Electric insulation sole material and preparation method thereof

Abstract

The invention discloses an electric insulation sole material and a preparation method thereof, and relates to the technical field of insulation rubber. The electric insulation sole material comprises the following raw material components in parts by weight: 100 parts of ethylene propylene diene monomer, 20-30 parts of maleic anhydride graft modified ethylene propylene diene monomer, 10-15 parts of fluororubber graft modified ethylene propylene diene monomer, 80-100 parts of modified filler, 4-6 parts of zinc oxide, 2-4 parts of an anti-aging agent, 1-2 parts of sulfur, 2-4 parts of a vulcanizing agent and 1-3 parts of a vulcanization accelerator. By adding maleic anhydride graft modified ethylene propylene diene monomer, fluororubber graft modified ethylene propylene diene monomer and modified filler, the mechanical property, temperature resistance, weather resistance and electrical insulation property of ethylene propylene diene monomer are reinforced.

Description

Technical Field

[0001] The invention relates to the technical field of insulating rubber, in particular to an electrically insulating sole material and a preparation method thereof. Background Art

[0002] As essential protective equipment for workers in the power industry, insulating shoes require materials with excellent electrical insulation, weather resistance, mechanical properties, and long-term stability. Of these, electrical insulation is naturally the most crucial. The electrical insulation performance of insulating shoe soles is primarily related to two key parameters: the rubber material's resistivity and breakdown voltage. The higher the resistivity, the better the rubber's insulation performance; the higher the breakdown voltage, the greater the guarantee of the rubber's insulation performance. However, resistivity and breakdown voltage don't have a direct positive correlation, so simply increasing the rubber's resistivity won't guarantee excellent electrical insulation. Only when both resistivity and breakdown voltage are guaranteed can a rubber material with excellent electrical insulation properties be produced and processed into insulating shoe soles to meet the insulation needs of power industry workers in high-voltage environments.

[0003] In summary, in order to improve the electrical insulation performance of the electrically insulating sole material and at the same time improve its related mechanical properties and anti-aging properties, the present invention provides an electrically insulating sole material and a preparation method thereof, which is of great significance. Summary of the Invention

[0004] The object of the present invention is to provide an electrically insulating sole material and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] An electrical insulating shoe sole material comprises the following raw material components: by weight, 100 parts of EPDM rubber, 20-30 parts of maleic anhydride grafted modified EPDM rubber, 10-15 parts of fluororubber grafted modified EPDM rubber, 80-100 parts of modified filler, 4-6 parts of zinc oxide, 2-4 parts of antioxidant, 1-2 parts of sulfur, 2-4 parts of vulcanizing agent, and 1-3 parts of vulcanization accelerator.

[0007] Furthermore, the preparation method of the fluororubber grafted modified EPDM rubber is as follows: fluororubber, maleic anhydride grafted modified EPDM rubber, and dicumyl peroxide are added into an extruder, and extruded and granulated at 160-180° C. to obtain the fluororubber grafted modified EPDM rubber.

[0008] Furthermore, the raw materials required for preparing the fluororubber grafted modified EPDM rubber include the following components: by weight, 4 to 6 parts of fluororubber, 15 to 20 parts of maleic anhydride grafted modified EPDM rubber, and 0.05 to 0.1 parts of dicumyl peroxide.

[0009] Furthermore, the preparation method of the fluororubber is as follows: (1) tetrafluoroethylene and perfluoroalkyl vinyl ether are mixed uniformly in a mass ratio of 1:1 to obtain a monomer; an emulsifier and a pH regulator are added to deionized water, and the mixture is stirred to obtain a reaction solution A; (2) under nitrogen protection, 10 to 20% of the total monomer mass and 50 to 70% of the total initiator mass are added to the reaction solution A, and the mixture is stirred at 2 to 4 MPa and 75 to 85° C. for 0.5 to 1 hour; and 40 to 70% of the total molecular weight regulator mass are added to the reaction system. 60% of the molecular weight regulator is added, and the monomer is continuously added to the reaction system with stirring until the amount of the monomer added is 50-70% of the total monomer mass, and the stirring reaction is carried out for 0.5-2h; then the remaining molecular weight regulator and initiator are continuously added to the reaction system, and the remaining monomer is continuously added to the reaction system with stirring, and the stirring reaction is continued for 0.5-2h, and the reaction is terminated. After filtering, washing, and drying, a fluoropolymer is obtained; (3) the fluoropolymer is added to an open mill and plasticized at 80-100°C for 10-20min to obtain a fluororubber.

