High-strength flame-retardant sealing strip and preparation method thereof

Abstract

The invention relates to the technical field of sealing strips, and discloses a high-strength flame-retardant sealing strip and a preparation method thereof.The preparation method of the sealing strip comprises the following steps that ethylene propylene diene monomer, basalt fiber grafted ethylene-octylene copolymer, modified carbon black, an antioxidant, a dispersing agent, a vulcanizing agent and an activating agent are mixed and subjected to overturning smelting and vulcanization forming, and the high-strength flame-retardant sealing strip is obtained. A halogen-free flame-retardant system is adopted, the ammonia-containing and phosphorus-containing flame retardant and the inorganic filler are introduced, all the components have a synergistic effect, the high-strength flame-retardant sealing strip has excellent flame retardance and heat resistance, meanwhile, secondary harm generated in the combustion process is avoided, carbon black can form a net-shaped structure in rubber, and therefore the flame-retardant performance of the high-strength flame-retardant sealing strip is improved. The basalt fibers form a reinforced framework in the rubber, and the prepared sealing strip is excellent in mechanical property, high in strength and excellent in comprehensive performance.

Description

Technical Field

[0001] The invention relates to the technical field of sealing strips, in particular to a high-strength flame-retardant sealing strip and a preparation method thereof. Background Art

[0002] Sealing strip is a product used to seal objects or spaces. Its main function is to prevent the penetration of liquids, gases, dust and other substances, so as to play the role of shock absorption, waterproofing, sound insulation, heat insulation, dust prevention and fixation. It is widely used in automobile manufacturing, construction, electronic equipment and other fields. There are many materials for sealing strips, mainly including rubber, silicone, polymer plastics, metals, etc. With the rapid development of the economy, my country's automobile industry has developed rapidly, and higher and higher requirements have been put forward for the materials used to manufacture automobile parts. The requirements for the safety performance of automobile sealing strips are also increasing. Not only good sealing performance is required, but also high strength, flame retardancy, weather resistance and other characteristics are required. EPDM rubber has good elasticity and excellent ozone resistance, heat resistance and aging resistance. It can be used for automobile door and window sealing strips, sealing rings, hoses for conveying coolant, etc. However, rubber materials are easy to burn when encountering fire sources or high temperature environments, and spread rapidly, there are certain safety hazards, and the strength is low, and it cannot resist external pressure well.

[0003] Chinese patent application CN110577706A discloses a halogen-free flame-retardant sealing strip EPDM rubber and its preparation method. The sealing strip is composed of EPDM rubber, carbon black, flame retardant, softening plasticizer, activator, vulcanizer. The sealing strip has good high temperature aging resistance and flame retardancy, but the dispersion between the raw materials is poor and the strength is average. Chinese patent application CN111138725A discloses a high-strength wear-resistant modified natural rubber and its preparation method, including natural rubber, EPDM rubber, butadiene rubber, reinforcing agent, epoxy resin, silane coupling agent, accelerator, antioxidant, emulsifier, plasticizer. The rubber has excellent mechanical strength, wear resistance and aging resistance, but poor flame retardancy.

[0004] Therefore, developing a sealing strip with high strength and good flame retardant performance has broad market prospects and application value. Summary of the invention

[0005] 1. Technical issues to be solved

[0006] In order to solve the above technical problems, the present invention provides a high-strength flame-retardant sealing strip and a preparation method thereof, which solves the problems of poor flame-retardant performance and general strength of the sealing strip.

[0007] (II) Technical solution

[0008] In order to achieve the above object, the present invention discloses a method for preparing a high-strength flame-retardant sealing strip, comprising the following steps:

[0009] S1. Ultrasonic dispersion of carbon black in an ethanol solution, after uniform dispersion, adding γ-glycidyloxypropyltriethoxysilane, stirring and mixing, heating, reacting, after the reaction is completed, filtering, washing with anhydrous ethanol, and drying at 60° C. for 12 h to obtain epoxy-modified carbon black;

[0010] S2, adding epoxy modified carbon black to an organic solvent, dispersing it uniformly by ultrasonication, adding diaminodiphenyl sulfone, stirring and mixing uniformly, heating, reacting, and after the reaction is completed, rotary evaporation to obtain modified carbon black;

