An intumescent flame-retardant modified ethylene propylene diene monomer rubber material, its preparation method and a sealing strip

Abstract

The present invention discloses an intumescent flame-retardant modified ethylene propylene diene monomer (EPDM) rubber material, comprising: 100 parts of EPDM, 1 - 5 parts of vulcanizing agent, 3 - 7 parts of lubricant, and 1 - 20 parts of intumescent flame retardant, wherein the intumescent flame retardant contains hypophosphorous acid-modified graphene oxide grafted with polyethyleneimine (PEI). A rubber composition is prepared by blending, and further made into a sealing strip. The technical solution of the present invention mainly solves the problem of poor flame retardancy of EPDM in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of flame-retardant rubber materials, and specifically to the technical field of the preparation of a phosphorus-nitrogen intumescent flame retardant-modified ethylene propylene diene monomer (EPDM) rubber material. Background Art

[0002] Ethylene propylene diene monomer (EPDM) is a widely used rubber material, usually copolymerized from ethylene, propylene and a small amount of non-conjugated diene, and it has high chemical stability, excellent heat resistance, weather resistance, ozone resistance and chemical corrosion resistance. EPDM has been widely used in fields such as automotive parts, aerospace components, heat-resistant and weather-resistant hoses, etc. However, EPDM has defects such as being easy to burn (the limiting oxygen index is about 19%) and being easy to produce black smoke when burning.

[0003] Graphene oxide has a large specific surface area (2630 m 2 / g), excellent thermal conductivity (5000 W·m -1 ·K -1 ) and an ultra-high Young's modulus (1100 GPa), and has been widely used in the rubber field. With its huge aspect ratio, it helps the chain confinement effect of EPDM, which can not only enhance the toughness of the EPDM substrate, but also endow it with higher strength. However, graphene oxide often shows insolubility and agglomeration tendency in the polymer matrix, which limits its industrial application. At the same time, the flame retardancy efficiency of GO itself is relatively low and cannot meet the requirements of current flame retardant standards. Fortunately, the oxygen-containing functional groups on the surface of GO can be modified by covalent or non-covalent modification to solve the above problems.

[0004] At the present stage, the modification methods of nanoparticles such as graphene and silica usually involve in-situ modification of the nanoparticles with silane coupling agents. However, the reaction of silane coupling agents is often accompanied by the self-condensation reaction of silane. At high silane contents, these silane coupling agent reaction processes are strongly affected by conditions such as temperature, so the controllability of the reaction becomes poor. Secondly, the condensation of silane coupling agents is accompanied by the release of ethanol VOC, resulting in excessive odor during the production process and in the final product. Summary of the Invention

[0005] The purpose of the present invention is to provide a rubber composition and its preparation method to solve the problem of poor flame retardancy of EPDM in the background art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: An intumescent flame retardant-modified ethylene propylene diene monomer rubber material, by mass, includes: 100 parts of EPDM, 1-5 parts of vulcanizing agent, 3-7 parts of lubricant, 1-20 parts of intumescent flame retardant, wherein: the intumescent flame retardant contains hypophosphorous acid-modified graphene oxide grafted with polyethyleneimine (PEI).

[0007] Further, the graphene oxide grafted with PEI is prepared by reacting polyethyleneimine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride with graphene oxide for 30 - 48 h.

[0008] Further, the intumescent flame retardant further contains zinc oxide-coated silica.

[0009] Further, the zinc oxide-coated silica is carboxylated and then stirred and reacted with graphene oxide grafted with PEI at 75 - 85 °C for 1 - 2 h to obtain SiO2@ZnO@GO-PEI.

[0010] Further, the intumescent flame retardant is prepared by stirring and reacting SiO2@ZnO@GO-PEI with formaldehyde and hypophosphorous acid at 60 - 75 °C for 3 - 7 h.

[0011] Further, the zinc oxide-coated silica is carboxylated by reacting with vinyltriethoxysilane, methacrylic acid, ammonium persulfate and sodium bisulfite.

