JP7334449B2 - Ethylene-isoolefin copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to novel ethylene-isoolefin copolymers which are excellent in heat resistance, radiation resistance, oxidation resistance and the like.

As a method for producing polyolefin by polymerization of olefin, it is already known to use a catalyst system consisting of a combination of a transition metal compound and an organometallic compound, and a metallocene catalyst using a metallocene and methylaluminoxane produces an olefin polymer. It is disclosed that it exhibits high activity during production (see, for example, Patent Document 1).

Metallocene catalysts can greatly change the polymerization performance by changing the structure of the metallocene compound, and it is possible to control the properties of the resulting polymer. Investigations are being made to use it as a constituent component of a polymerization catalyst (see, for example, Non-Patent Document 1). For example, a technique relating to a method for producing short-chain branched polyethylene using a zirconium complex in which a cyclopentadienyl group and an indenyl group are bonded via isopropylene bridges has been disclosed (see, for example, Patent Document 2). In addition, techniques have been disclosed in which a complex having a substituent at a specific site of a cyclopentadienyl group is used as an olefin polymerization catalyst (see Patent Documents 3 to 5, for example). Furthermore, a technique is disclosed in which a complex using an indenyl group having a substituent at a specific site is used as an olefin polymerization catalyst (see, for example, Patent Document 6).

The co-catalyst component of metallocene catalysts has also been investigated, and clay compounds ion-exchanged with organic cations have been disclosed as co-catalysts in place of methylaluminoxane, and polymers with high polymerization activity and good morphology in slurry polymerization processes have been disclosed. are being manufactured (see, for example, Patent Documents 7 to 9).

If the polyolefin provided by these polymerization catalysts is an ethylene homopolymer, it becomes opaque when molded into a container or the like. Moreover, since it is inferior in flexibility, it had the subject of being inferior in moldability.

Copolymers of ethylene and α-olefins such as 1-butene and 1-hexene have been proposed to improve the transparency and moldability of ethylene homopolymers. It is These ethylene-α-olefin copolymers have a tertiary carbon in the main chain due to their structure. The tertiary carbon moiety is easily affected by heat, radiation, ultraviolet rays, etc., and deterioration of the tertiary carbon moiety poses the problem that the ethylene-α-olefin copolymer is inferior in heat resistance, radiation resistance, etc. As a countermeasure, it was common to add heat-resistant stabilizers, UV-resistant stabilizers, antioxidants, and the like.

Therefore, as a polyolefin copolymer having no tertiary carbon, a method for producing an ethylene/1,1-disubstituted α-olefin copolymer (see, for example, Patent Document 10), a polyisobutylene-polyolefin copolymer (for example, See Patent Document 11) and the like have been proposed.

JP-A-58-19309 JP-A-05-43619 Japanese Patent No. 3192186 Japanese Patent No. 33205384 Japanese Patent No. 3537234 Japanese Patent No. 3717542 JP-A-7-224106 JP-A-10-324708 JP-A-11-335408 JP-A-2004-263050 JP-A-2004-175953

Chem. Rev. , 100, 1205 (2000).

However, in the various polymerization catalysts proposed in Patent Documents 1 to 9, Non-Patent Document 1, etc., polymerization of general-purpose olefins such as ethylene and propylene has been investigated, but isoolefins are represented. No specific consideration is given to special olefins.

In addition, in the production method proposed in Patent Document 10, the polymerization activity of the catalyst is extremely low, the catalyst has a relatively low molecular weight containing a large amount of catalyst residue, and the performance is also a problem. In addition, the polyisobutylene-polyolefin copolymer proposed in Patent Document 11 is a block copolymer produced by a cationic polymerization method, and its production method and polymer structure are completely different. It was different from coalescing.

An object of the present invention is to provide a novel ethylene-isoolefin copolymer which is excellent in heat resistance, radiation resistance, oxidation resistance and the like.

The inventors of the present invention have made intensive studies to achieve the above objects, and as a result, have found a novel ethylene-isoolefin copolymer that is excellent in heat resistance, radiation resistance, oxidation resistance, etc. by satisfying specific properties. , have completed the present invention.