[0011] S3, using acetone to activate the basalt fiber for 4 hours, after the treatment, the activated basalt fiber is obtained, the activated basalt fiber is added to the ethanol solution, and then γ-methacryloxypropyltrimethoxysilane is added, stirred and mixed, and reacted. After the reaction is completed, the fiber is filtered, washed with anhydrous ethanol, and dried in a vacuum drying oven at 80° C. for 12 hours to obtain olefinated basalt fiber;

[0012] S4, uniformly mixing the ethylene-octene copolymer, the olefinated basalt fiber, 9,10-dihydro-9-oxa-10-allylphosphaphenanthrene-10-oxide, maleic anhydride and the initiator, melt blending in a twin-screw extruder, extruding, and cooling to obtain the basalt fiber grafted ethylene-octene copolymer;

[0013] S5. Add EPDM rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant and dispersant into an internal mixer, mix at 115-120°C for 8-10 minutes, add vulcanizer and activator, mix for 10-15 minutes to obtain a mixture, and refining the mixture in an open mixer. After refining, cool and place for 12 hours, and then transfer to a flat vulcanizer for vulcanization molding, discharge the material, and obtain a high-strength flame-retardant sealing strip.

[0014] Preferably, the ethanol solution in S1 consists of anhydrous ethanol and deionized water in a mass ratio of 9:1.

[0015] Preferably, the mass ratio of carbon black, ethanol solution and γ-glycidyloxypropyltriethoxysilane in S1 is 100:1500-1800:15-25.

[0016] Preferably, the reaction temperature in S1 is 55-65° C., and the reaction time is 6-9 h.

[0017] Preferably, the organic solvent in S2 includes any one or more of N,N-dimethylformamide, toluene, and dimethyl sulfoxide.

[0018] Preferably, the mass ratio of the organic solvent, epoxy-modified carbon black and diaminodiphenyl sulfone in S2 is 950-1200:100:68-95.

[0019] Preferably, the reaction temperature in S2 is 95-105° C., and the reaction time is 4-6 h.

[0020] Preferably, the mass ratio of the activated basalt fiber, the ethanol solution and γ-methacryloxypropyltrimethoxysilane in S3 is 100:1800-2100:18-25.

[0021] Preferably, the ethanol solution in S3 consists of anhydrous ethanol and deionized water in a mass ratio of 1:1.

[0022] Preferably, the reaction temperature in S3 is 25-35° C., and the reaction time is 12-15 h.

[0023] Preferably, the mass ratio of the ethylene-octene copolymer, the olefinic basalt fiber, the 9,10-dihydro-9-oxa-10-allylphosphaphenanthrene-10-oxide, the maleic anhydride and the initiator in the S4 is 100:10-15:3-5:18-25:2-4.

[0024] Preferably, the temperature of melt blending in S4 is 165-195° C., and the time of melt blending is 8-12 min.

[0025] Preferably, the initiator in S4 is dicumyl peroxide.

[0026] Preferably, the mass ratio of EPDM rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant, dispersant, vulcanizer and activator in S5 is 100:6-10:2-4:1-1.5:0.3-0.5:2-3:1-2.

[0027] Preferably, the dispersant in S5 includes any one of polyvinyl pyrrolidone, polyacrylamide and polyvinyl alcohol.

[0028] Preferably, the antioxidant in S5 includes any one of antioxidant 168, antioxidant 1010, and antioxidant 1076.

[0029] Preferably, the vulcanizing agent in S5 is di-tert-butyl peroxide isopropylbenzene.

[0030] Preferably, the activator in S5 is stearic acid.

[0031] Preferably, in S5, the temperature of the refining in the open mill is 120-140° C., the refining time is 8-10 min, the temperature of the vulcanization molding in the flat vulcanizing agent is 155-185° C., and the vulcanization molding time is 10-15 min.

[0032] A high-strength flame-retardant sealing strip prepared by adopting the method for preparing the high-strength flame-retardant sealing strip.

[0033] (III) Beneficial technical effects

[0034] In the present invention, γ-glycidyloxypropyltriethoxysilane is used to modify carbon black, epoxy groups are introduced on the surface of carbon black to obtain epoxy-modified carbon black, amino groups on diaminodiphenyl sulfone react with epoxy groups on epoxy-modified carbon black to obtain modified carbon black, flame retardant is introduced on carbon black, and amino groups, imine and hydroxyl groups are introduced at the same time. γ-methacryloxypropyltrimethoxysilane is used to modify basalt fiber, alkenyl groups are introduced on basalt fiber to obtain alkenylated basalt fiber. Alkenylated basalt fiber, ethylene-octene copolymer, 9,10-dihydro-9-oxa-10-allylphosphaphenanthrene-10-oxide and maleic anhydride are melt blended in a twin-screw extruder, in-situ polymerization occurs, basalt fiber grafted ethylene-octene copolymer is obtained, and phosphorus-containing flame retardant is introduced. The EPDM rubber, basalt fiber grafted ethylene-octene copolymer and modified carbon black are mixed, mixed in an internal mixer with the help of an auxiliary agent, mixed in an open mixer, and vulcanized and formed in a flat vulcanizer to obtain a high-strength flame-retardant sealing strip.

