CN110922517A - Ethylene copolymer and preparation method thereof - Google Patents

Abstract

The invention relates to an ethylene copolymer and a preparation method thereof in the field of polymers. The ethylene copolymer comprises allylcyclopentane units and ethylene units, wherein the allylcyclopentane units are randomly distributed in a polymer molecular chain, the molar fraction of the allylcyclopentane units in the polymer molecular chain is x, and x is more than 0.1%; the molar fraction of ethylene units in the polymer molecule is 1-x. The ethylene copolymer can be prepared by carrying out olefin copolymerization reaction on ethylene and allyl cyclopentane in the presence of a catalyst composition for olefin polymerization containing a metallocene compound and alkylaluminoxane. The copolymer of ethylene and allyl cyclopentane has high allyl cyclopentane copolymerization unit content, and the method is simple to operate and worthy of popularization and application.

Description

Ethylene copolymer and preparation method thereof

Technical Field

The invention relates to the field of polymers, and in particular relates to an ethylene copolymer and a preparation method thereof.

Background

Single-site transition metal catalysts for olefin polymerization have been the focus of research in metallo-organic chemistry, catalytic chemistry, polymer chemistry and materials science for decades. By using the catalyst, the olefin polymer with uniform molecular weight distribution and chemical composition distribution can be obtained, and the molecular structure and the molecular weight of the polymer can be highly controlled by adjusting the structure of the catalyst. By means of a single-site catalyst, olefin polymers which are not obtainable by conventional Ziegler-Natta catalysts can be obtained.

Compared with the traditional Ziegler-Natta catalyst, the single-site catalyst has remarkable advantages in the copolymerization of olefin, and the advantages are shown in two aspects. In one aspect, the olefin copolymers obtained using the two catalyst systems are produced under the same or similar polymerization conditions, the single site catalyst product having a higher comonomer content than the Ziegler-Natta catalyst product; on the other hand, many monomers cannot be polymerized in Ziegler-Natta catalyst systems, whereas single-site catalysts allow these monomers, which are traditionally considered "non-polymerizable", to be effectively incorporated into the polymer chain. This provides further opportunities for the expansion of polyolefin materials, and the possibility of producing novel copolymers containing novel monomers, which copolymers may have properties not found in conventional polyolefin materials.

In current olefin polymerization production, comonomers are generally added to adjust the polymer composition to obtain a product with appropriate physical properties. Monomers generally employed include 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, and the like.

Cyclic olefin participates in polymerization, and a polymer material having good heat resistance and excellent optical properties, that is, a cycloolefin polymer (COP) or a cycloolefin copolymer, which has been known, can be obtained because the main chain of the polymer contains a cyclic structure, the rigidity of the polymer chain is greatly increased, and the crystallinity of the polymer is destroyed, so that the material obtains high heat resistance and high light transmittance.

Monomers with ring in the side chain, such as vinylcyclohexane, are also used in the copolymerization of olefins to obtain olefin polymer materials of novel structure and composition. However, in the structure of vinyl cyclohexane, vinyl is directly connected with cyclohexane substituent, so that steric hindrance in monomer coordination and insertion processes in polymerization is large, and copolymerization efficiency is influenced.

Disclosure of Invention

In order to solve the above problems in the prior art, the present invention provides an ethylene copolymer. In particular to an ethylene copolymer and a preparation method thereof. The ethylene copolymer is prepared by using a catalyst system for olefin polymerization consisting of a transition metal compound with a specific structure and alkylaluminoxane. Allylcyclopentane is also a vinyl monomer, but in allylcyclopentane there is a methylene group between the vinyl and cyclopentane substituents, which greatly reduces steric hindrance during polymerization and improves copolymerizability.

It is an object of the present invention to provide an ethylene copolymer, which is a copolymer of ethylene and allylcyclopentane, comprising allylcyclopentane units and ethylene units, and whose structure can be expressed by the following formula (I):

wherein the formula only represents chemical composition and does not represent that an allylcyclopentane unit and a vinyl unit form a block structure, the allylcyclopentane unit is randomly distributed in a polymer molecular chain, the molar fraction of the allylcyclopentane unit in the polymer molecular chain is x, and x is more than 0.1%, preferably x is more than 0.5%, and more preferably x is more than 3%; the molar fraction of ethylene units in the polymer molecule is 1-x.

The ethylene copolymer is characterized in that the ethylene copolymer is prepared by carrying out olefin copolymerization reaction on ethylene and allyl cyclopentane in the presence of a catalyst composition for olefin polymerization containing a metallocene compound and alkylaluminoxane.

