JPS6339905A - Production of ethylene copolymer - Google Patents

Abstract

PURPOSE:To produce the title copolymer low in stickiness and excellent in low-temperature sealability, heat resistance, tensile strength and ESCR resistance, by copolymerizing ethylene with an alpha-olefin in the presence of a specified catalyst. CONSTITUTION:A catalyst is obtained by mixing a transition metal compound component (a) comprising a titanium compound of the formula [wherein R is methyl, A is cyclopentadienyl, R<1-3> are each a 1-6C alkyl, a group (Rm-A), a halogen or H and m is 0-2) with an organoalminum compound (b) comprising an alumoxane obtained by reacting a trialkylaluminum with water. Ethylene is copolymerized with 1-25 mol% 4-20C alpha-olefin (e.g., butene) at 0-100 deg.C and a pressure of normal pressure - 50 kg/cm<2> for 10 min - 10 hr. in the presence of this catalyst in an inert hydrocarbon solvent to obtain an ethylene copolymer having at least two peaks showing melting points determined by differential scanning calorimetry, a Q value, which represents an MW distribution, of 1.5-4 and a density of 0.86-0.935g/cm<3>.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for producing ethylene copolymers. More specifically, the present invention produces an ethylene copolymer having a density of 0.86 to 0.935 t/d by copolymerizing ethylene and an α-olefin having 4 to 20 carbon atoms in the presence of a specific catalyst. It is about the method.

The ethylene copolymer obtained by the method of the present invention has a narrow molecular weight distribution and has a plurality of melting points measured by differential scanning calorimetry (DSC). , and has excellent low-temperature heat sealing properties, heat resistance, tensile strength, ESCR resistance, etc.

Prior Art Conventionally, in order to simultaneously improve the flatness, low-temperature heat-sealability, heat resistance, tensile strength, and ESCR resistance of ethylene copolymers, ethylene with a narrow molecular weight distribution and multiple melting points measured by DSC measurement and 4 carbon atoms were used. Copolymers with the above α-olefins are disclosed in JP-A-59-75910 and JP-A-59-75910.
As proposed in various publications such as No. 52643, by using a catalyst consisting of a solid catalyst component containing a dog halide and a T1 halide, and a halogenated organoaluminum compound, the resulting copolymer is completely dissolved. It is manufactured at a temperature of 120°C or higher, preferably 130°C or higher. With these methods, outside the above temperature range,
DSC of the copolymer obtained especially at temperatures below 100°C
The measured melting point will be of a single peak.

Furthermore, copolymerization of ethylene and α-olefin using a catalyst consisting of a cyclopentadienyl titanium compound and an alumoxane is described in 5 studies in 5.
surface 5science & Catajlys
is 25, @CataAytic Poj! yme
rizatioa of 01efins' p.

271-292, Kodansha / 11JLse
vier (1986), John A. Ii:w
en, r Ligand effects on
metajlJioenecatalyzed Zi
egil Jer-Natta po phantom yerizati
onJ, but it is limited to the polymerization of ethylene and propylene, and there is no report on ethylene and α-olefins having 4 to 20 carbon atoms.

SUMMARY OF THE INVENTION The present invention provides a method for preparing ethylene and a
-Density is 0.86-0.93 by copolymerizing olefin
In the method for producing an ethylene copolymer of 5 f/cd, the transition metal compound has the general formula (A) TiR"l
"R" In the formula, R is a methyl group, A is a cyclopentadienyl group, R1, ♂ and R3 are each independently an alkyl group having 1 to 6 carbon atoms, a group (Rm-A), halogen or hydrogen, m is 0.1 or 2, respectively], and the organoaluminum compound is alumoxane, and provides a method for producing an ethylene copolymer.

