A ternary ethylene propylene rubber and a method for preparing the same

Abstract

This invention discloses a EPDM rubber and its preparation method, comprising copolymerizing the EPDM rubber from a first structural unit provided by ethylene, a second structural unit provided by propylene, and a third structural unit provided by a polyene monomer. This invention achieves precise control of the molecular structure of the EPDM rubber by introducing a polyene monomer with a specific structure as the third monomer, and combining it with a restricted geometry catalyst or a vanadium-based catalyst, thereby improving the uniformity of the copolymer and the vulcanization efficiency. The resulting rubber exhibits a narrow molecular weight distribution, suitable Mooney viscosity, and good processing properties, making it suitable for high-performance rubber products. The preparation method is simple, environmentally friendly, and easy to industrialize.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a ternary ethylene propylene diene monomer (EPDM) rubber and its preparation method. Background Technology

[0002] Ethylene propylene diene monomer (EPDM) is a terpolymer of ethylene, propylene, and a small amount of non-conjugated diene third monomer. Due to its excellent ozone resistance, weather resistance, heat aging resistance, and electrical insulation properties, it is widely used in automotive sealing, building materials, and cable insulation.

[0003] Industrially used third monomers mainly include ethylene norbornene (ENB), dicyclopentadiene (DCPD), and 1,4-hexadiene (HD). However, these traditional third monomers each have their inherent limitations: ENB is expensive, increasing production costs; DCPD has a slow vulcanization reaction rate, affecting production efficiency; and HD's copolymerization activity and polymer chain branching structure are difficult to control precisely. These factors can all lead to problems such as excessively wide molecular weight distribution, uneven branching, and unsatisfactory vulcanization efficiency in the final product, thereby restricting further improvements in rubber processing performance and the physical and mechanical properties of vulcanized rubber.

[0004] With the deepening of the concept of green chemistry, polyene compounds, which are widely available and structurally diverse, are considered as potential materials to replace traditional third monomers. Introducing them into the main chain of ethylene propylene rubber is expected to improve the rubber's properties while giving the product better environmental friendliness.

[0005] CN 119661760 A discloses a method for preparing modified EPDM rubber. Through in-situ functionalization, controllable grafting at the double bond sites of EPDM is achieved without the ethylene-propylene segment participating in the reaction. The introduced ether compounds effectively inhibit gel formation, exhibiting advantages such as high reaction efficiency and few side reactions. CN 114634591 A discloses a liquid polyfarnesene rubber, its preparation method, and its applications. This method uses β-farnesene as a monomer for polymerization, followed by quenching, washing, and drying to obtain the final product. The prepared liquid rubber exhibits a low glass transition temperature (-120℃ to -80℃) and a high 1,4-structure content (60% to 99%), making it suitable for manufacturing high-performance tires or chemical protective clothing. CN 118027291 A discloses a myrcene / farnesene copolymer, its preparation method, and its applications. Both the myrcene and farnesene units include 1,2- and 1,4-structural units, with the 1,4-structured myrcene and 1,4-structured farnesene units each accounting for more than 40% of the total copolymer content. This copolymer possesses a high molecular weight and can be used as an elastomer, representing a promising green bio-based rubber product and providing a renewable alternative to petroleum resources.

[0006] However, successfully applying polyene monomers to the synthesis of EPDM faces a series of technical challenges: First, it is necessary to screen specific polyene monomers with suitable reactivity and spatial structure; second, it is essential to develop matching efficient catalytic systems and polymerization processes to achieve controlled copolymerization with ethylene and propylene, thereby obtaining rubber products with ideal molecular chain structures and comprehensive properties. Therefore, there is an urgent need in this field to develop a novel EPDM-based terephthalic acid (EPDM) rubber to overcome the shortcomings of traditional materials and meet the growing demand for high-performance, low-cost, and green rubber products. Summary of the Invention

[0007] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0008] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0009] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a ternary ethylene propylene diene monomer (EPDM) rubber and its preparation method.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a EPDM rubber, characterized in that: the EPDM rubber is copolymerized from a first structural unit provided by ethylene, a second structural unit provided by propylene and a third structural unit provided by a polyene monomer, and the chemical formula is shown in formula (I); the structural formula of the polyene monomer is shown in formula (III), and it contains at least three double bonds; Formula (I); In formula (I), R1 and R2 are independently selected from -H, -CH3, -CH2CH3 or substituents having the structure shown in formula (II).

