Modified EPDM rubber and preparation method thereof

Abstract

The present invention relates to the field of rubber and discloses a modified EPDM rubber and a preparation method thereof. The method comprises: contacting and reacting the EPDM rubber with a compound having a structure represented by formula (1) in the presence of an organic solvent and a catalyst having a structure represented by formula (2) under conditions of a cross-metathesis reaction of olefins. The EPDM rubber contains a first structural unit provided by ethylene, a second structural unit provided by propylene, and a third structural unit provided by a non-conjugated diene monomer. The method is characterized by rapid reaction and ease of implementation. The modified EPDM rubber prepared by this method has a high degree of unsaturation and grafting rate, and exhibits a good compatibilizing effect when the EPDM rubber is used in combination with a polar rubber.

Description

Technical Field

[0001] The present invention relates to the field of rubber, in particular to a method for preparing modified EPDM rubber and the modified EPDM rubber prepared by the method. Background Art

[0002] Ethylene propylene diene monomer (EPDM) has excellent physical and chemical properties such as high elasticity, viscoelasticity, electrical insulation, and is very prominent in applications such as engineering plastic toughening and ozone aging resistance. However, since EPDM belongs to non-polar rubber, its oil resistance, chemical reagent resistance, self-adhesion and mutual adhesion are relatively poor. By using it with diene rubber (such as natural rubber, butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber etc.), it is expected to obtain a rubber with relatively good comprehensive properties. However, EPDM and most diene rubbers have a large difference in polarity and saturation, are difficult to blend with polar polymers, and therefore its range of application is subject to certain restrictions. Therefore, it is particularly important to modify EPDM to enhance its compatibility with polar polymers.

[0003] Chemical modification of EPDM rubber involves introducing additional atoms or groups into the rubber's molecular chain through chemical reactions, imparting polarity or altering flexibility. This improves the compatibility of EPDM with diene rubber blends. This involves inserting polar groups such as acrylonitrile and carboxyl groups into the EPDM backbone, using the modified rubber as a compatibilizer to expand its applications. Acrylonitrile modification is a key method in the chemical modification of EPDM rubber. Through a chemical reaction between EPDM and acrylonitrile, acrylonitrile is introduced into the rubber's molecular chain, increasing its polarity and improving its compatibility with other polymers, thereby broadening its applications.

[0004] The acrylonitrile grafting reaction on EPDM rubber is primarily a free radical reaction, which can be carried out in melt, emulsion, and solution states, including thermomechanical chemical modification and solution modification. Different initiation systems generate different free radicals and have different modification effects.

[0005] However, the modified EPDM rubber obtained by free radical reaction grafting modification has a low grafting rate and low degree of unsaturation, which makes it poorly compatible when used with polar rubber, greatly limiting the application of EPDM rubber. Summary of the Invention

[0006] The purpose of the present invention is to overcome the problems of low grafting rate and unsaturation degree in the prior art when acrylonitrile is grafted to modify EPDM rubber, and to provide a method for preparing modified EPDM rubber and the modified EPDM rubber prepared by the method. The modified EPDM rubber has a good compatibilization effect when EPDM rubber and polar rubber are used in combination.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing modified EPDM rubber, characterized in that the method comprises: under the conditions of a cross-metathesis reaction of olefins, in the presence of an organic solvent and a catalyst having a structure represented by formula (3), contacting the EPDM rubber with a compound having a structure represented by formula (1), wherein the EPDM rubber contains a first structural unit provided by ethylene, a second structural unit provided by propylene, and a third structural unit provided by a non-conjugated diene monomer;

[0008]

[0009] In formula (2), R1 is hydrogen, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C2-C20 carboxylate group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C2-C20 alkenyloxy group, a substituted or unsubstituted C2-C20 alkynyloxy group, a substituted or unsubstituted C6-C20 aryloxy group, a substituted or unsubstituted C1-C20 alkylthio group, a substituted or unsubstituted C1-C20 alkylsulfonyl group, or a substituted or unsubstituted C1-C20 alkylsulfinyl group;

[0010] X1 and X2 are the same or different and are each independently an anionic ligand,

[0011] L1 and L2 are the same or different, and are each independently a neutral ligand, and optionally L1 and L2 can be linked to each other to form a di-coordinated neutral ligand;

[0012] Y is an anion;

[0013] n is an integer from 1 to 6.

[0014] The second aspect of the present invention provides a modified EPDM rubber prepared by the method of the present invention.

[0015] Through the above technical solution, the method for preparing modified EPDM rubber and the modified EPDM rubber prepared by the method provided by the present invention achieve the following beneficial effects:

[0016] The preparation method of the modified EPDM rubber provided by the invention has the characteristics of rapid reaction and simplicity and ease of implementation.

[0017] Furthermore, the modified EPDM rubber provided by the present invention has a high grafting rate and unsaturation. Specifically, the unsaturation of the modified EPDM rubber provided by the present invention is 0.42-1.05 mol / kg, and the grafting rate is 1.0-5.3% by weight.

[0018] Furthermore, compared with the existing EPDM rubber, the modified EPDM rubber provided by the present invention has a better compatibilization effect when the EPDM rubber and the polar rubber are used together.