[0010] Furthermore, the raw materials required for preparing the fluororubber include the following components: by weight, 10 parts of monomer, 0.01-0.1 parts of emulsifier, 0.01-0.1 parts of pH regulator, 0.05-0.15 parts of initiator, 0.1-1 parts of molecular weight regulator, and 50 parts of deionized water.

[0011] Furthermore, the emulsifier is ammonium perfluorooctanoate.

[0012] Furthermore, the pH regulator is sodium bicarbonate.

[0013] Furthermore, the initiator is ammonium persulfate.

[0014] Furthermore, the molecular weight regulator is diethyl malonate.

[0015] The present invention adopts EPDM as the main raw material, which has excellent properties such as aging resistance, weather resistance, elasticity and electrical insulation, but EPDM also has the disadvantages of poor self-adhesion and mutual adhesion. On the one hand, the poor self-adhesion makes the rubber material difficult to process and shape, which not only increases the scrap rate but also reduces the processing efficiency; on the other hand, even if the finished sole is processed and shaped, its own interlayer bonding ability is weak, and delamination will occur after bending and the influence of wet, acidic and alkaline environments. On the one hand, the poor mutual adhesion makes the interface between EPDM and other raw materials poor, and then makes it difficult for the prepared electrical insulating sole to meet actual requirements in terms of mechanical properties, physical properties, etc. Based on this, the present invention designs the addition of maleic anhydride grafted modified EPDM to improve the defects of EPDM, which can also serve as a compatibilizer to enhance the compatibility of EPDM with other components.

[0016] At the same time, in order to enhance the electrical insulation properties of EPDM rubber, the scheme further uses fluororubber to graft-modify maleic anhydride-grafted EPDM rubber to obtain fluororubber-grafted EPDM rubber. Fluororubber is obtained by polymerization and plasticization of tetrafluoroethylene and perfluoroalkyl vinyl ether. During the polymerization of tetrafluoroethylene and perfluoroalkyl vinyl ether, the polymerization density of the two can be more moderate by controlling the difference in the amount of raw materials added, thereby achieving a better modification effect of fluororubber on EPDM rubber. The fluororubber can enhance the high temperature resistance, weather resistance, and dielectric strength of EPDM rubber. The enhanced high temperature resistance can delay the oxidative degradation of EPDM rubber at high temperatures, and the weather resistance gives it a certain degree of UV resistance. In other words, both the enhanced high temperature resistance and weather resistance can improve the anti-aging properties of EPDM rubber and have the effect of maintaining the stability of the electrical insulation properties of the electrically insulating soles for a long time. The enhanced dielectric strength can make the prepared product have a higher breakdown voltage. That is, the fluororubber grafted modified EPDM rubber plays an important role in enhancing the electrical insulation performance of the electrical insulating sole material.

[0017] Furthermore, the preparation method of the modified filler is as follows: (1) mica and white carbon black are uniformly mixed in a mass ratio of 1:(1-3) to obtain a filler; an ethylene silane coupling agent, deionized water, and anhydrous ethanol are added into a reaction container in a mass ratio of 1:1:4, and acetic acid is added to adjust the pH of the solution to 4-6, and the mixture is stirred for 10-30 minutes to obtain a silane hydrolyzate; (2) the filler is added into a blender, stirred at a rate of 100-200 r / min, and the silane hydrolyzate is sprayed therein at the same time, and after spraying, the mixture is continued to be stirred for 1-3 hours, and dried to obtain a modified filler.

[0018] Furthermore, the amount of the vinyl silane coupling agent is 1 to 3% of the mass of the filler.

[0019] Furthermore, the vinyl silane coupling agent includes but is not limited to any one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, and vinyltriisopropoxysilane.

[0020] In the present invention, an ethylene-based silane coupling agent is used to modify the filler to enhance its dispersibility in EPDM rubber and prevent its agglomeration, thereby further enhancing the mechanical properties, physical properties, and electrical insulation properties of the electrically insulating sole material. The filler is obtained by mixing mica and white carbon black. The resistivity of white carbon black is slightly weak, but it can significantly enhance the tensile strength, tear resistance, and wear resistance of the electrically insulating sole material. The resistivity of mica is relatively high, and it mainly assists white carbon black in reinforcing the electrical insulation properties of the electrically insulating sole material. At the same time, since mica has a flaky structure, it can better cooperate with white carbon black to fill the void structure in the prepared electrically insulating sole, reduce the internal defects of the electrically insulating sole, and thereby enhance the breakdown voltage of the electrically insulating sole, which also affects the electrical insulation properties of the electrically insulating sole to a certain extent.

[0021] Furthermore, the antioxidant is antioxidant MB.

[0022] Furthermore, the vulcanizing agent is dicumyl peroxide.

[0023] Furthermore, the vulcanization accelerator is triallyl isocyanurate.

