Ethylene-propylene-diene monomer rubber sealing strip and preparation method thereof

Abstract

The invention relates to the field of sealing strips, in particular to an ethylene propylene diene monomer sealing strip and a preparation method thereof. Comprising the following components in parts by weight: 150-180 parts of ethylene propylene diene monomer, 60-90 parts of carbon black, 8-12 parts of white carbon black, 3-8 parts of a peroxide vulcanizing agent, 6-12 parts of zinc oxide, 12-16 parts of magnesium oxide, 10-18 parts of paraffin oil, 1-3 parts of an accelerant, 1-3 parts of stearic acid, 1-3 parts of an anti-aging agent and 1-3 parts of a coupling agent. According to the invention, a C-C cross-linked bond is generated through the synergistic effect between the carbon black and the white carbon black activated by the coupling agent and the free radical reaction of the peroxide vulcanizing agent, so that a high-density and uniform cross-linked network is formed, and the tensile strength of the ethylene propylene diene monomer sealing strip is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of sealing strips, and in particular to an EPDM rubber sealing strip and a preparation method thereof. Background Art

[0002] EPDM rubber is a copolymer of ethylene, propylene and a small amount of non-conjugated dienes. It is a type of EPDM rubber. Because its main chain is composed of chemically stable saturated hydrocarbons and only contains unsaturated double bonds in the side chains, it has excellent aging resistance such as ozone resistance, heat resistance, and weather resistance. It can be widely used in automotive parts, building waterproofing materials, wire and cable sheathing, heat-resistant hoses, tapes, automotive seals and other fields.

[0003] Door and window sealing strips are core components for building energy conservation and sealing protection. Their performance directly impacts a building's airtightness, watertightness, sound insulation, and thermal insulation. EPDM rubber, due to its excellent weather resistance, ozone resistance, and UV aging resistance, has become the preferred material for door and window sealing strips. However, the tensile strength of existing EPDM rubber is insufficient to meet these requirements, and it is prone to edge cracking during use. Therefore, there is an urgent need for an EPDM sealing strip with excellent tensile strength. Summary of the Invention

[0004] In order to improve the tensile strength of an EPDM rubber sealing strip, the present application provides an EPDM rubber sealing strip and a preparation method thereof.

[0005] In the first aspect, the present application provides an EPDM rubber sealing strip, which adopts the following technical solution: An EPDM rubber sealing strip comprises the following components in parts by weight: 150-180 parts of EPDM rubber, 60-90 parts of carbon black, 8-12 parts of white carbon black, 3-8 parts of a peroxide vulcanizer, 6-12 parts of zinc oxide, 12-16 parts of magnesium oxide, 10-18 parts of paraffin oil, 1-3 parts of an accelerator, 1-3 parts of stearic acid, 1-3 parts of an antioxidant, and 1-3 parts of a coupling agent.

[0006] By adopting the above technical solution, EPDM rubber serves as the matrix, providing rubber elasticity and basic mechanical properties. Carbon black can be added to the reaction as a core reinforcing agent, synergistically improving the tensile strength of the EPDM rubber with silica. The coupling agent then reacts with the rubber molecular chain to form a "filler-coupling agent-rubber" chemical connection, reducing filler agglomeration and enhancing interfacial adhesion. The peroxide curing agent can generate C-C crosslinks through free radical reactions, thus forming a high-density, uniform crosslinked network that provides rigid support for the EPDM rubber sealing strip, allowing stress to be effectively transferred through the crosslinks and improving the tensile strength of the EPDM rubber sealing strip. The addition of zinc oxide and magnesium oxide then coordinates the vulcanization process of the peroxide curing agent and stabilizes the vulcanization process. Through the synergistic effect of the above raw materials, the prepared EPDM rubber sealing strip has excellent tensile strength.

[0007] Preferably, the EPDM rubber sealing strip further comprises processing aid A and processing aid B, wherein the processing aid A is at least one of magnesium hydroxide and aluminum hydroxide, and the processing aid B is at least one of glycerol borate, glyceryl monostearate and glyceryl monomethacrylate.