Effect of the Invention The feature of the method of the present invention is that the general formula (Rm-A)TiR'R
FR'' [In the formula, R is a methyl group, A is a cyclopentadienyl group, R1, R2 and R3 each independently have a carbon number of 1
~6 alkyl group, group (Rm-A), halogen or hydrogen, m is 0.1 or 2, respectively] is used as a transition metal compound component, and by reaction with trialkylaluminum and water. Ethylene and an α-olefin having 4 to 20 carbon atoms are copolymerized in the presence of a catalyst containing the obtained alumoxane as an organic aluminum compound component.

In the method of the present invention, it is particularly preferable that the copolymerization reaction be carried out at a temperature of 100° C. or lower, such that the ethylene copolymer produced does not completely dissolve in the solvent.

The ethylene copolymer obtained by the method of the present invention has a density of 0.
．． It has a melting point of 86 to 0.935 f/cj, has multiple melting points measured by DSC, and has a Q value indicating molecular weight distribution of 1.
It is narrow at 5-4.

This copolymer has a narrow molecular weight distribution, has a low content of low molecular weight components, is less sticky, and has different crystallinity in DSC measurements, that is, a copolymer component that melts at low temperatures and a copolymer component that melts at high temperatures. Because it contains both components, it has excellent low-temperature heat-sealability, and is also excellent in heat resistance, tensile paper strength, ESCR resistance, etc.

DETAILED DESCRIPTION OF THE INVENTION The catalysts used in the present invention each consist of a combination of specific transition metal compound components and organoaluminium components.

The transition metal compound component has the general formula (Rm-A) TiRlR''R3 [wherein R is a methyl group, R is a cyclopentadienyl group, and R1, R2 and R3 are each independently a group having 1 to 6 carbon atoms. In particular, a titanium compound represented by a lower alkyl group, a group (Rm-A) (where R and A are as described above), halogen or hydrogen, and m is 0.1 or 2, respectively, is used.

Among these, bis(cyclopentagenyl) titanium dichloride, cyclopentagenyl titanium trichloride, bis(cyclopentagenyl) titanium chloride hydride, bis(cyclopentagenyl) titanium methyl chloride, bis(methylcyclopentagenyl) titanium chloride, Preferred are titanium dichloride, bis(methylcyclobentadienyl)titanium methyl chloride, and the like.

Among them, bis(cyclopentagenyl)titanium dichloride can be preferably used.

As the organoaluminum component, an alumoxane obtained by a reaction between trialkylaluminum and water is used.

Alumoxanes can be prepared under a variety of known conditions. For example, a salt having water of crystallization, such as copper sulfate pentahydrate, is usually added to an organic solvent such as benzene, toluene, or xylene, and then trialkylaluminum is added.
The desired alumoxane can be obtained by carrying out the reaction at a temperature of about 40 to 60°C. The amount of water usually used is 0.1 to 2 in molar ratio to trialkylaluminum,
Preferably it is 0.5 to 1.5. The obtained alumoxane is a cyclic or linear polymerized aluminum compound.

Examples of the trialkylaluminum used in the production of alumoxane include trimethylaluminum, triethylaluminum, triisopropylaluminum, triimbutylaluminum, and trioctylaluminum, and trimethylaluminum is particularly preferably used.

The amount of the catalyst component used is 0.01 to 5 otq/l, preferably 0.1 otq/l of the transition metal compound component in terms of titanium atoms.
~loq/l, the organoaluminum compound component has an At/Ti atomic ratio of 10 to 10 with respect to the transition metal compound component.
0. Goo, preferably 100 to 10,000.

The above catalyst components can be dissolved in organic solvents such as benzene, toluene, xylene, etc. and supplied separately to the polymerization tank, but it is preferable to mix them in advance before supplying them to the polymerization tank.

Polymerization of ethylene and α-olefin having carbons from 4 to 20 is as follows:
The polymerization is carried out in an inert hydrocarbon solvent such as benzene or toluene, and either continuous or discontinuous polymerization is possible. It is also possible to carry out the polymerization in the form of a gas phase method substantially in the absence of a solvent.