That is, the present invention relates to an ethylene-isoolefin copolymer characterized by satisfying at least the following properties (1) to (3).
(1) Melt mass flow rate (hereinafter also referred to as MFR) measured according to JIS K 7210 (1999) is 0.01 to 50 g/10 min.
(2) Density measured according to JIS K 6922-1 (1997) is 890-940 kg/m ³ .
(3) A transition metal content of 0.01 to 100 ppm.

The present invention will be described in detail below.

The ethylene-isoolefin copolymer of the present invention has at least (1) an MFR measured according to JIS K 7210 (1999) of 0.01 to 50 g/10 min, and (2) JIS K 6922-1 (1997). ( ³ ) a transition metal content of 0.01 to 100 ppm;

The novel ethylene-isoolefin copolymer of the present invention has (1) an MFR of 0.01 to 50 g/10 min, and is particularly excellent in moldability, so that the MFR is 0.5 to 25 g/10 min. is preferably of Here, if the MFR is less than 0.01 g/min, the melt fluidity is poor and the moldability is poor. On the other hand, when the MFR exceeds 50 g/10 min, the molecular weight is low and there may be problems in mechanical properties and the like.

The novel ethylene-isoolefin copolymer of the present invention (2) has a density of 890 to 940 kg/m ³ and is particularly well-balanced among heat resistance, radiation resistance, oxidation resistance, etc. and flexibility. Therefore, it is preferable that the weight is 915 to 930 kg/m ³ . Here, if the density is less than 890 kg/m ³ , the moldability will be poor. On the other hand, if the density exceeds 940 kg/m ³ , the flexibility will be poor.

The novel ethylene-isoolefin copolymer of the present invention has (3) a transition metal content of 0.01 to 100 ppm, and is particularly excellent in flexibility, transparency, weather resistance, and color tone balance. 0.1 to 35 ppm is preferable. Here, when the transition metal content is less than 0.01 ppm, the flexibility is inferior. On the other hand, if it exceeds 100 ppm, the weather resistance, heat resistance and color tone will be inferior. Examples of transition metals include transition metals generally known as catalyst residues, such as titanium, zirconium, and hafnium. , hafnium.

Furthermore, the novel ethylene-isoolefin copolymer of the present invention has an excellent balance of heat resistance, radiation resistance, oxidation resistance, etc., and moldability (4) Infrared spectroscopic measurement The number of terminal methyl groups per 1,000 carbon atoms measured by the method is preferably 20 to 300, particularly preferably 20 to 100.

The novel ethylene-isoolefin copolymer of the present invention may be any one as long as it belongs to the category of ethylene-isoolefin copolymers that satisfies the above properties. copolymers, ethylene-2-methyl-1-pentene copolymers, and the like. Further, it may be one obtained by copolymerizing other monomer components.

The novel ethylene-isoolefin copolymer of the present invention is a copolymer of ethylene and an isoolefin such as isobutene, 2-methyl-1-pentene, and other monomers within the scope of the present invention. It can be manufactured by As a specific production method at that time, for example, a method of copolymerizing ethylene and isoolefin using a catalyst for producing an ethylene-isoolefin copolymer using a transition metal compound can be mentioned. Examples of the isoolefin in that case include isobutene and 2-methyl-1-pentene. Examples of the polymerization method include solution polymerization method, bulk polymerization method, vapor phase polymerization method, slurry polymerization method and the like.

The catalyst for producing the ethylene-isoolefin copolymer using the transition metal compound at that time includes, for example, a transition metal compound (A), an activation cocatalyst (B) and an organoaluminum compound (C). A metallocene-based catalyst can be mentioned as an example.

Specific examples of the transition metal compound (A) at that time include diphenylmethylene(indenyl)(fluorenyl)titanium dichloride, phenyl(methyl)methylene(indenyl)(fluorenyl)titanium dichloride, diphenylmethylene(indenyl)(fluorenyl)zirconium Dichloride, diphenylmethylene (indenyl) (fluorenyl) hafnium dichloride, phenyl (methyl) methylene (indenyl) (fluorenyl) zirconium dichloride, phenyl (methyl) methylene (indenyl) (fluorenyl) hafnium dichloride and the like.