[0008] By adopting the above technical solution and compounding processing aids A and B, the tensile strength of EPDM rubber sealing strips can be effectively improved. The surfaces of magnesium hydroxide and aluminum hydroxide have hydroxyl groups, and glycerol borate can serve as a molecular bridge. The borate groups can form coordination bonds with metal ions on the surface of processing aid A. The carbon chains in glycerol borate can entangle with the molecular chains of EPDM rubber, forming a chemical-physical dual crosslink. This improves the interfacial adhesion between processing aid A and the EPDM rubber matrix. Furthermore, the coordination between glycerol borate and processing aid A effectively reduces the agglomeration of processing aid A, thereby reducing the hindrance to the movement of the EPDM rubber molecular chains. At the same time, the plasticizing effect of glycerol borate can be more evenly distributed around the filler through coordinated adsorption, enhancing the mobility of the chain segments and thus improving the tensile strength of the EPDM rubber sealing strip.

[0009] Glyceryl monostearate can form hydrogen bonds with the hydroxyl groups on the surface of magnesium hydroxide and aluminum hydroxide through its polar hydroxyl groups, forming a coating layer on the surface of the filler particles, effectively reducing the agglomeration of the filler. In addition, the long-chain alkyl group of glyceryl monostearate has good compatibility with the EPDM rubber molecular chain, which can reduce the surface energy of the filler-rubber interface and promote the bonding of the filler with the EPDM rubber matrix, thereby effectively improving the tensile strength of the EPDM rubber sealing strip.

[0010] The epoxy groups of glycerol monomethacrylate can undergo a ring-opening reaction with the hydroxyl groups on the surface of magnesium hydroxide and aluminum hydroxide to form a chemically bonded interface, promoting the uniform dispersion of the filler in the EPDM rubber matrix, thereby improving the tensile strength of the EPDM rubber sealing head.

[0011] Preferably, the weight portion of the processing aid A is 20-40 parts.

[0012] By adopting the above technical solution, when the weight of processing aid A is between 20 and 40 parts, the polar groups on the surface of processing aid A can form hydrogen bonds or coordination effects with the polar groups of processing aid B, so that the prepared EPDM rubber sealing strip has excellent tensile strength. When the weight of processing aid A is less than 20 parts, the action sites of processing aid A and processing aid B are limited, and a sufficient interfacial bonding network cannot be formed, resulting in limited tensile strength of the prepared EPDM rubber sealing strip. When the weight of processing aid A is greater than 40 parts, the filler particles are relatively large, agglomeration is likely to occur, and stress concentration points are formed, which in turn reduces the tensile strength of the EPDM rubber sealing strip.

[0013] Preferably, the processing aid A is magnesium hydroxide.

[0014] Preferably, the weight portion of the magnesium hydroxide is 25-35 parts.

[0015] By adopting the above technical solution, magnesium hydroxide and aluminum hydroxide are metal hydroxides that release water vapor when decomposed by heat, absorbing heat and diluting combustible gases. At the same time, magnesium oxide and aluminum oxide are generated to cover the surface, thereby inhibiting the combustion of the EPDM rubber sealing strip and achieving a flame retardant effect. Among them, the decomposition temperature of magnesium hydroxide is 340-430°C, and the decomposition temperature of aluminum hydroxide is 220-250°C. The decomposition temperature of magnesium hydroxide is higher than that of aluminum hydroxide, effectively reducing the phenomenon of premature release of crystal water and ensuring sufficient interfacial reaction with processing aid B. In addition, magnesium hydroxide has a larger specific surface area, which can provide more hydroxyl groups to react with processing aid B, and the resulting EPDM rubber sealing strip has a more ideal tensile strength.

[0016] Magnesium hydroxide can also be used as processing aid A. During the decomposition process, it can release water vapor, absorb heat and dilute combustible gases, while generating magnesium oxide to cover the surface, thereby inhibiting the combustion of EPDM rubber sealing strips and achieving a flame retardant effect.