Another object of the present invention is to provide a process for the preparation of said ethylene copolymers, which may comprise the steps of:

the ethylene copolymer is prepared by copolymerizing ethylene and allylcyclopentane in the presence of a catalyst composition for olefin polymerization comprising a metallocene compound and an alkylaluminoxane.

The polymerization reaction can be carried out in various alkyl substituted benzene (specifically, solvents such as toluene, xylene and the like), and can also be carried out in any alkane solvent; the amount of solvent is determined by the reactivity, which ensures good dissolution of the resulting polymer in the system, at least without affecting the dispersion.

In a specific implementation, the reaction may comprise the steps of:

the fully dried polymerization apparatus was evacuated, flushed with nitrogen and repeated several times. Then vacuumizing and filling ethylene, wherein the ethylene pressure is 1-10 (preferably 1-8) atmospheric pressure. Adding a reaction solvent and allyl cyclopentane, adding alkyl aluminoxane, heating to 0-120 ℃ (preferably 25-100 ℃, more preferably 50-80 ℃), adding a metallocene compound, timing, stopping ethylene after 10-40 minutes (preferably 15-30 minutes), adding acidified ethanol into a reaction solution, stirring (the stirring time can be more than 6 hours), filtering to obtain a polymer, and vacuum drying to obtain the catalyst.

The catalyst composition for olefin polymerization may be composed of the following components in the following amounts, and the metallocene compound and the alkylaluminoxane are used in a molar ratio of 1: (100 to 10000), preferably 1 (500 to 3000).

The polymerization temperature range for the olefin copolymerization reaction may be from 0 ℃ to 120 ℃, preferably from 25 ℃ to 100 ℃.

In a particular production process, ethylene is supplied continuously, maintaining a constant pressure.

The central metal atom of the metallocene compound may be at least one of titanium, zirconium or hafnium, preferably titanium or zirconium, more preferably zirconium.

The metallocene compound may be a bridged metallocene compound.

The metallocene compound may be a metallocene compound containing one or more bridges of carbon atoms or silicon atoms.

In particular, the metallocene compound may be selected from racemic vinylbridbisindenyl zirconium dichloride and/or diphenylmethyl-bridgecyclopentadienyl fluorenyl zirconium dichloride.

The metallocene compound may also be a non-bridged metallocene compound.

The non-bridged metallocene compound can be selected from general structural formulas Cp'₂MX₂At least one of the compounds of (a); wherein Cp 'can be selected from alkyl or aromatic group substituted cyclopentadienyl, indenyl or fluorenyl, two Cp' can be same or different, M can be selected from titanium, zirconium or hafnium, X can be selected from halogen, hydrocarbyl, hydrocarbyloxy or amino; preferably, the non-bridged metallocene compound may be one selected from bis (cyclopentadienyl) zirconium dichloride, bis (1-n-butyl-3-methylcyclopentadienyl) zirconium dichloride, bis (indenyl) zirconium dichloride.

The alkyl aluminoxane may be selected from compounds having the structure shown in formula (II) and/or formula (III):

wherein R and R' are each independently selected from alkyl, preferably methyl; n and m are each independently selected from integers of 4 to 30, preferably 10 to 30.

The invention has the beneficial effects that:

the copolymer of the ethylene and the allylcyclopentane has high allylcyclopentane copolymerization unit content, and the preparation method is simple and easy to implement.

Drawings

FIG. 1 is a GPC curve of the polymer in example 3.

FIG. 2 is a GPC curve of the polymer in example 5.

FIG. 3 is a DSC curve of the polymer of example 3.

FIG. 4 is a DSC curve of the polymer of example 5.

FIG. 5 shows the polymer of example 3¹³C-NMR spectrum.

FIG. 6 shows the polymer of example 5¹³C-NMR spectrum.

Detailed Description

The present invention will be further described with reference to the following examples. However, the present invention is not limited to these examples.

Source of raw materials

The starting materials used in this example were all commercially available.

The instrument used for GPC measurement in the present invention is a gel permeation chromatograph manufactured by Waters corporation as Waters Pallience GPCV 2000. Where PDI is Mw/Mn (ratio of weight average molecular weight to number average molecular weight), which is generally greater than 1, and the larger the value, the broader the molecular weight distribution.

¹³The apparatus used for the C-NMR measurement was a model AVANCEIII-400 NMR spectrometer manufactured by Bruker. The allylcyclopentane content (incorpor.) of the polymer is the mol% content.