[0019] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0020] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0021] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0022] A first aspect of the present invention provides a method for preparing modified EPDM rubber, characterized in that the method comprises: contacting EPDM rubber with a compound having a structure represented by formula (1) in the presence of an organic solvent and a catalyst having a structure represented by formula (3) under conditions of a cross-metathesis reaction of olefins, wherein the EPDM rubber contains a first structural unit provided by ethylene, a second structural unit provided by propylene, and a third structural unit provided by a non-conjugated diene monomer;

[0023]

[0024] In formula (2), R1 is hydrogen, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C2-C20 carboxylate group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C2-C20 alkenyloxy group, a substituted or unsubstituted C2-C20 alkynyloxy group, a substituted or unsubstituted C6-C20 aryloxy group, a substituted or unsubstituted C1-C20 alkylthio group, a substituted or unsubstituted C1-C20 alkylsulfonyl group, or a substituted or unsubstituted C1-C20 alkylsulfinyl group;

[0025] X1 and X2 are the same or different and are each independently an anionic ligand,

[0026] L1 and L2 are the same or different, and are each independently a neutral ligand, and optionally L1 and L2 can be linked to each other to form a di-coordinated neutral ligand;

[0027] Y is an anion;

[0028] n is an integer from 1 to 6.

[0029] According to the present invention, in formula (2), R1 is a substituted or unsubstituted C6-C20 aryl group, preferably a phenyl group.

[0030] According to the present invention, in formula (2), X1 and X2 can be various common anionic ligands, for example, each independently a halogen element, preferably X1 and X2 are chlorine elements.

[0031] According to the present invention, in formula (2), L1 and L2 can be various common neutral ligands, specific examples of which may include but are not limited to: amines, thioethers, carbenes, substituted or unsubstituted phosphines, and substituted or unsubstituted imidazolidines. Preferably, L1 and L2 are each independently selected from carbenes, substituted or unsubstituted phosphines, or substituted or unsubstituted imidazolidines; and the optional substituents in L1 and L2 are each independently selected from substituted or unsubstituted C1-C6 alkyl groups and substituted or unsubstituted C6-C10 aryl groups.

[0032] According to the present invention, in formula (2), Y is a halogen ion.

[0033] In one embodiment of the present invention, in formula (2), R1 is a phenyl group; X1 and X2 are chlorine elements; L1 is a substituted or unsubstituted imidazolidine, and the optional substituent in L1 is selected from substituted or unsubstituted C6-C10 aromatic groups; L2 is a phosphine; and Y is an iodine anion.

[0034] The phosphine may be a compound in which the hydrogen atoms in various phosphine molecules are partially or completely replaced by organic groups, preferably a trialkylphosphine. The organic groups may be the same or different and each may be selected from a chain alkyl group (e.g., a substituted or unsubstituted C1-C10 chain alkyl group) or a substituted or unsubstituted cycloalkyl group (e.g., a substituted or unsubstituted C6-C12 cycloalkyl group), preferably each selected from a substituted or unsubstituted cycloalkyl group, and more preferably a cyclohexyl group. Specifically, the phosphine may be a trialkylphosphine, specific examples of which may include, but are not limited to, one or more of trimethylphosphine, triethylphosphine, tri-n-butylphosphine, tri-sec-butylphosphine, tripropylphosphine, tripentylphosphine, trihexylphosphine, trioctylphosphine, and tricyclohexylphosphine.

[0035] According to the present invention, L1 is an imidazolidine having a structure shown in formula (3),

[0036]

[0037] In formula (3), R2 and R3 are the same or different and are each independently a substituted or unsubstituted C6-C20 aryl group.

[0038] Preferably, in formula (3), R2 and R3 are each independently R4, R5, R6, R7 and R8 are the same or different and are each independently selected from hydrogen or a substituted or unsubstituted C1-C5 alkyl group.

[0039] Preferably, in formula (3), R2 and R3 are R6 and R8 are the same or different and are each independently selected from hydrogen or a substituted or unsubstituted C1-C5 alkyl group.

[0040] Preferably, in formula (3), R2 and R3 are

[0041] In the present invention, specific examples of the C1-C5 alkyl group may include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, and n-pentyl.

[0042] In a preferred embodiment of the present invention, in formula (2), R1 is phenyl, L1 is substituted or unsubstituted imidazolidine, L2 is phosphine, X1 and X2 are chloride ions, Y is iodide ion, and n is an integer of 1-5.

[0043] In a more preferred embodiment of the present invention, in formula (2), R1 is phenyl, L1 is L2 is a trialkylphosphine, X1 and X2 are chloride ions, Y is an iodide ion, and n is 5.

[0044] In the present invention, in order to make the ionic catalyst have a better catalytic effect, it is further preferred that the ionic catalyst is an ionic catalyst having a structure shown in formula (4),

[0045]

[0046] In the above formula (4), PCy3 represents tricyclohexylphosphine, and Ph represents a phenyl group.

[0047] In the present invention, the substituted or unsubstituted C2-C20 alkenyl group may be linear or branched, and specific examples may include but are not limited to: ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl.

[0048] In the present invention, the substituted or unsubstituted C2-C20 alkynyl group may be linear or branched, and specific examples may include but are not limited to ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl, nonynyl and decynyl.

