Functionalized polyolefins, methods for their preparation and use

Abstract

This invention relates to a functionalized polyolefin, its preparation method, and its applications. The method involves copolymerizing a first monomer, a second monomer, and a third monomer in a solvent system under the action of a catalyst. The first monomer is either ethylene or an α-olefin; the second monomer is an acrylate; and the third monomer is either vinyl norbornene, ethylene-imide norbornene, or dicyclopentadiene. Compared with existing technologies, this invention uses an acrylate monomer, improving the efficiency of functionalized polyolefin production; it uses vinyl norbornene, which has low double bond steric hindrance, increasing the crosslinking speed; and because the crosslinking double bonds are located outside the ring, the low steric hindrance facilitates crosslinking.

Description

Technical Field

[0001] This invention belongs to the field of polyolefin material preparation technology, and relates to a functionalized polyolefin, its preparation method and application. Background Technology

[0002] Olefin polymers are widely used in packaging, transportation, medical, and cable industries. Polyolefin resins can be classified into homopolymers and copolymers according to their composition. Copolymers can be further classified into binary copolymers and ternary copolymers based on the composition of their comonomers. For example, ethylene propylene diene monomer (EPDM) rubber is a ternary copolymer of ethylene, propylene, and a small amount of non-conjugated diene. Its main chain consists of chemically stable saturated hydrocarbons, with unsaturated double bonds only in the side chains. Therefore, it exhibits excellent ozone resistance, heat resistance, weather resistance, and other aging resistance properties, and can be widely used in automotive parts, waterproof building materials, wire and cable sheathing, heat-resistant hoses, tapes, and automotive seals.

[0003] Conventional terpolymers consist entirely of nonpolar carbon chains, limiting their surface properties, adhesive properties, and compatibility. To improve these properties, a certain amount of polar functionalized groups needs to be introduced into the nonpolar carbon chains. CN111171204B discloses a polar polyolefin material, which is a random copolymer formed by copolymerizing an ethylene monomer represented by the formula CH2=CH2, a dimercyclopentadiene monomer or an ethylene-based norbornene monomer as the first comonomer, and a polar norbornene monomer as the second comonomer. In this patent, the cyclic norbornene monomer has a large rigid volume, which reduces the polymerization reactivity, resulting in low preparation efficiency of the polar polyolefin; at the same time, the steric hindrance of the exocyclic double bonds in the nonpolar norbornene is not conducive to further rapid crosslinking. Summary of the Invention

[0004] The purpose of this invention is to provide a functionalized polyolefin, its preparation method, and its application, which can improve the efficiency and crosslinking speed of functionalized polyolefin production.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] One of the technical solutions of the present invention provides a method for preparing functionalized polyolefins, wherein a first monomer, a second monomer, and a third monomer are copolymerized in a solvent system under the action of a catalyst, wherein the first monomer is ethylene or an α-olefin; the second monomer is an acrylate; and the third monomer is vinyl norbornene, ethylene-imide norbornene, or dicyclopentadiene.

[0007] Furthermore, the catalyst has the following structural formula:

[0008] Wherein, R is methyl, phenyl, or contains at least one C1-C1 group. 10 Phenyl groups that are either unsubstituted or substituted alkyl or alkoxy groups.

[0009] Specifically, the catalyst is wait.

[0010] Furthermore, when the first monomer is ethylene, its addition amount satisfies the reaction system pressure of 0.1-5 MPa, and the molar ratio of the second monomer to the third monomer is (0.1-5):(0.1-10).

[0011] Furthermore, the acrylate is butyl acrylate or polyethylene glycol methacrylate.

[0012] Furthermore, the amount of catalyst added is 0.1-100 μmol / L. Specifically, it can be 1-50 μmol / L, more specifically, 10-50 μmol / L, etc. For example, it can be 1 μmol / L, 10 μmol / L, 20 μmol / L, 50 μmol / L, etc.

[0013] Furthermore, the copolymerization reaction is carried out at a temperature of 60-130℃ for a time of 0.1-5 hours.

[0014] Furthermore, during the copolymerization reaction, the amount of the first monomer added is maintained until the system pressure is 0.1–5 MPa.

[0015] Furthermore, the solvent is one or a mixture of several of toluene, n-pentane, n-hexane, and n-heptane.