[0011] Formula (II); In equation (II), j, k, and q are each an independent integer of 0, 1, 2, or 3, and * indicates the connection position of the substituent; In formula (I), the structural units x, y, z, w are arranged randomly, and structural units x and w are obtained by polymerization of polyene monomers with the structure of formula (III) through 1, 2 or 1, 4. Formula (III); In equation (III), R1 and R2 have the same definitions as R1 and R2 in equation (I).

[0012] As a preferred embodiment of the EPDM rubber of the present invention, the content of the first structural unit is 40wt%-70wt%, the content of the second structural unit is 20wt%-50wt%, and the content of the third structural unit is 0.1wt%-15wt%, based on the total weight of the EPDM rubber.

[0013] As a preferred embodiment of the EPDM rubber of the present invention, the content of the third structural unit is 3wt%-8wt%.

[0014] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing ethylene propylene diene monomer (EPDM) rubber, characterized by comprising: Ethylene and propylene are mixed to prepare a mixed gas; Solvent, polyene monomer, catalyst system, mixed gas, and hydrogen are sequentially added to a reaction vessel and stirred to obtain EPDM rubber solution; The reaction was terminated by adding a terminator to the EPDM rubber solution, and then the rubber was precipitated with an alcohol solvent. After washing and drying, EPDM rubber was obtained.

[0015] In a preferred embodiment of the preparation method described in this invention, the polyene monomer is a terpene monomer, including one or more of farnesene, ocimene, and myrcene.

[0016] In a preferred embodiment of the preparation method described in this invention, the catalytic system comprises a main catalyst, a co-catalyst, and an activator; wherein the main catalyst comprises a CGC catalyst or a vanadium-based catalyst, the CGC catalyst being a catalyst comprising a metal center of titanium, zirconium, or hafnium, a cyclopentadienyl ligand, and a functional group coordinated to a nitrogen or oxygen atom, and the vanadium-based catalyst comprising vanadium oxychloride and vanadium acetylacetonate; the co-catalyst is an alkylaluminum compound, including one or more of trialkylaluminum, alkylaluminum halides, and alkylaluminoxanes; the activator comprises one or more of ethyl trichloroacetate, tris(pentafluorophenyl)boron, and triphenylmethyltetra(pentafluorophenyl)borate.

[0017] In a preferred embodiment of the preparation method described in this invention, the alkyl aluminum compound is triethylaluminum, triisobutylaluminum, diethylaluminum chloride, or methylaluminoxane.

[0018] In a preferred embodiment of the preparation method described in this invention, the solvent includes one or more of n-hexane, cyclohexane, pentane, or toluene.

[0019] In a preferred embodiment of the preparation method described in this invention, the amount of hydrogen added is such that the Mooney viscosity (ML(1+4)) of the obtained EPDM rubber is controlled to be between 20 and 80 at 125°C, and the number-average molecular weight is between 500 and 250,000.

[0020] As a preferred embodiment of the preparation method described in this invention, the reaction temperature in the reactor is 0°C to 70°C, the reaction pressure is 0.1 MPa to 1.0 MPa, and the reaction time is 0.5 hours to 2.5 hours.

[0021] Beneficial effects of this invention: This invention achieves precise control over the molecular structure of EPDM rubber by introducing a polyene monomer with a specific structure as a third monomer and combining it with a restricted geometry catalyst or a vanadium-based catalyst, thereby improving the uniformity of the copolymer and the vulcanization efficiency. The resulting rubber exhibits a narrow molecular weight distribution, suitable Mooney viscosity, and good processing properties, making it suitable for high-performance rubber products. The preparation method is simple, environmentally friendly, and easy to industrialize. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is the structural formula of the polyene monomer mentioned in this invention.

[0023] Figure 2 This is a SEM image of product A obtained in Example 1 of the present invention.

[0024] Figure 3 This is a SEM image of product A after mixing in Example 3 of the present invention. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] Unless otherwise specified, all raw materials used in the embodiments of this invention are commercially available. See Table 1 for details.

[0029] Table 1

[0030] Mooney viscosity was measured on a Mooney viscometer (MV-3000 type) according to GB / T 1232.1 standard.