[0017] When the weight proportion of magnesium hydroxide is between 25 and 35, the resulting EPDM rubber sealing strip has both ideal tensile strength and flame retardant effect. When the weight proportion of magnesium hydroxide is less than 25, the insufficient amount of magnesium hydroxide results in limited points of action with the processing aid B, and a sufficient interfacial bonding network cannot be formed, resulting in an insignificant effect on improving the tensile strength of the EPDM rubber sealing strip. When the weight proportion of magnesium hydroxide is greater than 35, the amount of magnesium hydroxide added is too much, and agglomeration is prone to occur. There are gaps or weak bonding areas at the interface between the agglomerates and the EPDM rubber, resulting in cracks at the agglomerates when the EPDM rubber sealing strip is stretched, affecting the tensile strength of the EPDM rubber sealing strip.

[0018] Preferably, the weight portion of the processing aid B is 3-5 parts.

[0019] By adopting the above technical solution, when the weight of processing aid B is between 3 and 5 parts, the processing aid B molecules can cover the active sites on the surface of processing aid A, ensuring the coordination between processing aid B and processing aid A, and effectively improving the tensile strength of the EPDM rubber sealing strip. When the weight of processing aid B is less than 3 parts, processing aid B cannot cover the polar hydroxyl groups on the surface of processing aid A, resulting in insufficient "filler-rubber" interface coupling, unsatisfactory filler dispersion and stress transfer efficiency, resulting in low tensile strength of the obtained EPDM rubber sealing strip. When the weight of processing aid B is greater than 5 parts, the excessive polar groups of processing aid B will increase the viscosity of the rubber compound, resulting in a sharp increase in mixing energy consumption, rough extrusion surface or even broken strips, and processing aid B is easy to agglomerate or migrate and precipitate in the EPDM rubber matrix to form a "free additive phase", which weakens the interfacial adhesion and causes a decrease in tensile strength.

[0020] Preferably, the processing aid B is glycerol borate.

[0021] By adopting the above technical solution, glycerol borate can act as a molecular bridge, the borate group can form a coordination bond with the metal ions on the surface of processing aid A, and the carbon chain in glycerol borate can be entangled with the molecular chain of EPDM rubber to form a chemical-physical double crosslinking, thereby improving the interfacial adhesion between processing aid A and the EPDM rubber matrix, which is more stable than the hydrogen bond of glycerol monostearate and the ring-opening reaction of glycerol monomethacrylate.

[0022] The decomposition temperature of glycerol borate matches that of magnesium hydroxide, and it can stably exist at the vulcanization temperature of the peroxide vulcanizer. Without affecting the free radicals generated by the decomposition of the peroxide vulcanizer, it can also "shield" the active sites on the surface of magnesium hydroxide through coordination, reducing the loss of free radical adsorption, increasing the cross-linking density by 10-15%, and making the vulcanized rubber network more uniform.

[0023] Glycerol borate itself also has a synergistic flame-retardant effect. When combined with magnesium hydroxide, it forms a triple flame-retardant mechanism of "heat absorption-carbonization-oxygen isolation". When magnesium hydroxide is heated and releases water vapor to dilute the combustible gas, glycerol borate decomposes to form borate. The low-melting-point borate can form a composite ceramic carbon layer with the metal oxide produced by the decomposition of processing aid A, significantly improving the high-temperature resistance and strength of the carbon layer, and preventing the spread of flames.

[0024] Glycerol borate itself can also participate in the reaction as an anti-low temperature additive. Glycerol borate can be inserted into the rubber molecular chains as an internal plasticizer to weaken the intermolecular forces, lower the glass transition temperature, and enable the chain segments to maintain mobility at low temperatures.

[0025] Preferably, the mass ratio of the processing aid B to the processing aid A is 1:6-10.

[0026] By adopting the above technical solution, when the mass ratio of processing aid B to processing aid A is in the range of 1:6-10, the resulting EPDM rubber sealing strip has excellent tensile strength and a certain flame retardant effect. When the proportion of processing aid B is too large, the molecules of processing aid B are too dense, resulting in an increase in the viscosity of the rubber compound, which hinders the segment movement of the EPDM rubber and reduces the tensile strength of the EPDM rubber sealing strip; when the proportion of processing aid A is too large, processing aid B cannot effectively wrap the particles of processing aid A, the filler dispersion becomes poor, and agglomerates are easily formed, resulting in a weakened interfacial adhesion between the filler and the EPDM rubber matrix and a reduced stress transfer efficiency, thereby making the tensile strength of the sealing strip not significantly improved, and even causing a decrease in tensile strength due to the formation of stress concentration points due to filler agglomeration. In a second aspect, the present application provides a method for preparing an EPDM rubber sealing strip, which adopts the following technical solution: A method for preparing an EPDM rubber sealing strip, for preparing the EPDM rubber sealing strip, comprises the following steps: S1: EPDM rubber, carbon black, white carbon black, zinc oxide, magnesium oxide, paraffin oil, stearic acid, antioxidant, coupling agent and other raw materials are mixed in a first stage according to the formula amount, and then a peroxide curing agent and an accelerator are added to the reaction system according to the formula amount for second stage mixing to obtain a rubber compound; S2: Cooling and shaping the rubber mixture to obtain an EPDM rubber sealing strip.