[0035] Compared with the prior art, the present invention has the following technical effects:

[0036] (1) The carbon black used in the present invention has a large specific surface area, excellent thermal stability, weather resistance and chemical stability. As a reinforcing filler, it can significantly improve the tensile strength, tear strength and wear resistance of EPDM rubber. Carbon black can form a network structure in the rubber, and the interaction between the carbon black and the rubber molecular chain enhances the mechanical properties of the rubber. Basalt fiber has excellent mechanical properties, chemical stability and thermal stability. It forms a reinforcing skeleton in the rubber, which can bear part of the tensile stress, enhance the tensile strength and modulus of EPDM rubber, and improve its heat resistance and dimensional stability. At the same time, it can also improve the vulcanization characteristics of the rubber. The double bonds in the ethylene-octene copolymer and the ethylene-propylene rubber can undergo cross-linking reaction to form a more compact network structure. At the same time, the active groups such as amino and hydroxyl groups introduced on the modified carbon black can form hydrogen bonds with the carboxyl groups introduced on the basalt fiber grafted ethylene-octene copolymer, and the synergistic effect further improves the processing performance and low-temperature toughness of the EPDM rubber, and improves the aging resistance and hot air aging resistance of the sealing strip.

[0037] (2) In the present invention, carbon black and basalt fiber are modified to effectively avoid agglomeration, and can be evenly dispersed in the matrix to form a uniform mechanical network structure. The obtained sealing strip has high strength and excellent mechanical properties. Furthermore, the diaminodiphenyl sulfone and phosphorus-containing flame retardant introduced into the matrix are not easy to precipitate and can maintain long-term flame retardancy. During the combustion process of the matrix, the phosphorus heterocycle and diaminodiphenyl sulfone contained therein will generate phosphoric acid-containing substances, promote the carbonization of the matrix, and prevent the combustion reaction from proceeding. At the same time, the PO· free radicals generated during the combustion process can capture ·OH and H· free radicals in the flame, interrupt the combustion chain reaction, and reduce the heat released by the combustion. The introduced nitrogen and sulfur elements can form non-combustible gases, dilute the concentration of oxygen in the combustion system, and further improve the flame retardant effect. The organic silicon introduced in the preparation of basalt fiber grafted ethylene-octene copolymer and modified carbon black can increase the density of the carbon layer. Carbon black will form a heat-insulating and oxygen-insulating carbon layer during the combustion process, blocking the transfer of heat and the entry of oxygen, thereby inhibiting the combustion process.

[0038] (3) The sealing strip prepared in the present invention uses EPDM rubber as the matrix and adopts a halogen-free flame retardant system. The components work synergistically and have excellent flame retardant and heat-resistant properties, while avoiding secondary hazards during the combustion process. At the same time, the sealing strip has excellent mechanical properties, high strength, and excellent comprehensive performance. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] Example 1

[0041] A method for preparing a high-strength flame-retardant sealing strip comprises the following steps:

[0042] S1. Ultrasonic dispersion of carbon black in an ethanol solution, wherein the ethanol solution is composed of anhydrous ethanol and deionized water in a mass ratio of 9:1. After uniform dispersion, γ-glycidyloxypropyltriethoxysilane is added, and the mass ratio of the added carbon black, ethanol solution, and γ-glycidyloxypropyltriethoxysilane is 100:1500:15. Stirring and mixing, heating, reacting at 55°C for 9 hours, and after the reaction is completed, filtering, washing with anhydrous ethanol, and drying at 60°C for 12 hours to obtain epoxy-modified carbon black;

[0043] S2. Add epoxy-modified carbon black to N,N-dimethylformamide, disperse uniformly by ultrasonication, then add diaminodiphenyl sulfone, the mass ratio of N,N-dimethylformamide, epoxy-modified carbon black and diaminodiphenyl sulfone is 950:100:68, stir and mix uniformly, heat up, react at 95°C for 6h, and after the reaction is completed, rotary evaporate to obtain modified carbon black;

