Impact-resistant wear-resistant well lid rubber material and preparation method thereof

Abstract

The invention discloses an anti-impact wear-resistant well lid rubber material, which is composed of a rubber compound, a nylon cord fabric and a rubber-coated steel wire, the rubber compound is composed of the following raw materials by weight: 100 parts of natural rubber, 2-5 parts of zinc oxide, 1-3 parts of stearic acid, 0.5-2 parts of an accelerator, 0.5-3 parts of sulfur, 1-2 parts of an anti-aging agent, 45-70 parts of carbon black, 1-8 parts of montmorillonite, and 2-6 parts of an FM coupling agent. The anti-aging agent comprises an anti-aging agent RD and an anti-aging agent 4010NA, and the weight ratio of the anti-aging agent RD to the anti-aging agent 4010NA in the anti-aging agent is 1: 1. The rubber material provided by the invention has excellent mechanical properties, and has stronger anti-pressure ability under high pressure or high impact load. And the manhole cover can bear large pressure and rapidly restore to the original shape, it is guaranteed that the manhole cover is not prone to deformation under high load or strong impact, and therefore the service life is prolonged, and safety is improved. The well lid rubber also has excellent elastic recovery capability and creep resistance, can ensure that the well lid rubber is not easy to permanently deform under the action of long-time pressure, and keeps the original functionality and safety.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber products, and in particular relates to an impact-resistant and wear-resistant manhole cover rubber material and a preparation method thereof. Background Art

[0002] With the continuous advancement of urbanization in my country and the rapid development of road and municipal infrastructure, a large number of manhole covers have been installed on urban roads. However, due to issues with material design, manufacturing processes, construction quality, and actual use, many manhole covers have become loose, sunken, or bulged. This not only causes vehicles to jump when passing through, but also causes unusual noises from the manhole covers, further increasing the frequency of manhole maintenance. Furthermore, unusual noises from manhole covers seriously impact residents' quality of life and have become a major source of public complaints. For example, a recent survey found that the integrity rate of manhole covers in Fuzhou, Xiamen, and Longyan, Fujian Province, was only 26.3%, with the majority experiencing varying degrees of sinking and loosening. Therefore, reducing maintenance frequency and addressing the issue of unusual noises from manhole covers have become critical and pressing issues.

[0003] The core reason for abnormal noise from manhole covers is the looseness and gap between the manhole cover and the base. When the tires of a vehicle run over, the edge of the manhole cover hits the base and makes noise. Currently, common manhole covers are mostly made of metal or cement. When these materials are used in conjunction with shock-proof rubber, high-frequency friction can easily cause severe wear to the shock-proof material, causing its performance to deteriorate rapidly. In order to improve the shockproof and impact-resistant effects, rubber gaskets are usually added to the manhole cover structure. However, the performance design of existing shock-proof rubber materials in terms of weather resistance, wear resistance, and fatigue resistance is still insufficient, resulting in poor long-term stability and the need for frequent replacement, which affects the overall service life of the manhole cover.

[0004] In recent years, the structural design of manhole covers has made certain progress in solving the problem of abnormal noise. However, in the research and development and application of flexible shock-proof materials, problems such as complex construction and insufficient performance stability are still faced. Chinese patent application number CN200710065807.3 discloses a high-strength and durable manhole cover and its preparation method. The weight ratio of the raw materials used is: tire recycled rubber 50-300, tire recycled rubber powder 50-250, accelerator 0.5-15, zinc oxide 0.5-30, calcium carbonate 10-200, stearic acid 0.1-10, antioxidant 0.5-20, sulfur 0.5-5, high wear-resistant carbon black 5-50; the preparation method is to mix the above raw materials, refine them, and then put them into a mold for molding. While improving product performance, this invention utilizes a large amount of solid waste such as waste rubber products and waste tires, eliminating the pollution of waste rubber to the environment. Chinese patent application number CN201811248377.3 discloses a high-strength, high-toughness polyvinyl chloride manhole cover and its preparation method. The manhole cover is composed of the following components by weight: 5-40 parts PVC resin; 60-95 parts ACR-g-VC resin; 2-8 parts modifier; 2-5 parts composite stabilizer; 0.5-2 parts internal lubricant; 0.5-1.2 parts external lubricant; 0.1-1 part light stabilizer; 0.1-1 part antioxidant; and 1-80 parts filler. The preparation method involves mixing the above substances to obtain a polyvinyl chloride mixture, which is then pelletized in a twin-screw extruder. After extrusion and pelletization, the pellets are then injected into an injection molding machine to form the manhole cover in one step. The manhole cover produced by this invention exhibits strong impact resistance, high tensile strength, good weather resistance, and low-temperature resistance. However, existing earthquake-proof materials still fail to meet practical application needs, and there is an urgent need to find more reliable solutions through innovative material design. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides an impact-resistant and wear-resistant manhole cover rubber material and a preparation method thereof.

