A copolymer of ethylene and alkenyl silicon-containing monomer and preparation method thereof

Abstract

The present invention relates to a copolymer of ethylene and alkenyl silicon-containing monomer and a preparation method thereof. The alkenyl silicon-containing monomer involved in the method is terminal alkenyl dimethylsiloxane, the main catalyst is an α-diimide post-transition metal complex, the co-catalyst is an organic aluminum compound, the molar ratio of the co-catalyst to the main catalyst is 100-2000:1, the concentration of the alkenyl silicon-containing monomer is 0.01 mol / L-3.0 mol / L, the reaction pressure is 0.1 MPa-5.0 MPa, the reaction temperature is 0-80°C, and the reaction time is 0.5-10 hours. The copolymerization method has simple process, mild conditions, high catalytic activity, and no gel. The obtained copolymer has excellent mechanical properties, surface properties, aging resistance, etc., and can be used for film materials or molded materials.

Description

Technical Field

[0001] The invention relates to the field of functionalized polyethylene, in particular to a copolymer of ethylene and olefinic silicon-containing monomers and a preparation method thereof. Background Art

[0002] Polyethylene has become the most widely used synthetic resin due to its good crystallinity, chemical stability, electrical insulation, excellent mechanical properties, processing properties, etc. However, since polyethylene is a non-polar material composed of saturated CH bonds, its ultimate application is limited. Therefore, the functionalization and high performance of polyethylene have always been an important direction of research and development in the field of polyolefins.

[0003] Silicon-containing functionalized polyolefins have excellent properties such as resistance to extreme environments, low surface energy and high spreadability, high air permeability and physiological inertness, and can be widely used in insulation coatings, pipes, adhesives, gaskets, cross-linked foams, etc. of various wires. Introducing silicone functional groups and silicone segments into the structure of polyethylene has greatly enriched the functionalization and high-performance methods of polyethylene. Therefore, silicon-containing functionalized polyethylene occupies an important position in the field of functional modification of polyethylene.

[0004] There are two main methods for preparing commercial silicon-functionalized polyethylene: (1) free radical copolymerization, i.e., copolymerization of ethylene and alkenyl silane monomers (such as vinyl trimethoxysilane, vinyl triethoxysilane, etc.) under high temperature and high pressure by free radical initiation; (2) post-functionalization, i.e., modifying the existing polyethylene resin by chemical and physical methods to achieve functionalization. Among the above methods, method (1) involves high temperature and high pressure, harsh reaction conditions, and uncontrollable copolymer structure. Method (2) is mainly used for polyethylene resin modification, but it is easy to cause polyethylene resin molecular weight decrease, yellow appearance and other undesirable phenomena. If coordination copolymerization is used, not only the polymerization process is simple and the conditions are mild, but also the insertion rate of the comonomer in the copolymer structure and its distribution in the polyethylene main chain can be controlled.

[0005] Regarding the coordination copolymerization of ethylene and alkenylsiloxane, in 2004, Ciolino et al. (Journal of Polymer Science: Part A: Polymer Chemistry, 2004, Vol. 42, 2462–2473) used the EtInd2ZrCl2 / MAO catalytic system to catalyze the copolymerization of ethylene / vinyl poly(dimethylsiloxane) (PDMS) at 90°C and 110°C to obtain the corresponding block copolymers. In 2016, the Brookhart research group used (α-diimine) Pd(Me)(CH3CN) + / B(C6F5)3 catalytic system catalyzes the copolymerization of ethylene and vinyltriethoxysilane (VTEoS), and the insertion rate of the comonomer VTEoS is 2.0 mol% (J.Am.Chem.Soc.2016,138,16120-16129). If (α-diimine)Ni(Me)(CH3CN) is used + The catalytic system of / B(C6F5)3 catalyzed the copolymerization of ethylene and vinyltriethoxysilane (VTEoS). When the concentration of VTEoS was 1.5 mol / L and the reaction temperature was 80℃ for 30 min, the catalyst activity was only 8×10 3 (molPolymer / molNi), the insertion rate of the comonomer VTEoS can reach 10.0mol% (J.Am.Chem.Soc.2017,139,16013-16022). However, whether it is vinyltrimethoxysilane (VTMoS) or vinyltriethoxysilane (VTEoS), the resulting copolymers are inevitably prone to crosslinking, resulting in high gel content and poor processing performance of the copolymers. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to provide a copolymer of ethylene and alkenyl silicon-containing monomer and a preparation method thereof. The method has a simple polymerization process, mild conditions, and the insertion rate of the alkenyl silicon-containing monomer in the copolymer structure and its distribution in the polyethylene main chain are controllable. The obtained copolymer is not easy to crosslink, has a very low gel content, is easy to process, and has excellent mechanical properties, and can be used for film materials or molding materials.