[0024] Furthermore, the method for preparing the electrically insulating sole material comprises the following steps:

[0025] Step 1: Add EPDM rubber, maleic anhydride grafted modified EPDM rubber, and fluororubber grafted modified EPDM rubber into an open mill according to the formula amount, and plasticize at 50-70° C. for 1-2 hours to obtain a masterbatch;

[0026] Step 2: Add modified filler, zinc oxide and antioxidant to the masterbatch of step 1, and mix at 100-120° C. for 10-30 minutes to obtain a rubber compound;

[0027] Step 3: adding sulfur, a vulcanizing agent, and a vulcanization accelerator to the rubber material of step 2, and vulcanizing the rubber material at 160-180° C. for 10-30 minutes to obtain an electrically insulating sole material.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention introduces maleic anhydride grafted modified EPDM rubber to improve the defects of poor self-adhesion and mutual adhesion of EPDM rubber; at the same time, it can be used as a compatibilizer to promote the compatibility of EPDM rubber with fluororubber grafted modified EPDM rubber and modified fillers, greatly reducing the internal defects of the electrical insulating sole material and making its quality more uniform;

[0030] (2) The present invention introduces fluororubber grafted modified EPDM rubber, which has good compatibility with EPDM rubber and can enhance the high temperature resistance, weather resistance and dielectric strength of EPDM rubber; the high temperature resistance and weather resistance make it have good anti-aging properties, thereby ensuring the long-term stability of the electrical insulation performance of EPDM rubber; the dielectric strength enhances the breakdown voltage of EPDM rubber; that is, fluororubber grafted modified EPDM rubber has an important role in enhancing the electrical insulation performance of EPDM rubber;

[0031] (3) The fluororubber prepared in the present invention can be further controlled by a molecular weight regulator to obtain a fluororubber with good processing fluidity. The good processing fluidity can also increase the grafting rate of the fluororubber graft-modified EPDM rubber, which has a certain impact on the quality of the subsequent electrical insulating sole material. The fewer the internal defects of the electrical insulating sole material, the better its electrical insulating performance.

[0032] (4) The present invention introduces a modified filler, which has good compatibility with EPDM rubber and can greatly enhance the tensile strength, tear resistance, wear resistance and aging resistance of EPDM rubber; at the same time, due to its good compatibility and the synergistic effect of mica and silica, it can greatly reduce the internal defects of the prepared electrically insulating sole, thereby enhancing the electrical insulation performance of the electrically insulating sole material.

[0033] In summary, in the present invention, EPDM rubber is reinforced and modified by grafting maleic anhydride to modify EPDM rubber, grafting fluororubber to modify EPDM rubber, and modifying fillers to obtain an electrical insulating sole material with excellent mechanical properties, aging resistance, and electrical insulation properties. The electrical insulating soles made from the material can better meet the insulation needs of power industry workers in high voltage environments. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0035] It should be noted that the following parts are by weight, and the purchasers of all raw materials involved in the present invention are exemplified without any special restrictions as follows:

[0036] EPDM rubber, brand: 25, product number: 025, purchased from Anhui Lixin Rubber Technology Co., Ltd.;

[0037] Maleic anhydride grafted modified EPDM rubber, purity ≥95%, maleic anhydride grafting rate 1%, purchased from Dongguan Zhangmutou Chengjie Plastic Raw Materials Co., Ltd.;

[0038] Zinc oxide, purity ≥99%, particle size: D50 5 μm, antioxidant MB, purity ≥98%, dicumyl peroxide, purity ≥98%, sulfur, purity ≥99%, and white carbon black, purity ≥99%, particle size: D50 20 nm, were purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0039] Triallyl isocyanurate, purity ≥99%, CAS No. 1025-15-6, sodium bicarbonate, purity ≥99.5%, diethyl malonate, purity ≥99%, vinyltrimethoxysilane, purity ≥99%, purchased from Hubei Qifei Pharmaceutical Chemical Co., Ltd.

[0040] Tetrafluoroethylene, purity ≥99%, was purchased from Shanghai Baoyang Baoxin Biotechnology Co., Ltd.;

[0041] Perfluoroalkyl vinyl ether, purity ≥98%, ammonium perfluorooctanoate, purity ≥98%, mica, purity ≥99%, particle size: D50 20 nm, purchased from Hebei Zhentian Food Additive Co., Ltd.

[0042] Ammonium persulfate, purity ≥98.5%, was purchased from Shandong Qiben Industrial Co., Ltd.

