A highly elastic and highly resilient vinyl elastomer and a method for making the same

Abstract

This invention discloses a highly elastic and resilient vinyl elastomer and its preparation method. The method includes: solution polymerization of ethylene, comonomers, and functional monomers in the presence of a catalyst to obtain a vinyl copolymer precursor; subsequently, dissolving the precursor in an organic solvent, adding a ring-closing reagent to perform an intramolecular ring-closing reaction, and adding a monofunctional end-capping agent to terminate the reaction; and obtaining the vinyl elastomer after separation, washing, and drying. By controlling the monomer feed in stages, a gradient structure is formed in the molecular chain, with ethylene-rich segments at both ends and α-olefin-rich segments in the middle. Combined with the intramolecular ring-closing structure, topological constraints are introduced, significantly improving the material's elastic recovery performance while maintaining thermoplastic processability. The resulting material exhibits a resilience of over 63%, a compression set of less than 24%, a melt strength of over 7.1 cN, and a gel content of less than 1.2%.

Description

Technical Field

[0001] This invention relates to the field of advanced petrochemical new materials technology, and in particular to a high-elasticity, high-resilience vinyl elastomer and its preparation method. Background Technology

[0002] Polyolefin elastomers, due to their combination of thermoplastic processability, flexibility, and weather resistance, have become an important development direction for high-elasticity, high-resilience vinyl materials. Current research and industrial applications mainly focus on ethylene-α-olefin random copolymers and olefin block copolymers obtained through chain shuttle polymerization. Related reports indicate that the elasticity of these materials is typically improved by adjusting the type, molecular weight, and crystallinity of comonomers, and further enhanced by blending, crosslinking, or foaming. Meanwhile, polyolefin elastomer preparation technology is continuously advancing. Public information has been released regarding the construction of a 50,000-ton / year industrial pilot plant for polyolefin elastomers, and there are also public reports of large-scale production of POE via gas-phase method, indicating that this field is gradually extending from basic equipment to high-performance and large-scale applications.

[0003] However, current technologies primarily rely on random copolymerization, multi-block design, blending toughening, or subsequent crosslinking modification. There are relatively few publicly available solutions that simultaneously construct gradient segment distributions and intrachain closed-loop constraint structures within the molecular chain. Especially when pursuing high elasticity, high resilience, and low compression set, conventional vinyl elastomers tend to exhibit problems such as significant hysteresis loss, high permanent deformation, insufficient melt strength, or the need for complex post-processing. Current technologies lack a method for preparing vinyl elastomers that can simultaneously consider segment gradient distribution, topological constraint effects, and thermoplastic processability at the molecular structure level. Therefore, it is necessary to develop new molecular structure design and preparation routes to meet the comprehensive performance requirements of high-resilience elastic materials. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a high-elasticity, high-resilience vinyl elastomer and its preparation method. By controlling the polymerization process of ethylene, α-olefin comonomers, and functional monomers in stages, the resulting vinyl copolymer precursor forms a gradient structure along the molecular chain direction, with relatively ethylene-rich segments at both ends and relatively α-olefin-rich segments in the middle. Furthermore, a ring-closing reaction reagent is introduced under dilute solution conditions to induce intramolecular ring-closing reactions in the polymer chains, thereby constructing a vinyl elastomer with an intramolecular ring-closing structure. Through this structural design, while maintaining the thermoplastic processing properties of the material, the introduction of chain segment gradient distribution and topological constraint effects is beneficial for improving the material's elastic recovery ability and reducing permanent deformation, thus obtaining a vinyl elastomer material with both high elasticity and high resilience.

[0005] This invention can be achieved through the following technical solutions:

[0006] A method for preparing a highly elastic and resilient vinyl elastomer includes the following steps:

[0007] Step 1: In the presence of a catalyst, ethylene, α-olefin comonomer and functional monomer containing unsaturated double bonds are subjected to solution polymerization to obtain vinyl copolymer precursor;

[0008] Step 2: Dissolve the vinyl copolymer precursor in an organic solvent, add a ring-closing reaction reagent to carry out an intramolecular ring-closing reaction, then add a monofunctional end-capping agent to terminate the reaction, separate, wash and dry to obtain a high-elasticity, high-resilience vinyl elastomer.

[0009] Preferably, the catalyst in step 1 is a metallocene catalyst or a post-transition metal single-center catalyst.

[0010] Preferably, in step 1, the α-olefin comonomer is selected from one or more of 1-butene, 1-hexene, and 1-octene.

