A class of isoprene-based elastomers and their preparation methods

Abstract

A kind of pinene base elastomer and its preparation method belong to the technical field of polymer materials. It is a kind of two or three copolymer prepared by copolymerization of pinene, conjugated diene and styrene, ethylene catalyzed by rare earth catalyst. The content of pinene in two or three copolymer is 5% to 100% by mole percentage, and the number average molecular weight is 1×10 4 ~80×10 4 . By changing the ligand and central metal of rare earth catalyst, the cis-1,4 selectivity of pinene and conjugated diene polymerization is 2% to 98%, the trans-1,4 selectivity is 2% to 98%, and the 3,4 selectivity is 2% to 93%. The polystyrene block of styrene polymerization can be syndiotactic or random polystyrene. By using the rare earth catalyst with high tolerance and selectivity, the crude pinene separated from carbon five fraction is directly polymerized, and the controllable copolymerization of pinene, ethylene, conjugated olefin including butadiene, isoprene, myrcene and styrene is realized, and pinene base elastomer with controllable composition, sequence structure, stereo configuration and molecular weight is prepared. It has important significance for efficient utilization of carbon five fraction and development of new materials.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and relates to a class of isoprene-based elastomers and their preparation methods. Background Technology

[0002] Isoprene (1,3-pentadiene) is one of the main components of the C5 fraction of petroleum, accounting for about 11.0%, making it the third most abundant chemical raw material after cyclopentadiene and isoprene. Pure isoprene can be separated from the C5 fraction as a polymerization monomer. Currently, this separated pure polymer-grade isoprene has not only achieved selective homopolymerization but also controlled copolymerization with monomers such as butadiene and styrene, producing high-performance isoprene rubber, butyl pentadiene rubber, integrated rubber, and isoprene-styrene block copolymers.

[0003] Currently, the C5 fraction separation process can only separate crude isoprene, which is mainly composed of isoprene. Crude isoprene contains isoprene, alkynes, cyclopentene, cyclopentadiene, alkanes, etc. Using this complex crude isoprene as a monomer can only produce petroleum resins, and cannot produce higher value-added rubber and elastomer materials. To improve the utilization value of isoprene, researchers have studied it as a new monomer material. The anionic initiator butyllithium can achieve homopolymerization of isoprene and copolymerization with styrene, obtaining polyisoprene and isoprene-styrene alternating copolymers dominated by trans-1,4 structural units. The coordination polymerization catalyst Ziegler-Natta neodymium-based catalyst achieved homopolymerization of isoprene and copolymerization with isoprene, obtaining polyisoprene and isoprene-isoprene copolymer rubbers dominated by cis-1,4 structural units. When butyllithium and Ziegler-Natta neodymium catalysts catalyze the polymerization of isoprene, harmful impurities such as cyclopentadiene and alkynes must be removed from the monomer. Coordination polymerization catalysts such as titanium-based and rare-earth-based catalysts can also achieve isoprene polymerization, and by controlling the ligand structure, polyisoprene with up to 90% content of cis-1,4-, cis-1,2-, and trans-1,4- structural units can be obtained. However, titanium-based catalysts have low catalytic activity; even with the most active catalyst, the yield of polyisoprene is only 66% after 4 hours of polymerization. Both of these metallocene catalysts require the use of pure isoprene as the monomer.

[0004] To date, the isoprene monomers used for polymerization must be pure or free of harmful impurities such as cyclopentadiene and alkynes. Moreover, there is limited research on copolymerization of isoprene with other olefins. Currently, only isoprene-isoprene and isoprene-butadiene copolymers with cis-1,4 structural units as the main components, as well as isoprene-styrene alternating copolymers with trans-1,4 structural units as the main components, can be obtained. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a class of isoprene-based elastomers and their preparation method. This invention utilizes the design and synthesis of rare-earth catalysts, employing crude isoprene separated from C5 fractions as the polymerization monomer. It achieves controlled copolymerization of crude isoprene, mesoprene, and ethylene, along with conjugated olefins including butadiene, isoprene, myrcene, and styrene, to prepare isoprene-based elastomers with controllable composition, sequence structure, stereoconfiguration, and molecular weight. This method eliminates the need for purification of crude isoprene, significantly reducing the energy consumption in preparing isoprene-based rubber. This is of great significance for the efficient utilization of high-value-added C5 fractions and the development of new materials.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A type of isoprene-based elastomer, wherein the isoprene-based elastomer is polymerized from isoprene, and is a type of binary or ternary copolymer prepared by copolymerization of isoprene with conjugated olefins and ethylene catalyzed by rare earth catalysts; wherein the isoprene content in the binary or ternary copolymer is 5%-100% by molar percentage, and the number average molecular weight is 1×10⁻⁶. 4 ~80×10 4 .