[0027] By adopting the above technical means, the present application prepares an EPDM rubber sealing strip through one-stage mixing, two-stage mixing, cooling and shaping. The process is simple and easy to operate, thereby preparing an EPDM rubber sealing strip with excellent tensile strength.

[0028] In summary, this application includes at least one of the following beneficial technical effects: 1. This application uses EPDM rubber as a matrix to provide rubber elasticity and basic mechanical properties. Carbon black can be added as a core reinforcing agent to the reaction and synergistically improve the tensile strength of the EPDM rubber with silica. A coupling agent then reacts with the rubber molecular chain to form a "filler-coupling agent-rubber" chemical connection, reducing filler agglomeration and enhancing interfacial bonding. The peroxide curing agent can generate CC cross-linking bonds through free radical reactions, thereby forming a high-density, uniform cross-linking network, providing rigid support for the EPDM rubber sealing strip and effectively improving the tensile strength of the EPDM rubber sealing strip. 2. The present application compounds magnesium hydroxide and glycerol borate, wherein glycerol borate acts as a molecular bridge to effectively improve the interfacial adhesion between magnesium hydroxide and the EPDM rubber matrix. The plasticizing effect of glycerol borate can enhance the segment mobility of the EPDM rubber molecules, thereby effectively improving the tensile strength of the EPDM rubber sealing strip. At the same time, magnesium hydroxide itself can act as a flame retardant, and glycerol borate itself can act as a low-temperature resistance additive, so that the resulting EPDM rubber sealing strip has excellent tensile strength as well as flame retardant effect and low-temperature resistance. 3. In this application, the mass ratio of processing aid B to processing aid A is set within the range of 1:6-10, and the resulting EPDM rubber sealing strip has excellent tensile strength, reducing the phenomenon of increased rubber viscosity caused by excessive processing aid B and the phenomenon of weak interfacial bonding between the filler and the ternary rubber matrix caused by excessive processing aid A. DETAILED DESCRIPTION

[0029] The raw materials in this application include the following parts: Glyceryl borate: a commercially available product with CAS number 49625-59-42; Glyceryl monostearate: a commercially available product with CAS number 123-94-4; Glyceryl monomethyl vinylate: a commercial product with CAS number 5919-74-4; Peroxide curing agent: selected from alkyl peroxide or diacyl peroxide, this application takes alkyl peroxide as an example; Coupling agent: selected from silane coupling agent or titanate coupling agent, and this application takes silane coupling agent as an example.

[0030] The present application is further described in detail below with reference to the following examples and comparative examples. Example 1

[0031] An EPDM rubber sealing strip comprises the following components in parts by weight: 160g of EPDM rubber, 75g of carbon black, 10g of white carbon black, 6g of alkyl peroxide, 9g of zinc oxide, 14g of magnesium oxide, 14g of paraffin oil, 2g of accelerator TMTD, 2g of stearic acid, 2g of antioxidant MB, and 2g of alkyl coupling agent.

[0032] A method for preparing an EPDM rubber sealing strip, for preparing the EPDM rubber sealing strip, comprises the following steps: S1: EPDM rubber, carbon black, white carbon black, zinc oxide, magnesium oxide, paraffin oil, stearic acid, antioxidant, coupling agent and other raw materials are mixed in a first stage according to the formula amount, and then a peroxide curing agent and an accelerator are added to the reaction system according to the formula amount for second stage mixing to obtain a rubber compound; S2: Cooling and shaping the rubber mixture to obtain an EPDM rubber sealing strip.