Examples of the activating cocatalyst (B) include organic modified clay (B-1), which is clay modified with an organic compound, methylaluminoxane (B-2), (methyl-isobutyl)aluminoxane (B-3), and the like. can do

Specific examples of organic compounds constituting the organically modified clay include N,N-dimethyl-behenylamine hydrochloride, N-methyl-N-ethyl-behenylamine hydrochloride, and N-methyl-Nn-propyl-behenylamine. Compounds such as hydrochlorides, N,N-dioleyl-methylamine hydrochloride, N,N-dimethyl-octadecaneamine hydrochloride, N,N-dimethyl-hexadecaneamine hydrochloride, and hydrofluorides of the hydrochlorides of the above compounds , hydrobromide, hydroiodide or sulfate; P,P-dimethyl-behenylphosphine hydrochloride, P,P-diethyl-behenylphosphine hydrochloride, P,P-dipropyl-behenylphosphine Compounds such as hydrochlorides and compounds obtained by replacing the hydrochlorides of the above compounds with hydrofluoride, hydrobromide, hydroiodide or sulfate can be exemplified, and clay compounds include montmorillonite and smectite. , hectorite, and the like.

As methylaluminoxane (B-2) and (methyl-isobutyl)aluminoxane (B-3), commercially available products (trade name) TMAO-200 (methylaluminoxane type) manufactured by Tosoh Finechem Co., Ltd., ( Trade name) MMAO-3A ((methyl-isobutyl)aluminoxane type), solid polymethylaluminoxane and the like can be exemplified.

Specific examples of the organoaluminum compound (C) include alkylaluminums such as trimethylaluminum, triethylaluminum and triisobutylaluminum.

The catalyst can be prepared as a metallocene-based catalyst by blending the transition metal compound (A), the activating cocatalyst (B) and the organoaluminum compound (C), and the blending ratio at that time is arbitrary. For example, the molar ratio of component (A) to component (C) per metal atom is preferably in the range of component (A):component (C) = 100:1 to 1:100000, particularly 1:1 to 1:10000. A range is preferred. The weight ratio of component (A) to component (B) is preferably component (A): component (B) = 10:1 to 1:10000, particularly 3:1 to 1:1000. Preferably.

Examples of the polymerization process for producing the novel ethylene-isoolefin copolymer of the present invention include slurry polymerization, gas phase polymerization, high pressure polymerization, solution polymerization and bulk polymerization. In the gas phase polymerization method, an ethylene-isoolefin copolymer having a regular particle shape can be efficiently and stably produced. Solvents used in liquid phase polymerization, such as slurry polymerization and solution polymerization, may be any commonly used organic solvents, specifically benzene, toluene, xylene, pentane, and hexane. , heptane and the like.

In addition, polymerization conditions such as polymerization temperature, polymerization time, polymerization pressure, and monomer concentration are arbitrary. The polymerization pressure is preferably in the range of normal pressure to 3000 kg/cm ² G. It is also possible to adjust the molecular weight by using hydrogen or the like during polymerization. Polymerization can be carried out by any of a batch system, a semi-continuous system, and a continuous system, and can be carried out in two or more stages by changing the polymerization conditions. Further, the ethylene-isoolefin copolymer obtained after the polymerization is separated and recovered from the polymerization solvent by a conventionally known method, and can be obtained by drying.

Since the novel ethylene-isoolefin copolymer of the present invention does not have tertiary carbon on its main chain, it has excellent radiation resistance and oxidation resistance, and is superior to conventional ethylene-α-olefin copolymers. It is possible to reduce the amount of weather stabilizers, UV inhibitors, antioxidants, etc. required for coalescence as much as possible. Become.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a novel ethylene-isoolefin copolymer excellent in heat resistance, radiation resistance, oxidation resistance and the like.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these. Unless otherwise specified, reagents and the like used were commercial products or those synthesized according to known methods.

～Pulverization of organically modified clay～
A jet mill (manufactured by Seishin Enterprise Co., Ltd. (trade name) CO-JET SYSTEM α MARK III) was used, and the particle size after pulverization was measured using a Microtrac particle size distribution analyzer (manufactured by Nikkiso Co., Ltd. (trade name) MT3000). Measured as a dispersant.

～Catalyst preparation, polymerization and solvent purification～
All were performed under an inert gas atmosphere.

～Triisobutyl Aluminum～
A hexane solution (20% by weight) manufactured by Tosoh Finechem Co., Ltd. was used as the hexane solution (20% by weight).

~MFR~
Measured according to JIS K 7210 (1999).

～Density～
Measured according to JIS K 6922-1 (1997).

