JP3205001B2 - Ultra pure propylene polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a process for producing ultrapure propylene (co) polymer and to the (co) polymer obtained thereby.

It is known that the metal content of a propylene (co) polymer used in the form of a film as a dielectric capacitor must be as low as possible. In particular, "condenser grade" propylene polymers should have relatively low ash (less than 50 ppm) and a chlorine content of less than 10 ppm. In order to reduce catalyst residues and ash to such low values, it has hitherto been necessary to carry out expensive purification treatments of the polymer after the polymerization.

[0003] European Patent Application EP 0340688A
No. 2 describes a method for producing a condenser-grade propylene polymer which does not require post-polymerization treatment. The process comprises an Al-trialkyl compound and at least one Si-OR (R = hydrocarbon group) under gas phase polymerization conditions requiring very long (more than 6 hours) residence time and very high pressure. A catalyst is used which is obtained by reacting a silicon compound with a solid component supported on a magnesium halide in active form with a titanium halide and a phthalate ester. This polymer has an ash content of 17 to 42 ppm, a titanium content of 0.25 to 0.6 ppm, and a chlorine content of 5 to 15 pp.
m, Al content is 4.2 to 10 ppm.

Here, an Al-trialkyl compound is prepared by converting an active form of magnesium dihalide, titanium chloride or chloroalcoholate supported thereon, and a compound of the general formula Wherein R and R ¹ are the same or different and are a C _2-18 alkyl, C _3-18 cycloalkyl, C _6-18 aryl, C _7-18 arylalkyl or alkylaryl group. By polymerizing the monomer in the liquid monomer in the presence of a catalyst obtained by reacting with a solid catalyst component consisting of an ether represented by the formula, an ultrapure propylene (co) polymer can be effectively obtained. discovered.

The propylene (co) polymer obtained by the method of the present invention has an ash content of less than 15 ppm and a chlorine content of 5 ppm.
less than 5 ppm, Al content less than 5 ppm, and Mg and T
It is characterized in that the i content is below the detection limits of the used X-ray fluorescence method and atomic absorption method (2 ppm and 1 ppm, respectively, measured by X-ray fluorescence for Mg and by atomic absorption method for Ti). is there.

[0006] The polymer of the present invention comprises polypropylene having an isotactic index of more than 90, and propylene;
R consists of a crystalline copolymer with CH ₂ ＣＨCHR olefin wherein R is hydrogen or an alkyl group having 2 to 8 carbon atoms.

In the process according to the invention, the residence time of the catalyst in the polymerization zone can be reduced to 2 hours, but is generally between 4 and 8 hours.

In the ethers of the formula (I), preferably, R and R ¹ are isobutyl or R is isopropyl and R ¹ is isoamyl or cyclohexyl. Ethers of the formula (I) are described in EP-A-0361493. A preferred titanium compound is TiCl ₄ and Al
The alkyl compound is preferably Al-triisobutyl.

[0009] The solid catalyst component is prepared by adding excess TiCl ₄ to 10
Obtained by reacting with MgCl ₂ .nROH adduct at 0-120 ° C., where n is a number from 1 to 3 and R is ethyl, butyl or isobutyl. After the reaction, excess TiCl ₄ is filtered off at high temperature and the solid is
Treat at least once more with excess TiCl ₄ at 120 ° C. Excess TiCl ₄ is filtered off at elevated temperature and the solid is washed with hexane or heptane until no chloride ions are present in the washings.

By using the ether of formula (I) in the preparation of the catalyst component, the molar ratio of Al to Ti can be reduced to less than 50 in order to obtain a polymer having a low Al content in the polymerization.

Moreover, this constitutes a special embodiment of the invention, but it has been found that after polymerization, the aluminum content can be further reduced by countercurrent washing of the polymer with liquid propylene. If the catalyst used is prepared from Al-triisobutyl, the Al content in the polymer can be reduced very effectively. In this case, the Al content is reduced to less than 3 ppm.

The polymerization of propylene or its mixture with other alpha-olefins is carried out at a temperature of from 70 to 90 ° C. If the activity of the catalyst is high, a residence time of 4 to 8 hours is usually sufficient.

As already mentioned, the propylene polymers according to the invention are suitable for the production of capacitors and electric circuits.