[0012] Further, the zinc oxide-coated silica is prepared by using silica, zinc nitrate and ethylene glycol as raw materials, stirring and reacting for 3 - 5 h, and then sintering for 2.5 - 4 h under a protective gas atmosphere.

[0013] Further, it is characterized in that: EPDM and the lubricant are mixed evenly in a mixer at 55 - 75 °C, and then an anti-aging agent, a vulcanizing agent and an intumescent flame retardant are added in an open mill, and the temperature is raised to 115 - 130 °C and mixed evenly to obtain the product.

[0014] A sealing strip contains the above-mentioned intumescent flame retardant modified ethylene propylene diene monomer (EPDM) material.

[0015] A sealing strip, the preparation process includes: EPDM and the lubricant are mixed evenly in a mixer at 55 - 75 °C, and then an anti-aging agent, a vulcanizing agent and an intumescent flame retardant are added in an open mill, and the temperature is raised to 115 - 130 °C, mixed evenly and cooled to room temperature to obtain the base material. Set the screw speed of the twin-screw extruder to 200 r / min, the feeding section temperature to 50 °C, the die head temperature to 100 °C, and the temperatures of the other sections are between 80 °C and 85 °C. The base material is extruded and vulcanized and shaped to obtain the product.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. Zinc oxide is used to coat and modify silica to prepare SiO2@ZnO, which reduces the number of hydroxyl groups on the surface of silica, improves the agglomeration of silica, enhances the dispersion effect of silica, and further improves the mechanical properties of EPDM. At the same time, it also overcomes the defect that traditional silane coupling agents are prone to generate VOC gases such as ethanol after use.

[0018] 2. The surface of SiO2@ZnO was carboxylated to provide subsequent carboxyl reaction sites with GO-PEI.

[0019] 3. Macromolecules of PEI were grafted onto the surface of graphene oxide. The steric hindrance effect of PEI improved the dispersion of graphene oxide in the material, and meanwhile, a large number of amino groups were provided to lay a foundation for subsequent modification.

[0020] 4. GO-PEI formed a cage-like structure under electrostatic action and wrapped around the outer layer of SiO2@ZnO, weakening the hydrogen bonds between SiO2@ZnO particles and preventing a large amount of aggregation of SiO2@ZnO during the mixing process of the rubber substrate. The SiO2@ZnO nanoparticles, on the other hand, could effectively alleviate the severe stacking of GO-PEI sheets. At the same time, the GO nanosheets had a large specific surface area, so they could absorb and disperse energy during the tensile property test, which also contributed to the improvement of the toughness of the EPDM substrate. In addition, the large π bond of the aromatic ring in graphene oxide could absorb ultraviolet light through the electronic transition of π electrons under ultraviolet radiation, enhancing the anti-aging performance of the sealing strip.

[0021] 5. The unreacted amino groups on PEI further reacted with formaldehyde and hypophosphorous acid to graft phosphorus elements onto the flame retardant, forming an intumescent flame retardant system with phosphorus as the acid source, amino groups as the gas source, and graphene as the carbon source, overcoming the defects of traditional ammonium polyphosphate series intumescent flame retardants, such as easy moisture absorption, large addition amount, and easy deterioration of rubber substrate properties. At the same time, the zinc element in SiO2@ZnO had a good smoke suppression effect, significantly reducing the smoke generation amount of the rubber material during combustion. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the preparation of SiO2@ZnO and carboxylated SiO2@ZnO in this application.

[0023] Figure 2 It is a schematic diagram of the preparation of PEI-grafted GO material (GO-PEI), and only part of the PEI molecular chains are drawn in the figure.

[0024] Figure 3 It is a schematic diagram of the preparation of SiO2@ZnO@GO-PEI and P-SiO2@ZnO@GO-PEI, and only part of the carboxylated SiO2@ZnO and part of the amino-grafted hypophosphorous acid are drawn in the figure. Detailed Embodiments

[0025] To make the technical means, distinguishing features, achieved purposes, and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0026] In the embodiments of the present invention, various raw materials and reagents used are commercially available without special instructions, and the parts are in mass parts without special instructions.