[0007] The present invention provides a copolymer of ethylene and alkenyl silicon-containing monomers and a preparation method thereof, comprising the following steps:

[0008] In the form of coordination copolymerization, the olefinic silicon-containing monomer is dissolved in an organic solvent under an ethylene atmosphere, and a coordination copolymerization reaction is carried out under the action of a main catalyst and a co-catalyst.

[0009] After the reaction is completed, a terminator is added to terminate the reaction, and the obtained solid polymer is filtered, washed, and dried;

[0010] The general structural formula of the main catalyst is:

[0011]

[0012] In formula (I), R1, R2, R3, and R4 are the same or different and are H, C1-C12 alkyl, halogen, C1-C4 alkoxy, hydroxy, nitro, or trifluoromethyl; M is a late transition metal nickel or palladium; X1 and X2 are the same or different and are halogen, C1-C4 alkyl, aryl, nitrile, or C1-C4 ether;

[0013] The co-catalyst is an organic aluminum compound.

[0014] The present invention discloses a copolymer of ethylene and alkenyl silicon-containing monomer and a preparation method thereof, wherein the alkenyl silicon-containing monomer is terminal alkenyl disiloxane.

[0015] The present invention discloses a copolymer of ethylene and alkenyl silicon-containing monomers and a preparation method thereof, wherein in the formula (I) of the main catalyst, R1, R2, R3, and R4 are preferably H, C1-C4 alkyl, halogen, C1-C4 alkoxy, hydroxyl, nitro, and trifluoromethyl, respectively.

[0016] The present invention discloses a copolymer of ethylene and alkenyl silicon-containing monomers and a preparation method thereof, wherein the organic aluminum compound is preferably an alkyl aluminum compound, and more preferably aluminum sesquioxide or triethyl aluminum.

[0017] The present invention discloses a copolymer of ethylene and olefinic silicon-containing monomers and a preparation method thereof, wherein the molar ratio of the co-catalyst to the main catalyst is 100 to 2000:1, preferably 200 to 1000:1.

[0018] The present invention discloses a copolymer of ethylene and alkenyl silicon-containing monomers and a preparation method thereof, wherein the solvent is toluene, n-hexane, dichloromethane or chlorobenzene.

[0019] The present invention discloses a copolymer of ethylene and alkenyl silicon-containing monomer and a preparation method thereof, wherein the concentration of the alkenyl silicon-containing monomer is 0.01 mol / L to 3.0 mol / L, preferably 0.1 mol / L to 1.0 mol / L, the reaction pressure is 0.1 to 5.0 MPa, preferably 0.1 MPa to 3.0 MPa, the reaction temperature is 0 to 80° C., preferably 20 to 60° C., and the reaction time is 0.5 to 10 hours, preferably 0.5 to 5 hours.

[0020] Compared with the prior art, the present invention has the following obvious advantages:

[0021] The present invention provides a copolymer of ethylene and alkenyl silicon-containing monomer and a preparation method thereof. The copolymer prepared combines the excellent properties of polyethylene and alkenyl silicon-containing monomer, especially the terminal alkenyl disiloxane of the selected alkenyl silicon-containing monomer is not easy to hydrolyze, and at the same time provides a branched structure of two siloxane lengths. In addition, the copolymerization method is simple in process, mild in conditions, high in catalytic activity, and free of gel. The obtained copolymer has excellent mechanical properties, surface properties, aging resistance, etc., and can be used for film materials or molding materials.