～Transition metal content～
The ash content of the obtained ethylene-isoolefin copolymer was measured by elemental analysis.

~ Number of terminal methyl groups ~
It was measured by FT-IR ((trade name) SPECTRUM ONE manufactured by PERKIN ELMER).

～melting point～
Using a differential scanning calorimeter (manufactured by SII Nanotechnology Co., Ltd. (trade name) DSC6200), the sample was held at 200 ° C. for 5 minutes, cooled to -20 ° C., and then heated at a rate of 10 ° C./min. It was calculated by measuring the crystal melting peak when the

Example 1
(1) Denaturation of clay 300 mL of industrial alcohol (manufactured by Nippon Alcohol Sales Co., Ltd. (trade name) Ekinen F-3) and 300 mL of distilled water are placed in a 1 L flask, and 15.0 g of concentrated hydrochloric acid and dimethylbehenylamine (manufactured by Lion Corporation) are added. , (trade name) Armine DM22D) 42.4 g (120 mmol) was added and heated to 45°C to disperse 100 g of synthetic hectorite (manufactured by Tetsutani Co., Ltd., (trade name) Laponite RDS). and stirred for 1 hour while maintaining the temperature. This slurry was separated by filtration, washed twice with 600 mL of water at 60° C., and dried in a dryer at 85° C. for 12 hours to obtain 122 g of organically modified clay. This organically modified clay was pulverized by a jet mill to a median diameter of 15 μm.

(2) Preparation of catalyst suspension After purging a 1000 mL flask equipped with a thermometer and a reflux tube with nitrogen, the organically modified clay (50.0 g) obtained in (1) and 216 mL of hexane were added, and then (diphenyl 1.21 g of methylene(indenyl)(fluorenyl)zirconium dichloride and 284 mL of 20% triisobutylaluminum) were added and stirred at 60° C. for 3 hours. After cooling to 45° C., the supernatant was removed, and after washing with 400 mL of hexane five times, 400 mL of hexane was added to obtain a catalyst suspension (solid weight content: 12.0 wt %).

(3) Polymerization 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 1.0 g of the catalyst suspension obtained in (2) (equivalent to 120 mg of solid content) were added to a 2 L autoclave and heated to 70°C. After raising the temperature, 50 g of isobutene was added, and ethylene was continuously supplied so that the partial pressure was 0.80 MPa. After 60 minutes, the pressure was released, and the slurry was filtered and dried to obtain 73 g of an ethylene-isobutene copolymer.

The resulting ethylene-isobutene copolymer had an MFR of 17 g/10 min, a density of 923 kg/m ³ , a terminal methyl group number of 31/1000 carbon atoms, a zirconium content of 6.3 ppm, and a melting point of 110°C. , was white. Table 1 shows the evaluation results. The ethylene-isobutene copolymer was melted in the air at 140° C. for 10 minutes and evaluated for stability.

Example 2
(1) Modification of Clay The same method as in Example 1 (1) was used.

(2) Preparation of catalyst suspension After purging a 500 mL flask equipped with a thermometer and a reflux tube with nitrogen, the organically modified clay (37.5 g) obtained in (1) and 162 mL of hexane were added, and then (phenyl (Methyl)methylene(indenyl)(fluorenyl)zirconium dichloride (818 mg) and 20% triisobutylaluminum (213 mL) were added and stirred at 60° C. for 3 hours. After cooling to 45° C., the supernatant was removed, and after washing with 350 mL of hexane five times, 350 mL of hexane was added to obtain a catalyst suspension (solid weight content: 12.0 wt %).

(3) Polymerization 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 1.0 g of the catalyst suspension obtained in (2) (equivalent to 120 mg of solid content) were added to a 2 L autoclave and heated to 70°C. After raising the temperature, 45 g of isobutene was added, and ethylene was continuously supplied so that the partial pressure was 0.80 MPa. After 60 minutes, the pressure was released, and the slurry was filtered and dried to obtain 58 g of an ethylene-isobutene copolymer.

The resulting ethylene-isobutene copolymer had an MFR of 22 g/10 min, a density of 925 kg/m ³ , a terminal methyl group number of 22/1000 carbon atoms, and a zirconium content of 7.9 ppm. It had a melting point of 115° C. and was white in color. Table 1 shows the evaluation results. The ethylene-isobutene copolymer was melted in the air at 140° C. for 10 minutes and evaluated for stability.