[0043] Example 1: A method for preparing an electrically insulating sole material:

[0044] 1. Preparation of fluororubber: (1) 5 parts of tetrafluoroethylene and 5 parts of perfluoroalkyl vinyl ether were mixed to obtain monomers; 0.05 parts of ammonium perfluorooctanoate and 0.05 parts of sodium bicarbonate were added to 50 parts of deionized water, and the mixture was stirred to obtain reaction solution A; (2) Under nitrogen protection, 1.5 parts of monomers and 0.06 parts of ammonium persulfate were added to reaction solution A, and the mixture was stirred at 3 MPa and 80°C for 45 minutes; 0.2 parts of sodium persulfate were added to the reaction system. 5 parts of diethyl malonate, and at the same time, continue to stir and add 4.5 parts of monomer to the reaction system, and stir and react for 1 hour; then continue to add 0.25 parts of diethyl malonate and 0.04 parts of ammonium persulfate to the reaction system, and at the same time, continue to stir and add 4 parts of monomer to the reaction system, and continue to stir and react for 1 hour, terminate the reaction, filter, wash, and dry to obtain a fluoropolymer; (3) add the fluoropolymer to an open mill, and plasticize at 90°C for 15 minutes to obtain a fluororubber;

[0045] 2. Preparation of fluororubber grafted modified EPDM rubber: 5 parts of fluororubber, 17.5 parts of maleic anhydride grafted modified EPDM rubber, and 0.075 parts of dicumyl peroxide were added to an extruder and extruded and granulated at 170°C to obtain fluororubber grafted modified EPDM rubber;

[0046] 3. Preparation of modified filler: (1) 35 parts of mica and 70 parts of white carbon black were mixed uniformly to obtain filler; 2.1 parts of vinyltrimethoxysilane, 2.1 parts of deionized water, and 8.4 parts of anhydrous ethanol were added to a reaction vessel, and acetic acid was added to adjust the pH of the solution to 5, and the mixture was stirred for 20 minutes to obtain a silane hydrolyzate; (2) the filler was added to a blender, stirred at a rate of 150 r / min, and the silane hydrolyzate was sprayed therein. After spraying, the mixture was stirred for 2 hours, and dried to obtain a modified filler;

[0047] 4. Preparation of electrical insulating sole material: (1) Adding EPDM rubber, maleic anhydride grafted modified EPDM rubber, and fluororubber grafted modified EPDM rubber into an open mill according to the formula amount, and plasticizing at 60°C for 1.5 hours to obtain a masterbatch; (2) Adding modified filler, zinc oxide, and antioxidant to the masterbatch in (1), and mixing at 110°C for 20 minutes to obtain a rubber compound; (3) Adding sulfur, a vulcanizing agent, and a vulcanization accelerator to the rubber compound in (2), and vulcanizing treatment at 170°C for 20 minutes to obtain an electrical insulating sole material;

[0048] The raw material components of the electrical insulating sole material are as follows, by weight: 100 parts of EPDM rubber, 25 parts of maleic anhydride grafted modified EPDM rubber, 12.5 parts of fluororubber grafted modified EPDM rubber, 90 parts of modified filler, 5 parts of zinc oxide, 3 parts of antioxidant MB, 1.5 parts of sulfur, 3 parts of diisopropylbenzene peroxide, and 2 parts of triallyl isocyanurate.

[0049] Example 2: A method for preparing an electrically insulating sole material:

[0050] 1. Preparation of fluororubber: (1) Mix 5 parts of tetrafluoroethylene and 5 parts of perfluoroalkyl vinyl ether to obtain a monomer; add 0.05 parts of ammonium perfluorooctanoate and 0.05 parts of sodium bicarbonate to 50 parts of deionized water, stir and mix to obtain a reaction solution A; (2) Under nitrogen protection, add 1 part of the monomer and 0.05 parts of ammonium persulfate to the reaction solution A, stir and react at 3 MPa and 80°C for 45 minutes; then add 0. 2 parts of diethyl malonate, and at the same time, 4 parts of monomer are added to the reaction system with continuous stirring, and the reaction is stirred for 1 hour; then 0.3 parts of diethyl malonate and 0.05 parts of ammonium persulfate are added to the reaction system, and at the same time, 5 parts of monomer are added to the reaction system with continuous stirring, and the reaction is continued with stirring for 1 hour, and the reaction is terminated. The fluorine-containing polymer is obtained by filtering, washing, and drying; (3) the fluorine-containing polymer is added to an open mill and plasticized at 90°C for 15 minutes to obtain a fluororubber;

[0051] 2. Preparation of fluororubber grafted modified EPDM rubber: 4 parts of fluororubber, 17.5 parts of maleic anhydride grafted modified EPDM rubber, and 0.05 parts of dicumyl peroxide were added to an extruder, and extruded and granulated at 170°C to obtain fluororubber grafted modified EPDM rubber;