[0033] The temperature of the first mixing stage was 120° C., and the mixing time was 10 min; the temperature of the second mixing stage was 80° C., and the mixing time was 3 min.

[0034] Example 2-3 In Example 2-3, based on the preparation method of Example 1, the components of the EPDM rubber sealing strip were adjusted. The specific adjustments are shown in Table 1.

[0035] Comparative Examples 1-3 Comparative Examples 1-3 Based on the preparation method of Example 1, the components of the EPDM rubber sealing strip were adjusted. The specific adjustments are shown in Table 1.

[0036] Performance testing The EPDM rubber sealing strips of Examples 1-3 and Comparative Examples 1-3 were analyzed, and the specific detection method was as follows: tensile strength The tensile strength of EPDM rubber sealing strips was tested according to GB / T 528-2008 standard (dumbbell-shaped specimen).

[0037] According to the above detection method, the test results of Examples 1-3 and Comparative Examples 1-3 were obtained, as shown in Table 1 below.

[0038] Table 1 Components and performance test table of EPDM rubber sealing strips of Examples 1-3 and Comparative Examples 1-3

[0039] Referring to Table 1, by comparing Examples 1-3 and Comparative Examples 1-3, it can be seen that the tensile strength of the EPDM rubber sealing strips obtained in Examples 1-3 is significantly higher than the tensile strength of the EPDM rubber sealing strips obtained in Comparative Examples 1-3. This may be because carbon black serves as a core reinforcing agent during the preparation process, which has a significant effect on improving the tensile strength of the EPDM rubber sealing strips. The addition of silica can cooperate with carbon black to construct a "double filler network" to further improve the tensile strength of the EPDM rubber sealing strips. The peroxide curing agent generates CC cross-linking bonds through free radical reactions, providing rigid support for the EPDM rubber sealing strips, thereby increasing the tensile strength of the EPDM rubber sealing strips.

[0040] Example 4 Example 4 Based on the preparation method of Example 1, 30 g of magnesium hydroxide (processing aid A) and 4 g of glycerol borate (processing aid B) were added to S1, and other conditions remained unchanged.

[0041] Examples 5-9 In Examples 5-9, based on the preparation method of Example 4, the types of processing aid A and processing aid B were adjusted. The specific adjustments are shown in Table 2.

[0042] Performance testing The EPDM rubber sealing strips of Examples 4-9 above were analyzed, and the specific detection method is as follows: 1. Flame retardancy The oxygen index method is tested according to the method specified in GB / T 10707-2008, and the oxygen index is used to indicate the flame retardant effect of EPDM rubber sealing strips.

[0043] 2. Low temperature resistance The low-temperature resistance of EPDM rubber sealing strips was tested according to the method specified in GB / T 7758-2020. The sample was stretched to 50% elongation at a standard temperature, cooled to -70°C and held for 10 minutes. The temperature was then increased at a rate of 1°C / min, and the shrinkage of the sample was recorded at different temperatures. By plotting temperature-shrinkage curves, the temperatures at which 30% and 70% shrinkage were determined (TR30 and TR70), respectively, to characterize the material's ability to retain low-temperature elasticity.

[0044] According to the above detection method, the test results of Example 1 and Examples 4-9 were obtained, as shown in Table 2 below.

[0045] Table 2 Types and performance test table of processing aids A and B in Example 1 and Examples 4-9

[0046] Referring to Table 2, by comparing Example 1 with Example 4-9, it can be seen that the tensile strength of the EPDM rubber sealing strip obtained in Example 4-9 is significantly higher than that of the EPDM rubber sealing strip obtained in Example 1. By comparing Example 4-6 with Example 7-9, it can be seen that the tensile strength of the EPDM rubber sealing strip obtained in Example 4-6 is higher than that of the EPDM rubber sealing strip obtained in Example 7-9. This indicates that when the processing aid A is magnesium hydroxide, the effect of improving the tensile strength of the EPDM rubber sealing strip is better, which may be because the hydroxyl groups on the surface of the magnesium hydroxide are more dense. The magnesium hydroxide has a high degree of polymerization and a strong polarity, and can form a more stable combination with the processing aid B. When the processing aid B is glycerol borate, the tensile strength of the obtained EPDM rubber sealing strip is the best. This may be because glycerol borate can act as a molecular bridge, strongly connecting with the surface of magnesium hydroxide through the borate group, and entangled with the molecular chain of EPDM rubber through the carbon chain, thereby improving the interfacial adhesion between magnesium hydroxide and EPDM rubber. At the same time, the coordination effect between glycerol borate and magnesium hydroxide effectively reduces the agglomeration of magnesium hydroxide, thereby effectively improving the tensile strength of the EPDM rubber sealing strip.