[0044] S3, using acetone to activate the basalt fiber for 4 hours, after the treatment, to obtain activated basalt fiber, the activated basalt fiber is added to an ethanol solution, the ethanol solution is composed of anhydrous ethanol and deionized water in a mass ratio of 1:1, and then γ-methacryloxypropyltrimethoxysilane is added, wherein the mass ratio of the activated basalt fiber, the ethanol solution, and γ-methacryloxypropyltrimethoxysilane is 100:1800:18, stirred and mixed, reacted at 25°C, the reaction time is 15h, after the reaction is completed, filtered, washed with anhydrous ethanol, and dried in a vacuum drying oven at 80°C for 12h to obtain olefinated basalt fiber;

[0045] S4, mixing ethylene-octene copolymer, olefinic basalt fiber, 9,10-dihydro-9-oxa-10-allylphosphaphenanthrene-10-oxide, maleic anhydride and initiator dicumyl peroxide in a mass ratio of 100:10:3:18:2, and melt blending in a twin-screw extruder at a temperature of 165° C. for 12 min, extruding, cooling, and obtaining basalt fiber grafted ethylene-octene copolymer;

[0046] S5. Add ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant 1010 and dispersant polyvinyl pyrrolidone into an internal mixer, mix at 115°C for 10 minutes, add vulcanizer di-tert-butyl peroxyisopropylbenzene and activator stearic acid, wherein the mass ratio of the added ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant 1010, dispersant polyvinyl pyrrolidone, vulcanizer and activator is 100:6:2:1:0.3:2:1, mix for 15 minutes to obtain a mixture, and refine the mixture in an open mill at a refining temperature of 120°C for 10 minutes. After refining, cool and stand for 12 hours, and then transfer to a flat vulcanizer for vulcanization molding at a vulcanization molding temperature of 155°C for 15 minutes. Discharge the material to obtain a high-strength flame-retardant sealing strip.

[0047] Example 2

[0048] A method for preparing a high-strength flame-retardant sealing strip comprises the following steps:

[0049] S1. Ultrasonic dispersion of carbon black in an ethanol solution, wherein the ethanol solution is composed of anhydrous ethanol and deionized water in a mass ratio of 9:1. After uniform dispersion, γ-glycidyloxypropyltriethoxysilane is added, and the mass ratio of the added carbon black, ethanol solution, and γ-glycidyloxypropyltriethoxysilane is 100:1700:18. Stirring and mixing, heating, reacting at 60°C for 8 hours, and after the reaction is completed, filtering, washing with anhydrous ethanol, and drying at 60°C for 12 hours to obtain epoxy-modified carbon black;

[0050] S2. Add epoxy-modified carbon black to N,N-dimethylformamide, disperse uniformly by ultrasonication, then add diaminodiphenyl sulfone, the mass ratio of N,N-dimethylformamide, epoxy-modified carbon black and diaminodiphenyl sulfone is 1100:100:85, stir and mix uniformly, heat up, react at 100°C for 5h, and after the reaction is completed, rotary evaporate to obtain modified carbon black;

[0051] S3, using acetone to activate the basalt fiber for 4 hours, after the treatment, to obtain activated basalt fiber, the activated basalt fiber is added to an ethanol solution, the ethanol solution is composed of anhydrous ethanol and deionized water in a mass ratio of 1:1, and then γ-methacryloxypropyltrimethoxysilane is added, wherein the mass ratio of the activated basalt fiber, the ethanol solution, and γ-methacryloxypropyltrimethoxysilane is 100:1950:21, stirred and mixed, reacted at 30°C, the reaction time is 14h, after the reaction is completed, filtered, washed with anhydrous ethanol, and dried in a vacuum drying oven at 80°C for 12h to obtain olefinated basalt fiber;

[0052] S4, uniformly mixing ethylene-octene copolymer, olefinic basalt fiber, 9,10-dihydro-9-oxa-10-allylphosphaphenanthrene-10-oxide, maleic anhydride and initiator dicumyl peroxide in a mass ratio of 100:12:3.5:20:2.5, melt blending in a twin-screw extruder at a temperature of 175° C. for 9 min, extruding, cooling, and obtaining basalt fiber grafted ethylene-octene copolymer;