[0027] Detection method of the rubber composition: Under standard laboratory environment (23°C, 55%), parameters such as tensile strength and elongation at break are carried out with reference to GB / T 528, vertical burning grade and limiting oxygen index are carried out with reference to GB / T 10707, smoke density grade is carried out with reference to GB 8624, artificial weathering is carried out with reference to GB / T 15255, the aging condition is cycle No. 4 in Method A, the determination of odor grade is carried out with reference to the T / CMIF 12 standard issued by China National Machinery Industry Corporation, the evaluation of VOCs is carried out with reference to HJ / T 400, and the sum of 8 parameters such as benzene, toluene, xylene, ethylbenzene, styrene, formaldehyde, acetaldehyde, and acrolein is determined.

[0028] Preparation of SiO2@ZnO: 1 g of SiO2 and 0.85 g of Zn(NO3)2·6H2O are ultrasonically dispersed in 100 ml of methanol solvent, heated to 85°C and stirred for 30 min, then 50 ml of ethylene glycol is added dropwise to the solution and stirred for another 3 h. After the reaction is completed, it is cooled to room temperature. The product is filtered and washed 3 times with ethanol solution, and then put into a tubular furnace, sintered at 400 - 450°C for 3 h under an argon atmosphere to obtain SiO2@ZnO.

[0029] Preparation of GO-PEI: 2.5 g of polyethyleneimine (PEI) and 3.5 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl) are dispersed and dissolved in 500 ml of methanol solution. After dispersing and stirring for 30 min, 4 g of graphene oxide (GO) is added and stirred for another 36 h. Dialysis is carried out in the solution for 48 hours using a dialysis membrane (Mn: 1×10 4 gmol -1 ) to remove unreacted PEI. The product is obtained as polyethyleneimine grafted graphene oxide (GO-PEI) after filtration, washing, and drying.

[0030] Preparation of SiO2@ZnO@GO-PEI: Take 1 g of SiO2@ZnO and ultrasonically disperse it in 100 ml of methanol solvent, adjust the pH to 6.5 with acetic acid, then add 0.6 g of vinyltriethoxysilane (A-151), heat it in a water bath at 80°C for 2 h, then add 0.4 g of methacrylic acid (MAA), 0.1 g of ammonium persulfate (APS), and 0.1 g of sodium bisulfite (RH) and continue to react for 3.5 h to carboxylate the surface of SiO2@ZnO. Then add 1.5 g of GO-PEI, maintain the environment at 80°C and continue to stir for 1 h. The product is obtained as SiO2@ZnO@GO-PEI after filtration, washing, and drying.

[0031] Preparation of P-SiO2@ZnO@GO-PEI: 1 g of SiO2@ZnO@GO-PEI was dispersed in 100 ml of deionized water, 2 ml of formaldehyde and 5 ml of hypophosphorous acid solution were added dropwise, and the temperature was raised to 70 °C and stirred for 5 h. After the reaction was completed and cooled to room temperature, the product was filtered, washed, and dried to obtain hypophosphorous acid-phosphorylated modified SiO2@ZnO@GO-PEI (P-SiO2@ZnO@GO-PEI).

[0032] Comparative Example 1: 100 parts of EPDM rubber and 5 parts of stearic acid were put into a mixer and heated to 60 °C to be mixed evenly. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were 80 °C. It was extruded and vulcanized and shaped.

[0033] Comparative Example 2: 10 parts of nano-silica, 100 parts of EPDM rubber, and 5 parts of stearic acid were put into a mixer and heated to 60 °C to be mixed evenly. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. It was extruded and vulcanized and shaped.

[0034] Comparative Example 3: 10 parts of nano-silica and 3 parts of silane coupling agent vinyltriethoxysilane (VTES) were mixed evenly, and then 100 parts of EPDM rubber and 5 parts of stearic acid were put into a mixer and heated to 60 °C to be mixed evenly. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. It was extruded and vulcanized and shaped.