[0049] In the present invention, the substituted or unsubstituted C1-C20 alkyl group may be linear or branched, and specific examples may include but are not limited to: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl, undecyl, dodecyl, octadecyl.

[0050] In the present invention, specific examples of the substituted or unsubstituted C6-C20 aryl group may include, but are not limited to, phenyl, methylphenyl, and naphthyl.

[0051] In the present invention, the substituted or unsubstituted C2-C20 carboxylate group refers to a carboxylate group containing Specific examples may include, but are not limited to, methyl propionate, ethyl acetate, and propyl formate.

[0052] In the present invention, specific examples of the substituted or unsubstituted C1-C20 alkoxy group may include, but are not limited to, methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, tert-butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, and octadecyloxy.

[0053] In the present invention, specific examples of the substituted or unsubstituted C2-C20 alkenyloxy group may include, but are not limited to, 1-allyloxy, 2-allylbutoxy, and 1-allylpentoxy.

[0054] In the present invention, specific examples of the substituted or unsubstituted C2-C20 alkynyloxy group may include, but are not limited to, 1-propargyloxy, 2-ynylbutoxy, and 1-ynylpentoxy.

[0055] In the present invention, specific examples of the substituted or unsubstituted C6-C20 aryloxy group may include, but are not limited to, phenoxy and naphthyloxy.

[0056] In the present invention, the substituted or unsubstituted C1-C20 alkylthio group is a straight-chain or branched C1-C20 alkyl group bonded through a sulfur atom, and specific examples include but are not limited to methylthio (CH3-S-), ethylthio, propylthio, butylthio, pentylthio, 1-methylpropylthio, 2-methylpropylthio and 1,1-dimethylethylthio.

[0057] In the present invention, specific examples of the substituted or unsubstituted C1-C20 alkylsulfonyl group may include, but are not limited to, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, and nonylsulfonyl.

[0058] In the present invention, specific examples of the substituted or unsubstituted C1-C20 alkylsulfinyl group may include, but are not limited to, methylsulfinyl and ethylsulfinyl.

[0059] In the present invention, the ionic catalyst of the structure shown in formula (2) can be synthesized by a method commonly used in the field of organic synthesis. For example, a Lewis acid can be contacted with a compound shown in formula (5) to react to obtain a compound of the structure shown in formula (2).

[0060]

[0061] In formula (5), the definitions of R1, L1, L2, X1 and X2 are the same as those described above and will not be described in detail here.

[0062] The conditions for the contact reaction of the Lewis acid with the compound represented by formula (5) are not particularly limited. Generally, the temperature of the contact can be 20-100°C, and the molar ratio of the Lewis acid to the compound represented by formula (5) can be 1-5:1. The Lewis acid can be a conventional choice, such as iodine. The time of the contact can be appropriately selected according to the temperature at which the contact is performed. The contact is preferably carried out under an inert atmosphere, and the inert atmosphere refers to a compound that does not chemically interact with the reactants and reaction products, such as nitrogen and one or more gases of the zeroth group elements in the periodic table, such as argon. The mixture obtained by the contact can be purified by various methods commonly used in the art to obtain an ionic catalyst of the structure represented by formula (2), for example, the obtained mixture can be separated by column chromatography. Specifically, the obtained mixture can be eluted with an aluminum oxide column and dichloromethane as an eluent to obtain an ionic catalyst of the structure represented by formula (2).

[0063] According to the present invention, the non-conjugated diene monomer can be a non-conjugated diene commonly used in the art, so long as it can cause ethylene propylene diene monomer to undergo an olefin cross-metathesis reaction with acrylonitrile having a structure represented by formula (1). For example, it can be one or more of 1,4-hexadiene, dicyclopentadiene (DCPD) and 5-ethylidene-2-norbornene. In order to obtain a higher grafting rate, dicyclopentadiene (DCPD) is preferred.

[0064] According to the present invention, the conditions for the olefin cross-metathesis reaction are not particularly limited and can be selected according to conventional methods in the art. For example, the olefin cross-metathesis reaction is preferably carried out under an inert atmosphere.

[0065] In the present invention, the inert atmosphere refers to a gas that does not participate in the reaction, such as nitrogen and one or more gases of Group 0 elements in the periodic table, such as argon.

[0066] The conditions for the cross-metathesis reaction of olefins include: a reaction temperature of 20-150° C., preferably 40-130° C.; and a reaction time of 0.5-5 hours, preferably 1-3 hours.

[0067] According to the present invention, the amounts of the EPDM rubber, the acrylonitrile having the structure represented by formula (1), and the ionic catalyst can vary within a wide range, as long as a rapid reaction can be achieved and a modified EPDM rubber having a target saturation and a high grafting rate can be obtained. Relative to 100 parts by weight of the EPDM rubber, the amount of the acrylonitrile having the structure represented by formula (1) is 0.05-20 parts by weight, preferably 1-12 parts by weight; and the amount of the ionic catalyst is 0.05-10 parts by weight, preferably 0.2-5 parts by weight.