[0053] S5. Add ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant 1010 and dispersant polyvinyl pyrrolidone into an internal mixer, mix at 118°C for 9 minutes, add vulcanizer di-tert-butyl peroxyisopropylbenzene and activator stearic acid, wherein the mass ratio of the added ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant 1010, dispersant polyvinyl pyrrolidone, vulcanizer and activator is 100:8:2.5:1.2:0.4:2.5:1.5, mix for 12 minutes to obtain a mixture, and refine the mixture in an open mill at a refining temperature of 125°C for 9 minutes. After refining, cool and stand for 12 hours, and then transfer to a flat vulcanizer for vulcanization molding at a vulcanization molding temperature of 165°C for 12 minutes. Discharge the material to obtain a high-strength flame-retardant sealing strip.

[0054] Example 3

[0055] A method for preparing a high-strength flame-retardant sealing strip comprises the following steps:

[0056] S1. Evenly mix ethylene-octene copolymer, olefinic basalt fiber, 9,10-dihydro-9-oxa-10-allylphosphaphenanthrene-10-oxide, maleic anhydride and initiator dicumyl peroxide in a mass ratio of 100:14:4.5:24:3.5, melt blend in a twin-screw extruder at a temperature of 185° C. for 11 min, extrude, cool, and obtain basalt fiber grafted ethylene-octene copolymer;

[0057] S2. Add ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant 1010 and dispersant polyvinyl pyrrolidone into an internal mixer, mix at 118°C for 9 minutes, add vulcanizing agent di-tert-butyl peroxyisopropylbenzene and activating agent stearic acid, wherein the mass ratio of the added ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant 1010, dispersant polyvinyl pyrrolidone, vulcanizing agent and activating agent is 100:8:2.5:1.2:0.4:2.5:1.5, mix for 12 minutes to obtain a mixture, and refine the mixture in an open mill at a refining temperature of 125°C for 9 minutes. After refining, cool and stand for 12 hours, and then transfer to a flat vulcanizer for vulcanization molding at a vulcanization molding temperature of 165°C for 12 minutes. Discharge the material to obtain a high-strength flame-retardant sealing strip.

[0058] The preparation method of the modified carbon black and olefinic basalt fiber is the same as the preparation method of the modified carbon black and olefinic basalt fiber in Example 2.

[0059] Example 4

[0060] A method for preparing a high-strength flame-retardant sealing strip comprises the following steps:

[0061] S1. Add ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant 1010 and dispersant polyvinyl pyrrolidone into an internal mixer, mix at 118°C for 9 minutes, add vulcanizing agent di-tert-butyl peroxyisopropylbenzene and activating agent stearic acid, wherein the mass ratio of the added ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant 1010, dispersant polyvinyl pyrrolidone, vulcanizing agent and activating agent is 100:9:3.5:1.4:0.45:2.5:1.5, mix for 14 minutes to obtain a mixture, and refining the mixture in an open mill at a refining temperature of 135°C for 9 minutes. After refining, cool and place for 12 hours, and then transfer to a flat vulcanizer for vulcanization molding at a vulcanization molding temperature of 175°C for 14 minutes. Discharge the material to obtain a high-strength flame-retardant sealing strip.

[0062] The preparation method of the modified carbon black and basalt fiber grafted ethylene-octene copolymer is the same as the preparation method of the modified carbon black and basalt fiber grafted ethylene-octene copolymer in Example 3.

[0063] Example 5

[0064] A method for preparing a high-strength flame-retardant sealing strip comprises the following steps:

[0065] S1. Ultrasonic dispersion of carbon black in an ethanol solution, wherein the ethanol solution is composed of anhydrous ethanol and deionized water in a mass ratio of 9:1. After uniform dispersion, γ-glycidyloxypropyltriethoxysilane is added, and the mass ratio of the added carbon black, ethanol solution, and γ-glycidyloxypropyltriethoxysilane is 100:1800:25. Stirring and mixing, heating, reacting at 65°C for 6 hours, and filtering after the reaction is completed. Washing with anhydrous ethanol and drying at 60°C for 12 hours to obtain epoxy-modified carbon black;

[0066] S2. Add epoxy-modified carbon black to N,N-dimethylformamide, disperse uniformly by ultrasonication, then add diaminodiphenyl sulfone, the mass ratio of N,N-dimethylformamide, epoxy-modified carbon black and diaminodiphenyl sulfone is 1200:100:95, stir and mix uniformly, heat up, react at 105°C for 4h, and after the reaction is completed, rotary evaporate to obtain modified carbon black;