The melting point of the polymer was determined using a TAQ-100 differential scanning calorimeter. Approximately 2 mg of the polymer sample was heated from 0 ℃ to 160 ℃ at a heating rate of 10 ℃ per minute under a nitrogen atmosphere, and after a residence time of 1 minute at 160 ℃, the polymer sample was cooled to 0 ℃ at a rate of 10 ℃ per minute for 1 minute, and then heated from 0 ℃ to 160 ℃ at a heating rate of 10 ℃ per minute. And recording the second heating data.

Example 1

The fully dried polymerization apparatus was evacuated, flushed with nitrogen and repeated three times. Then vacuumizing, controlling by an electromagnetic valve, and filling ethylene, wherein the ethylene pressure is 1 atmospheric pressure. 25.8 ml of toluene, which is a reaction solvent, and 0.2 ml of allylcyclopentane were added, 3 ml of Methylaluminoxane (MAO) solution (containing 5 mmol of MAO) was added, the temperature was raised to 70 ℃ and 1 ml of toluene solution containing 5. mu.mol of racemic vinylbridge bisindenyl zirconium dichloride (produced by STREM) was added to start timekeeping. After 15 minutes, the ethylene was turned off, 300mL of acidified ethanol (concentrated HCl volume fraction 10%) was added to the reaction mixture, stirred for more than 6 hours, filtered to give a polymer, dried at 60 ℃ under vacuum for 24 hours, and weighed. The polymerization results are shown in Table 1.

Example 2

The fully dried polymerization apparatus was evacuated, flushed with nitrogen and repeated three times. Then vacuumizing, controlling by an electromagnetic valve, and filling ethylene, wherein the ethylene pressure is 1 atmospheric pressure. 25.5 ml of toluene, which is a reaction solvent, and 0.5 ml of allylcyclopentane were added, 3 ml of Methylaluminoxane (MAO) solution (containing 5 mmol of MAO) was added, the temperature was raised to 70 ℃ and 1 ml of toluene solution containing 5. mu.mol of racemic vinylbridge bisindenyl zirconium dichloride (produced by STREM) was added to start timekeeping. After 15 minutes, ethylene was turned off, 300mL of acidified ethanol was added to the reaction solution, stirred for more than 6 hours, filtered to give a polymer, dried at 60 ℃ under vacuum for 24 hours, and weighed. The polymerization results are shown in Table 1.

Example 3

The fully dried polymerization apparatus was evacuated, flushed with nitrogen and repeated three times. Then vacuumizing, controlling by an electromagnetic valve, and filling ethylene, wherein the ethylene pressure is 1 atmospheric pressure. 25.2 ml of toluene, which is a reaction solvent, and 0.8 ml of allylcyclopentane were added, 3 ml of Methylaluminoxane (MAO) solution (containing 5 mmol of MAO) was added, the temperature was raised to 70 ℃ and 1 ml of toluene solution containing 5. mu.mol of racemic vinylbridge bisindenyl zirconium dichloride was added to start timekeeping. After 15 minutes, ethylene was turned off, 300mL of acidified ethanol was added to the reaction solution, stirred for more than 6 hours, filtered to give a polymer, dried at 60 ℃ under vacuum for 24 hours, and weighed. The polymerization results are shown in Table 1.

Example 4

The fully dried polymerization apparatus was evacuated, flushed with nitrogen and repeated three times. Then vacuumizing, controlling by an electromagnetic valve, and filling ethylene, wherein the ethylene pressure is 1 atmospheric pressure. 25.8 ml of toluene, which is a reaction solvent, and 0.2 ml of allylcyclopentane were added, 3 ml of a Methylaluminoxane (MAO) solution (containing 5 mmol of MAO) was further added, the temperature was raised to 70 ℃ and 1 ml of a toluene solution containing 5. mu.mol of diphenylmethylcyclopentadienylfluorenylzirconium dichloride (produced by STREM) was added to start timekeeping. After 30 minutes, the ethylene was turned off, 300mL of acidified ethanol was added to the reaction solution, stirred for more than 6 hours, filtered to give a polymer, dried at 60 ℃ under vacuum for 24 hours, and weighed. The polymerization results are shown in Table 1.