[0008] Furthermore, the isoprene is selected from a mixture mainly composed of isoprene separated from C5 fractions. The conjugated olefin is selected from one or a mixture of two of styrene, butadiene, isoprene, and myrcene.

[0009] Furthermore, the rare earth catalyst includes a main catalyst and a co-catalyst. The main catalyst is a rare earth metal compound with the molecular formula CpLnR2X. n Wherein, Cp is selected from cyclopentadienyl, substituted cyclopentadienyl, indene, substituted indene, fluorenyl, or substituted fluorenyl; Ln is selected from rare earth metals; R is an alkyl group directly attached to a rare earth metal, selected from CH2SiMe3, CH2C6H4NMe2-o, CH2Ph, CH2CH=CH2, 1,3-C3H4(Me), 1,3-C3H3(SiMe3)2, CH(SiMe3)2, CH3, CH2CH3, i-Pr, t-Bu; X is a coordinating group on the rare earth metal, selected from Lewis bases containing O, N, P, or S heteroatoms; n is the number of Lewis bases, selected from 0 or 1. The cocatalyst is an organoboron reagent, or a mixture of alkylaluminum and organoboron reagents. The organoboron reagents are selected from [Ph3C][B(C6F5)4], [PhMe2NH][B(C6F5)4], [HNMe(C 18 H 37[B(C6F5)4] and [B(C6F5)3] are selected as one or a mixture of several of these. Alkyl aluminum reagents are selected from one or a mixture of several of these, including trimethylaluminum, triethylaluminum, triisobutylaluminum, and methylaluminoxane.

[0010] A method for preparing a class of isoprene-based elastomers includes the following steps:

[0011] Under the protection of inert nitrogen or argon gas, organic solvent and rare earth catalyst are added to a dried and deoxygenated polymerization reactor according to the specified ratio. The temperature is controlled by stirring at -20 ℃ to 80 ℃. The monomers are mixed or added stepwise to the reaction system, and the reaction is carried out for 5 minutes to 4 hours to obtain the corresponding random, multi-block, or block copolymers. The polymer is terminated, precipitated, washed, and dried using traditional post-treatment methods to obtain the copolymer. The monomers are a mixture of three types of monomers: isoprene, conjugated olefin, and ethylene; or a mixture of two types of monomers: isoprene and conjugated olefin; or a mixture of two types of monomers: isoprene and ethylene.

[0012] Furthermore, in the rare earth catalyst, when the co-catalyst is an organoboron reagent, the molar ratio of the organoboron reagent to the rare earth metal compound is 1; when the co-catalyst is an alkylaluminum, the molar ratio of the alkylaluminum to the rare earth metal compound is 0-500.

[0013] Furthermore, the molar ratio of the polymer monomer to the rare earth metal compound is 1000-500000.

[0014] Furthermore, the organic solvent is selected from one or a mixture of two or more of the following: n-hexane, cyclohexane, n-heptane, benzene, toluene, xylene, chlorobenzene, dichlorobenzene, and trichlorobenzene.

[0015] Furthermore, in the preparation method, when the monomers are isoprene, butadiene, isoprene, and myrcene: by controlling the ligand structure and central metal of the rare earth catalyst, the polymerization of the monomers exhibits a cis-1,4-selectivity of 2%-98%, an isoprene trans-1,4-selectivity of 2%-98%, and a myrcene and isoprene 3,4-selectivity of 2%-93%. When the monomer is styrene, by controlling the ligand structure and central metal of the rare earth catalyst, the polystyrene blocks can be syndiotactic or atactic polystyrene during polymerization.