[0016] The second technical solution of the present invention provides a functionalized polyolefin, which is prepared by any of the preparation methods described above, and the stress threshold Δσ at 300% strain after vulcanization and crosslinking is the same as that before vulcanization and crosslinking. 300％ The pressure ranges from 0.1 MPa to 15 MPa, with an optimal range of 3 MPa to 15 MPa.

[0017] The third technical solution of the present invention provides an application of functionalized polyolefins in packaging materials, automotive parts, and medical materials.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) The polymerization activity is an order of magnitude higher than that of existing technologies such as CN111171204B.

[0020] (2) Due to the use of fewer rigid cyclic monomers, it has better flexibility and its elongation at break is twice that of the polyolefin material provided by CN111171204B.

[0021] (3) Because the crosslinking double bonds are located outside the ring (e.g., when the third monomer is vinyl norbornene), the steric hindrance is relatively small, making crosslinking easier. The stress threshold (Δσ) at 300% strain before vulcanization of crosslinked polyolefins. 300％ The pressure ranges from 0.1 MPa to 15 MPa. Attached Figure Description

[0022] Figure 1 A comparison of the mechanical properties of functionalized ethylene terpolymers and vulcanized polymers. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0024] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0025] Example 1: Preparation of Catalyst 1

[0026]

[0027] In the first flask, p-toluenesulfonic acid (4.14 g, 24 mmol) and THF (60 mL) were added, cooled to 0 °C, and stirred for 10 min. Then, n-butyllithium (19.2 mL, 2.5 M n-hexane solution, 48 mmol) was slowly added. After the addition was complete, the mixture was stirred at 25 °C for 1 h, and then cooled to -78 °C. In the second flask, PPhCl2 (3.25 mL, 24 mmol) and THF (60 mL) were added, and the mixture was cooled to -78 °C. The solution from the first flask was then added to the second flask, and the mixture was slowly heated to 0 °C and stirred for 1.5 h, and then cooled to -78 °C. In the third flask, 1-bromo-2-(2,6-dimethoxyphenyl)benzene (7.0 g, 24 mmol) and THF (140 mL) were added, and the mixture was cooled to -78 °C. Then, n-butyllithium (11.2 mL, 2.5 M n-hexane solution, 28 mmol) was added, and the mixture was stirred at -78 °C for 1 h. Maintaining a temperature of -78°C, the material from the second flask was added to the third flask. After the addition was complete, the temperature was slowly raised to 25°C and stirred overnight. The solvent was removed under vacuum, and the residue was added to 50 mL of water and acidified with dilute hydrochloric acid to pH 2. Extraction was performed with CH2Cl2, followed by drying with anhydrous Na2SO4 and removal of the solvent under vacuum. The resulting solid was slurried with DCM and diethyl ether, filtered, and dried to obtain a white solid, namely 9.1 g of the catalyst ligand.

[0028] The catalyst ligand (535.0 mg, 1.0 mmol), (TMEDA)PdMe2 (252.7 mg, 1.0 mmol), and THF (10 mL) were added to a round-bottom flask and stirred at room temperature for 1 h. Pyridine (395.5 mg, 5 mmol) was added and stirring continued for 1 h. Diethyl ether (30 mL) was added, and a solid precipitated at –25 °C. The precipitate was filtered, the filter cake was washed with diethyl ether, and dried under vacuum to obtain 0.41 g of a white solid, which is catalyst 1.

[0029] 1 H NMR(500MHz,Chloroform-d)δ8.38-6.52(m,20H),3.67(s,3H),2.77(s,3H),2.26(s,3H),0.30(d,3H).

[0030] Example 2-11 Catalyst 1 catalyzes the polymerization of ethylene-acrylate-third monomer

[0031] A 1000 mL stainless steel reactor equipped with a magnetically coupled mechanical stirrer was vacuum-dried at 90 °C for 1 h. After cooling to 25 °C, 200 mL of reaction solvent (toluene), acrylate, the third monomer, a 2 mL solution of BHT (2,6-di-tert-butyl-p-cresol) in toluene, and a 2 mL solution of catalyst 1 (10 μmol) in dichloromethane were added to the reactor. The reactor was stirred and heated to the polymerization temperature of 95 °C, then ethylene was introduced into the reactor at 2 MPa and maintained. After the polymerization time (1 h) was reached, the ethylene pressure was released to atmospheric pressure and the reactor was cooled to 30 °C. 400 mL of ethanol was added to the reactor to precipitate the polymer, which was then filtered and the filter cake was vacuum-dried. The results are shown in Table 1.