[0022] The present invention is further described below by way of examples, but the present invention is not limited thereto. DETAILED DESCRIPTION

[0023] Example 1

[0024] In a 200mL clean and dry autoclave, 21.9mL of toluene, 5μmol of catalyst [C6H5-N=C(H)-C(H)=N-C6H5]NiBr2, and vinylpentamethyldisiloxane with a concentration of 0.05mol / L were added in sequence under ethylene atmosphere. Stirring was started and the mixture was placed in a 0℃ oil bath until the temperature was constant. Then, 0.3mL of co-catalyst AlEt2Cl (Al / Ni=500) was added. The ethylene pressure was adjusted and maintained at 2.0MPa. After reacting for 0.5 hour, the introduction of ethylene gas and stirring were stopped. After the pressure was released, the reaction was terminated with ethanol solution. The obtained polymer was filtered, washed, and dried to obtain 3.47g of copolymer with a catalytic activity of 1.39×10 6 g polymer / (molM·h), Si content is 0.8wt%.

[0025] Example 2

[0026] In a 200mL clean and dry autoclave, 47.4mL of n-hexane, 5μmol of catalyst [2,6-(CH3)2C6H3-N=C(H)-C(CH)=N-2(F)C6H4]NiBr2, and 0.1mol / L of vinyltetramethyldisiloxane were added in sequence under ethylene atmosphere. Stirring was started and the mixture was placed in a 20℃ oil bath until the temperature was constant. Then, 0.5mL of cocatalyst AlEt2Cl (Al / Ni=800) was added. The ethylene pressure was adjusted and maintained at 0.5MPa. After reacting for 1 hour, the ethylene gas and stirring were stopped. After the pressure was released, the reaction was terminated with ethanol solution. The obtained polymer was filtered, washed, and dried to obtain 3.2g of copolymer. The catalytic activity was 6.50×10 5 g polymer / (molM·h), Si content is 1.3wt%.

[0027] Example 3

[0028] In a 200mL clean and dry autoclave, 44.8mL of toluene, 5μmol of catalyst [2,6-(i-C3H7)2C6H3-N=C(H)-C(CH)=N-2(Cl)C6H4]NiBr2, and 0.5mol / L of allyltetramethyldisiloxane were added in turn under ethylene atmosphere. Stirring was started and the mixture was placed in a 40℃ oil bath until the temperature was constant. Then 0.3mL of cocatalyst AlEt2Cl (Al / Ni=500) was added. The ethylene pressure was adjusted and maintained at 5.0MPa. After 2 hours of reaction, the introduction of ethylene gas and stirring were stopped. After the pressure was released, the reaction was terminated with ethanol solution. The obtained polymer was filtered, washed, and dried to obtain 5.3g of copolymer. The catalytic activity was 5.3×10 5g polymer / (molM·h), Si content is 2.8wt%.

[0029] Example 4

[0030] In a 200mL clean and dry autoclave, 42.2mL of dichloromethane, 5μmol of catalyst [2,6-(CH3)2C6H3-N=C(H)-C(H)=N-2,6-(Br)2C6H3]Pd(CH3)(OEt2), and vinyl pentamethyldisiloxane were added in sequence under ethylene atmosphere. The concentration was 0.5mol / L. Stirring was started and the mixture was placed in an 80℃ oil bath. After the temperature was constant, 0.5mL of cocatalyst AlEt2Cl (Al / Ni=800) was added. The ethylene pressure was adjusted and maintained at 0.1MPa. After 6 hours of reaction, the ethylene gas and stirring were stopped. After the pressure was released, the reaction was terminated with ethanol solution. The obtained polymer was filtered, washed, and dried to obtain 8.3g of copolymer. The catalytic activity was 2.75×10 5 g polymer / (molM·h), Si content is 3.3wt%.