Example 3
(1) Modification of Clay The same method as in Example 1 (1) was used.

(2) Preparation of catalyst suspension After purging a 500 mL flask equipped with a thermometer and a reflux tube with nitrogen, the organically modified clay (45.0 g) obtained in (1) and 194 mL of hexane were added, and then (diphenyl 1.25 g of methylene (indenyl) (fluorenyl) hafnium dichloride and 256 mL of 20% triisobutylaluminum were added and stirred for 3 hours at 60° C. After cooling to 45° C., the supernatant liquid was removed and diluted with 360 mL of hexane for 5 minutes. After washing twice, 360 ml of hexane was added to obtain a catalyst suspension (solid weight: 12.0 wt %).

(3) Polymerization 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 1.0 g of the catalyst suspension obtained in (2) (equivalent to 120 mg of solid content) were added to a 2 L autoclave and heated to 70°C. After raising the temperature, 51 g of isobutene was added, and ethylene was continuously supplied so that the partial pressure was 0.80 MPa. After 60 minutes, the pressure was released, and the slurry was filtered and dried to obtain 64 g of an ethylene-isobutene copolymer.

The resulting ethylene-isobutene copolymer had an MFR of 0.25 g/10 min, a density of 916 kg/m ³ , a terminal methyl group number of 34/1000 carbon atoms, and a hafnium content of 14 ppm. It had a melting point of 103° C. and was white. Table 1 shows the evaluation results. The ethylene-isobutene copolymer was melted in the air at 140° C. for 10 minutes and evaluated for stability.

Example 4
(1) and (2) Modification of Clay and Preparation of Catalyst Suspension The same methods as (1) and (2) of Example 3 were carried out.

(3) Polymerization 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 1.0 g of the catalyst suspension obtained in (2) (equivalent to 120 mg of solid content) were added to a 2 L autoclave and heated to 70°C. After raising the temperature, 57 g of 2-methyl-1-pentene was added, and ethylene was continuously supplied so that the partial pressure became 0.80 MPa. After 60 minutes, the pressure was released, and the slurry was filtered and dried to obtain 28 g of ethylene-2-methyl-1-pentene copolymer.

The resulting ethylene-2-methyl-1-pentene copolymer had an MFR of 12 g/10 min, a density of 924 kg/m ³ , terminal methyl groups of 23/1000 carbon atoms, and contained hafnium. The amount was 34 ppm, the melting point was 103° C., and it was white. Table 1 shows the evaluation results. The ethylene-2-methyl-1-pentene copolymer was melted in the air at 140° C. for 10 minutes and evaluated for stability.

Example 5
(1) Preparation of catalyst suspension After purging a 100 mL flask with nitrogen, add 52.4 g (60.4 mL) of toluene and a toluene suspension (21.8 g) of solid polymethylaluminoxane manufactured by Tosoh Finechem Co., Ltd. (12.1% by weight of polymethylaluminoxane (in toluene suspension), 41% by weight of aluminum atoms (in polymethylaluminoxane)) and 122 mg of diphenylmethylene (indenyl) (fluorenyl) zirconium dichloride were added and By stirring for 12 hours, a catalyst suspension was obtained (solid weight: 3.6 wt%).

(2) Polymerization 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 1.4 g of the catalyst suspension obtained in (2) (equivalent to 50 mg of solid content) were added to a 2 L autoclave and heated to 70°C. After raising the temperature, 45 g of isobutene was added, and ethylene was continuously supplied so that the partial pressure was 0.80 MPa. After 60 minutes, the pressure was released, and the slurry was filtered and dried to obtain 29 g of an ethylene-isobutene copolymer.

The resulting ethylene-isobutene copolymer had an MFR of 0.07 g/10 min, a density of 926 kg/m ³ , a terminal methyl group number of 18/1000 carbon atoms, and a zirconium content of 12 ppm. It had a melting point of 118° C. and was white in color. Table 1 shows the evaluation results. The ethylene-isobutene copolymer was melted in the air at 140° C. for 10 minutes and evaluated for stability.