[0067] S3, using acetone to activate the basalt fiber for 4 hours, after the treatment, to obtain activated basalt fiber, the activated basalt fiber is added to an ethanol solution, the ethanol solution is composed of anhydrous ethanol and deionized water in a mass ratio of 1:1, and then γ-methacryloxypropyltrimethoxysilane is added, wherein the mass ratio of the activated basalt fiber, the ethanol solution, and γ-methacryloxypropyltrimethoxysilane is 100:2100:25, stirred and mixed, reacted at 35°C, the reaction time is 12h, after the reaction is completed, filtered, washed with anhydrous ethanol, and dried in a vacuum drying oven at 80°C for 12h to obtain olefinated basalt fiber;

[0068] S4, uniformly mixing ethylene-octene copolymer, olefinic basalt fiber, 9,10-dihydro-9-oxa-10-allylphosphaphenanthrene-10-oxide, maleic anhydride and initiator dicumyl peroxide in a mass ratio of 100:15:5:25:4, melt blending in a twin-screw extruder at a temperature of 195° C. for 8 min, extruding, cooling, and obtaining basalt fiber grafted ethylene-octene copolymer;

[0069] S5. Add ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant 1010 and dispersant polyvinyl pyrrolidone into an internal mixer, mix at 120°C for 8 minutes, add vulcanizer di-tert-butyl peroxyisopropylbenzene and activator stearic acid, wherein the mass ratio of the added ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant 1010, dispersant polyvinyl pyrrolidone, vulcanizer and activator is 100:10:4:1.5:0.5:3:2, mix for 10 minutes to obtain a mixture, and refine the mixture in an open mixer at a refining temperature of 140°C for 8 minutes. After refining, cool and stand for 12 hours, and then transfer to a flat vulcanizer for vulcanization molding at a vulcanization molding temperature of 185°C for 10 minutes. Discharge the material to obtain a high-strength flame-retardant sealing strip.

[0070] Comparative Example 1

[0071] A method for preparing a flame retardant sealing strip comprises the following steps:

[0072] S1. Use acetone to activate the basalt fiber for 4 hours. After the treatment, the activated basalt fiber is obtained. The activated basalt fiber is added to an ethanol solution, which is composed of anhydrous ethanol and deionized water in a mass ratio of 1:1. Then, γ-methacryloxypropyltrimethoxysilane is added, wherein the mass ratio of the activated basalt fiber, the ethanol solution, and the γ-methacryloxypropyltrimethoxysilane is 100:1950:21. The mixture is stirred and reacted at 30°C for 14 hours. After the reaction is completed, the mixture is filtered, washed with anhydrous ethanol, and dried in a vacuum drying oven at 80°C for 12 hours to obtain olefinated basalt fiber.

[0073] S2, mixing ethylene-octene copolymer, olefinic basalt fiber, 9,10-dihydro-9-oxa-10-allylphosphaphenanthrene-10-oxide, maleic anhydride and initiator dicumyl peroxide in a mass ratio of 100:14:4.5:24:3.5, melt blending in a twin-screw extruder at a temperature of 185° C. for 11 min, extruding, cooling, and obtaining basalt fiber grafted ethylene-octene copolymer;

[0074] S3. Add ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, carbon black, antioxidant 1010 and dispersant polyvinyl pyrrolidone into an internal mixer, mix at 118°C for 9 minutes, add vulcanizer di-tert-butyl peroxyisopropylbenzene and activator stearic acid, wherein the mass ratio of the added ethylene propylene diene monomer rubber, basalt fiber grafted ethylene-octene copolymer, carbon black, antioxidant 1010, dispersant polyvinyl pyrrolidone, vulcanizer and activator is 100:9:3.5:1.4:0.45:2.5:1.5, mix for 14 minutes to obtain a mixture, and refine the mixture in an open mill at a refining temperature of 135°C for 9 minutes. After the refining is completed, cool and stand for 12 hours, and then transfer to a flat vulcanizer for vulcanization molding at a vulcanization molding temperature of 175°C for 14 minutes. Discharge the material to obtain a flame retardant sealing strip.