[0052] 3. Preparation of modified filler: (1) 50 parts of mica and 50 parts of white carbon black were mixed uniformly to obtain filler; 1 part of vinyltrimethoxysilane, 1 part of deionized water, and 4 parts of anhydrous ethanol were added to a reaction vessel, and acetic acid was added to adjust the pH of the solution to 5, and stirred for 20 minutes to obtain a silane hydrolyzate; (2) The filler was added to a blender, stirred at a rate of 150 r / min, and the silane hydrolyzate was sprayed therein. After spraying, the mixture was stirred for 2 hours, and dried to obtain a modified filler;

[0053] 4. Preparation of electrical insulating sole material: (1) Adding EPDM rubber, maleic anhydride grafted modified EPDM rubber, and fluororubber grafted modified EPDM rubber into an open mill according to the formula amount, and plasticizing at 60°C for 1.5 hours to obtain a masterbatch; (2) Adding modified filler, zinc oxide, and antioxidant to the masterbatch in (1), and mixing at 110°C for 20 minutes to obtain a rubber compound; (3) Adding sulfur, a vulcanizing agent, and a vulcanization accelerator to the rubber compound in (2), and vulcanizing treatment at 170°C for 20 minutes to obtain an electrical insulating sole material;

[0054] The raw material components of the electrical insulating sole material are as follows, by weight: 100 parts of EPDM rubber, 25 parts of maleic anhydride grafted modified EPDM rubber, 12.5 parts of fluororubber grafted modified EPDM rubber, 90 parts of modified filler, 5 parts of zinc oxide, 3 parts of antioxidant MB, 1.5 parts of sulfur, 3 parts of diisopropylbenzene peroxide, and 2 parts of triallyl isocyanurate.

[0055] Example 3: A method for preparing an electrically insulating sole material:

[0056] 1. Preparation of fluororubber: (1) 5 parts of tetrafluoroethylene and 5 parts of perfluoroalkyl vinyl ether were mixed to obtain a monomer; 0.05 parts of ammonium perfluorooctanoate and 0.05 parts of sodium bicarbonate were added to 50 parts of deionized water and stirred to obtain a reaction solution A; (2) Under nitrogen protection, 2 parts of the monomer and 0.07 parts of ammonium persulfate were added to the reaction solution A, and the mixture was stirred at 3 MPa and 80°C for 45 minutes; 0. 3 parts of diethyl malonate, and at the same time, 5 parts of monomer are added to the reaction system with continuous stirring, and the reaction is stirred for 1 hour; then 0.2 parts of diethyl malonate and 0.03 parts of ammonium persulfate are added to the reaction system, and at the same time, 3 parts of monomer are added to the reaction system with continuous stirring, and the reaction is stirred for 1 hour, and the reaction is terminated. The fluorine-containing polymer is obtained by filtering, washing, and drying; (3) the fluorine-containing polymer is added to an open mill and plasticized at 90°C for 15 minutes to obtain a fluorine rubber;

[0057] 2. Preparation of fluororubber grafted modified EPDM rubber: 6 parts of fluororubber, 17.5 parts of maleic anhydride grafted modified EPDM rubber, and 0.1 parts of dicumyl peroxide were added to an extruder and extruded and granulated at 170°C to obtain fluororubber grafted modified EPDM rubber;

[0058] 3. Preparation of modified filler: (1) 25 parts of mica and 75 parts of white carbon black were mixed uniformly to obtain filler; 3 parts of vinyltrimethoxysilane, 3 parts of deionized water, and 12 parts of anhydrous ethanol were added to a reaction vessel, and acetic acid was added to adjust the pH of the solution to 5, and stirred for 20 minutes to obtain a silane hydrolyzate; (2) The filler was added to a blender, stirred at a rate of 150 r / min, and the silane hydrolyzate was sprayed therein. After spraying, the mixture was stirred for 2 hours, and dried to obtain a modified filler;

[0059] 4. Preparation of electrical insulating sole material: (1) Adding EPDM rubber, maleic anhydride grafted modified EPDM rubber, and fluororubber grafted modified EPDM rubber into an open mill according to the formula amount, and plasticizing at 60°C for 1.5 hours to obtain a masterbatch; (2) Adding modified filler, zinc oxide, and antioxidant to the masterbatch in (1), and mixing at 110°C for 20 minutes to obtain a rubber compound; (3) Adding sulfur, a vulcanizing agent, and a vulcanization accelerator to the rubber compound in (2), and vulcanizing treatment at 170°C for 20 minutes to obtain an electrical insulating sole material;

[0060] The raw material components of the electrical insulating sole material are as follows, by weight: 100 parts of EPDM rubber, 25 parts of maleic anhydride grafted modified EPDM rubber, 12.5 parts of fluororubber grafted modified EPDM rubber, 90 parts of modified filler, 5 parts of zinc oxide, 3 parts of antioxidant MB, 1.5 parts of sulfur, 3 parts of diisopropylbenzene peroxide, and 2 parts of triallyl isocyanurate.