[0032] Table 1. Polymerization results of ethylene-acrylate-third monomer

[0033]

[0034]

[0035] In the table above, BA represents butyl acrylate, VNB represents vinyl norbornene, EGMA represents polyethylene glycol methacrylate, ENB represents ethylidene norbornene, and DCPD represents dicyclopentadiene.

[0036] In the table above, the concentrations of the second and third monomers are represented by their respective concentration values.

[0037] Examples 12-17: Vulcanization Crosslinking of Terpolymers

[0038] 3.0 g of polymer (corresponding to the copolymers prepared in Examples 2, 4, 6, 9, 10, and 11 respectively, in Examples 12 to 17) was dissolved in 100 mL of toluene at 90 °C. 150 mg of zinc oxide, 30 mg of stearic acid, 15 mg of MBT, 20 mg of TMTD, and 30 mg of sulfur were added, and the mixture was stirred for 30 min and then vacuum dried. The resulting polymer was cured at 160 °C and 10 MPa for 20 min on a flat vulcanizing machine. The polymers before and after crosslinking were subjected to a 300% strain cyclic tensile test to measure the stress (σ) at 300% strain. 前 and σ 后 ), calculate the stress threshold (Δσ) at 300% strain before and after crosslinking. 300％ =σ 后 -σ 前 The results are shown in Table 2.

[0039] Comparative Examples 1-2: Vulcanization Crosslinking of Ethylene-Dicyclopentadiene-Polar Norbornene Polymers

[0040] The results were largely the same as in Example 15, except that the acrylate was replaced with dicyclopentadiene and the third monomer was replaced with polar norbornene. The results are shown in Table 2. NBOH represents 5-norbornene-2-methanol, and NBOAC represents 5-norbornene-2-ylacetic acid ester.

[0041] Table 2 Stress changes before and after crosslinking

[0042]

[0043]

[0044] Figure 1 This is a comparison of the mechanical properties of functionalized ethylene terpolymer (Example 9) and the cross-linked polymer after vulcanization (Example 15). The figure shows the stress threshold (Δσ) of the cross-linked polymer at 300% strain. 300％ The pressure is as high as 10.2 MPa. The third monomer, ENB and DCPD in Examples 16 and 17, has a relatively large double bond steric hindrance, with Δσ... 300％ The pressure was reduced to 4.2 MPa and 4.5 MPa. In contrast, in Comparative Examples 1 and 2, the Δσ of the ethylene terpolymer with polar norbornene as the second monomer and dicyclopentadiene as the third monomer after vulcanization and crosslinking was significantly lower. 300％ Only 2.5MPa and 1.7MPa.

[0045] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing functionalized polyolefins, characterized in that, The copolymerization reaction is carried out in a solvent system by a first monomer, a second monomer, and a third monomer under the action of a catalyst, wherein the first monomer is ethylene; the second monomer is one of acrylates; and the third monomer is one of vinyl norbornene, ethylene-imide norbornene, or dicyclopentadiene. The acrylate is butyl acrylate or polyethylene glycol methacrylate; the amount of the first monomer added is such that the reaction system pressure is 0.1-5 MPa, and the molar ratio of the second monomer to the third monomer is (0.1-5):(0.1-10); The catalyst is added in an amount of 0.1-100 μmol / L; The catalyst has the following structural formula: Wherein, R is methyl, phenyl, or contains at least one C1 to C2. 10 Unsubstituted or substituted alkyl or alkoxy phenyl groups; The copolymerization reaction temperature is 60-130℃.

2. The method for preparing a functionalized polyolefin according to claim 1, characterized in that, The copolymerization reaction takes 0.1-5 hours.

3. The method for preparing a functionalized polyolefin according to claim 1, characterized in that, The solvent is one or a mixture of several of toluene, n-pentane, n-hexane, and n-heptane.

4. A functionalized polyolefin, prepared by any one of the preparation methods described in claims 1-3, wherein the stress threshold Δσ at 300% strain after vulcanization crosslinking is the same as that before vulcanization crosslinking. 300％ The pressure ranges from 0.1 MPa to 15 MPa.

5. The application of the functionalized polyolefin as described in claim 4 in packaging materials, automotive parts, and medical materials.

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