[0031] Compositional analysis by proton nuclear magnetic resonance (¹H NMR) was performed on a nuclear magnetic resonance spectrometer (400 MHz) in accordance with the quantitative principle standard of ASTM D5017.

[0032] Molecular weight was determined by gel permeation chromatography (GPC) according to ASTM D5296 standard on a gel permeation chromatograph.

[0033] Vinyl content was determined by Fourier transform infrared spectroscopy (FT-IR) on a Fourier transform infrared spectrometer according to GB / T 6040 standard.

[0034] The tensile strength and elongation at break of the vulcanizate were determined on a universal testing machine in accordance with GB / T 528 standard.

[0035] The tear strength of the vulcanizate was determined on a universal testing machine according to GB / T 529 standard.

[0036] The compression set of vulcanized rubber was measured in accordance with GB / T 7759.1 using a compression set apparatus and a heat aging chamber.

[0037] The heat resistance of vulcanizates to air aging was tested in a hot air aging chamber according to GB / T 3512 standard.

[0038] Example 1 2L of fully dehydrated n-hexane, 10g of ocimene, 5μmol of a hexane solution containing a defined geometry catalyst (CGC, titanium metal center), and methylaluminoxane (MAO) were added sequentially to a 5L high-pressure reactor that had been thoroughly baked and purged with nitrogen. The Al / Ti molar ratio was 500:1. The activator was tris(pentafluorophenyl)boron with a B / Ti molar ratio of 1:1.

[0039] The reactor was sealed, and a mixture of ethylene and propylene (ethylene:propylene weight ratio = 60:40) was introduced to maintain the pressure inside the reactor at 0.5 MPa. Hydrogen was then introduced as a molecular weight regulator, controlling the hydrogen partial pressure to 0.01 MPa. Stirring was started, and polymerization was carried out at 20°C for 0.5 hours. After the reaction, the reaction solution was depressurized to atmospheric pressure, and an ethanol solution containing 1 wt% antioxidant was added to terminate the reaction and precipitate the rubber. The precipitated rubber was washed three times with ethanol and dried to constant weight in a vacuum drying oven at 50°C to obtain a white, sheet-like EPDM rubber product A, with the structural formula shown in formula (a). Equation (a); Where y is an integer between 5000 and 6000, z is an integer between 1000 and 2000, and x+w is an integer between 50 and 100.

[0040] Figure 1 The structure is that of ocimene, a polyene monomer. The Mooney viscosity (ML(1+4)) of product A at 125°C was tested to be 35. The ethylene unit content is 65 wt%, the propylene unit content is 30 wt%, and the myrcene unit content is 5 wt%. The morphology of the raw rubber was tested using SEM, as shown below. Figure 2 As shown.

[0041] Example 2 The difference from Example 1 is that the third monomer was replaced with farnesene, with an amount of 15g; the main catalyst was replaced with vanadium oxychloride (VOCl3), with an amount of 0.1mmol; the co-catalyst was diethylaluminum chloride (Et2AlCl), with an Al / V molar ratio of 20:1; and the activator was ethyl trichloroacetate, with an amount of 0.2mmol. The reaction temperature was 30℃, the reaction pressure was 0.8MPa, and everything else was the same as in Example 1, resulting in EPDM rubber product B with the structural formula shown in formula (b). Equation (b); Where y is an integer between 4000 and 5000, z is an integer between 2000 and 2500, and x+w is an integer between 10 and 30.

[0042] Its Mooney viscosity is 55, ethylene unit content is 58 wt%, propylene unit content is 40 wt%, and farnesene unit content is 2 wt%.

[0043] Comparative Example 1 The difference from Example 1 is that the polyene monomer ocimene is replaced with the traditional third monomer ethylene norbornene (ENB), otherwise it is the same as Example 1, resulting in comparative sample C.

[0044] Its Mooney viscosity is 38, ethylene unit content is 66 wt%, propylene unit content is 29 wt%, and ENB unit content is 5 wt%.

[0045] Comparative Example 2 The difference from Example 2 is that the polyene monomer farnesene is replaced with the traditional third monomer ethylene norbornene (ENB), while the rest is the same as in Example 1, resulting in comparative sample D.

[0046] Its Mooney viscosity is 58, ethylene unit content is 59 wt%, propylene unit content is 39 wt%, and ENB unit content is 2 wt%.