[0011] Preferably, the functional monomer containing unsaturated double bonds in step 1 is selected from one or more of 5-vinyl-2-norbornene, 5-vinyl-2-norbornene, ethylidene norbornene, and 1,7-octadiene.

[0012] Preferably, in step 1, the total molar amount of ethylene, α-olefin comonomer, and functional monomer is 62-72 mol%, the amount of α-olefin comonomer is 27-37 mol%, and the amount of functional monomer is 0.3-1.0 mol.

[0013] Preferably, in step 1, the solution polymerization is carried out by controlling the monomer feed composition in stages.

[0014] Preferably, the organic solvent in step 2 is selected from one or more of cyclohexane, n-hexane, toluene, and xylene.

[0015] Preferably, the ring-closing reagent in step 2 is selected from dithiol compounds or diazide compounds.

[0016] Preferably, the temperature of the intramolecular ring-closing reaction in step 2 is 20-90℃, and the reaction time is 0.5-24h.

[0017] Preferably, the monofunctional end-capping agent in step 2 is selected from monofunctional compounds corresponding to the ring-closing reaction reagent.

[0018] The beneficial effects of this invention are:

[0019] This invention achieves a synergistic enhancement of the high resilience of vinyl elastomers through molecular structure design. During preparation, a staged control of monomer feeding is employed to create a gradient structure along the length of the molecular chain, with relatively ethylene-rich ends and a relatively α-olefin-rich middle section. The two ethylene-rich segments form physical cross-linking points within the material, providing the driving force for elastic recovery, while the α-olefin-rich middle section imparts good flexibility and energy dissipation capability. Furthermore, by introducing dithiol or diazide-based ring-closing reagents under dilute solution conditions, precise intramolecular ring-closing reactions occur in the polymer chains. While maintaining the thermoplastic processability of linear molecules, an intrachain topological constraint structure is introduced, effectively limiting the slippage and deentanglement of molecular chains under stress. The synergistic effect of these two factors endows the material with excellent comprehensive properties, achieving a resilience of over 63%, compression set controlled below 24%, and a significantly increased melt strength exceeding 7.1 cN. Simultaneously, the gel content is below 1.2%, demonstrating that the reaction process is primarily intramolecular ring-closing with minimal cross-linking. The vinyl elastomer provided by this invention has the advantages of high elasticity, high resilience, low permanent deformation and good thermoplastic processability. It can be widely used in the fields of seals, cushioning materials, sports equipment and other fields, and has important industrial application value. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0021] Figure 1 For the hardness, compression set, and resilience of vinyl elastomers;

[0022] Figure 2 The gel content and melt strength of the vinyl elastomer. Detailed Implementation

[0023] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0024] In the following examples, the amount of the ring-closing reaction reagent is 0.25-0.60 times the molar amount of the reactive groups in the vinyl copolymer precursor; the amount of the monofunctional end-capping agent is 0.05-0.30 times the amount of the ring-closing reaction reagent.

[0025] Example 1: A method for preparing a highly elastic and resilient vinyl elastomer, comprising the following steps:

[0026] Step 1: Add 500 mL of cyclohexane to a 2 L high-pressure reactor that has been fully purged with nitrogen, heat to 70 °C, and introduce ethylene while stirring until saturation. Under nitrogen protection, add dimethylsilylbis(indenyl)zirconium dichloride, 1-octene, and 5-vinyl-2-norbornene sequentially to the reactor. Polymerization is carried out by controlling the monomer feed composition in stages (the first stage introduces a higher proportion of ethylene to form ethylene-rich segments, the second stage increases the proportion of 1-octene to form α-olefin-rich segments, and the third stage...). To restore a higher ethylene ratio and form another ethylene-rich segment, the total amount of monomers fed was controlled so that the final copolymer composition met the following requirements: based on the total molar amounts of ethylene, 1-octene, and 5-vinyl-2-norbornene, the amount of ethylene was 72.7 mol%, the amount of 1-octene was 27 mol%, and the amount of 5-vinyl-2-norbornene was 0.3 mol%. After the polymerization reaction proceeded for 45 min, the reaction solution was injected into a large amount of ethanol to precipitate the polymer. After washing and drying, the vinyl copolymer precursor was obtained.