[0016] The beneficial effects of the isoprene-based elastomer and its preparation method provided by this invention are as follows:

[0017] This invention achieves the direct polymerization of crude isoprene separated from C5 fraction by employing a designed and synthesized rare earth catalyst. Because the catalyst is resistant to substances such as cyclopentadiene and alkynes in crude isoprene, and is only active for the polymerization of crude isoprene and mesoprene, but inactive for the polymerization of monoolefins, there is no need for time-consuming and energy-intensive separation and purification of crude isoprene. Furthermore, it enables the controlled copolymerization of crude isoprene and mesoprene with ethylene and conjugated olefins (including butadiene, isoprene, myrcene, and styrene), preparing isoprene-based elastomers with controllable composition, sequence structure, stereoconfiguration, and molecular weight. This is of great significance for the high-value-added utilization of C5 fraction and the development of new materials. Attached Figure Description

[0018] Figure 1 The NMR spectrum of polyisoprene is shown in Comparative Example 1.

[0019] Figure 2 The DSC curve of polyisoprene is shown in Comparative Example 1.

[0020] Figure 3 The NMR spectrum of poly(imiprene) in Example 5;

[0021] Figure 4 The DSC curve of polyisoprene in Example 5;

[0022] Figure 5 The NMR spectrum of the polyblock copolymer of isoprene and styrene in Example 7 is shown below.

[0023] Figure 6 The DSC curve of the isoprene-styrene multiblock copolymer of Example 7 is shown.

[0024] Figure 7 The NMR spectrum of the random copolymer of isoprene and styrene in Example 8 is shown.

[0025] Figure 8 The image shows the DSC curve of the random copolymer of isoprene and styrene in Example 8. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments.

[0027] The present invention provides the following embodiments as further illustration, but these are not intended to limit the scope of protection of the claims of the present invention. Using carbon nuclear magnetic resonance spectroscopy (NMR spectroscopy)... 1 H-、 13The content and structure (molar percentage, %) of the obtained resorcinol elastomer component were determined by C-NMR. The molecular weight and molecular weight distribution index (weight-average molecular weight to number-average molecular weight) of the resorcinol elastomer were determined by gel permeation chromatography (GPC). The glass transition temperature (Tg) of the polymer was determined by differential calorimetry (DSC). g ) and melting point (T m ).

[0028] Examples 1-4 describe the preparation of rare earth catalysts:

[0029] Example 1: Preparation of (C5H4Me)Y(CH2SiMe3)2(THF)

[0030] In a glove box, 10 mmol of YCl3 was weighed and placed in a Schlenk flask containing a magnetic stir bar. 20 mL of tetrahydrofuran was added, the flask was sealed, and the mixture was removed from the glove box and stirred at 40°C for 12 h. The activated white suspension of YCl3(THF)3 was then placed in the glove box. 30 mmol of trimethylsilylmethyllithium LiCH2SiMe3 was weighed and dissolved in 40 mL of tetrahydrofuran. This solution was then added dropwise to the activated white suspension of YCl3(THF)3. After reacting for 30 min, the tetrahydrofuran solvent was removed under vacuum. 20 mL of n-hexane was added for extraction, and the extract was frozen in a refrigerator to remove byproducts. The mixture was then filtered while cold, and the n-hexane solvent was removed under vacuum to obtain 4.546 g of white solid Y(CH2SiMe3)3(THF)2. In a glove box, 7.25 mmol of Y(CH2SiMe3)3(THF)2 was weighed and placed in a round-bottom flask containing a magnetic stir bar. 10 mL of n-hexane solvent was added to dissolve the solid. 7.25 mmol of methylcyclopentadiene (C5H5Me) was weighed, dissolved in 1.0 mL of n-hexane, and added dropwise to a reaction flask at room temperature. The reaction was stirred at room temperature for 2 h, then concentrated under reduced pressure to approximately 1 mL, and placed in a -30°C refrigerator overnight. Recrystallization yielded 3.772 g of crystals (C5H4Me)Y(CH2SiMe3)2THF, with a yield of 80%.