[0031] Example 5

[0032] In a 200mL clean and dry autoclave, 10mL of chlorobenzene, 5μmol of catalyst [2,6-(i-C3H7)2C6H3-N=C(H)-C(H)=N-2,6-(I)2C6H3]NiBr2, and 1.0mol / L of vinyltetramethyldisiloxane were added in sequence under ethylene atmosphere, and stirring was started. At the same time, the mixture was placed in a 60℃ oil bath until the temperature was constant, and then 0.6mL of cocatalyst AlEt2Cl (Al / Ni=1000) was added. The ethylene pressure was adjusted and maintained at 4.0MPa. After reacting for 10 hours, the introduction of ethylene gas and stirring were stopped. After the pressure was released, the reaction was terminated with ethanol solution. The obtained polymer was filtered, washed, and dried to obtain 7.5g of copolymer. The catalytic activity was 1.5×10 5 g polymer / (molM·h), Si content is 3.8wt%.

[0033] Example 6

[0034] In a 200mL clean and dry autoclave, 10mL of n-hexane, 5μmol of catalyst [2,6-(C2H5)2C6H3-N=C(H)-C(H)=N-2-(OCH3)C6H4]Pd(C6H5)(CH3CN), and 1.0mol / L of allyltetramethyldisiloxane were added in sequence under ethylene atmosphere. Stirring was started and the mixture was placed in a 40℃ oil bath until the temperature was constant. Then, 0.9mL of cocatalyst AlEt2Cl (Al / Ni=1500) was added. The ethylene pressure was adjusted and maintained at 3.0MPa. After reacting for 1 hour, the ethylene gas and stirring were stopped. After the pressure was released, the reaction was terminated with ethanol solution. The obtained polymer was filtered, washed, and dried to obtain 4.3g of copolymer. The catalytic activity was 8.5×10 5 g polymer / (molM·h), Si content is 2.1wt%.

[0035] Example 7

[0036] In a 200mL clean and dry autoclave, toluene, catalyst [2,6-(i-C3H7)2C6H3-N=C(H)-C(H)=N-2-(OH)C6H4]NiBr2 5μmol, vinyl pentamethyl disiloxane, concentration of 2.0mol / L, were added in sequence under ethylene atmosphere, and stirring was started. At the same time, the mixture was placed in a 40℃ oil bath until the temperature was constant, and then 1.2mL of cocatalyst AlEt2Cl (Al / Ni=2000) was added. The ethylene pressure was adjusted and maintained at 1.0MPa. After reacting for 0.5 hours, the ethylene gas and stirring were stopped. After the pressure was released, the reaction was terminated with ethanol solution. The obtained polymer was filtered, washed, and dried to obtain 1.7g of copolymer. The catalytic activity was 6.7×10 5 g polymer / (molM·h), Si content is 2.8wt%.

[0037] Example 8

[0038] In a 200mL clean and dry autoclave, chlorobenzene, catalyst [2,6-(CH3)2C6H3-N=C(H)-C(H)=N-4-(CF3)C6H4]PdCl2 5μmol, vinyl pentamethyl disiloxane, concentration of 3.0mol / L, were added in sequence under ethylene atmosphere, and stirring was started. At the same time, the mixture was placed in a 60℃ oil bath until the temperature was constant, and then 0.6mL of cocatalyst AlEt2Cl (Al / Ni=1000) was added. The ethylene pressure was adjusted and maintained at 0.5MPa. After reacting for 2 hours, the introduction of ethylene gas and stirring were stopped. After the pressure was released, the reaction was terminated with ethanol solution. The obtained polymer was filtered, washed, and dried to obtain 7.5g of copolymer. The catalytic activity was 7.5×10 5 g polymer / (molM·h), Si content is 1.6wt%.