[0027] Step 2: Dissolve 50g of the vinyl copolymer precursor in 1L of cyclohexane. Under a nitrogen atmosphere, add the ring-closing reagent 1,6-hexanedithiol (0.25 times the molar amount of the double bond from 5-vinyl-2-norbornene in the vinyl copolymer precursor). React at 20°C for 24h. Then add the monofunctional end-capping agent n-propanethiol (0.10 times the amount of 1,6-hexanedithiol) to quench unreacted active groups and terminate the reaction. Pour the reaction solution into a large volume of stirred ethanol / acetone mixed solvent for sedimentation separation. The solid product is precipitated. The product is repeatedly washed, filtered, and dried in a vacuum oven to constant weight to finally obtain a high-elasticity, high-resilience vinyl elastomer.

[0028] Example 2: A method for preparing a highly elastic and resilient vinyl elastomer, comprising the following steps:

[0029] Step 1: Add 500 mL of toluene to a 2 L high-pressure reactor that has been fully purged with nitrogen, heat to 70 °C, and introduce ethylene under stirring until saturation. Under nitrogen protection, add dicyclopentadienyl zirconium dichloride, 1-hexene, and ethylene-neobornene sequentially to the reactor. Polymerization is carried out by controlling the monomer feed composition in stages (the first stage introduces a higher proportion of ethylene to form ethylene-rich segments, the second stage increases the proportion of 1-hexene to form α-olefin-rich segments, and the third stage restores a higher proportion of ethylene to form another ethylene-rich segment). Control the total amount of monomers to ensure that the final copolymer composition meets the following requirements: based on the total molar amount of ethylene, 1-hexene, and ethylene-neobornene, the amount of ethylene is 67.35 mol%, the amount of 1-hexene is 32 mol%, and the amount of ethylene-neobornene is 0.65 mol%. After the polymerization reaction proceeds for 45 min, inject the reaction solution into a large amount of ethanol to precipitate the polymer. After washing and drying, the vinyl copolymer precursor is obtained.

[0030] Step 2: Dissolve 50g of the vinyl copolymer precursor in 1.2L of toluene. Under a nitrogen atmosphere, add dropwise the ring-closing reagent 1,8-octanedithiol (0.50 times the molar amount of the double bond from ethylidene norbornene in the vinyl copolymer precursor). React at 55℃ for 12h. Then add the monofunctional end-capping agent ethanethiol (0.18 times the amount of 1,8-octanedithiol) to quench unreacted active groups and terminate the reaction. Pour the reaction solution into a large volume of stirred ethanol / acetone mixed solvent for sedimentation separation. The solid product is precipitated. The product is repeatedly washed, filtered, and dried in a vacuum oven to constant weight to finally obtain a high-elasticity, high-resilience vinyl elastomer.

[0031] Example 3: A method for preparing a highly elastic and resilient vinyl elastomer, comprising the following steps:

[0032] Step 1: Add 500 mL of n-hexane to a 2 L high-pressure reactor that has been fully purged with nitrogen, heat to 70 °C, and introduce ethylene with stirring until saturation. Under nitrogen protection, add α-diimine nickel complex, 1-butene, and 1,7-octadiene sequentially to the reactor. Polymerization is carried out by controlling the monomer feed composition in stages (the first stage introduces a higher proportion of ethylene to form ethylene-rich segments, the second stage increases the proportion of 1-butene to form α-olefin-rich segments, and the third stage restores a higher proportion of ethylene to form the other end of the ethylene-rich segments). Control the total amount of monomers to ensure that the final copolymer composition meets the following requirements: based on the total molar amounts of ethylene, 1-butene, and 1,7-octadiene, the amount of ethylene is 62 mol%, the amount of 1-butene is 37 mol%, and the amount of 1,7-octadiene is 1.0 mol%. After the polymerization reaction proceeds for 45 min, inject the reaction solution into a large amount of ethanol to precipitate the polymer. After washing and drying, the vinyl copolymer precursor is obtained.

[0033] Step 2: Dissolve 50g of the vinyl copolymer precursor in 1.5L of n-hexane. Under a nitrogen atmosphere, add dropwise the ring-closing reagent 4,4'-diazidodiphenylmethane (0.60 times the molar amount of the double bond from 1,7-octadiene in the vinyl copolymer precursor). React at 90℃ for 0.5h. Then add the monofunctional end-capping agent benzyl azide (0.30 times the amount of 4,4'-diazidodiphenylmethane) to quench unreacted active groups and terminate the reaction. Pour the reaction solution into a large volume of stirred ethanol / acetone mixed solvent for sedimentation separation. The solid product is precipitated, washed and filtered repeatedly, and dried to constant weight in a vacuum oven to finally obtain a high-elasticity, high-resilience vinyl elastomer.

[0034] Comparative Example 1: The difference between this comparative example and Example 1 is that it does not use staged feeding.