[0035] Comparative Example 4: 10 parts of zinc oxide and 3 parts of silane coupling agent vinyltriethoxysilane (VTES) were mixed evenly, and then 100 parts of EPDM rubber and 5 parts of stearic acid were put into a mixer and heated to 60 °C to be mixed evenly. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. It was extruded and vulcanized and shaped.

[0036] Comparative Example 5: 10 parts of graphene oxide were mixed evenly with 3 parts of silane coupling agent vinyltriethoxysilane (VTES), and then together with 100 parts of EPDM rubber and 5 parts of stearic acid were put into an internal mixer and heated to 60 °C for even mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. It was extruded and vulcanized and shaped.

[0037] Comparative Example 6: 5 parts of nano-silica, 5 parts of graphene oxide were mixed evenly with 3 parts of silane coupling agent vinyltriethoxysilane (VTES), and then together with 100 parts of EPDM rubber and 5 parts of stearic acid were put into an internal mixer and heated to 60 °C for even mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. It was extruded and vulcanized and shaped.

[0038] Comparative Example 7: 5 parts of zinc oxide, 5 parts of graphene oxide were mixed evenly with 3 parts of silane coupling agent vinyltriethoxysilane (VTES), and then together with 100 parts of EPDM rubber and 5 parts of stearic acid were put into an internal mixer and heated to 60 °C for even mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. It was extruded and vulcanized and shaped.

[0039] Comparative Example 8: 4 parts of nano-silica, 3 parts of zinc oxide, 3 parts of graphene oxide were mixed evenly with 3 parts of silane coupling agent vinyltriethoxysilane (VTES), and then together with 100 parts of EPDM rubber and 5 parts of stearic acid were put into an internal mixer and heated to 60 °C for even mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. It was extruded and vulcanized and shaped.

[0040] Comparative Example 9: 10 parts of ammonium polyphosphate were mixed evenly with 3 parts of silane coupling agent vinyltriethoxysilane (VTES), and then together with 100 parts of EPDM rubber and 5 parts of stearic acid were put into an internal mixer and heated to 60 °C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and uniformly mixed in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. Extrusion molding and vulcanization and shaping were carried out.

[0041] Comparative Example 10: 10 parts of ammonium polyphosphate were put into an internal mixer together with 100 parts of EPDM rubber and 5 parts of stearic acid and heated to 60 °C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and uniformly mixed in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. Extrusion molding and vulcanization and shaping were carried out.

[0042] Example 1: 3 parts of SiO2@ZnO were put into an internal mixer together with 100 parts of EPDM rubber and 5 parts of stearic acid and heated to 60 °C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and uniformly mixed in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. Extrusion molding and vulcanization and shaping were carried out.

[0043] Example 2: 5 parts of SiO2@ZnO were put into an internal mixer together with 100 parts of EPDM rubber and 5 parts of stearic acid and heated to 60 °C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and uniformly mixed in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. Extrusion molding and vulcanization and shaping were carried out.

[0044] Example 3: 10 parts of SiO2@ZnO were put into an internal mixer together with 100 parts of EPDM rubber and 5 parts of stearic acid and heated to 60 °C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and uniformly mixed in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. Extrusion molding and vulcanization and shaping were carried out.

[0045] Example 4: 3 parts of GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into a mixer and heated to 60 °C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120 °C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50 °C, the die head temperature is 100 °C, and the temperatures of the other sections are between 80 °C. Extrusion molding and vulcanization are carried out for shaping.

[0046] Example 5: 5 parts of GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into a mixer and heated to 60 °C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120 °C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50 °C, the die head temperature is 100 °C, and the temperatures of the other sections are between 80 °C. Extrusion molding and vulcanization are carried out for shaping.

[0047] Example 6: 10 parts of GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into a mixer and heated to 60 °C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120 °C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50 °C, the die head temperature is 100 °C, and the temperatures of the other sections are between 80 °C. Extrusion molding and vulcanization are carried out for shaping.