[0006] The technical solutions of the present invention are as follows:

[0007] One of the purposes of the present invention is to provide an impact-resistant and wear-resistant manhole cover rubber material, which is composed of a rubber mix, nylon cord fabric, and rubber-coated steel wire, wherein the rubber mix is ​​composed of the following raw materials in parts by weight: 100 parts of natural rubber, 2 to 5 parts of zinc oxide, 1 to 3 parts of stearic acid, 0.5 to 2 parts of an accelerator, 0.5 to 3 parts of sulfur, 1 to 2 parts of an anti-aging agent, 45 to 70 parts of carbon black, 1 to 8 parts of montmorillonite, and 2 to 6 parts of an FM coupling agent.

[0008] Furthermore, the anti-aging agent includes anti-aging agent RD and anti-aging agent 4010NA.

[0009] Furthermore, the weight ratio of the anti-aging agent RD to the anti-aging agent 4010NA in the anti-aging agent is 1:1.

[0010] Furthermore, the carbon black is N330 carbon black.

[0011] The second purpose of the present invention is to provide a method for preparing an impact-resistant and wear-resistant manhole cover rubber material. The raw materials of the rubber compound are mixed to obtain a mixed rubber strip, which is pressed together with nylon cord fabric and rubber-coated steel wires arranged perpendicular to each other in a mold and vulcanized at 150°C for 10 minutes to obtain the impact-resistant and wear-resistant manhole cover rubber material.

[0012] Furthermore, the method specifically includes the following steps:

[0013] S1: After mixing the raw materials according to a set ratio to obtain a rubber mix, the rubber mix is ​​pressed into a 1.5 mm thick film on an open mixing mill, and then cut into 8 mm wide strips for standby use;

[0014] S2: Cutting the nylon cord fabric into narrow strips with a width of 8 to 9 mm, wherein the nylon thread of the nylon cord fabric has a diameter of 0.5 mm, and setting aside;

[0015] S3: Cut the rubber-coated steel wire at a 45° angle into narrow strips with a width of 8 to 9 mm. The diameter of each rubber-coated steel wire is 0.32 mm and set aside.

[0016] S4: The three strip-shaped raw materials cut in steps S1 to S3 are placed layer by layer in a mold in the following order: 1 layer of rubber mix, 2 layers of rubber-coated steel wire, 1 layer of nylon cord fabric, and 2 to 3 layers of rubber mix, wherein the 2 layers of rubber-coated steel wire are placed crosswise at 45 degrees. The placed strips and the mold are pressed on a hot press at room temperature for 2 minutes, and then the strips are removed from the mold to obtain blanks;

[0017] S5: Preheat the mold on a hot press at 150° C. for 5 minutes, and directly and quickly place the blank into the mold, place the upper and lower cover plates, put it into the hot press, and vulcanize it at 150° C. for 10 minutes to obtain the impact-resistant and wear-resistant manhole cover rubber material.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The impact-resistant and wear-resistant manhole cover rubber material provided by the present invention has excellent mechanical properties, which means that it has stronger compressive resistance under high pressure or high impact loads. It can also withstand greater pressure and quickly return to its original shape, ensuring that the manhole cover is not easily deformed under high load or strong impact, thereby improving its service life and safety. The present invention has excellent elastic recovery ability and creep resistance, which can ensure that the manhole cover rubber is not easily permanently deformed under long-term pressure, maintaining its original functionality and safety. It also has excellent impact resistance, high impact resistance, strain-induced crystallization ability, heat-oxidation aging resistance and heat-oxidation aging resistance.

[0020] 2. In the present invention, the montmorillonite improves the crystallization properties of the material. The FM coupling agent enhances dispersion and improves the interfacial bonding between the filler and the matrix, as well as the bonding between the steel wire and the rubber, thereby improving the material's impact crack resistance. The steel wire layer and nylon cord fabric enhance the material's strength and impact resistance. The FM coupling agent provides in-situ interface modification, is simple to operate, has low energy consumption, and high production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a comparison chart of the compression properties of an impact-resistant and wear-resistant manhole cover rubber material of Example 1 of the present invention and commercially available rubber;

[0022] Figure 2 This is a comparison chart of the tensile properties of an impact-resistant and wear-resistant manhole cover rubber material of Example 1 of the present invention and commercially available rubber;