The present invention will be described with reference to the following examples, but is not limited to these examples. Parts per million
(ppm) is based on the weight of the polymer. Total ash is A
According to STM D-229.86, instead of 5 g, 20
Measured using 0 g of polymer, Mg, Al, and C
The l content is measured by X-ray fluorescence analysis, and the Ti content is measured by an atomic absorption method. Melt index (MIL)
It is measured according to ASTM D-1238, condition L.

Example 1 625 cc of TiCl _{4 in} a 1 liter flask equipped with a condenser, mechanical stirrer and thermometer under a nitrogen atmosphere.
And then 25 g of U.S. Pat. No. 4,469,64.
MgCl ₂ was prepared by the method and the raw material described in Example 1 No. 8. Introducing 2.1C ₂ H ₅ OH adduct.
This adduct is introduced at 0 ° C. This mixture is added for 1 hour
Bring to 00 ° C. When the temperature reaches 40 ° C, 21.7mm
ol of 2-isopropyl-2-isoamyl-1,3-dimethoxypropane is added and the mixture is kept at 100 ° C. for 2 hours, after which it precipitates and the supernatant is siphoned off.

550 ml of TiCl ₄ are added and the mixture is heated with stirring at 120 ° C. for 1 hour. The stirring is then stopped, the mixture is allowed to settle, and the supernatant is siphoned off. The solid is then washed six times with 200 ml of hexane at 60 ° C., then three times at room temperature and dried under vacuum.

The solid thus obtained comprises 4.1% by weight of Ti and 13.6% by weight of 2-isopropyl-2.
-Isoamyl-1,3-dimethoxypropane. The ether used in this example is prepared by the method described in Example 1 of EP-A-0361493.

In a 950 l loop reactor temperature-controlled to 70 ° C., continuously, a sufficient amount of propylene and hydrogen to obtain a MIL of 2 to 2.5, the catalyst component as an oily paste ( 250 g / l) and Al-triisobutyl as a 10% by weight heptane solution. Al /
The Ti atomic ratio is 30, which is kept constant.

The flow rate of propylene is 88.5 kg / h,
On the other hand, the flow rate of the catalyst component is adjusted so that the concentration of the polymer in the reactor becomes constant (0.29 kg / l slurry). The average residence time is 6 hours. Other operating conditions are shown in Table 1.

Example 2 The catalyst used in this example is prepared by the method and starting materials of Example 1 except that 2-cyclohexyl-2-isopropyl-1,3-dimethoxypropane is used as the ether. This solid catalyst component contains 3.44% by weight of Ti and 11.5% by weight of ether. The ether used in this example was EP 0
Prepared by the method described in Example 5 of 361493. The polymerization of propylene is carried out under the same conditions as in Example 1.
Table 1 shows the obtained results.

COMPARATIVE EXAMPLE 1 The catalyst used in this example is 1 instead of ether.
Except for using 6.3 mmol of diisobutyl phthalate,
Prepared under the same conditions as in Example 1.

In this case, the propylene polymerization is carried out by Al / Ti
At a molar ratio of 10 using cyclohexyl (methyl) dimethoxysilane added to Al-triisobutyl. Other operating conditions and results are shown in Table 1.

[0023]

[Table 1]

────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Giovanni, Ferrara, Baruzzi, Via, Mario, Atsui, 37 (56) References JP-A-64-51408 (JP, A) JP-A-63-295607 ( JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 10/06 C08F 4/658 CA, REGISTRY (STN)

Claims (4)

(57) [Claims] 1. A process for the production of an ultrapure propylene polymer having a total ash content of less than 15 ppm or a copolymer with a CH ₂ ＣＨCHR olefin wherein R is hydrogen or an alkyl group having 2 to 8 carbon atoms. Wherein the Al-trialkyl compound is an active form of magnesium dihalide, titanium chloride or chloroalcoholate supported thereon, and the general formula Wherein R and R ¹ are the same or different and are a C _2-18 alkyl, C _3-18 cycloalkyl, C _6-18 aryl, C _7-18 arylalkyl or alkylaryl group. A method for polymerizing a monomer in a liquid monomer in the presence of a catalyst obtained by reacting with a solid catalyst component comprising an ether represented by the following formula: 2. The method according to claim 1, wherein the Al-trialkyl compound is Al-triisobutyl. 3. The residence time of the catalyst in the polymerization zone is 4-8.
The method of claim 1, wherein the time is time. 4. The method according to claim 2, wherein the (co) polymer is further washed with liquid propylene in a countercurrent manner, whereby a (co) polymer having an Al content of less than 3 ppm is obtained. Method.