[0031] Example 2, {C 13 Preparation of H9(SiMe3)}Lu(CH2SiMe3)2(NHC)

[0032] In a glove box, 10 mmol of LuCl3 was weighed and placed in a Schlenk flask containing a magnetic stir bar. 20 mL of tetrahydrofuran was added, the flask was sealed, and the mixture was removed from the glove box and stirred at 40 °C for 12 h. The activated LuCl3(THF)3 white suspension was then placed in the glove box. 30 mmol of trimethylsilylmethyllithium LiCH2SiMe3 was weighed and dissolved in 40 mL of tetrahydrofuran. This solution was then added dropwise to the activated LuCl3(THF)3 white suspension. After reacting for 30 min, the tetrahydrofuran solvent was removed under vacuum. 20 mL of n-hexane was added for extraction, and the extract was frozen in a refrigerator to remove byproducts. The mixture was then filtered while cold, and the n-hexane solvent was removed under vacuum to obtain 4.546 g of white solid Lu(CH2SiMe3)3(THF)2. In a glove box, 7.25 mmol of Lu(CH2SiMe3)3(THF)2 was weighed and placed in a round-bottom flask containing a magnetic stir bar. 10 mL of n-hexane solvent was added to dissolve the solid. Weigh out 7.25 mmol of fluorene C. 13 H 10 (SiMe3) was dissolved in 1.0 mL of n-hexane and added dropwise to a reaction flask at room temperature. The reaction was stirred at room temperature for 2 h, then concentrated under reduced pressure to approximately 1 mL, and placed in a -30 °C refrigerator overnight. Recrystallization yielded 3.772 g of crystals {C 13 H9(SiMe3)}Lu(CH2SiMe3)2THF. In a glove box, weigh 2.0 mmol of 1,3-diisopropylimidazolium hydrochloride into a round-bottom flask, add 10 mL of toluene to prepare a suspension, and add dropwise 6 mL of a 2.0 mmol trimethylsilylmethyllithium solution in toluene while stirring. Stir overnight at room temperature. Add the mixture dropwise to 2.0 mmol {C 13 The mixture was stirred in 10 mL of toluene solution of H9(SiMe3)}Lu(CH2SiMe3)2THF at room temperature for 1 h. After the reaction was complete, the system was filtered, and the filtrate was concentrated and stored at -30°C. o Recrystallization at C yielded 1.035 g {C} 13 H9(SiMe3)}Lu(CH2SiMe3)2(NHC), yield 82%.

[0033] Example 3, Preparation of (C9H7)Sc(CH2C6H4NMe2-o)2

[0034] In a glove box, 100.0 mmol of N,N-dimethyl-o-toluidine was added to 40 mL of diethyl ether solution and stirred. Then, 100.0 mmol of n-butyllithium solution was added, and the reaction was carried out at room temperature with stirring for 3 days. After the reaction was complete, the diethyl ether solvent was removed under vacuum, and the residual solid was washed with n-hexane and dried to obtain 12.549 g of pale yellow solid LiCH2C6H4NMe2-o. In a glove box, 10.0 mmol of ScCl3 powder was weighed and added to 8 mL of tetrahydrofuran. 30.0 mmol of solid LiCH2C6H4NMe2-o was weighed and dissolved in 14 mL of tetrahydrofuran. After complete dissolution, it was added dropwise to the tetrahydrofuran suspension of ScCl3 and reacted for 0.5 h. After the reaction was complete, the tetrahydrofuran solvent was removed under vacuum, and 28 mL of toluene was added to the residual solid to dissolve it. The mixture was filtered, and the filtrate was dried under vacuum to remove the toluene, yielding 4.301 g of yellowish-brown powder Sc(CH2C6H4NMe2-o)3. Weigh 4.0 mmol of Sc(CH2C6H4NMe2-o)3 into a Schlenk flask equipped with a magnetic stir bar in a glove box, and dissolve it in 12 mL of tetrahydrofuran solvent. Weigh 4.8 mmol of indene, dissolve it in 6 mL of tetrahydrofuran, and add it to the Schlenk flask at room temperature. Seal the Schlenk flask, remove it from the glove box, place it in an oil bath, heat to 40 °C, and stir for 1 h. Remove it from the glove box, remove the solvent under vacuum, extract the residual solid with toluene, concentrate it, and place it in a -30 °C refrigerator overnight. Recrystallize to obtain 1.271 g of yellow crystals (C9H7)Sc(CH2C6H4NMe2-o)2, yield: 84%.