Polymerization pressure is normal pressure ~ sokg/d, ethylene partial pressure is normal pressure ~
40#/cIi and the polymerization temperature is 0 to 100°C, preferably 20 to 90°C. When the polymerization temperature deviates from the low temperature side, it is difficult to obtain high activity, and when the polymerization temperature deviates from the high temperature side, it becomes difficult to obtain a high molecular weight copolymer.

The polymerization time is 10 minutes to 10 hours, preferably 0.5 to 6 hours. When the polymerization time is short, the resulting copolymer tends to have a single peak melting point as measured by DSC. Long-term polymerization may be industrially disadvantageous.

Molecular weight adjustment during polymerization can be carried out by known means, such as hydrogen,
Paper cutting can be carried out depending on the polymerization temperature, etc.

The α-olefins having 4 to 20 carbon atoms used in the present invention include, for example, butene, hexene, 4-methylpentene-1, octene, decene, hexadecene, octadecene, and mixtures thereof, particularly those having 6 to 20 carbon atoms. α of 20
-Olefin is preferable for obtaining a copolymer having the desired properties.

Density 0.86-G, 935t7 obtained by the method of the present invention
The cd ethylene copolymer usually contains α-olefin in a proportion of about 1 to 25 moles. Generally, as the density increases, the melting point measured by DSC increases, and the plurality becomes unclear, so if low-temperature heat sealability is particularly important, the density of the copolymer should be 0.925 f/- or less. In such a case, the α-olefin is contained in the ethylene copolymer in a proportion of about 2 to 25 mol %.

The ethylene copolymer obtained by the method of the present invention has a density of 0.86 to 53 sr/-, and has two peaks indicating the melting point measured by differential scanning calorimeter (DSC). It has more than one of the above.

This ethylene copolymer has a Q value (number average molecular weight: 0, weight average molecular t: Mw
(defined as Q-Mw/Mn) is narrow at 1.5 to 4. Therefore, the copolymer obtained by the method of the present invention is suitable for extrusion molded products such as films and sheets that require low-temperature heat sealability, heat resistance, tensile strength, tear strength, etc.

Experimental Examples In the following experimental examples, Mw and Mn were measured by gel permeation chromatography (GPC) under the following conditions.

Equipment: Manufactured by Waters Temperature: 150°C Column: r4DsoM/SJ a book [manufactured by Showa Denko ■]
Solvent: 0-dichlorobenzene flow i: 1 d/min Injection concentration: 2 q/* Melting point measurement using a differential scanning calorimeter (DSC) was performed under the following conditions.

Equipment a: Perkin-EIlmer n-type sample weight: sMl Measurement method: Hold at 160°C for 3 minutes, then heat at 10°C/min for 5
Cool to 0°C, hold at 50°C for 3 minutes after cooling, then raise temperature at 10°C/min Temperature calibration: Calibrated using In, Gas Bi, Pb, and Sn.

Example 1 (Preparation of alumoxane) Copper sulfate pentahydrate 11. A toluene diluted solution xz4.2* (t+7 mmol) having a trimethylaluminum concentration of 10% was added dropwise at -20° C. with stirring over 1 hour, and the mixture was allowed to react for approximately 3 hours. next,
Gradually return to room temperature, then at around 10℃ for 3 hours, then at 30℃
Let it react for 24 hours. The remaining solid sulfuric acid steel was separated, and toluene and unreacted trimethylaluminum were distilled off to obtain 2.9 tons of methylalumoxane. It was dissolved again in 100 d of toluene and used in the following polymerization.

(Copolymerization of ethylene and hexene) In an autoclave with contents FF 11.5 t, 200 ml of toluene and the methylalumoxane obtained above were added at 60°C to 3.33 miIJ mol in terms of At atoms and bis(cyclopentadienyl) titanium. 0.021 mmol of dichloride (equivalent to Tixq) and 60 ml of hexene were added, and the mixture was heated at a pressure of 8 #/iG while continuously supplying ethylene.
Time polymerization was performed. After the polymerization is complete, ethanol is added to decompose the catalyst and then dried to complete ethylene-hexene copolymerization 29
I got 1. The Ti yield was 29,000 f-1%/f-TI. The physical properties of the obtained polymer are shown in Table-2.