[0047] Compared with Example 1, the flame retardant effect of the EPDM rubber sealing strips obtained in Examples 4-9 has been greatly improved. This may be because the processing aid A, as a metal hydroxide, releases water vapor during the heating process, absorbs heat and dilutes the combustible gas, which can play a flame retardant role. Among them, the flame retardant effect of the EPDM rubber sealing strips obtained in Examples 4-6 is better than the flame retardant effect of the EPDM rubber sealing strips obtained in Examples 7-9. This may be because the decomposition temperature of magnesium hydroxide is higher, and the water vapor generated by decomposition can be more evenly dispersed, which is more effective in diluting the combustible gas. The generated magnesium peroxide can cover the surface and inhibit the combustion of the EPDM rubber sealing strip. In addition, glycerol borate has a flame retardant synergistic effect. It forms a triple flame retardant mechanism of "heat absorption-carbonization-oxygen isolation" in combination with magnesium hydroxide, further improving the flame retardant effect of the EPDM rubber sealing strip.

[0048] Compared with Example 1, the low-temperature resistance of the EPDM rubber sealing strips obtained in Examples 4-9 is improved, which may be because the processing aid B can promote the EPDM rubber molecular segments to maintain their mobility under low-temperature conditions.

[0049] Examples 10-13 In Examples 10-13, based on the preparation method of Example 4, the amount of magnesium hydroxide added was adjusted, and the specific adjustments are shown in Table 3.

[0050] Comparative Examples 4-5 Comparative Example 4-5 Based on the preparation method of Example 4, the addition amount of magnesium hydroxide was adjusted, and the specific adjustments are shown in Table 3.

[0051] The EPDM rubber sealing strips of Examples 10-13 and Comparative Examples 4-5 were subjected to the above performance tests. The test results are shown in Table 3.

[0052] Table 3 The amount of magnesium hydroxide added and the performance test table of Example 4, Examples 10-13 and Comparative Examples 4-5

[0053] Referring to Table 3, it can be seen from Example 4, Examples 10-13 and Comparative Examples 4-5 that when the amount of magnesium hydroxide added is 20-40 g, especially when the amount of magnesium hydroxide added is in the range of 25-35 g, the resulting EPDM rubber sealing strip has excellent tensile strength. The tensile strength of the EPDM rubber sealing strip obtained in Comparative Examples 4-5 is significantly less than the tensile strength of the EPDM rubber sealing strip obtained in Examples 4 and 10-13. This may be because when the amount of magnesium hydroxide added is too little, the action points of magnesium hydroxide and glycerol borate are limited, and the two cannot form a sufficient interfacial bonding network. When the amount of magnesium hydroxide added is too much, agglomeration is likely to occur, forming stress concentration points, resulting in an unsatisfactory effect on the tensile strength of the EPDM rubber sealing strip.

[0054] Examples 14-15 Examples 14-15 are based on the preparation method of Example 4, except that the amount of glycerol borate added is adjusted. The specific adjustments are shown in Table 4.

[0055] Comparative Examples 6-7 Comparative Examples 6-7 were prepared according to the method of Example 4, except that the amount of glycerol borate added was adjusted. The specific adjustments are shown in Table 4.

[0056] The EPDM rubber sealing strips of Examples 14-15 and Comparative Examples 6-7 were subjected to the above performance tests. The test results are shown in Table 4.