[0048] Example 7: 5 parts of SiO2@ZnO, 5 parts of GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into a mixer and heated to 60 °C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120 °C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50 °C, the die head temperature is 100 °C, and the temperatures of the other sections are between 80 °C. Extrusion molding and vulcanization are carried out for shaping.

[0049] Example 8: 5 parts of SiO2@ZnO, 5 parts of GO, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into a mixer and heated to 60 °C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120 °C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50 °C, the die head temperature is 100 °C, and the temperatures of the other sections are between 80 °C. Extrusion molding and vulcanization are carried out for shaping.

[0050] Example 9: 3 parts of SiO2@ZnO@GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into an internal mixer and heated to 60°C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120°C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50°C, the die head temperature is 100°C, and the temperatures of the other sections are between 80°C. It is extruded and vulcanized and shaped.

[0051] Example 10: 5 parts of SiO2@ZnO@GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into an internal mixer and heated to 60°C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120°C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50°C, the die head temperature is 100°C, and the temperatures of the other sections are between 80°C. It is extruded and vulcanized and shaped.

[0052] Example 11: 10 parts of SiO2@ZnO@GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into an internal mixer and heated to 60°C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120°C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50°C, the die head temperature is 100°C, and the temperatures of the other sections are between 80°C. It is extruded and vulcanized and shaped.

[0053] Example 12: 1 part of P-SiO2@ZnO@GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into an internal mixer and heated to 60°C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120°C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50°C, the die head temperature is 100°C, and the temperatures of the other sections are between 80°C. It is extruded and vulcanized and shaped.

[0054] Example 13: 3 parts of P-SiO2@ZnO@GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into an internal mixer and heated to 60°C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120°C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50°C, the die head temperature is 100°C, and the temperatures of the other sections are between 80°C. It is extruded and vulcanized and shaped.

[0055] Example 14: 5 parts of P-SiO2@ZnO@GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into a kneader and heated to 60°C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120°C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50°C, the die head temperature is 100°C, and the temperatures of the other sections are between 80°C. It is extruded and vulcanized and shaped.

[0056] Example 15: 10 parts of P-SiO2@ZnO@GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into a kneader and heated to 60°C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120°C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50°C, the die head temperature is 100°C, and the temperatures of the other sections are between 80°C. It is extruded and vulcanized and shaped.

[0057] Example 16: 15 parts of P-SiO2@ZnO@GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into a kneader and heated to 60°C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120°C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50°C, the die head temperature is 100°C, and the temperatures of the other sections are between 80°C. It is extruded and vulcanized and shaped.

[0058] Example 17: 5 parts of SiO2@ZnO@GO-PEI, 5 parts of ammonium polyphosphate, 100 parts of EPDM rubber, and 5 parts of stearic acid are put into a kneader and heated to 60°C for uniform mixing. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur are added and uniformly mixed in an open mill at 120°C. After the rubber compound is sheeted and cooled to room temperature, the screw speed of the twin-screw extruder is set at 200 r / min, the feeding section temperature is 50°C, the die head temperature is 100°C, and the temperatures of the other sections are between 80°C. It is extruded and vulcanized and shaped.

[0059] Example 18: 5 parts of ammonium polyphosphate were mixed evenly with 3 parts of vinyltriethoxysilane (VTES), a silane coupling agent, and then put into a kneader together with 5 parts of SiO2@ZnO@GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid. The temperature was raised to 60 °C and mixed evenly. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. It was extruded and vulcanized and shaped.

[0060] Example 19: 5 parts of GO-PEI and 5 parts of ammonium polyphosphate were put into a kneader together with 100 parts of EPDM rubber and 5 parts of stearic acid. The temperature was raised to 60 °C and mixed evenly. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. It was extruded and vulcanized and shaped.