[0035] A method for preparing a highly elastic and resilient vinyl elastomer includes the following steps:

[0036] Step 1: Add 500 mL of cyclohexane to a 2 L high-pressure reactor that has been fully purged with nitrogen, heat to 70 °C, and introduce ethylene under stirring until saturation; under nitrogen protection, add dimethylsilylbis(indenyl)zirconium dichloride to the reactor in sequence, and add all the metered 1-octene and 5-vinyl-2-norbornene to the reactor at once. After the polymerization reaction proceeds for 45 min, inject the reaction solution into a large amount of ethanol to precipitate the polymer. After washing and drying, the vinyl copolymer precursor is obtained.

[0037] Step 2: Dissolve 50g of the vinyl copolymer precursor in 1L of cyclohexane. Under a nitrogen atmosphere, add the ring-closing reagent 1,6-hexanedithiol (0.25 times the molar amount of the double bond from 5-vinyl-2-norbornene in the vinyl copolymer precursor). React at 20°C for 24h. Then add the monofunctional end-capping agent n-propanethiol (0.10 times the amount of 1,6-hexanedithiol) to quench unreacted active groups and terminate the reaction. Pour the reaction solution into a large volume of stirred ethanol / acetone mixed solvent for sedimentation separation. The solid product is precipitated. The product is repeatedly washed, filtered, and dried in a vacuum oven to constant weight to finally obtain a high-elasticity, high-resilience vinyl elastomer.

[0038] Comparative Example 2: The difference between this comparative example and Example 1 is that no ring-closing reaction reagent is added.

[0039] A method for preparing a highly elastic and resilient vinyl elastomer includes the following steps:

[0040] Step 1: Add 500 mL of cyclohexane to a 2 L high-pressure reactor that has been fully purged with nitrogen, heat to 70 °C, and introduce ethylene while stirring until saturation. Under nitrogen protection, add dimethylsilylbis(indenyl)zirconium dichloride, 1-octene, and 5-vinyl-2-norbornene sequentially to the reactor. Polymerization is carried out by controlling the monomer feed composition in stages (the first stage introduces a higher proportion of ethylene to form ethylene-rich segments, the second stage increases the proportion of 1-octene to form α-olefin-rich segments, and the third stage...). To restore a higher ethylene ratio and form another ethylene-rich segment, the total amount of monomers fed was controlled so that the final copolymer composition met the following requirements: based on the total molar amounts of ethylene, 1-octene, and 5-vinyl-2-norbornene, the amount of ethylene was 72.7 mol%, the amount of 1-octene was 27 mol%, and the amount of 5-vinyl-2-norbornene was 0.3 mol%. After the polymerization reaction proceeded for 45 min, the reaction solution was injected into a large amount of ethanol to precipitate the polymer. After washing and drying, the vinyl copolymer precursor was obtained.

[0041] Step 2: Dissolve 50g of vinyl copolymer precursor in 1L of cyclohexane and react at 20°C for 24h under a nitrogen atmosphere. Pour the reaction solution into a large amount of stirred ethanol / acetone mixed solvent for sedimentation and separation, and precipitate solid product. The product is repeatedly washed, filtered, and dried in a vacuum oven to constant weight to finally obtain high elasticity and high resilience vinyl elastomer.

[0042] Performance testing

[0043] 1. Rebound performance test

[0044] The resilience of vinyl elastomers was tested in accordance with ASTM D2632 standard.

[0045] 2. Hardness test

[0046] The hardness of vinyl elastomers was tested in accordance with GB / T 2411-2008 standard.

[0047] 3. Compression Permanent Deformation Test

[0048] The compression set properties of vinyl elastomers were tested in accordance with GB / T 7759.1-2015.

[0049] 4. Gel content test

[0050] The gel content of vinyl elastomers was tested according to ASTM D2765 standard.

[0051] 5 Melt strength test

[0052] The melt strength of vinyl elastomers was tested in accordance with the GB / T 45336-2025 standard.