[0075] Comparative Example 2

[0076] A method for preparing a flame retardant sealing strip comprises the following steps:

[0077] S1. Ultrasonic dispersion of carbon black in an ethanol solution, wherein the ethanol solution is composed of anhydrous ethanol and deionized water in a mass ratio of 9:1. After uniform dispersion, γ-glycidyloxypropyltriethoxysilane is added, and the mass ratio of the added carbon black, ethanol solution, and γ-glycidyloxypropyltriethoxysilane is 100:1700:18. Stirring and mixing, heating, reacting at 60°C for 8 hours, and after the reaction is completed, filtering, washing with anhydrous ethanol, and drying at 60°C for 12 hours to obtain epoxy-modified carbon black;

[0078] S2. Add epoxy-modified carbon black to N,N-dimethylformamide, disperse uniformly by ultrasonication, then add diaminodiphenyl sulfone, the mass ratio of N,N-dimethylformamide, epoxy-modified carbon black and diaminodiphenyl sulfone is 1100:100:85, stir and mix uniformly, heat up, react at 100°C for 5h, and after the reaction is completed, rotary evaporate to obtain modified carbon black;

[0079] S3, uniformly mixing ethylene-octene copolymer, basalt fiber, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, maleic anhydride and initiator dicumyl peroxide in a mass ratio of 100:14:4.5:24:3.5, melt blending in a twin-screw extruder at a temperature of 185° C. for 11 min, extruding, cooling, and obtaining a modified ethylene-octene copolymer;

[0080] S4. Add ethylene propylene diene monomer rubber, modified ethylene-octene copolymer, modified carbon black, antioxidant 1010 and dispersant polyvinyl pyrrolidone into an internal mixer, mix at 118°C for 9 minutes, add vulcanizer di-tert-butyl peroxyisopropylbenzene and activator stearic acid, wherein the mass ratio of the added ethylene propylene diene monomer rubber, modified ethylene-octene copolymer, modified carbon black, antioxidant 1010, dispersant polyvinyl pyrrolidone, vulcanizer and activator is 100:9:3.5:1.4:0.45:2.5:1.5, mix for 14 minutes to obtain a mixture, and refine the mixture in an open mill at a refining temperature of 135°C for 9 minutes. After refining, cool and stand for 12 hours, and then transfer to a flat vulcanizer for vulcanization molding at a vulcanization molding temperature of 175°C for 14 minutes. Discharge the material to obtain a flame retardant sealing strip.

[0081] The carbon black used in the embodiments and comparative examples of the present invention was purchased from Qingdao Degussa Chemical Co., Ltd. with a model of N330; the basalt fiber was purchased from Zhejiang Shijin Company with a length of 6 mm and a diameter of 13 μm; the EPDM rubber was purchased from PetroChina Jilin Chemical Engineering Co., Ltd. with a model of 2070; the ethylene-octene copolymer (POE) was purchased from Dow Chemical Corporation of the United States with a model of 8149; and other undisclosed reagents were all commercially available.

[0082] The flame retardant sealing strips prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to corresponding tests, and the test methods and test results are as follows:

[0083] (1) Flame retardant performance test: The flame retardant sealing strips prepared in Examples 1-5 and Comparative Examples 1-2 were cut into strips with a size of 100 mm × 100 mm × 3 mm and placed on a JF-5 fully automatic oxygen index instrument for a limiting oxygen index test. The samples were placed vertically, ignited, and their oxygen concentrations were measured. Each group was tested three times and the average value was taken.

[0084] (2) Mechanical property test: The flame-retardant sealing strips prepared in Examples 1-5 and Comparative Examples 1-2 were used as samples and subjected to tensile property tests on a CTM8000 universal material testing machine. The test standard was in accordance with the test standard of GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber". The test temperature was 25°C, the load was 1000N, the tensile rate was 500mm / min, the specimen was dumbbell-shaped, and each group was tested three times to take the average value.

[0085] The above test results are shown in Table 1:

[0086] Table 1

[0087]

[0088] According to the test results in Table 1, it can be seen that the limiting oxygen index of the samples corresponding to Examples 1-5 all reach the flame retardant level, have excellent flame retardant properties, and have the characteristics of high strength. Among them, the limiting oxygen index of the sample corresponding to Example 4 reaches 36.9%, the tensile strength is 15.0MPa, and the elongation at break is 481%. In Comparative Example 1, the carbon black was not modified and directly added to the matrix. The dispersibility of carbon black in the matrix deteriorated, and the compatibility with the raw materials was poor, which had a certain effect on the flame retardant properties and greatly reduced the mechanical properties. In Comparative Example 2, the basalt fiber was not modified, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added at the same time. The dispersibility of basalt fiber and phosphorus-containing flame retardant deteriorated, the overall performance of the sample decreased, the flame retardancy was greatly reduced, and the mechanical properties deteriorated.