[0068] According to the present invention, the EPDM rubber can be any EPDM rubber in the prior art that can undergo an olefin cross-metathesis reaction with acrylonitrile having a structure represented by formula (1). For example, based on the total weight of the EPDM rubber, the content of the first structural unit provided by ethylene in the EPDM rubber is 50-70 wt%, and the content of the third structural unit provided by the non-conjugated diene monomer is 4-8 wt%.

[0069] In the present invention, based on the total weight of the EPDM rubber, the total content of the first structural unit provided by ethylene, the second structural unit provided by propylene and the third structural unit provided by the non-conjugated diene is 100 wt%.

[0070] Furthermore, the weight average molecular weight of the EPDM rubber is 100,000-400,000.

[0071] In the present invention, it should be noted that in the EPDM rubber, the first structural unit provided by ethylene has a structure represented by formula (I), and the second structural unit provided by propylene has a structure represented by formula (II).

[0072] -CH2-CH2- Formula (I),

[0073] According to the present invention, the method of adding the ionic catalyst is not particularly limited. The catalyst can be added to the reaction system of EPDM rubber and acrylonitrile having the structure represented by formula (1) in a one-time addition or multiple additions.

[0074] Considering that adding the catalyst all at once can easily cause side reactions in the acrylonitrile of the structure represented by formula (1) in the reaction system, it is preferably added in multiple additions. More preferably, the catalyst is added to the reaction system in 2-6 additions, with the interval between two adjacent additions being 3-15 minutes, and the difference in the amount of catalyst added in any two additions being less than 5% by weight of the total amount of catalyst added. Adding the catalyst in this manner is beneficial for improving the grafting rate of the modified EPDM rubber.

[0075] Further preferably, in order to make the catalyst have a better catalytic effect, the catalyst is added to the reaction system in the form of a solution (preferably the catalyst is dissolved in the organic solvent) in 2-6 times, and the time interval between two adjacent additions is 3-15 minutes, and the difference in the amount of catalyst added in any two times accounts for less than 5 weight% of the total amount of catalyst added.

[0076] According to the present invention, the organic solvent used to prepare the modified EPDM rubber can be any of a variety of existing organic substances that can serve as a reaction medium. Preferably, the organic solvent is one or more of toluene, xylene, chlorobenzene, substituted or unsubstituted C6-C12 cycloalkanes, substituted or unsubstituted C5-C10 linear alkanes, tetrahydrofuran, acetone, and 1,4-dioxane. More preferably, the organic solvent is one or more of toluene, xylene, chlorobenzene, cyclohexane, n-hexane, tetrahydrofuran, acetone, and 1,4-dioxane; most preferably, toluene and / or xylene. These solvents can be used alone or in combination. The amount of the organic solvent used can be selected according to conventional methods in the art and will not be further described herein.

[0077] According to the present invention, the method for preparing the modified EPDM rubber further comprises a purification step. The purification step may be a conventional purification step in the art, for example, filtering the reaction solution obtained after the reaction through a nickel mesh, adding acetone to the filtrate to form a precipitate, and then filtering, washing, and drying the resulting precipitate.

[0078] The second aspect of the present invention provides a modified EPDM rubber prepared by the method of the present invention.

[0079] According to the present invention, the unsaturation degree of the modified EPDM rubber is 0.42-1.06 mol / kg, preferably 0.42-0.96 mol / kg.

[0080] The unsaturation degree of the modified EPDM rubber in the present invention is determined by iodine titration.

[0081] According to the present invention, the weight average molecular weight of the modified EPDM rubber is 100,000-400,000.

[0082] The weight average molecular weight of the modified EPDM rubber in the present invention is determined by gel permeation chromatography (GPC).

[0083] According to the present invention, the grafting rate of the modified EPDM rubber is 1-5.3% by weight.

[0084] In the present invention, the grafting rate is the mass content of acrylonitrile having the structure represented by formula (1) in the modified EPDM rubber.

[0085] In the present invention, when the non-conjugated diene monomer is dicyclopentadiene (DCPD), at least part of the third structural unit containing the modified group has a structure represented by formula (III),

[0086]

[0087] The present invention will be described in detail below through examples.

[0088] In the following preparation examples and embodiments, the performance measurements involved are as follows:

[0089] (1) Determination of the structure of the ionic catalyst in Preparation Example 1: The nuclear magnetic resonance (HNMR) spectrum was measured on an INOVA 500 MHz NMR spectrometer from VARIAN, USA, using tetramethylsilane (TMS) as the internal standard. 1 H-NMR) and carbon nuclear magnetic resonance spectroscopy ( 13 C-NMR); crystals of appropriate size were selected for X-ray single crystal diffraction measurement on a BRUKER SMART 1000CCD X-ray diffractometer;

[0090] (2) The grafting rate was determined by the following method:

[0091] Add measured amounts of ethylene propylene rubber (W1 / g) and xylene to a nitrogen-protected reaction flask. After the ethylene propylene rubber is completely dissolved, add acrylonitrile, and then add the catalyst solution of formula (5) in batches. The reaction is allowed to proceed for a certain period of time. After the reaction is complete, the reaction product is precipitated with acetone. The remaining reactants in the reaction flask are dissolved with an appropriate amount of xylene and then precipitated with acetone. All precipitates are extracted with DMF Soxhlet and then vacuum-dried at 60°C to obtain the grafted product. The grafted product is weighed (W2 / g) and the grafting rate is calculated as follows:

[0092]

[0093] (3) The unsaturation of modified EPDM rubber is determined by iodine titration as follows: 2 g of modified EPDM rubber sample is accurately weighed and placed in a 250 mL ground-mouth conical flask. 50 mL of CCl4 is added to dissolve the sample. 20 mL of iodine bromide (IBr) solution is added with a pipette. After sufficient shaking, the sample is placed in a dark place for 1 hour. Then, 10 mL of 10 wt% potassium iodide solution is added and shaken. The solution is titrated with 0.1 N sodium thiosulfate standard solution until the solution turns yellow. 5 mL of starch indicator is added and the titration is continued until the blue color disappears, which is the end point. A blank test is also performed. The unsaturation is calculated as follows:

[0094]

[0095] Where V0 is the volume of sodium thiosulfate standard solution consumed in the blank test, mL; V is the volume of sodium thiosulfate standard solution consumed in the sample, mL; C is the concentration of the sodium thiosulfate standard solution, mol / L; and m is the mass of the sample, g. The unit of unsaturation is mol / kg.

[0096] (4) The weight average molecular weight of the modified EPDM rubber was determined by gel permeation chromatography (GPC) using a Waters 1515 Isocratic HPLC gel chromatograph.

[0097] The compound represented by formula (7) was purchased from J&K Technology Co., Ltd.

[0098] Wherein Cy is cyclohexyl;

[0099] EPDM terpolymer ESPRENE 305, purchased from Sumitomo, Japan, has an ethylene structural unit content of 65 wt%, a non-conjugated diene monomer structural unit content of 7 wt%, and a weight-average molecular weight of 120,000. The non-conjugated diene monomer is dicyclopentadiene (DCPD);

[0100] EPDM 3280, purchased from Yanshan Petrochemical Company, the EPDM rubber has an ethylene structural unit content of 55% by weight, a non-conjugated diene monomer structural unit content of 5% by weight, a weight-average molecular weight of 300,000, and the non-conjugated diene monomer is ENB;

[0101] Catalyst I, having the structure shown below, was purchased from J&K Technology Co., Ltd.

[0102] Wherein, PCy3 represents tricyclohexylphosphine, and Ph represents phenyl;

[0103] Acrylonitrile was purchased from J&K Technology Co., Ltd.

[0104] Carbon black N550 was purchased from Shanghai Cabot Chemical Co., Ltd.

[0105] Carbon black N330 was purchased from Shanghai Cabot Chemical Co., Ltd.

[0106] ASTM103# oil, purchased from Ningbo Xiejin Chemical Co., Ltd.;

[0107] Accelerator TMTD was purchased from Shanghai Jingyi Rubber Technology Co., Ltd.

[0108] Sulfur was purchased from Shijiazhuang Ruituo Chemical Technology Co., Ltd.

[0109] Nitrile rubber, 3945, was purchased from Lanxess;

[0110] EPDM, 2450, purchased from Lanxess;

[0111] Other raw materials are commercially available.

[0112] Preparation Example 1

[0113] Under nitrogen protection, 0.76 g of iodine, 0.85 g of the compound represented by formula (7) and 20 mL of dichloromethane were added to a 100 mL three-necked flask and stirred at room temperature (25°C) for 0.5 hours. The obtained mixture was separated by aluminum oxide column chromatography (developing solvent: dichloromethane). The obtained eluate was concentrated and washed with cyclohexane to obtain 1.31 g of a yellow solid catalyst. The obtained catalyst was subjected to nuclear magnetic resonance spectroscopy ( 1 H-NMR) and carbon nuclear magnetic resonance spectroscopy ( 13 C-NMR) and X-ray single crystal diffraction analysis confirmed that the obtained catalyst had the structure shown in formula (6).

[0114] 1 H-NMR (400MHz, DMSO) δ (ppm): 1.35-2.06 (m, 33H), 1.81 (s, 18H), 2.62 (m, 4H), 6.11 (d, 1H), 7.38-7.50 (m, 5H), 7.59-7.67 (m, 3H).

[0115] 13 C-NMR (100MHz, DMSO) δ (ppm): 24.8, 25.5, 26.2, 26.3, 26.4, 26.6, 31.9, 32.1, 129.1, 129.2, 129.3, 129.5, 130.7, 134.2, 134.3, 193.0.

[0116]

[0117] In formula (6), C y It is cyclohexyl.

[0118] Example 1

[0119] This embodiment is used to illustrate the modified EPDM rubber and its preparation method provided by the present invention.

[0120] Under nitrogen, 10 g of EPDM 305 rubber and 1.2 g of acrylonitrile were dissolved in 85 mL of xylene solution until completely dissolved to form a reaction system. Simultaneously, 0.05 g of the ionic catalyst represented by formula (6) prepared in Preparation Example 1 was weighed and dissolved in 10 mL of xylene solution to obtain catalyst solution C1.