[0061] Example 4: Example 4 is based on Example 1, with the following adjustments made: the raw material components of the electrically insulating sole material, and other processes remain unchanged, specifically:

[0062] The raw material components of the electrical insulating sole material are: by weight, 100 parts of EPDM rubber, 20 parts of maleic anhydride grafted modified EPDM rubber, 10 parts of fluororubber grafted modified EPDM rubber, 80 parts of modified filler, 5 parts of zinc oxide, 3 parts of antioxidant MB, 1.5 parts of sulfur, 3 parts of diisopropyl benzene peroxide, and 2 parts of triallyl isocyanurate.

[0063] Example 5: Example 5 is based on Example 1, with the following adjustments made: the raw material components of the electrically insulating sole material, and other processes remain unchanged, specifically:

[0064] The raw material components of the electrical insulating sole material are: by weight, 100 parts of EPDM rubber, 30 parts of maleic anhydride grafted modified EPDM rubber, 15 parts of fluororubber grafted modified EPDM rubber, 100 parts of modified filler, 5 parts of zinc oxide, 3 parts of antioxidant MB, 1.5 parts of sulfur, 3 parts of diisopropyl benzene peroxide, and 2 parts of triallyl isocyanurate.

[0065] The following control experiments are conducted based on Example 1, and comparative examples 1 to 4 are set as follows:

[0066] Comparative Example 1: Comparative Example 1 is based on Example 1, with the following adjustments: no maleic anhydride graft-modified EPDM rubber is added, and other processes remain unchanged, specifically:

[0067] A method for preparing an electrically insulating sole material:

[0068] 4. Preparation of electrical insulating sole material: (1) Adding EPDM rubber and fluororubber grafted modified EPDM rubber into an open mill according to the formula amount, and plasticizing at 60°C for 1.5 hours to obtain a masterbatch; (2) Adding modified filler, zinc oxide, and antioxidant to the masterbatch in (1), and mixing at 110°C for 20 minutes to obtain a rubber compound; (3) Adding sulfur, a vulcanizing agent, and a vulcanization accelerator to the rubber compound in (2), and vulcanizing treatment at 170°C for 20 minutes to obtain an electrical insulating sole material;

[0069] The raw material components of the electrical insulating sole material are as follows, by weight: 100 parts of EPDM rubber, 12.5 parts of fluororubber grafted modified EPDM rubber, 90 parts of modified filler, 5 parts of zinc oxide, 3 parts of antioxidant MB, 1.5 parts of sulfur, 3 parts of diisopropylbenzene peroxide, and 2 parts of triallyl isocyanurate.

[0070] Comparative Example 2: Comparative Example 2 is based on Example 1, with the following adjustments: fluororubber graft-modified EPDM rubber is not added, and other processes remain unchanged, specifically:

[0071] A method for preparing an electrically insulating sole material:

[0072] 4. Preparation of electrical insulating sole material: (1) Adding EPDM rubber and maleic anhydride grafted modified EPDM rubber into an open mill according to the formula amount, and plasticizing at 60°C for 1.5 hours to obtain a masterbatch; (2) Adding modified filler, zinc oxide, and antioxidant to the masterbatch in (1), and mixing at 110°C for 20 minutes to obtain a rubber compound; (3) Adding sulfur, a vulcanizing agent, and a vulcanization accelerator to the rubber compound in (2), and vulcanizing treatment at 170°C for 20 minutes to obtain an electrical insulating sole material;

[0073] The raw material components of the electrical insulating sole material are as follows, by weight: 100 parts of EPDM rubber, 25 parts of maleic anhydride grafted modified EPDM rubber, 90 parts of modified filler, 5 parts of zinc oxide, 3 parts of antioxidant MB, 1.5 parts of sulfur, 3 parts of diisopropylbenzene peroxide, and 2 parts of triallyl isocyanurate.