[0089] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that all equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A method for preparing a high-strength flame-retardant sealing strip, characterized in that: The steps include: S1. Ultrasonic dispersion of carbon black in an ethanol solution, after uniform dispersion, adding γ-glycidyloxypropyltriethoxysilane, stirring and mixing, heating, reacting, after the reaction is completed, filtering, washing, and drying at 60° C. for 12 h to obtain epoxy-modified carbon black; S2, adding epoxy modified carbon black to an organic solvent, dispersing it uniformly by ultrasonication, adding diaminodiphenyl sulfone, stirring and mixing uniformly, heating, reacting, and after the reaction is completed, rotary evaporation to obtain modified carbon black; S3, activating the basalt fiber to obtain activated basalt fiber, adding the activated basalt fiber to an ethanol solution, and then adding γ-methacryloxypropyltrimethoxysilane, stirring and mixing, reacting, and after the reaction is completed, filtering, washing, and vacuum drying at 60° C. for 12 hours to obtain olefinated basalt fiber; S4, uniformly mixing the ethylene-octene copolymer, the olefinated basalt fiber, 9,10-dihydro-9-oxa-10-allylphosphaphenanthrene-10-oxide, maleic anhydride and the initiator, melt blending in a twin-screw extruder, extruding, and cooling to obtain the basalt fiber grafted ethylene-octene copolymer; S5. Add EPDM rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant and dispersant into an internal mixer and mix them. Then add vulcanizer and activator and mix them to obtain a mixture. Refine the mixture in an open mixer. After the refining is completed, cool it and transfer it to a flat vulcanizer for vulcanization molding. Discharge the material to obtain a high-strength flame-retardant sealing strip.

2. The method for preparing a high-strength flame-retardant sealing strip according to claim 1, characterized in that: The mass ratio of carbon black, ethanol solution and γ-glycidyloxypropyltriethoxysilane in S1 is 100:1500-1800:15-25, the reaction temperature is 55-65° C., and the reaction time is 6-9 hours.

3. The method for preparing a high-strength flame-retardant sealing strip according to claim 1, characterized in that: The organic solvent in S2 includes any one or two of N,N-dimethylformamide, toluene and dimethyl sulfoxide.

4. The method for preparing a high-strength flame-retardant sealing strip according to claim 1, characterized in that: The mass ratio of the organic solvent, epoxy-modified carbon black and diaminodiphenyl sulfone in S2 is 950-1200:100:68-95, the reaction temperature is 95-105° C., and the reaction time is 4-6 hours.

5. The method for preparing a high-strength flame-retardant sealing strip according to claim 1, characterized in that: The mass ratio of the activated basalt fiber, ethanol solution and γ-methacryloxypropyltrimethoxysilane in S3 is 100:1800-2100:18-25, the reaction temperature is 25-35° C., and the reaction time is 12-15 hours.

6. The method for preparing a high-strength flame-retardant sealing strip according to claim 1, characterized in that: The mass ratio of ethylene-octene copolymer, olefinic basalt fiber, 9,10-dihydro-9-oxa-10-allylphosphaphenanthrene-10-oxide, maleic anhydride and initiator in S4 is 100:10-15:3-5:18-25:2-4, the melt blending temperature is 165-195°C, and the melt blending time is 8-12min.

7. The method for preparing a high-strength flame-retardant sealing strip according to claim 1, characterized in that: The initiator in S4 is dicumyl peroxide.

8. The method for preparing a high-strength flame-retardant sealing strip according to claim 1, characterized in that: The mass ratio of EPDM rubber, basalt fiber grafted ethylene-octene copolymer, modified carbon black, antioxidant, dispersant, vulcanizer and activator in S5 is 100:6-10:2-4:1-1.5:0.3-0.5:2-3:1-2.

9. The method for preparing a high-strength flame-retardant sealing strip according to claim 1, characterized in that: In the S5, the temperature of refining in the open mill is 120-140° C., the refining time is 8-10 min, the temperature of vulcanization molding in the flat vulcanizing agent is 155-185° C., and the vulcanization molding time is 10-15 min.

10. A high-strength flame-retardant sealing strip prepared by the method for preparing a high-strength flame-retardant sealing strip according to any one of claims 1 to 9.

Images