[0053] Table 1 Performance test results of vinyl elastomers

[0054] sample Hardness (Shore A) Rebound rate (%) Compression set (%) Gel content (%) Melt strength (cN) Example 1 72 68 19 0.7 8.5 Example 2 70 66 20 0.8 7.7 Example 3 69 63 24 1.2 7.1 Comparative Example 1 65 51 35 0.6 4.4 Comparative Example 2 71 57 28 0 5.6

[0055] As shown in Table 1, the vinyl elastomers prepared in all embodiments exhibit excellent comprehensive properties, with a hardness ranging from 69 to 72 Shore A, a resilience of 63-68%, a compression set controlled at 19-24%, a gel content of less than 1.2%, and a melt strength of 7.1-8.5 cN. This superior performance is attributed to the unique molecular structure design of this invention: First, the staged controlled polymerization enables the molecular chain to form a gradient structure with ethylene-rich ends (hard segments) and α-olefin-rich middle (soft segments). The hard segment regions form physical cross-linking points to provide the driving force for resilience, while the soft segment regions provide flexibility. Second, the intramolecular ring-closure reaction under dilute solution conditions introduces a topological constraint structure within the chain, effectively limiting the slippage and untangling of the molecular chain under stress. The synergistic effect of these two factors allows the material to achieve a comprehensive performance of high resilience, low compression set, and excellent melt strength while maintaining thermoplastic processability.

[0056] In contrast, Comparative Example 1, which did not employ staged feeding, yielded a product with a hardness of only 65 Shore A, a low rebound rate of 51%, a high compression set of 35%, and a melt strength of 4.4 cN. This is because a single feeding process only yields an unreturned copolymer, failing to form a gradient hard segment structure rich in ethylene at both ends. This results in a lack of physical cross-linking points, making the molecular chains prone to irreversible slippage during stretching and shrinkage, manifesting as poor elastic recovery, large permanent deformation, and insufficient melt strength. Comparative Example 2, without the addition of a ring-closing reactive agent, yielded a product with a rebound rate of only 57%, a compression set of 28%, and a melt strength of 5.6 cN, all significantly inferior to Example 1. This is due to the lack of topological constraints from intrachain closed rings. Linear molecular chains are still prone to interchain slippage and entanglement dissociation under external forces, failing to effectively dissipate energy and recover quickly. This indicates that relying solely on a gradient structure is insufficient to achieve optimal elastic performance; the introduction of intrachain closed rings plays a crucial role in improving overall performance.

[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a highly elastic and resilient vinyl elastomer, characterized in that, Includes the following steps: Step 1: In the presence of a catalyst, ethylene, α-olefin comonomer and functional monomer containing unsaturated double bonds are subjected to solution polymerization to obtain vinyl copolymer precursor; Step 2: Dissolve the vinyl copolymer precursor in an organic solvent, add a ring-closing reaction reagent to carry out an intramolecular ring-closing reaction, then add a monofunctional end-capping agent to terminate the reaction, separate, wash and dry to obtain a high-elasticity, high-resilience vinyl elastomer.

2. The method for preparing a high-elasticity, high-resilience vinyl elastomer according to claim 1, characterized in that, The catalyst in step 1 is a metallocene catalyst or a post-transition metal single-center catalyst.

3. The method for preparing the high-elasticity, high-resilience vinyl elastomer according to claim 1, characterized in that, In step 1, the α-olefin comonomer is selected from one or more of 1-butene, 1-hexene, and 1-octene.

4. The method for preparing a high-elasticity, high-resilience vinyl elastomer according to claim 1, characterized in that, In step 1, the functional monomer containing unsaturated double bonds is selected from one or more of 5-vinylidene-2-norbornene, 5-vinyl-2-norbornene, ethylidene norbornene, and 1,7-octadiene.

5. The method for preparing a high-elasticity, high-resilience vinyl elastomer according to claim 1, characterized in that, In step 1, based on the total molar amounts of ethylene, α-olefin comonomer, and functional monomer, the amount of ethylene is 62-72 mol%, the amount of α-olefin comonomer is 27-37 mol%, and the amount of functional monomer is 0.3-1.0 mol.

6. The method for preparing a high-elasticity, high-resilience vinyl elastomer according to claim 1, characterized in that, In step 1, solution polymerization is carried out by controlling the monomer feed composition in stages.

7. The method for preparing a high-elasticity, high-resilience vinyl elastomer according to claim 1, characterized in that, In step 2, the organic solvent is selected from one or more of cyclohexane, n-hexane, toluene, and xylene.

8. The method for preparing a high-elasticity, high-resilience vinyl elastomer according to claim 1, characterized in that, In step 2, the ring-closing reaction reagent is selected from dithiol compounds or diazide compounds.

9. The method for preparing a high-elasticity, high-resilience vinyl elastomer according to claim 1, characterized in that, The temperature for the intramolecular ring-closing reaction in step 2 is 20-90℃, and the reaction time is 0.5-24h.

10. The method for preparing a high-elasticity, high-resilience vinyl elastomer according to claim 1, characterized in that, The monofunctional end-capping agent in step 2 is selected from monofunctional compounds corresponding to the ring-closing reaction reagent.

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