[0074] Comparative Example 3: Comparative Example 3 is based on Example 1, with the following adjustments: only white carbon black is used as the filler, and other processes remain unchanged, specifically:

[0075] A method for preparing an electrically insulating sole material:

[0076] 3. Preparation of modified filler: (1) Add 2.1 parts of vinyltrimethoxysilane, 2.1 parts of deionized water, and 8.4 parts of anhydrous ethanol into a reaction vessel, and add acetic acid to adjust the pH of the solution to 5, and stir and mix for 20 minutes to obtain a silane hydrolyzate; (2) Add 105 parts of white carbon black into a blender, stir at a rate of 150 r / min, and spray the silane hydrolyzate therein. After spraying, continue stirring and mixing for 2 hours, and dry to obtain a modified filler;

[0077] 4. Preparation of electrical insulating sole material: (1) Adding EPDM rubber, maleic anhydride grafted modified EPDM rubber, and fluororubber grafted modified EPDM rubber into an open mill according to the formula amount, and plasticizing at 60°C for 1.5 hours to obtain a masterbatch; (2) Adding modified filler, zinc oxide, and antioxidant to the masterbatch in (1), and mixing at 110°C for 20 minutes to obtain a rubber compound; (3) Adding sulfur, a vulcanizing agent, and a vulcanization accelerator to the rubber compound in (2), and vulcanizing treatment at 170°C for 20 minutes to obtain an electrical insulating sole material;

[0078] The raw material components of the electrical insulating sole material are as follows, by weight: 100 parts of EPDM rubber, 25 parts of maleic anhydride grafted modified EPDM rubber, 12.5 parts of fluororubber grafted modified EPDM rubber, 90 parts of modified filler, 5 parts of zinc oxide, 3 parts of antioxidant MB, 1.5 parts of sulfur, 3 parts of diisopropylbenzene peroxide, and 2 parts of triallyl isocyanurate.

[0079] Comparative Example 4: Comparative Example 4 is based on Example 1, with the following adjustments: the filler is not modified, and other processes remain unchanged, specifically:

[0080] A method for preparing an electrically insulating sole material:

[0081] 3. Prepare filler: (1) Mix 35 parts of mica and 70 parts of white carbon black to obtain filler;

[0082] 4. Preparation of electrical insulating sole material: (1) adding EPDM rubber, maleic anhydride grafted modified EPDM rubber, and fluororubber grafted modified EPDM rubber into an open mill according to the formula amount, and plasticizing at 60°C for 1.5 hours to obtain a masterbatch; (2) adding filler, zinc oxide, and antioxidant to the masterbatch in (1), and mixing at 110°C for 20 minutes to obtain a rubber compound; (3) adding sulfur, a vulcanizing agent, and a vulcanization accelerator to the rubber compound in (2), and vulcanizing treatment at 170°C for 20 minutes to obtain an electrical insulating sole material;

[0083] The raw material components of the electrical insulating sole material are as follows, by weight: 100 parts of EPDM rubber, 25 parts of maleic anhydride grafted modified EPDM rubber, 12.5 parts of fluororubber grafted modified EPDM rubber, 90 parts of filler, 5 parts of zinc oxide, 3 parts of antioxidant MB, 1.5 parts of sulfur, 3 parts of diisopropylbenzene peroxide, and 2 parts of triallyl isocyanurate.

[0084] Performance testing: The electrically insulating sole materials prepared in Examples 1 to 5 and Comparative Examples 1 to 4 were processed into experimental samples of a size of 20 cm (length) × 10 cm (width) × 1 cm (thickness), and the mechanical properties, high temperature resistance, and electrical insulation performance were tested, as follows:

[0085] 1. Mechanical properties: According to the standard of GB / T 529-2008, the tear strength and elongation at break are tested;

[0086] 2. High temperature resistance: According to the standard GB / T 3512-2014, the test samples were placed in an aging test chamber and aged at 175°C for 72 hours, and then their mechanical properties were tested;

[0087] 3. Electrical insulation performance: (1) According to the standard GB / T 1408.1-2016, test its breakdown voltage strength; (2) According to the standard GB / T 1410-2006, test its volume resistivity.

[0088] The test data results are shown in Table 1 below:

[0089] Table 1

[0090]

[0091]

[0092] Result analysis: From the data in Table 1 above, it can be seen that the present invention achieves enhanced modification of the mechanical properties, anti-aging properties, and electrical insulation properties of EPDM rubber through the synergistic effect of maleic anhydride grafted modified EPDM rubber, fluororubber grafted modified EPDM rubber, and modified fillers. Among them, maleic anhydride grafted modified EPDM rubber mainly plays a role in enhancing the compatibility between rubbers; fluororubber grafted modified EPDM rubber, on the one hand, also has the effect of enhancing compatibility, and at the same time, it can also enhance the high temperature resistance and dielectric strength of EPDM rubber, thereby significantly enhancing the anti-aging properties and electrical insulation properties of the electrical insulating sole material; modified fillers mainly play a role in improving the mechanical properties and electrical insulation properties of EPDM rubber. In the present invention, the control of the ratio of mica and white carbon black and the modification of the vinyl silane coupling agent are extremely important.