[0035] Example 4, Preparation of (C5H5)Nd(CH2C6H4NMe2-o)2

[0036] In a glove box, 10 mmol of NdCl3 powder was weighed and added to 8 mL of tetrahydrofuran. 30 mmol of solid LiCH2C6H4NMe2-o was weighed and dissolved in 14 mL of tetrahydrofuran. After complete dissolution, the dissolved solid was added dropwise to the NdCl3 tetrahydrofuran suspension. The mixture was stirred at 25 °C for 12 h. After the reaction was complete, the tetrahydrofuran solvent was removed under vacuum. 30 mL of toluene was added to the remaining solid to dissolve it. The mixture was filtered, and the filtrate was dried under vacuum to remove the toluene, yielding 4.926 g of brownish-yellow powder Nd(CH2C6H4NMe2-o)3. In a glove box, 4 mmol of Nd(CH2C6H4NMe2-o)3 was weighed and placed in a round-bottom flask containing a magnetic stir bar. 12 mL of tetrahydrofuran solvent was added to dissolve the NdCl3. 4.80 mmol of cyclopentadiene was weighed, dissolved in 6 mL of tetrahydrofuran, and added to a round-bottom flask. The mixture was stirred at 25 °C for 12 h. The solvent was removed under vacuum, and the residual solid was washed with n-hexane, filtered, and the filter residue was dried under vacuum to remove n-hexane, yielding 1.849 g of brownish-yellow powder (C5H5)Nd(CH2C6H4NMe2-o)2, with a yield of 80%.

[0037] Example 5: Preparation of poly(imrepinephrine) by homopolymerization of crude isoprene

[0038] In a glove box, 10 μmol of the catalyst (C5H4Me)Y(CH2SiMe3)2(NHC) prepared in Example 1 was added to a gaiwan flask and dissolved in 2 mL of toluene. Then, an equimolar amount of [Ph3C][B(C6F5)4] in 2 mL of toluene solution was added with stirring. Next, 1.5307 g of crude isoprene, obtained from the C5 fraction, was added. Its composition was isoprene (44.5 wt%), cyclopentene (17.8 wt%), cyclopentene (0.5 wt%), dicyclopentene (0.2 wt%), and other components such as alkynes and alkanes (37 wt%). The reaction was stirred at 25 °C for 2 min. The reaction was terminated by adding methanol, and the polymer was washed with methanol and dried under vacuum to obtain 0.6800 g of the polymer product.

[0039] The results of polymer structure and performance analysis are as follows: The NMR spectrum of the polymerization product is consistent with that of Example 5, indicating that only isoprene in crude isoprene underwent polymerization, and other components did not participate in polymerization. The polymerization product is polyisoprene, with the ratio of cis-1,4 / trans-1,4 / cis-1,2 / trans-1,2 structural units being 2 / 94 / 1 / 3; the polymerization product T g The temperature was -36 °C; the number average molecular weight of the polymer was 7.3 × 10⁻⁶. 4 Molecular weight distribution index (M w / M n The molecular weight of polyisoprene is 1.75, and other components in crude isoprene do not affect the molecular weight of polyisoprene.

[0040] Example 6: Preparation of isoprene-myrcene block copolymer

[0041] In a glove box, 10 μmol of the catalyst {C} prepared in Example 2 above was added to a flask. 13 H9(SiMe3)}Lu(CH2SiMe3)2(NHC) was dissolved in 8 mL of chlorobenzene, and then an equimolar amount of [PhMe2NH][B(C6F5)4]8 mL of chlorobenzene solution was added with stirring. Then, a mixture of 15 μmol triethylaluminum and 7.6539 g crude isoprene (containing 50 mmol isoprene) was added, and the mixture was stirred at 25 °C for 2 h to polymerize. Then, a mixture of 15 μmol triethylaluminum and 50 mmol myrcene was added, and the mixture was stirred at 25 °C for 2 h to terminate the reaction. The polymer was washed with methanol and dried under vacuum to obtain 10.2177 g of polymerized product.

[0042] The results of polymer structure and performance analysis are as follows: NMR spectroscopy analysis of the polymer product indicates that it is an isoprene-myrcene block copolymer. The isoprene content is 50% and the myrcene content is 50% by mole percentage. The ratio of polyisoprene cis-1,4 / trans-1,4 / cis-1,2 / trans-1,2 structural units is 30 / 54 / 1 / 15, and the ratio of myrcene cis-1,4 / trans-1,4 / 3,4- / 1,2- structural units is 6 / 4 / 90 / 0. The number-average molecular weight of the isoprene-myrcene block copolymer is 33 × 10⁻⁶. 4 Molecular weight distribution index (M w / M n The value is 2.25, T g The temperature is -49℃.