Examples 2-7 Except that the amount of hexene used, the amount of bis(cyclopentadienyl) titanium dichloride used (amount of titanium compound), polymerization temperature, polymerization time, and one type of comonomer were changed as shown in Table 1. Polymerization was carried out in the same manner as in Example 1. The results are shown in Table-1 and Table-2.

Comparative Example 1 Bis(cyclopentagenyl)zirconium dichloride was used in place of bis(cyclopentagenyl)titanium dichloride in a thickness of 0.0014 mmol, and the polymerization time was 6.
The experiment was carried out in the same manner as in Example 1 except that the time was changed to 0 minutes.
An ethylene-hexene copolymer of No. 1 was obtained. Zr yield is 1
s s o o o t-1? -. As shown in Table 2, the obtained copolymer had a single melting point in DSC measurement.

Comparative Example 2 In addition to bis(cyclopentagenyl)titanium dichloride, 021 mmol of TiCt4Q (equivalent to 1η Ti atom) was used, 8Qd of hexane was added, and the mixture was heated at 70°C for 1.
Polymerization was carried out in the same manner as in Example 1, except that the polymerization was carried out for 5 hours, to obtain 32 polymers. The Ti yield was as low as 3000F-calm τl, and as shown in Shigeru-2, the obtained copolymer had a melting point of one in DSC measurement and a large Q value.

(Left below) Example 8 Bis(cyclopentadienyl)titanium dichloride 0
．． 021 mmol (corresponding to 1 cape of Ti atom) and 3.33 mmol of alumoxane in terms of M atom were brought into contact in 2 d of toluene, and then 2 ml of hexane was added to prepare a catalyst liquid.

High-density polyethylene pellets (301F) were placed in an autoclave with an internal volume of 1.5 tons, and the above catalyst preparation solution was added at 60° C. and dispersed for 10 minutes. Next, add hexene 3II to this
After adding j, polymerization was carried out for 2.5 hours at a pressure of 9 kg/cIliG1 while continuously supplying ethylene. During the course of the polymerization, 1.5 d of hexene was added 1 hour after the start of polymerization.

The pellet serving as a carrier was removed to obtain a polymer of 13.4 f. Ti yield 134000 p-pr%r-Ti
.

The melting points measured by DSC were 102.7°C, 117°C and 122°C.

Patent Applicant Mitsubishi Yuka Co., Ltd. Agent Masahisa Hase Patent Attorney Patent Attorney Takaya Yamamoto Procedural Amendment (Voluntary) June 10, 1985 1, Indication of Case Patent Application No. 182986 of 1985 λ
Title of the invention Process for producing ethylene copolymer λ Relationship to the case of the person making the amendment Patent applicant address 2-5-2 Marunouchi, Chiyoda-ku, Tokyo Name (6
05) Mitsubishi Yuka Co., Ltd. Main Agent Address: 2-5-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Yuka Co., Ltd. Brief description of drawings in the specification and drawing a Contents of amendment <1) I [B8 Page 17, between lines 17 and 18

[Brief explanation of drawings]

FIG. 1 is intended to assist in understanding the technical content of the present invention regarding Ziegler catalysts. (Attachment 21 Drawing Attachment Figure 1 is attached.)

Claims (1)

[Claims] (1) Copolymerizing ethylene with an α-olefin having 4 to 20 carbon atoms in the presence of a catalyst consisting of a transition metal compound and an organoaluminum compound to achieve a density of 0.86 to 0.935 g.
/cm^3, the transition metal compound has the general formula (Rm-A)TiR^1R^
2R^3 [wherein, R is a methyl group, A is a cyclopentadienyl group, R^1, R^2 and R^3 are each independently an alkyl group having 1 to 6 carbon atoms, a group (R_m-A ), halogen or hydrogen, m is 0, 1 or 2, respectively], and the organoaluminum compound is an alumoxane.