[0121] The reaction system was heated to 120°C, and 2 mL of catalyst solution C1 was added. After reacting for 10 minutes, the remaining 8 mL of catalyst solution was evenly divided into four portions and added to the reaction system at 10-minute intervals. The reaction was stopped 10 minutes after the last portion of catalyst solution C1 was added to the reaction system. The total reaction time was 1 hour. After the reaction was completed, the reaction solution was filtered through a nickel mesh while still hot. Acetone was added to the filtrate to remove impurities and precipitate. The precipitate was separated and washed with acetone until the filtrate was clear. The precipitate was dried in a vacuum oven at 60°C for 14 hours to obtain modified EPDM rubber A1. The properties of the modified EPDM rubber were analyzed and measured, and the results are shown in Table 1.

[0122] Example 2

[0123] Modified EPDM rubber was prepared using the same method as in Example 1, except that the reaction system was heated to 120°C, and 10 mL of catalyst solution C1 was added all at once. The reaction was allowed to proceed for 1 hour. This yielded modified EPDM rubber A2. The properties of the modified EPDM rubber were analyzed and measured, and the results are shown in Table 1.

[0124] Example 3

[0125] Modified EPDM rubber was prepared using the same method as in Example 1, except that the reaction system was heated to 120°C, and then catalyst solution C1 was added to the reaction system in two additions: 5 mL each time, at the start of the reaction, when the reaction system was heated to 120°C, and 15 minutes after the reaction. The reaction was stopped after 1 hour. This yielded modified EPDM rubber A3. The properties of the modified EPDM rubber were analyzed and measured, and the results are shown in Table 1.

[0126] Comparative Example 1

[0127] EPDM terpolymer ESPRENE 305, i.e., unmodified EPDM terpolymer, was used as reference EPDM rubber D1, and the reference EPDM rubber D1 was analyzed and measured. The results are shown in Table 1.

[0128] Example 4

[0129] This embodiment is used to illustrate the modified EPDM rubber and its preparation method provided by the present invention.

[0130] Modified EPDM rubber was prepared using the same method as in Example 1, except that the reaction time was 2 hours, i.e., the reaction was stopped 70 minutes after the last portion of the catalyst solution was added to the reaction system. Modified EPDM rubber A4 was obtained. The properties of the modified EPDM rubber were analyzed and measured, and the results are shown in Table 1.

[0131] Example 5

[0132] The modified EPDM rubber was prepared by the same method as in Example 1, except that the reaction system was heated to 80° C. to obtain modified EPDM rubber A5. The properties of the modified EPDM rubber were analyzed and measured, and the results are shown in Table 1.

[0133] Example 6

[0134] The modified EPDM rubber was prepared by the same method as in Example 1, except that 0.9 g of acrylonitrile was added to obtain modified EPDM rubber A6. The properties of the modified EPDM rubber were analyzed and measured, and the results are shown in Table 1.

[0135] Example 7

[0136] Modified EPDM rubber was prepared using the same method as in Example 1, except that 0.1 g of the ionic catalyst of formula (6) obtained in Preparation Example 1 was weighed and dissolved in 10 mL of xylene solution. The catalyst was then divided into five equal portions, each of which was added in the same manner as in Example 1 to obtain modified EPDM rubber A7. The properties of the modified EPDM rubber were analyzed and measured, and the results are shown in Table 1.

[0137] Example 8

[0138] This embodiment is used to illustrate the modified EPDM rubber and its preparation method provided by the present invention.

[0139] Under nitrogen protection, 10 g of EPDM rubber ESPRENE 305 and 0.1 g of acrylonitrile were dissolved in 85 mL of xylene solution until completely dissolved to form a reaction system. At the same time, 0.5 g of the ionic catalyst of the structure represented by formula (6) obtained in Preparation Example 1 was weighed and dissolved in 10 mL of xylene solution to obtain catalyst solution C8.

[0140] The reaction system was heated to 40°C, and 2 mL of catalyst solution C8 was added. After reacting for 10 minutes, the remaining 8 mL of catalyst solution was evenly divided into four portions and added to the reaction system at 10-minute intervals. The reaction was stopped 10 minutes after the last portion of catalyst solution C8 was added to the reaction system. The total reaction time was 2 hours. After the reaction was completed, the reaction solution was filtered through a nickel mesh while still hot. Acetone was added to the filtrate to remove impurities and precipitate. The precipitate was separated and washed with acetone until the filtrate was clear. The precipitate was dried in a vacuum oven at 60°C for 14 hours to obtain modified EPDM rubber A8. The properties of the modified EPDM rubber were analyzed and measured, and the results are shown in Table 1.

[0141] Example 9

[0142] This embodiment is used to illustrate the modified EPDM rubber and its preparation method provided by the present invention.

[0143] 10 g of EPDM rubber 3280 and 0.6 g of acrylonitrile were dissolved in 85 mL of xylene solution under N2 protection until completely dissolved to form a reaction system; at the same time, 0.02 g of the ionic catalyst of the structure represented by formula (6) obtained in Preparation Example 1 was weighed and dissolved in 10 mL of xylene solution to obtain catalyst solution C9.