[0043] Example 7: Preparation of a multiblock copolymer of isoprene and styrene

[0044] In a glove box, 10 μmol of the catalyst (C9H7)Sc(CH2C6H4NMe2-o)2 prepared in Example 3 was added to a glove-shaped flask and dissolved in 8 mL of toluene. Then, an equimolar amount of [Ph3C][B(C6F5)4] in 8 mL of toluene solution was added with stirring. Then, 1 mmol of triethylaluminum, 7.6539 g of crude isoprene (containing 50 mmol of isoprene), and 50 mmol of styrene were added as a mixture at room temperature. The mixture was stirred and polymerized at 25 °C for 3 h. The reaction was terminated by adding methanol, and the polymer was washed with methanol and dried under vacuum to obtain 8.6135 g of the polymer product.

[0045] The results of polymer structure and performance analysis are as follows: NMR spectroscopy analysis of the polymer product indicates that it is a polyblock copolymer of isoprene and styrene, with an isoprene content of 45% and a styrene content of 55% by molar percentage. The ratio of polyisoprene cis-1,4 / trans-1,4 / cis-1,2 / trans-1,2 structural units is 85 / 3 / 0 / 11, and the styrene blocks have a syndiotactic structure. The number-average molecular weight of the isoprene-styrene polyblock copolymer is 23 × 10⁻⁶. 4 Molecular weight distribution index (M w / M n The value is 2.01, T g -49 ℃, T m The temperature is 259℃.

[0046] Example 8: Preparation of a random copolymer of isoprene and styrene

[0047] In a glove box, 10 μmol of the catalyst (C) prepared in Example 4 above was added to a flask. 13 H9)Nd(CH2C6H4NMe2-o)2 was dissolved in 4 mL of toluene, and then an equimolar amount of [Ph3C][B(C6F5)4] in 4 mL of toluene was added with stirring. The mixture was heated to 70 °C, and then a mixture of 0.5 mmol trimethylaluminum, 3.0616 g crude isoprene (containing 20 mmol isoprene), and 20 mmol styrene was added. The mixture was stirred at 70 °C for 2 h. The reaction was terminated by adding methanol, and the polymer was washed with methanol and dried under vacuum to obtain 3.4454 g of the polymer product.

[0048] The structural and performance analysis results of the polymerization product are as follows: NMR spectroscopy analysis of the polymerization product indicates that it is a random copolymer of isoprene and styrene, with an isoprene content of 41% and a styrene content of 59% by mole percentage. The ratio of polyisoprene 1,4 / 1,2 structural units is 88 / 12. The number-average molecular weight of the isoprene-styrene random copolymer is 13 × 10⁻⁶. 4 Molecular weight distribution index (M w / M n The value is 1.96, T g The temperature is 15℃.

[0049] Example 9: Preparation of the copolymer of isoprene and ethylene

[0050] In a glove box, add 10 mL of toluene solution containing 3.0616 g of crude isoprene (containing 20 mmol of isoprene) to a two-necked flask. Seal the flask with a glass connector and transfer it from the glove box to an ethylene fume hood. Connect it to the Schlenk and ethylene branches. After several nitrogen purgings, add 1.01 × 10⁻⁶ g of crude isoprene solution. 5Ethylene under pressure of Pa was introduced into a two-necked flask and stirred for 2 min. Then, 10 μmol of the catalyst (C9H7)Sc(CH2C6H4NMe2-o)2 prepared in Example 3 above and an equimolar amount of [Ph3C][B(C6F5)4] in 4 mL of toluene solution were rapidly added to the two-necked flask through a sealing needle. The polymerization reaction was carried out at 25 °C for 10 min. The reaction was terminated by adding methanol, and the polymer was washed with methanol and dried under vacuum to obtain 2.7 g of the polymer product.