Example 6
(1) Preparation of catalyst suspension After purging a 100 mL flask with nitrogen, 39.3 g (45.3 mL) of toluene and a toluene suspension (16.4 g) of solid polymethylaluminoxane manufactured by Tosoh Finechem Co., Ltd. (12.1% by weight of polymethylaluminoxane (in toluene suspension), 41% by weight of aluminum atoms (in polymethylaluminoxane)) and 104 mg of diphenylmethylene (indenyl) (fluorenyl) hafnium dichloride were added and By stirring for 12 hours, a catalyst suspension was obtained (solid weight: 3.6 wt%).

(2) Polymerization 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 3.5 g of the catalyst suspension obtained in (2) (equivalent to 125 mg of solid content) were added to a 2 L autoclave and heated to 70°C. After raising the temperature, 53 g of isobutene was added, and ethylene was continuously supplied so that the partial pressure was 0.80 MPa. After 60 minutes, the pressure was released, and the slurry was filtered and dried to obtain 53 g of an ethylene-isobutene copolymer.

The resulting ethylene-isobutene copolymer had an MFR of 0.03 g/10 min, a density of 927 kg/m ³ , a terminal methyl group number of 21/1000 carbon atoms, and a hafnium content of 34 ppm. It had a melting point of 119° C. and was white. Table 1 shows the evaluation results. The ethylene-isobutene copolymer was melted in the air at 140° C. for 10 minutes and evaluated for stability.

Comparative example 1
(1) Preparation of catalyst solution 23.7 mg (36.8 µmol) of diphenylmethylene (cyclopentadienyl) (9-fluorenyl) hafnium dichloride was weighed into a previously dried glass container equipped with a stirrer under a nitrogen atmosphere. was dissolved in 2.8 ml of toluene, 1.87 mmol (2.1 ml) of a toluene solution of tri(isobutyl)aluminum (tri(isobutyl)aluminum 20 wt%) was added in terms of aluminum, and the mixture was stirred for 1 hour. 17.9 mg (22.3 μmol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate was weighed into another glass container previously dried and equipped with a stirrer under a nitrogen atmosphere, and 3.5 ml of toluene was added. 3.0 ml of the above mixed solution was added to the solution dissolved by the above to prepare a catalyst solution.

(2) Polymerization 24 ml of toluene and a toluene solution of tri(isobutyl)aluminum (20 wt% of tri(isobutyl)aluminum) were placed in a 100 ml stainless steel reactor equipped with a stirrer and dried in advance under a nitrogen atmosphere. 0.85 mmol, and 5 ml of the catalyst solution obtained in (1) above (17.2 μmol in terms of hafnium) were added. Next, 21.5 g (0.38 mol) of isobutene was introduced, then the ethylene partial pressure was set to 0.14 MPa, and a copolymerization reaction was carried out at room temperature for 1 hour. Unreacted ethylene and isobutene were removed under reduced pressure, polymerization was terminated, and the resulting polymer was vacuum dried to obtain 3.03 g of polymer.

The obtained polymer was an ethylene-isobutene copolymer with an isobutene content of 36.5 mol %, but had a high MFR of 51 g/10 min and a high hafnium content of 1000 ppm. Although the obtained ethylene-isobutene copolymer was white, it was melted in the air at 140° C. for 10 minutes and evaluated for stability.

Comparative example 2
(1) Preparation of catalyst solution 30.9 mg (55.5 µmol) of diphenylmethylene (cyclopentadienyl) (9-fluorenyl) zirconium dichloride was weighed into a glass container equipped with a stirrer, dried in advance and placed under a nitrogen atmosphere. was dissolved in 1.7 ml of toluene, 2.80 mmol (3.3 ml) of a toluene solution of tri(isobutyl)aluminum (tri(isobutyl)aluminum 20 wt%) was added in terms of aluminum, and the mixture was stirred for 1 hour. 31.0 mg (38.7 μmol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate was weighed into another glass container previously dried and equipped with a stirrer under a nitrogen atmosphere, and 7.8 ml of toluene was added. 3.5 ml of the above mixed solution was added to the solution dissolved by the above to prepare a catalyst solution.