[0061] Example 20: 5 parts of SiO2@ZnO and 5 parts of ammonium polyphosphate were put into a kneader together with 100 parts of EPDM rubber and 5 parts of stearic acid. The temperature was raised to 60 °C and mixed evenly. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. It was extruded and vulcanized and shaped.

[0062] Example 21: 5 parts of SiO2@ZnO, 5 parts of GO-PEI, and 5 parts of ammonium polyphosphate were put into a kneader together with 100 parts of EPDM rubber and 5 parts of stearic acid. The temperature was raised to 60 °C and mixed evenly. Then, 3 parts of antioxidant 4010 and 2 parts of sulfur were added and mixed evenly in an open mill at 120 °C. After the rubber compound was sheeted and cooled to room temperature, the screw speed of the twin-screw extruder was set at 200 r / min, the feeding section temperature was 50 °C, the die head temperature was 100 °C, and the temperatures of the other sections were between 80 °C. It was extruded and vulcanized and shaped.

[0063] Example 22: Prepare P-GO-PEI by referring to the preparation method of P-SiO2@ZnO@GO-PEI. Take 5 parts of P-GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid and put them into a kneader. Heat up to 60 °C and mix evenly. Then add 3 parts of antioxidant 4010 and 2 parts of sulfur, and heat up to 120 °C in an open mill to mix evenly. After the rubber compound is sheeted and cooled to room temperature, set the screw speed of the twin-screw extruder to 200 r / min, the temperature of the feeding section to 50 °C, the temperature of the die head to 100 °C, and the temperatures of the other sections to be between 80 °C. Extrude and vulcanize and shape.

[0064] Example 23: Prepare P-SiO2@CuO@GO-PEI by referring to the preparation method of P-SiO2@ZnO@GO-PEI. Take 5 parts of P-SiO2@CuO@GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid and put them into a kneader. Heat up to 60 °C and mix evenly. Then add 3 parts of antioxidant 4010 and 2 parts of sulfur, and heat up to 120 °C in an open mill to mix evenly. After the rubber compound is sheeted and cooled to room temperature, set the screw speed of the twin-screw extruder to 200 r / min, the temperature of the feeding section to 50 °C, the temperature of the die head to 100 °C, and the temperatures of the other sections to be between 80 °C. Extrude and vulcanize and shape.

[0065] Example 24: Prepare P-SiO2@MgO@GO-PEI by referring to the preparation method of P-SiO2@ZnO@GO-PEI. Take 5 parts of P-SiO2@MgO@GO-PEI, 100 parts of EPDM rubber, and 5 parts of stearic acid and put them into a kneader. Heat up to 60 °C and mix evenly. Then add 3 parts of antioxidant 4010 and 2 parts of sulfur, and heat up to 120 °C in an open mill to mix evenly. After the rubber compound is sheeted and cooled to room temperature, set the screw speed of the twin-screw extruder to 200 r / min, the temperature of the feeding section to 50 °C, the temperature of the die head to 100 °C, and the temperatures of the other sections to be between 80 °C. Extrude and vulcanize and shape.

[0066] The experimental data are recorded in the following table. Among them: the unit of tensile strength is MPa, the unit of elongation at break is %, the unit of compression set is %, the unit of limiting oxygen index is %, and the vertical burning grades from poor to excellent are: not passing ( / ), V-2, V-1, and V-0. The unit of smoke density is %, the odor grade is divided into 1-5 levels, and the unit of VOCs is g·cm -3 。

[0067]

[0068]

[0069] By analyzing Comparative Examples 1 and 2, we can find that the addition of nano-silica will significantly deteriorate the mechanical properties of the material, and has little impact on other properties of the material. Further analyzing Comparative Examples 3-8, it is not difficult to see that materials such as nano-silica, zinc oxide, and graphene oxide modified with silane coupling agent vinyltriethoxysilane significantly contribute to improving the mechanical properties of the EPDM substrate, but at the same time, it also brings problems such as an increase in odor level and an increase in VOC emissions. This is mainly because traditional silane coupling agents are prone to generate VOC gases such as ethanol after use, resulting in an increase in odor in the product and the product production process. It is worth mentioning that Comparative Example 4 using zinc oxide is significantly superior to other control groups in terms of the smoke density index, indicating that zinc elements have an obvious effect on reducing the smoke generation amount during the combustion of rubber materials. Finally, analyzing Comparative Examples 9 and 10, ammonium polyphosphate with and without silane coupling agent modification can significantly improve the flame retardancy of the material, but unmodified ammonium polyphosphate will significantly deteriorate the mechanical properties of the material, and compared with the blank sample, both will increase the VOC content and odor level of the product.