[0039] Example 9

[0040] In a 200mL clean and dry autoclave, n-hexane, catalyst [2,6-(i-C3H7)2C6H3-N=C(H)-C(H)=N-4-(NO2)C6H4]NiBr25μmol, vinyltetramethyldisiloxane, concentration of 0.1mol / L, were added in sequence under ethylene atmosphere, and stirring was started. At the same time, the mixture was placed in a 40℃ oil bath until the temperature was constant, and then 0.5mL of cocatalyst AlEt2Cl (Al / Ni=800) was added. The ethylene pressure was adjusted and maintained at 0.5MPa. After 5 hours of reaction, the ethylene gas and stirring were stopped. After the pressure was released, the reaction was terminated with ethanol solution. The obtained polymer was filtered, washed, and dried to obtain 8.1g of copolymer. The catalytic activity was 3.3×10 5 g polymer / (molM·h), Si content is 0.5wt%.

[0041] Example 10

[0042] In a 200mL clean and dry autoclave, dichloromethane, catalyst [2-(OCH3)C6H4-N=C(H)-C(H)=N-2-(OCH3)C6H4]NiBr2 5μmol, allyltetramethyldisiloxane, concentration 0.01mol / L, were added in turn under ethylene atmosphere, stirring was started, and the mixture was placed in a 20℃ oil bath until the temperature was constant, and then 0.06mL of cocatalyst AlEt2Cl (Al / Ni=100) was added, and the propylene pressure was adjusted and maintained at 0.5MPa. After reacting for 0.5 hours, the introduction of ethylene gas and stirring were stopped, and the reaction was terminated with ethanol solution after the pressure was released. The obtained polymer was filtered, washed, and dried to obtain 4.1g of copolymer. The catalytic activity was 1.7×10 6 g polymer / (molM·h), Si content is 0.3wt%.

Claims

1. A method for preparing a copolymer of ethylene and an olefinic silicon-containing monomer, characterized in that: The following steps are involved: In the form of coordination copolymerization, the alkenyl silicon-containing monomer is dissolved in an organic solvent under an ethylene atmosphere, and a coordination copolymerization reaction is carried out under the action of a main catalyst and a co-catalyst. After the reaction is completed, a terminator is added to terminate the reaction, and the obtained solid polymer is filtered, washed, and dried; The general structural formula of the main catalyst is: In formula (I), R1, R2, R3, and R4 are the same or different and are H, C1-C12 alkyl, halogen, C1-C4 alkoxy, hydroxyl, nitro, or trifluoromethyl; M is a late transition metal nickel or palladium; X1 and X2 are the same or different and are halogen, C1-C4 alkyl, aryl, nitrile, or C1-C4 ether; The co-catalyst is an organoaluminum compound; The alkenyl silicon-containing monomer is terminal alkenyl disiloxane.

2. The method for preparing a copolymer of ethylene and alkenyl silicon-containing monomer according to claim 1, characterized in that: In the main catalyst formula (I), R1, R2, R3, and R4 are H, C1-C4 alkyl, halogen, C1-C4 alkoxy, hydroxyl, nitro, and trifluoromethyl, respectively.

3. The method for preparing a copolymer of ethylene and alkenyl silicon-containing monomer according to claim 1, characterized in that: The organic aluminum compound is an alkyl aluminum compound, including aluminum sesquioxide or triethyl aluminum.

4. The method for preparing a copolymer of ethylene and alkenyl silicon-containing monomer according to claim 1, characterized in that: The molar ratio of the co-catalyst to the main catalyst is 100 to 2000:

1.

5. The method for preparing a copolymer of ethylene and alkenyl silicon-containing monomer according to claim 1, characterized in that: The solvent is toluene, n-hexane, dichloromethane or chlorobenzene.

6. The method for preparing a copolymer of ethylene and alkenyl silicon-containing monomer according to claim 1, characterized in that: The concentration of the alkenyl silicon-containing monomer is 0.01 mol / L to 3.0 mol / L, the reaction pressure is 0.1 MPa to 5.0 MPa, the reaction temperature is 0 to 80°C, and the reaction time is 0.5 to 10 hours.

7. The method for preparing a copolymer of ethylene and alkenyl silicon-containing monomer according to claim 1, characterized in that: The concentration of the alkenyl silicon-containing monomer is 0.1 mol / L to 1.0 mol / L, the reaction pressure is 0.1 MPa to 3.0 MPa, the reaction temperature is 20 to 60°C, and the reaction time is 0.5 to 5 hours.

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