Example 5

The fully dried polymerization apparatus was evacuated, flushed with nitrogen and repeated three times. Then vacuumizing, controlling by an electromagnetic valve, and filling ethylene, wherein the ethylene pressure is 1 atmospheric pressure. 25.5 ml of toluene, which is a reaction solvent, and 0.5 ml of allylcyclopentane were added, 3 ml of a Methylaluminoxane (MAO) solution (containing 5 mmol of MAO) was added, the temperature was raised to 70 ℃ and 1 ml of a toluene solution containing 5. mu.mol of diphenylmethylcylobride cyclopentadienyl fluorenyl zirconium dichloride was added to start timekeeping. After 30 minutes, the ethylene was turned off, 300mL of acidified ethanol was added to the reaction solution, stirred for more than 6 hours, filtered to give a polymer, dried at 60 ℃ under vacuum for 24 hours, and weighed. The polymerization results are shown in Table 1.

Example 6

The fully dried polymerization apparatus was evacuated, flushed with nitrogen and repeated three times. Then vacuumizing, controlling by an electromagnetic valve, and filling ethylene, wherein the ethylene pressure is 1 atmospheric pressure. 25.2 ml of toluene, which is a reaction solvent, and 0.8 ml of allylcyclopentane were added, 3 ml of Methylaluminoxane (MAO) solution (containing 5 mmol of MAO) was added, the temperature was raised to 70 ℃ and 1 ml of toluene solution containing 5. mu.mol of diphenylmethylcyclopentadienylfluorenyl zirconium dichloride was added to start timekeeping. After 30 minutes, the ethylene was turned off, 300mL of acidified ethanol was added to the reaction solution, stirred for more than 6 hours, filtered to give a polymer, dried at 60 ℃ under vacuum for 24 hours, and weighed. The polymerization results are shown in Table 1.

TABLE 1

Claims (10)

1. An ethylene copolymer comprising allylcyclopentane units and ethylene units and having the general structural formula:

wherein the allylcyclopentane units are randomly distributed in the polymer molecular chain, the molar fraction of the allylcyclopentane units in the polymer molecular chain is x, x is more than 0.1%, and x is preferably more than 0.5%; the molar fraction of ethylene units in the polymer molecule is 1-x.

2. The ethylene copolymer as claimed in claim 1, wherein the ethylene copolymer is obtained by copolymerizing ethylene and allylcyclopentane in the presence of a catalyst composition for olefin polymerization comprising a metallocene compound and an alkylaluminoxane.

3. The process for the preparation of ethylene copolymers according to claim 1 or 2, characterized by comprising the steps of:

the ethylene copolymer is prepared by copolymerizing ethylene and allylcyclopentane in the presence of a catalyst composition for olefin polymerization comprising a metallocene compound and an alkylaluminoxane.

4. The production method according to claim 3, characterized in that:

in the catalyst composition for olefin polymerization, the molar ratio of the metallocene compound to the alkylaluminoxane is in the range of 1: (100 to 10000), preferably 1 (500 to 3000).

5. The production method according to claim 3, characterized in that:

the polymerization temperature range of the olefin copolymerization reaction is 0-120 ℃, and preferably 25-100 ℃.

6. The production method according to claim 3, characterized in that:

the central metal atom of the metallocene compound is at least one of titanium, zirconium or hafnium, preferably titanium or zirconium.

7. The production method according to claim 3, characterized in that:

the metallocene compound is a metallocene compound containing one or more bridges of carbon atoms or silicon atoms.

8. The production method according to claim 3, characterized in that:

the metallocene compound is a bridged metallocene compound;

preferably, the metallocene compound is selected from racemic vinylbridbisindenyl zirconium dichloride or diphenylmethyl-bridcyclopentadienyl fluorenyl zirconium dichloride.

9. The production method according to claim 3, characterized in that:

the metallocene compound is a non-bridged metallocene compound;

the non-bridged metallocene compound is selected from general structural formula Cp'₂MX₂At least one of the compounds of (a); wherein Cp' is selected from alkyl or aromatic group substituted cyclopentadienyl, indenyl or fluorenyl, M is selected from titanium, zirconium or hafnium, X is selected from halogen, hydrocarbyl, hydrocarbyloxy or amine;

preferably, the non-bridged metallocene compound is selected from one of bis (cyclopentadienyl) zirconium dichloride, bis (1-n-butyl-3-methylcyclopentadienyl) zirconium dichloride, bis (indenyl) zirconium dichloride.

10. The method according to any one of claims 3 to 9, wherein: the alkyl aluminoxane is selected from compounds with the structures shown in formula (II) and/or formula (III):

wherein R and R' are each independently selected from alkyl, preferably methyl; n and m are each independently selected from integers of 4 to 30, preferably 10 to 30.

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