[0051] The structural and performance analysis results of the polymerization product are as follows: NMR spectroscopy analysis of the polymerization product shows that it is an isoprene-ethylene copolymer, with an isoprene content of 12% and an ethylene content of 88% by mole percentage. The ratio of polyisoprene cis-1,4 / trans-1,4 / cis-1,2 / trans-1,2 structural units is 88 / 2 / 0 / 10, with isoprene structural units isolated and inserted into polyethylene blocks. The number-average molecular weight of the isoprene-ethylene copolymer is 9.8 × 10⁻⁶. 4 Molecular weight distribution index (M w / M n The value is 1.86, T g -49 ℃, T m It is 130 ℃.

[0052] Example 10 Preparation of a terpolymer of pentadiene, styrene, and ethylene

[0053] In a glove box, add 10 mmol of styrene, 1.5308 g of crude isoprene (containing 10 mmol of isoprene), and 20 mL of toluene solution to a two-necked flask. Seal the flask with a glass connector and transfer it from the glove box to an ethylene fume hood. Connect it to the Schlenk and ethylene branches. After several nitrogen purgings, add 1.01 × 10⁻⁶ ppm of styrene. 5 Ethylene at a pressure of Pa was introduced into a two-necked flask, mixed and stirred for 5 min, and then 10 μmol of the catalyst {C} prepared in Example 2 above was added. 13 H9(SiMe3)}Lu(CH2SiMe3)2(NHC) and an equimolar amount of [Ph3C][B(C6F5)4]4 in 4 mL of toluene solution were rapidly added to a two-necked flask through a sealing needle. The polymerization reaction was carried out at 50 °C for 10 min. The reaction was terminated by adding methanol, and the polymer was washed with methanol and dried under vacuum to obtain 1.9 g of the polymer product.

[0054] The structural and performance analysis results of the polymerization product are as follows: NMR spectroscopy analysis of the polymerization product shows that it is a terpolymer of isoprene-styrene-ethylene, with isoprene content of 18%, styrene content of 22%, and ethylene content of 60% by molar percentage. The ratio of polyisoprene cis-1,4 / trans-1,4 / cis-1,2 / trans-1,2 structural units is 35 / 52 / 1 / 12. The number-average molecular weight of the isoprene-styrene-ethylene copolymer is 19.3 × 10⁻⁶. 4 Molecular weight distribution index (M w / M n The value is 1.56, T g -30 ℃, T m It is 130 ℃.

[0055] Comparative Example 1: Preparation of Poly(imrene) from Pure Isopentadiene

[0056] In a glove box, 10 μmol of the catalyst (C5H4Me)Y(CH2SiMe3)2(NHC) prepared in Example 1 was added to a 100 mL flask. After dissolving in 2 mL of toluene, an equimolar amount of [Ph3C][B(C6F5)4] in 2 mL of toluene was added with stirring. Then, 10 mmol of pure isoprene was added, and the reaction was stirred at 25 °C for 2 min. The reaction was terminated by adding methanol, and the polymer was washed with methanol and dried under vacuum to obtain isoprene homopolymer with a yield of 98%. The structural and property analysis results of the obtained polyisoprene are as follows: number average molecular weight is 7.6 × 10⁻⁶. 4 Molecular weight distribution index (M w / M n The value is 1.48, T g The temperature was -36 °C, and the ratio of cis-1,4 / trans-1,4 / cis-1,2 / trans-1,2 structural units was 2 / 94 / 1 / 3. Comparison with Example 5 shows that the metallocene catalyst reported in this patent exhibits identical effects in catalyzing the polymerization of pure isoprene and crude isoprene. Other components in the crude isoprene, besides isoprene, do not affect the catalytic activity or selectivity, and these components can be used as polymerization solvents.

[0057] Comparative Example 2

[0058] In a glove box, add 9 μmol of catalyst Nd(P) to a 120 mL ampoule. 2043. After dissolving in 2 mL of n-hexane, add 45 μmol of triisobutylaluminum while stirring. Seal the ampoule with a latex tube and a glass plug, and react in a 50°C oil bath outside the glove box for 15 min. Use a sealing needle to remove 27 μmol of diethylaluminum chloride from the glove box and add it to the ampoule. Continue reacting in a 50°C oil bath for 15 min to obtain the aged Ziegler-Natta rare earth catalyst Nd(P) 204 3 / triisobutylaluminum / diethylaluminum chloride. 1.5307 g of crude isoprene was added to this catalyst, and the reaction was stirred at 60 °C for 12 h; no polymerization product was formed. The Ziegler-Natta rare earth catalyst, which can catalyze the efficient polymerization of pure butadiene and isoprene, cannot catalyze the polymerization of crude isoprene. Compared with Example 5, it can be seen that cyclopentadiene and other substances in crude isoprene can poison the traditional Ziegler-Natta rare earth catalyst, preventing it from catalyzing the polymerization of crude isoprene, while the metallocene catalyst reported in this patent is completely unaffected.