[0070] Comparing Examples 1, 2, 3 with Comparative Examples 2, 3, 4, we can find that the nano-silica coated with zinc oxide has an obvious strengthening effect on the material. This is because the number of hydroxyl groups on the surface of nano-silica is reduced after being coated with zinc oxide, thereby reducing the agglomeration phenomenon of silica in the rubber substrate. However, it still has a certain impact on the elongation at break of the material. We guess that this is because as the amount of SiO2@ZnO increases, the stress concentration points in the rubber substrate also increase, thus causing the deterioration of the toughness of the material. At the same time, the smoke density of the material decreases, but the odor level increases slightly.

[0071] Analyzing Examples 4-6 and Comparative Example 5, it can be seen that the graphene oxide grafted with polyethyleneimine has a more obvious strengthening and toughening effect on the material. This may rely on the effect of the linear molecular chain of polyethyleneimine. The rich amino groups on the surface of polyethyleneimine combine with the carboxyl groups on the surface of graphene oxide, improving the overlapping phenomenon between the layers of graphene oxide and making the graphene oxide more evenly and fully dispersed. At the same time, the introduction of nitrogen elements also has a certain promoting effect on the flame retardancy of the material.

[0072] Comprehensively analyzing Examples 7-11, it can be seen that SiO2@ZnO@GO-PEI is significantly superior to the combination of SiO2@ZnO, GO-PEI, SiO2@ZnO, and GO in terms of both flame retardancy and mechanical properties. This may be because the carboxylated SiO2@ZnO and the amino groups on GO-PEI can be electrostatically connected, and then through their respective steric hindrance effects, the dispersion of SiO2@ZnO and the delamination of GO-PEI are realized, enabling the reinforcing material to be fully dispersed in the rubber substrate and also improving the flame retardancy of the material.

[0073] Upon further observation of Examples 12 - 16, it can be seen that P - SiO2@ZnO@GO - PEI modified by hypophosphorous acid not only significantly improves the tensile strength of the material, but also more significantly enhances the flame retardant effect. This is because an intumescent flame retardant system is formed within the P - SiO2@ZnO@GO - PEI molecule, with phosphoric acid as the acid source, amine groups as the gas source, and graphene as the carbon source. At the same time, combined with the strengthening effect of SiO2@ZnO and the flame retardant and smoke suppression effects of ZnO, the flame retardant and smoke suppression performance of the material is significantly improved.

[0074] Comparing the above - mentioned examples with Examples 17 - 21, at the same addition amount, the performance of Example 17 is significantly weaker than that of Example 14. The defect in mechanical properties mainly comes from the agglomeration of ammonium polyphosphate in the rubber matrix, and the flame retardant effect may also be related to the agglomeration of ammonium polyphosphate. Since it fails to disperse sufficiently, the rubber matrix in the non - dispersed part is extremely easy to burn. Comparing and observing Example 18, after modifying ammonium polyphosphate with a silane coupling agent, although it can slightly improve the mechanical properties and flame retardant properties of the material, the odor level of the material is more affected, and the VOCs emissions also increase significantly.

