. in another 10 liter container over 1 hour. After the dropwise addition, the temperature of the resulting mixture was raised to 110 ° C. over 4 hours, and when it reached 110 ° C., 52.2 g of diisobutyl phthalate (DIBP) was added, and the mixture was kept at the same temperature while stirring for 2 hours. Retained. The solid part was then collected by hot filtration, and the solid part was resuspended in 2750 ml of titanium tetrachloride, and then heated again at 110 ° C. for 2 hours.

  After the heating, the solid part was again collected by hot filtration, and washed with decane and hexane at 110 ° C. until no titanium compound was detected in the washing solution. The solid titanium catalyst component (a) prepared as described above was stored as a hexane slurry, of which -part was dried to examine the catalyst composition. The solid titanium catalyst component (a) contained 3% by weight of titanium, 58% by weight of chlorine, 18% by weight of magnesium and 21% by weight of DIBP.

[polymerization]
An autoclave with a stirrer having an internal volume of 5 liters was charged with 1.5 kg of liquefied propylene and 50 g of butene. Furthermore, the MgCl2-supported solid titanium catalyst obtained above was charged in an amount of 18 mg, triethylaluminum in an amount of Al / Ti (molar ratio) = 70, and dicyclopentyldimethoxysilane in a 70-fold mol amount with respect to Ti. Polymerization was performed at 70 ° C. for 2 hours. Hydrogen was charged with 2 NL. After the polymerization, the polypropylene powder was washed with a mixed solvent of isopropanol and heptane, and the powder was separated by filtration and dried by heating.

[Pelletization]
To 100 parts by weight of the obtained powder, 0.2 part by weight of 3,5-di-t-butyl-4-hydroxytoluene as an antioxidant and tetrakis [methylene-3 (3,5- Di-t-butyl-4-hydroxyphenyl) propionate] Incorporating 0.2 parts by weight of methane and 0.01 parts by weight of calcium stearate as a neutralizing agent, the resin temperature is 230 ° C. using a twin screw extruder. It was melt-kneaded and pelletized.

2) Sheet molding The pellets obtained above were processed into a sheet using a press molding machine.
Heated at 230 ° C. for 6 minutes, melted, pressurized with 10 kgf for 1 minute, and subjected to cooling treatment to obtain a 0.5 mm thick sheet.

3) Biaxially stretched film The sheet obtained in 2) above was cut into 85 mm × 85 mm, and biaxially stretched under the following conditions to obtain a biaxially stretched film having a thickness of 14 μm.
Stretching device: KAROIV manufactured by Bruckner
Preheating temperature: 155 ° C
Preheating time: 60 seconds Stretching ratio: 5 × 7 times (5 times in MD direction, 7 times in TD direction) Sequential biaxial stretching Stretching speed: 10 m / min The physical properties measured for the obtained pellets and films are summarized in Table 1.

  The same procedure as in Example 1 was conducted except that 20 g of 1-butene was charged in the polymerization. The results are summarized in Table 1.

  The same procedure as in Example 1 was performed except that the preheating temperature for biaxial stretching was 150 ° C. The results are summarized in Table 2.

  The same procedure as in Example 2 was performed except that the preheating temperature for biaxial stretching was 150 ° C. The results are summarized in Table 2.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that 1-butene was not charged and homopolymerization was performed. The results are summarized in Table 1.

[Comparative Example 2]
The same procedure as in Example 1 was conducted except that 2.2 g of ethylene was charged instead of 1-butene. The results are summarized in Table 1.

[Comparative Example 3]
The same procedure as in Comparative Example 1 was performed except that the preheating temperature for biaxial stretching was 150 ° C. The results are summarized in Table 2.

[Comparative Example 4]
The same procedure as in Comparative Example 2 was performed except that the preheating temperature for biaxial stretching was 150 ° C. The results are summarized in Table 2.

Claims (4)

Polypropylene that satisfies the following requirements [1] to [3] simultaneously.
[1] The melt flow rate (MFR) is 0.5 to 30 g / 10 min.
[2] Ash content is 30 ppm or less, and chlorine content is 5 ppm or less.
[3] The content of α-olefin having 4 or more carbon atoms is 0.05 to 5% by weight   The polypropylene according to claim 1, wherein the α-olefin having 4 or more carbon atoms is 1-butene.   A stretched film obtained using the polypropylene according to claim 1.   The stretched film according to claim 3, which is a capacitor film used as an insulator of a capacitor.