[0023] Figure 3 Graph showing tensile stress-strain curves of an impact-resistant and wear-resistant manhole cover rubber material and commercially available rubber in Example 1 of the present invention;

[0024] Figure 4 This is a graph showing the change in height of an impact-resistant and wear-resistant manhole cover rubber material of Example 1 and a commercially available rubber during 30 days of pressure;

[0025] Figure 5 This is a comparison chart of the tensile strength of an impact-resistant and wear-resistant manhole cover rubber material of Example 1 of the present invention and commercially available rubber after being subjected to an equivalent impact for 30 days;

[0026] Figure 6 This is a graph showing the change in dynamic stiffness of an impact-resistant and wear-resistant manhole cover rubber material and commercially available rubber versus equivalent impact time in Example 1 of the present invention;

[0027] Figure 7 Schematic diagram of the change of rubber stress with the number of loading cycles during dynamic cyclic loading of an impact-resistant and wear-resistant manhole cover rubber material of Example 1 and commercially available rubber in the present invention;

[0028] Figure 8 Figure 1 is a graph showing the change in crack propagation rate with loading cycles for a rubber material for a manhole cover according to Example 1 of the present application and a commercially available rubber;

[0029] Figure 9 Figure 2 is a graph showing the effect of filler network on crack propagation for a rubber material for a manhole cover according to Example 1 of the present application and a commercially available rubber;

[0030] Figure 10 Figure 3 is a graph showing the change in Akron abrasion with carbon black content for a rubber material for a manhole cover according to Example 1 of the present application and a commercially available rubber;

[0031] Figure 11 Figure 4 is a graph showing the effect of different types of carbon black on the width of the wear groove for a rubber material according to Example 1 of the present application;

[0032] Figure 12 Figure 5 is a graph showing the compression performance of rubber materials according to Comparative Examples 1-4 of the present application;

[0033] Figure 13 Figure 6 is a graph showing the change in height over a 30 day compression period for rubber materials according to Comparative Examples 1-4 of the present application;

[0034] Figure 14 Figure 7 is a graph showing the tensile performance of rubber materials according to Comparative Examples 1-4 of the present application;

[0035] Figure 15 Figure 8 is a graph showing the toughness of rubber materials according to Comparative Examples 1-4 of the present application;

[0036] Figure 16 Figure 9 is a graph showing the toughness of rubber materials according to Comparative Examples 1-4 of the present application;

[0037] Figure 17 Figure 10 is a graph showing the volume abrasion of a rubber material according to Comparative Example 3 of the present application as a function of carbon black loading and particle size;

[0038] Figure 18 Figure 11 is a graph showing the morphology of the worn surface of a rubber material according to Comparative Example 3 of the present application. DETAILED DESCRIPTION

[0039] The application will be described below in connection with the preferred embodiments, and with reference to the accompanying drawings, in which: Figure 1-18, to further illustrate the present invention, the endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values; for numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein; the materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels; the experimental methods in the following examples, unless otherwise specified, are all conventional methods.

[0040] Example 1

[0041] This embodiment provides an impact-resistant and wear-resistant manhole cover rubber material, which is composed of a rubber mix, nylon cord fabric, and rubber-coated steel wire, wherein the rubber mix is ​​composed of the following raw materials in parts by weight: 100 parts of natural rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 1 part of an accelerator, 2 parts of sulfur, 1 part of an anti-aging agent, 45 parts of carbon black, 5 parts of montmorillonite, and 4 parts of an FM coupling agent.

[0042] In this embodiment, the anti-aging agent includes anti-aging agent RD and anti-aging agent 4010NA.

[0043] In this embodiment, the weight ratio of the anti-aging agent RD to the anti-aging agent 4010NA in the anti-aging agent is 1:1.

[0044] In this embodiment, the carbon black is N330 carbon black.

[0045] Example 2

[0046] This embodiment provides an impact-resistant and wear-resistant manhole cover rubber material, which is basically the same as Example 1, except that the raw material composition of the rubber compound is different.

[0047] The impact-resistant and wear-resistant manhole cover rubber material described in this embodiment is composed of a rubber mix, nylon cord fabric, and rubber-coated steel wire, wherein the rubber mix is ​​composed of the following raw materials in parts by weight: 100 parts of natural rubber, 2 parts of zinc oxide, 1 part of stearic acid, 0.5 parts of accelerator, 3 parts of sulfur, 1.5 parts of anti-aging agent, 45 parts of carbon black, 1 part of montmorillonite, and 2 parts of FM coupling agent.

[0048] Example 3

[0049] This embodiment provides an impact-resistant and wear-resistant manhole cover rubber material, which is basically the same as Example 1, except that the raw material composition of the rubber compound is different.