[0075] Finally, comparing Examples 22, 23, 24 with Example 14, the various properties of P - GO - PEI are significantly inferior to those of P - SiO2@ZnO@GO - PEI. This may be because the lack of the strengthening effect, smoke suppression effect and steric hindrance effect of SiO2@ZnO leads to certain agglomeration of P - GO - PEI. Looking at Examples 23 and 24 again, where the metal element is changed from Zn to Cu and Mg, the performance is slightly lower than that of P - SiO2@ZnO@GO - PEI. This may be highly related to the characteristics of the element itself. The effect of using Zn element is more obvious in terms of flame retardancy and smoke suppression.

[0076] Some samples participated in the artificial weathering test, and the test results are shown in the following table:

[0077]

[0078] From the data comparison of the above - mentioned comparative examples and examples, P - SiO2@ZnO@GO - PEI has obvious advantages in weather resistance. We guess that on the one hand, the large π - bond of the aromatic ring in graphene oxide can absorb ultraviolet light through the electronic transition of π electrons under ultraviolet radiation, improving the anti - ultraviolet aging performance of the sealing strip; on the other hand, the grafting reaction between the amine groups on the surface of the grafted polyethyleneimine and the carboxyl groups on the surface of graphene oxide reduces the number of oxygen - containing groups in the flame retardant, thus improving the anti - thermal aging performance of the product. At the same time, the improvement of the flame retardant performance of the material also improves the heat resistance of the material to a certain extent.

[0079] The foregoing has shown and described the basic principles, main features and advantages of the present invention. For a person skilled in the art, it is obvious that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and without departing from the spirit or basic features of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

[0080] In addition, it should be understood that although this specification is described according to the embodiments and the drawings, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An ethylene propylene diene monomer (EPDM) rubber material modified by intumescent flame retardancy, by mass parts, comprising: 100 parts of EPDM, 1 - 5 parts of vulcanizing agent, 3 - 7 parts of lubricant, 1 - 20 parts of intumescent flame retardant, characterized in that: the intumescent flame retardant contains graphene oxide grafted with PEI modified by hypophosphorous acid; The graphene oxide grafted with PEI is prepared by reacting polyethyleneimine, 1 - ethyl-(3 - dimethylaminopropyl)carbodiimide hydrochloride with graphene oxide for 30 - 48 h; The intumescent flame retardant also contains zinc oxide-coated silica; The zinc oxide-coated silica is carboxylated and then reacted with graphene oxide grafted with PEI at 75 - 85 °C for 1 - 2 h to obtain SiO2@ZnO@GO-PEI; The intumescent flame retardant is prepared by reacting SiO2@ZnO@GO-PEI with formaldehyde and hypophosphorous acid at 60 - 75 °C for 3 - 7 h; The zinc oxide-coated silica is carboxylated by reacting with vinyltriethoxysilane, methacrylic acid, ammonium persulfate and sodium bisulfite; The zinc oxide-coated silica is prepared by using silica, zinc nitrate and ethylene glycol as raw materials, stirring and reacting for 3 - 5 h, and then sintering for 2.5 - 4 h under a protective gas atmosphere; 2. The preparation method of an intumescent flame retardant modified ethylene propylene diene monomer rubber material according to claim 1, wherein: EPDM and the lubricant are mixed evenly in a mixer at 55 - 75 °C, and then anti-aging agent, vulcanizing agent and intumescent flame retardant are added in an open mill, and the temperature is raised to 115 - 130 °C and mixed evenly to obtain the product; 3. A sealing strip, characterized in that: It contains the ethylene propylene diene monomer rubber material modified by the intumescent flame retardant described in claim 1.

4. The sealing strip according to claim 3, wherein: The preparation process of the sealing strip includes: EPDM and the lubricant are mixed evenly in a mixer at 55 - 75 °C, and then anti-aging agent, vulcanizing agent and intumescent flame retardant are added in an open mill, the temperature is raised to 115 - 130 °C, mixed evenly and cooled to room temperature to obtain the base material. The screw speed of the twin-screw extruder is set at 200 r / min, the temperature of the feeding section is 50 °C, the temperature of the die head is 100 °C, and the temperature of the remaining sections is between 80 °C and 85 °C. The base material is extruded and vulcanized and shaped to obtain the product.

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