[0144] The reaction system was heated to 130°C, and 2 mL of catalyst solution C9 was added. After 15 minutes of reaction, the remaining 8 mL of catalyst solution was evenly divided into four portions and added to the reaction system at 15-minute intervals. The reaction was stopped 105 minutes after the last portion of catalyst solution C9 had been added to the reaction system. The total reaction time was 3 hours. After the reaction was completed, the reaction solution was filtered through a nickel mesh while still hot. Acetone was added to the filtrate to remove impurities and precipitate. The precipitate was separated and washed with acetone until the filtrate was clear. The precipitate was dried in a vacuum oven at 60°C for 14 hours to obtain modified EPDM rubber A9. The properties of the modified EPDM rubber were analyzed and measured, and the results are shown in Table 1.

[0145] Comparative Example 2

[0146] EPDM 3280, i.e., unmodified EPDM rubber, was used as reference EPDM rubber D2, and the reference EPDM rubber D2 was analyzed and measured. The results are shown in Table 1.

[0147] Comparative Example 3

[0148] Under nitrogen protection, 10 g of EPDM 305 and 1.2 g of acrylonitrile were dissolved in 100 mL of xylene solution until completely dissolved to form a reaction system. Simultaneously, 0.05 g of catalyst I was weighed and dissolved in 10 mL of xylene solution to obtain catalyst solution C1.

[0149] The resulting reaction system was heated to 70°C. 2 mL of catalyst solution C1 was added to the reaction system. After a 5-minute reaction, the remaining 8 mL of catalyst solution C1 was evenly divided into four portions and added to the reaction system at 5-minute intervals. The reaction was stopped 5 minutes after the last portion of catalyst solution C1 had been added to the reaction system. The total reaction time was 30 minutes. After the reaction was completed, the reaction solution was filtered through a nickel mesh while still hot. Acetone was added to the filtrate to remove impurities and precipitate. The precipitate was separated and washed with acetone until the filtrate was clear. The precipitate was then dried in a vacuum oven at 60°C for 14 hours to obtain modified EPDM rubber D3. The properties of the modified EPDM rubber were analyzed and measured, and the results are shown in Table 1.

[0150] Table 1

[0151]

[0152] Test Example 1

[0153] The vulcanization properties of the modified EPDM rubbers A1-A9 prepared in Examples 1-9 of the present invention were measured according to the following method.

[0154] 100 parts by weight of the modified EPDM rubber A1 prepared in Example 1 of the present invention was placed on a double-roll rubber mixer. At a temperature of 35±5° C., 5 parts by weight of activated zinc oxide, 1 part by weight of stearic acid, 80 parts by weight of carbon black N550, 50 parts by weight of ASTM 103# oil, 1 part by weight of accelerator TMTD, and 1.5 parts by weight of sulfur were added successively. The mixture was uniformly mixed and kneaded for 21 minutes to obtain a blend. The blend was then vulcanized on a hydraulic plate vulcanizer at a temperature of 160° C. and a pressure of 15 MPa for 15 minutes to obtain a vulcanized EPDM rubber sheet.

[0155] The vulcanized EPDM rubber film was tested according to the method in GB / T16584-1996, and the vulcanization speed parameter positive vulcanization time TC90 was recorded. The test results are shown in Table 2.

[0156] The vulcanization properties of modified EPDM rubbers A2-A9 and D3 were tested according to the above method. The test results are shown in Table 2.

[0157] Comparative test example 1

[0158] An EPDM rubber film was prepared using the same method as in Test Example 1, except that commercially available EPDM rubber D1 (ESPRENE 305) was used instead of the modified EPDM rubber. The test results are shown in Table 2.

[0159] Comparative test example 2

[0160] An EPDM rubber film was prepared using the same method as in Test Example 1, except that commercially available EPDM rubber D2 (3280) was used instead of the modified EPDM rubber. The test results are shown in Table 2.

[0161] Table 2

[0162]

[0163] Test Example 2

[0164] The modified EPDM rubbers A1-A9 and modified EPDM rubber D3 prepared in Examples 1-9 of the present invention and Comparative Example 3 were subjected to compatibilization performance measurement according to the following method.

[0165] Taking the combination of EPDM and NBR as an example, the carbon black masterbatch mixing process was adopted to preliminarily investigate the compatibilization effect of EPDM grafted acrylonitrile on EPDM / NBR blends. The basic formula (parts by mass) is: NBR 70, EPDM 30, modified EPDM 5, antioxidant (commercially available) MB 1, stearic acid 0.5, paraffin 1, carbon black N33040, polystyrene 10, dioctyl phthalate 12, diisopropyl peroxide 3, trimethylolpropane trimethacrylate 1, trimethylolmethylamine 0.5, triallyl isocyanurate 2.

[0166] The tensile strength was tested according to the method in GB 528-1998. The test results are shown in Table 3.

[0167] According to the method in GB / T16584-1996, the vulcanized EPDM rubber and NBR were tested with film, and the vulcanization speed parameter positive vulcanization time TC90 was recorded. The test results are shown in Table 3.

[0168] Comparative test example 4

[0169] The same method as in Test Example 2 was used to prepare a blend of EPDM and NBR, except that no modified EPDM was added during the test. The test results are shown in Table 3.

[0170] Comparative test example 5

[0171] The same method as in Test Example 2 was used to prepare a blend of EPDM rubber and NBR, except that modified EPDM rubber D3 was used instead of modified EPDM rubber A1 during the test. The test results are shown in Table 3.