[0047] Example 3 Products (rubber) A, B, C, and D obtained from the examples and comparative examples were compounded and vulcanized according to the same formula. The formula was: 100 parts rubber, 50 parts carbon black N550, 5 parts zinc oxide, 1 part stearic acid, 1.5 parts accelerator tetramethylthiuram disulfide, and 1.5 parts sulfur.

[0048] The physical and mechanical properties and SEM morphology of the vulcanized rubber were tested. The mechanical property results are shown in Table 2 below. Representative morphology product A is shown in the figure. Figure 3 As shown.

[0049] Table 2

[0050] As shown in Table 2 above, the vulcanizates made from EPDM rubber (products A and B) provided by this invention have better mechanical properties such as tensile strength and tear strength than traditional ENB type EPDM, while also having lower compression set and better heat aging resistance.

[0051] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A EPDM rubber, characterized in that: Ethylene propylene diene monomer (EPDM) rubber is copolymerized from a first structural unit provided by ethylene, a second structural unit provided by propylene, and a third structural unit provided by a polyene monomer, as shown in formula (I); the polyene monomer has the structural formula shown in formula (III) and contains at least three double bonds. Equation (I); In formula (I), R1 and R2 are selected from -H, -CH3, -CH2CH3 or substituents having the structure shown in formula (II); Formula (II); In equation (II), j, k, q are integers of 0, 1, 2 or 3, and * indicates the connection position of the substituent; In formula (I), the structural units x, y, z, w are arranged randomly, and structural units x and w are obtained by polymerization of polyene monomers with the structure of formula (III) through 1, 2 or 1, 4. Formula (III); In equation (III), R1 and R2 have the same definitions as R1 and R2 in equation (I).

2. The EPDM rubber as described in claim 1, characterized in that: The polyene monomer is a terpene monomer, including one or more of farnesene, ocimene, and myrcene.

3. The EPDM rubber as described in claim 1, characterized in that: Based on the total weight of EPDM rubber, the content of the first structural unit is 40wt%-70wt%, the content of the second structural unit is 20wt%-50wt%, and the content of the third structural unit is 0.1wt%-15wt%.

4. The EPDM rubber as described in claim 3, characterized in that: The content of the third structural unit is 3wt%-8wt%.

5. The method for preparing EPDM rubber according to any one of claims 1-4, characterized in that: include, Ethylene and propylene are mixed to prepare a mixed gas; Solvent, polyene monomer, catalyst system, mixed gas, and hydrogen are sequentially added to a reaction vessel and stirred to obtain EPDM rubber solution; The reaction was terminated by adding a terminator to the EPDM rubber solution, and then the rubber was precipitated with an alcohol solvent. After washing and drying, EPDM rubber was obtained.

6. The preparation method according to claim 5, characterized in that: The catalytic system includes a main catalyst, a co-catalyst, and an activator; wherein the main catalyst includes a CGC catalyst or a vanadium-based catalyst, the CGC catalyst being a catalyst containing a metal center of titanium, zirconium, or hafnium coordinated with a cyclopentadienyl ligand and a functional group bonded to a nitrogen or oxygen atom, and the vanadium-based catalyst including vanadium trichloride and vanadium acetylacetonate; the co-catalyst is an alkylaluminum compound, including one or more of trialkylaluminum, alkylaluminum halides, and alkylaluminoxanes; the activator includes one or more of ethyl trichloroacetate, tris(pentafluorophenyl)boron, and triphenylmethyltetra(pentafluorophenyl)borate.

7. The preparation method according to claim 6, characterized in that: The alkylaluminum compound is triethylaluminum, triisobutylaluminum, diethylaluminum chloride, or methylaluminoxane.

8. The preparation method according to claim 5, characterized in that: The solvent includes one or more of n-hexane, cyclohexane, pentane, or toluene.

9. The preparation method according to claim 5, characterized in that: The amount of hydrogen added is used to control the Mooney viscosity (ML(1+4)) of the obtained EPDM rubber at 125°C to be between 20 and 80; and the number average molecular weight to be between 500 and 250,000.

10. The preparation method according to claim 5, characterized in that: The reaction temperature in the reactor is 0℃ to 70℃, the reaction pressure is 0.1MPa to 1.0MPa, and the reaction time is 0.5 hours to 2.5 hours.

Images