[0059] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A class of isoprene-based elastomers characterized in that, The said isoprene-based elastomer is polymerized from isoprene, and is a kind of two or three copolymers prepared by copolymerization of isoprene and conjugated olefin, ethylene catalyzed by rare earth catalyst; wherein the combined isoprene content in the two or three copolymers is 5%-100% by mole percentage, and the number average molecular weight is 1×10 4 80×10 4 ; The rare earth catalyst comprises a main catalyst and a cocatalyst, the main catalyst is a rare earth metal compound, the molecular formula of the rare earth metal compound is CpLnR2X n wherein R is selected from CH2SiMe3, CH2C6H4NMe2-o, CH2Ph, CH2CH=CH2, 1,3-C3H4(Me), 1,3-C3H3(SiMe3)2, CH(SiMe3)2, CH3, CH2CH3, i-Pr, t-Bu; X is selected from Lewis bases containing O, N, P, S heteroatoms, and n is selected from 0 or 1; the cocatalyst is an organic boron reagent, or a mixture of an alkyl aluminum and an organic boron reagent; The molecular formula of the rare-earth metal compound is CpLnR2X n wherein Cp is selected from cyclopentadienyl, substituted cyclopentadienyl, indenyl, substituted indenyl, fluorenyl or substituted fluorenyl; Ln is selected from rare-earth metal; R is an alkyl group directly connected to the rare-earth metal; X is a coordinating group on the rare-earth metal; and n is the number of Lewis bases.

2. The class of spirocyclic elastomers according to claim 1, characterized in that The piperylene is selected from a mixture mainly containing piperylene separated from carbon five fraction.

3. The class of spirocyclic elastomers according to claim 1, wherein The conjugated olefin is selected from one or a mixture of two of styrene, butadiene, isoprene and laurylene.

4. The class of spirocyclic elastomers according to claim 1, wherein The organic boron reagent is selected from one or a mixture of several of [Ph3C][B(C6F5)4], [PhMe2NH][B(C6F5)4], [HNMe(C6F5)2][B(C6F5)4], B(C6F5)3. 18 H 37 )2][B(C6F5)4], B(C6F5)3. The aluminum alkyl reagent is selected from one or a mixture of several of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum and methyl aluminoxane.

5. The process for preparing a piperylenyl elastomer according to any one of claims 1 to 4, characterized in that The method comprises the following steps: Under the protection of inert gas, the organic solvent and the rare earth catalyst are added into a polymerization reactor in a proportion, the temperature is controlled at-20℃ to 80℃ by stirring, the polymerization monomer is mixed or added into the reaction system in steps, the reaction is carried out for 5 minutes to 4 hours, and a corresponding random, multi-block or block copolymer is obtained; the polymer is terminated, precipitated, washed and dried by using a traditional post-treatment method, and the copolymer is obtained; the polymerization monomer is a mixture of three of piperylene, conjugated olefin and ethylene, or a mixture of two of piperylene and conjugated olefin, or a mixture of two of piperylene and ethylene.

6. The process for preparing an interpentadiene-based elastomer according to claim 5, characterized in that, When the cocatalyst is an organic boron reagent, the molar ratio of the organic boron reagent to the metallocene rare earth metal compound is 1; when the cocatalyst is an alkyl aluminum, the molar ratio of the alkyl aluminum to the metallocene rare earth metal compound is 0 to 500.

7. The process for preparing an interpentadiene-based elastomer according to claim 5, characterized in that, The molar ratio of the polymerization monomer to the metallocene rare earth metal compound is 1000 to 500000.

8. The process for preparing a class of interpentadiene-based elastomers according to claim 5, characterized in that The organic solvent is selected from one or a mixture of two or more of n-hexane, cyclohexane, n-heptane, benzene, toluene, xylene, chlorobenzene, dichlorobenzene and trichlorobenzene.

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