(2) Polymerization 24 ml of toluene and a toluene solution of tri(isobutyl)aluminum (20 wt% of tri(isobutyl)aluminum) were placed in a 100 ml stainless steel reactor equipped with a stirrer and dried in advance under a nitrogen atmosphere. 0.85 mmol, and 5 ml of the catalyst solution obtained in (1) above (17.2 μmol in terms of zirconium) were added. Next, 21.5 g (0.38 mol) of isobutene was introduced, then the ethylene partial pressure was set to 0.14 MPa, and a copolymerization reaction was carried out at room temperature for 20 minutes. Unreacted ethylene and isobutene were removed under reduced pressure, the polymerization was stopped, and the resulting polymer was vacuum dried to obtain 0.79 g of polymer.

The obtained polymer was an ethylene-isobutene copolymer with an isobutene content of 5.9 mol %, but the number of terminal methyl groups was 10/1000 carbon atoms, and the ethylene-isobutene copolymer had a low isobutene residue content. It had a high MFR of 70 g/10 min and a high zirconium content of 2000 ppm. Although the obtained ethylene-isobutene copolymer was white, it was melted in the air at 140° C. for 10 minutes and evaluated for stability.

Comparative example 3
(1) Modification of Clay Modification of clay was performed in the same manner as in Example 1 (1).

(2) Preparation of catalyst suspension After purging a 300 mL flask equipped with a thermometer and a reflux tube with nitrogen, 25.0 g of the organically modified clay obtained in (1) and 108 mL of hexane were added, and then ethylene (cyclopenta 419 mg of dienyl)(fluorenyl)zirconium dichloride and 142 mL of 20% triisobutylaluminum were added and stirred at 60° C. for 3 hours. After cooling to 45° C., the supernatant was removed, and after washing with 200 mL of hexane five times, 200 mL of hexane was added to obtain a catalyst suspension (solid weight: 12.5 wt %).

(3) Polymerization 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 1.0 g of the catalyst suspension obtained in (2) (equivalent to 125 mg of solid content) were added to a 2 L autoclave and heated to 70°C. After raising the temperature, 48 g of isobutene was added, and ethylene was continuously supplied so that the partial pressure became 0.80 MPa. The resulting slurry was filtered and dried to obtain 56 g of polymer. The number of terminal methyl groups in this polymer could not be confirmed, and the introduction of isobutene could not be confirmed. Table 1 shows the evaluation results.

Comparative example 4
(1) Modification of Clay Modification of clay was performed in the same manner as in Example 1 (1).

(2) Preparation of catalyst suspension After purging a 300 mL flask equipped with a thermometer and a reflux tube with nitrogen, 25.0 g of the organically modified clay obtained in (1) and 108 mL of hexane were added, and then dimethylsilylene (indenyl ) 586 mg of (fluorenyl)zirconium dichloride and 142 mL of 20% triisobutylaluminum were added and stirred at 60°C for 3 hours. After cooling to 45° C., the supernatant liquid was removed, and after washing with 200 mL of hexane five times, 200 mL of hexane was added to obtain a catalyst suspension (solid weight content: 12.5 wt %).

(3) Polymerization 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 1.0 g of the catalyst suspension obtained in (2) (equivalent to 125 mg of solid content) were added to a 2 L autoclave and heated to 70°C. After raising the temperature, 48 g of isobutene was added, and ethylene was continuously supplied so that the partial pressure was 0.80 MPa. After 60 minutes had passed, the pressure was released and an attempt was made to produce an ethylene-isobutene copolymer. The resulting slurry was filtered and dried to obtain 34 g of polymer. The number of terminal methyl groups in this polymer could not be confirmed, and the introduction of isobutene could not be confirmed. Table 1 shows the evaluation results.

The novel ethylene-isoolefin copolymer of the present invention has excellent heat resistance, radiation resistance, and oxidation resistance, and is expected to be used in the field of medical containers, etc., which require extremely high cleanliness and radiation resistance to sterilize. It becomes possible.

Claims (2)

An ethylene-isoolefin copolymer characterized by satisfying at least the following properties (1) to (4) .
(1) According to JIS K 7210 (1999), the melt mass flow rate measured at a measurement temperature of 190° C. and a load of 2.16 kg is 0.03 to 22 g/10 min.
(2) The density measured according to JIS K 6922-1 (1997) is 916-927 kg/m ³ .
(3) The content of zirconium and/or hafnium is 0.01-100 ppm.
(4) The number of terminal methyl groups per 1,000 carbon atoms measured by infrared spectroscopy is 18 to 34. The ethylene-isoolefin copolymer according to claim 1, which is a random copolymer.