[0057] Table 4 Glycerol borate addition amount and performance test table of Example 4, Examples 14-15 and Comparative Examples 6-7

[0058] Referring to Table 4, it can be seen from the comparison of Example 4, Examples 14-15 and Comparative Examples 6-7 that when the addition amount of glycerol borate is in the range of 3-5 g, the obtained EPDM rubber sealing strip has ideal tensile strength. This may be because when the addition amount of glycerol borate is too small, glycerol borate cannot cover the polar hydroxyl groups on the surface of magnesium hydroxide, resulting in unsatisfactory filler dispersion and stress transfer efficiency, resulting in lower tensile strength. When the addition amount of glycerol borate is too much, the viscosity of the rubber compound increases, resulting in reduced tensile strength.

[0059] Examples 16-17 Examples 16-17 are based on the preparation method of Example 4, except that the total amount of magnesium hydroxide and glycerol borate is maintained at 34 g, and the mass ratio of glycerol borate to magnesium hydroxide is adjusted. The specific adjustment is shown in Table 5.

[0060] Comparative Examples 8-9 Comparative Examples 8-9: Based on the preparation method of Example 4, the total amount of magnesium hydroxide and glycerol borate was maintained at 34 g, and the mass ratio of glycerol borate to magnesium hydroxide was adjusted. The specific adjustment is shown in Table 5.

[0061] The EPDM rubber sealing strips of Examples 16-17 and Comparative Examples 8-9 were subjected to the above performance tests. The test results are shown in Table 5.

[0062] Table 5 Mass ratio of glycerol borate to magnesium hydroxide and performance test table of Example 4, Examples 16-17 and Comparative Examples 8-9

[0063] Referring to Table 4, it can be seen from Example 4, Examples 16-17 and Comparative Examples 8-9 that when the mass ratio of glycerol borate to magnesium hydroxide is 1:6-10, especially when the mass ratio of glycerol borate to magnesium hydroxide is 1:7.5, the resulting EPDM rubber sealing strip has excellent tensile strength. This may be because when the proportion of magnesium hydroxide is too large, glycerol borate cannot effectively wrap the magnesium hydroxide and easily forms agglomerates, resulting in a weakened interfacial adhesion between the filler and the EPDM rubber matrix, resulting in an unsatisfactory effect on the improvement of tensile strength. When the proportion of glycerol borate is too large, it is easy to increase the viscosity of the rubber compound, which hinders the segment movement of the EPDM rubber and leads to unsatisfactory tensile strength.

[0064] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An EPDM rubber sealing strip, characterized in that: The invention comprises the following components in parts by weight: 150-180 parts of EPDM rubber, 60-90 parts of carbon black, 8-12 parts of white carbon black, 3-8 parts of peroxide vulcanizer, 6-12 parts of zinc oxide, 12-16 parts of magnesium oxide, 10-18 parts of paraffin oil, 1-3 parts of accelerator TMTD, 1-3 parts of stearic acid, 1-3 parts of antioxidant MB and 1-3 parts of coupling agent.

2. The EPDM rubber sealing strip according to claim 1, characterized in that: The invention also includes a processing aid A and a processing aid B, wherein the processing aid A is at least one of magnesium hydroxide and aluminum hydroxide, and the processing aid B is at least one of glycerol borate, glyceryl monostearate and glyceryl monomethacrylate.

3. The EPDM rubber sealing strip according to claim 2, characterized in that: The weight portion of the processing aid A is 20-40 parts.

4. The EPDM rubber sealing strip according to claim 2, characterized in that: The processing aid A is magnesium hydroxide.

5. The EPDM rubber sealing strip according to claim 4, characterized in that: The weight portion of the magnesium hydroxide is 25-35 parts.

6. The EPDM rubber sealing strip according to claim 2, characterized in that: The weight portion of the processing aid B is 3-5 parts.

7. The EPDM rubber sealing strip according to claim 6, characterized in that: The processing aid B is glycerol borate.

8. The EPDM rubber sealing strip according to claim 2, characterized in that: The mass ratio of the processing aid B to the processing aid A is 1:6-10.

9. The method for preparing an EPDM rubber sealing strip according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: EPDM rubber, carbon black, white carbon black, zinc oxide, magnesium oxide, paraffin oil, stearic acid, antioxidant, coupling agent and other raw materials are mixed in a first stage according to the formula amount, and then a peroxide curing agent and an accelerator are added to the reaction system according to the formula amount for second stage mixing to obtain a rubber compound; S2: Cooling and shaping the rubber mixture to obtain an EPDM rubber sealing strip.

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