[0093] In summary, the present invention prepares an electrically insulating sole material with excellent mechanical properties, anti-aging properties and electrical insulation properties. The electrically insulating sole processed thereby can better meet the insulation needs of power industry workers in high voltage environments.

[0094] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An electrically insulating sole material, characterized in that: The raw material components include: by weight, 100 parts of EPDM rubber, 20-30 parts of maleic anhydride grafted modified EPDM rubber, 10-15 parts of fluororubber grafted modified EPDM rubber, 80-100 parts of modified filler, 4-6 parts of zinc oxide, 2-4 parts of antioxidant, 1-2 parts of sulfur, 2-4 parts of vulcanizing agent, and 1-3 parts of vulcanization accelerator.

2. The electrically insulating sole material according to claim 1, characterized in that: The preparation method of the fluororubber grafted modified EPDM rubber is as follows: fluororubber, maleic anhydride grafted modified EPDM rubber and dicumyl peroxide are added into an extruder, and granulated by extrusion at 160-180° C. to obtain the fluororubber grafted modified EPDM rubber.

3. The electrically insulating sole material according to claim 2, characterized in that: The raw materials required for preparing the fluororubber grafted modified EPDM rubber include the following components: 4-6 parts of fluororubber, 15-20 parts of maleic anhydride grafted modified EPDM rubber, and 0.05-0.1 parts of dicumyl peroxide, calculated by weight.

4. The electrically insulating sole material according to claim 2, characterized in that: The preparation method of the fluororubber is: (1) Tetrafluoroethylene and perfluoroalkyl vinyl ether are mixed uniformly in a mass ratio of 1:1 to obtain a monomer; an emulsifier and a pH adjuster are added to deionized water, and the mixture is stirred to obtain a reaction solution A; (2) Under nitrogen protection, 10-20% of the total monomer mass and 50-70% of the total initiator mass are added to the reaction solution A, and the mixture is stirred at 2-4 MPa and 75-85° C. for 0.5-1 h; then 40-60% of the total molecular weight regulator mass is added to the reaction system, and the monomer is continuously added to the reaction system with stirring until the monomer addition amount is 50-70% of the total monomer mass, and the mixture is stirred for 0.5-2 h; then the remaining molecular weight regulator and initiator are continuously added to the reaction system, and the remaining monomer is continuously added to the reaction system with stirring, and the mixture is stirred for 0.5-2 h, and the reaction is terminated. The fluorine-containing polymer is obtained by filtering, washing, and drying; (3) Add the fluorine-containing polymer to an open mill and plasticize at 80-100° C. for 10-20 minutes to obtain fluororubber.

5. The electrically insulating sole material according to claim 4, characterized in that: The raw materials required for preparing the fluororubber include the following components: by weight, 10 parts of monomer, 0.01-0.1 parts of emulsifier, 0.01-0.1 parts of pH regulator, 0.05-0.15 parts of initiator, 0.1-1 parts of molecular weight regulator, and 50 parts of deionized water.

6. The electrically insulating sole material according to claim 1, characterized in that: The preparation method of the modified filler is: (1) Mica and white carbon black are mixed uniformly in a mass ratio of 1:(1-3) to obtain a filler; vinyl silane coupling agent, deionized water, and anhydrous ethanol are added into a reaction vessel in a mass ratio of 1:1:4, and acetic acid is added to adjust the pH of the solution to 4-6, and the mixture is stirred for 10-30 minutes to obtain a silane hydrolyzate; (2) Add the filler into a mixer and stir at a rate of 100 to 200 r / min while spraying the silane hydrolyzate therein. After spraying, continue stirring and mixing for 1 to 3 hours, and obtain the modified filler after drying.

7. The electrically insulating sole material according to claim 6, characterized in that: The amount of the vinyl silane coupling agent is 1-3% of the mass of the filler, wherein the vinyl silane coupling agent includes any one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, and vinyltriisopropoxysilane.

8. A method for preparing an electrically insulating shoe sole material according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Add EPDM rubber, maleic anhydride grafted modified EPDM rubber, and fluororubber grafted modified EPDM rubber into an open mill according to the formula amount, and plasticize at 50-70° C. for 1-2 hours to obtain a masterbatch; Step 2: Add modified filler, zinc oxide and antioxidant to the masterbatch of step 1, and mix at 100-120° C. for 10-30 minutes to obtain a rubber compound; Step 3: adding sulfur, a vulcanizing agent, and a vulcanization accelerator to the rubber material of step 2, and vulcanizing the rubber material at 160-180° C. for 10-30 minutes to obtain an electrically insulating sole material.

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