[0172] Table 3

[0173]

[0174] As can be seen from Table 1, acrylonitrile can be modified onto EPDM rubber by adopting the cross-metathesis reaction, and the grafting rate is relatively high and the reaction is fast.

[0175] When Example 1 and Example 9 are compared with Comparative Example 1 and Comparative Example 2 (unmodified EPDM rubber), respectively, the unsaturation degree of the modified EPDM rubber obtained in the present invention is 0.42-0.96 mol / kg, which is significantly improved compared with the unmodified EPDM rubber. This is because the side chain double bonds of the EPDM rubber are increased after the olefin cross-metathesis reaction between acrylonitrile and EPDM rubber in the present invention.

[0176] Comparing Examples 1 and 2, it can be seen that the modified EPDM rubber obtained by the method of incremental catalyst addition has a higher grafting yield. This is likely due to the fact that the catalyst concentration in the system is higher after the catalyst is added all at once, which makes acrylonitrile more susceptible to cross-metathesis polymerization, reducing the amount of acrylonitrile participating in the modification reaction and ultimately leading to a lower grafting yield. Furthermore, Examples 2 to 9 demonstrate that adjusting the reaction conditions can effectively control the degree of reaction, thereby obtaining modified EPDM rubber with a desired grafting yield.

[0177] It can be seen from the data in Table 2 that the modified EPDM rubber provided by the present invention has a significantly improved vulcanization rate compared with the unmodified EPDM rubber. This is mainly due to the introduction of acrylonitrile into the modified EPDM rubber and the increase in unsaturation to a certain extent.

[0178] As can be seen from the data in Table 3, adding a small amount of the modified graft copolymer to the blend of EPDM and NBR significantly increases the vulcanization rate and the tensile strength of the vulcanized rubber. This demonstrates that the modified EPDM rubber provided by the present invention does have a good compatibilizing effect.

[0179] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0180] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0181] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing modified EPDM rubber, characterized in that: The method comprises: under the conditions of a cross-metathesis reaction of olefins, in the presence of an organic solvent and a catalyst having a structure represented by formula (2), contacting and reacting EPDM rubber with a compound having a structure represented by formula (1), wherein the EPDM rubber contains a first structural unit provided by ethylene, a second structural unit provided by propylene, and a third structural unit provided by a non-conjugated diene monomer; In formula (2), R1 is a phenyl group, L1 is a substituted or unsubstituted imidazolidine group, L2 is a phosphine group, X1 and X2 are chloride ions, Y is an iodide ion, and n is an integer from 1 to 5; The non-conjugated diene monomer is dicyclopentadiene; The catalyst is added to the contact reaction system in 2-6 times, and the time interval between two adjacent additions is 3-15 minutes, and the difference in the amount of the catalyst added in any two times accounts for less than 5 weight% of the total amount of the catalyst added; The conditions for the cross-metathesis reaction of olefins include: a reaction temperature greater than 80° C. and less than or equal to 130° C., and a reaction time of 1-3 hours; Relative to 100 parts by weight of the EPDM rubber, the amount of acrylonitrile having the structure represented by formula (1) is 9-12 parts by weight; the amount of the ionic catalyst is 0.2-5 parts by weight; The unsaturation degree of the modified EPDM rubber is 0.42-1.06 mol / kg; The grafting rate of the modified EPDM rubber is 1-5.3% by weight.

2. The method according to claim 1, wherein In formula (2), L2 is a trialkylphosphine.

3. The method according to claim 1 or 2, wherein: The L1 is an imidazolidine having a structure shown in formula (3), L2 is a trialkylphosphine, In formula (3), R2 and R3 are the same or different and are each independently a C6-C20 aryl group.

4. The method according to claim 3, wherein: In formula (3), R2 and R3 are each independently R4, R5, R6, R7 and R8 are the same or different and are independently selected from hydrogen or C1-C5 alkyl.

5. The method according to claim 4, wherein In formula (3), R2 and R3 are 6. The method according to any one of claims 1-2, 4-5, wherein: The cross-metathesis reaction of olefins is carried out under an inert atmosphere.

7. The method according to any one of claims 1-2, 4-5, wherein the content of the first structural unit provided by ethylene in the EPDM rubber is 50-70% by weight, and the content of the third structural unit provided by the non-conjugated diene monomer is 4-8% by weight; The weight average molecular weight of the EPDM rubber is 100,000-400,000.

8. The method according to any one of claims 1-2, 4-5, wherein: The organic solvent is selected from one or more of toluene, xylene, chlorobenzene, substituted or unsubstituted C6-C12 cycloalkanes, substituted or unsubstituted C5-C10 linear alkanes, tetrahydrofuran, acetone and 1,4-dioxane.

9. The modified EPDM rubber prepared by the method according to any one of claims 1 to 8.

10. The modified EPDM rubber according to claim 9, wherein The unsaturation degree of the modified EPDM rubber is 0.42-1.06 mol / kg; and / or, the grafting rate of the modified EPDM rubber is 1-5.3 wt %; And / or, the weight average molecular weight of the modified EPDM rubber is 100,000-400,000.

11. The modified EPDM rubber according to claim 10, wherein The unsaturation degree of the modified EPDM rubber is 0.42-0.96 mol / kg.

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