[0050] The impact-resistant and wear-resistant manhole cover rubber material described in this embodiment is composed of a rubber mix, nylon cord fabric, and rubber-coated steel wire, wherein the rubber mix is ​​composed of the following raw materials in parts by weight: 100 parts of natural rubber, 3 parts of zinc oxide, 3 parts of stearic acid, 2 parts of accelerator, 0.5 parts of sulfur, 2 parts of anti-aging agent, 45 parts of carbon black, 8 parts of montmorillonite, and 6 parts of FM coupling agent.

[0051] Example 4

[0052] This embodiment provides a method for preparing the impact-resistant and wear-resistant manhole cover rubber material described in Example 1, comprising the following steps:

[0053] S1: After mixing the raw materials according to a set ratio to obtain a rubber mix, the rubber mix is ​​pressed into a 1.5 mm thick film on an open mixing mill, and then cut into 8 mm wide strips for standby use;

[0054] S2: Cutting the nylon cord fabric into narrow strips with a width of 8 mm, wherein the nylon thread of the nylon cord fabric has a diameter of 0.5 mm, and setting aside;

[0055] S3: Cut the rubber-coated steel wire into narrow strips with a width of 8 mm at a 45° angle. The diameter of each rubber-coated steel wire is 0.32 mm and set aside.

[0056] S4: The three strip-shaped raw materials cut in steps S1 to S3 are placed layer by layer in a mold in the following order: 1 layer of mixed rubber, 2 layers of rubber-coated steel wire, 1 layer of treated nylon cord fabric, and 2 layers of mixed rubber, wherein the 2 layers of rubber-coated steel wire are placed crosswise at 45 degrees. The placed strips and the mold are pressed on a hot press at room temperature for 2 minutes, and then the strips are removed from the mold to obtain blanks;

[0057] S5: Preheat the mold on a hot press at 150° C. for 5 minutes, and directly and quickly place the blank into the mold, place the upper and lower cover plates, put it into the hot press, and vulcanize it at 150° C. for 10 minutes to obtain the impact-resistant and wear-resistant manhole cover rubber material.

[0058] Example 5

[0059] This embodiment provides a method for preparing the impact-resistant and wear-resistant manhole cover rubber material described in Example 1, comprising the following steps:

[0060] S1: After mixing the raw materials according to a set ratio to obtain a rubber mix, the rubber mix is ​​pressed into a 1.5 mm thick film on an open mixing mill, and then cut into 8 mm wide strips for standby use;

[0061] S2: Cutting the nylon cord fabric into narrow strips with a width of 9 mm, wherein the nylon thread of the nylon cord fabric has a diameter of 0.5 mm, and setting aside;

[0062] S3: Cut the rubber-coated steel wire into narrow strips with a width of 9 mm at a 45° angle. The diameter of each rubber-coated steel wire is 0.32 mm and set aside.

[0063] S4: The three strip-shaped raw materials cut in steps S1 to S3 are placed layer by layer in a mold in the order of 1 layer of mixed rubber, 2 layers of rubber-coated steel wire, 1 layer of treated nylon cord fabric, and 3 layers of mixed rubber, wherein the 2 layers of rubber-coated steel wire are placed crosswise at 45 degrees. The placed strips and the mold are pressed on a hot press at room temperature for 2 minutes, and then the strips are removed from the mold to obtain blanks;

[0064] S5: Preheat the mold on a hot press at 150° C. for 5 minutes, and directly and quickly place the blank into the mold, place the upper and lower cover plates, put it into the hot press, and vulcanize it at 150° C. for 10 minutes to obtain the impact-resistant and wear-resistant manhole cover rubber material.

[0065] Comparative Example 1

[0066] The rubber material of this comparative example is composed of the following raw materials in parts by weight: 100 parts of PVA resin, 3 parts of organotin stabilizer, 0.8 parts of stearic acid, 10 parts of dioctyl terephthalate, and 3 parts of carbon black. The rubber material of this comparative example is recorded as R1.

[0067] Comparative Example 2

[0068] The difference from Example 1 is that:

[0069] The rubber material of this comparative example is composed of the following raw materials in parts by weight: 100 parts of nitrile rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 1 part of accelerator, 2 parts of sulfur, 0.5 parts of anti-aging agent RD, and 30 parts of N330 carbon black. The rubber material of this comparative example is recorded as R2.

[0070] Comparative Example 3

[0071] The rubber material of this comparative example is composed of the following raw materials in parts by weight: 100 parts of nitrile rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 1 part of accelerator, 2 parts of sulfur, 0.5 parts of anti-aging agent 4010NA, and 40 parts of N330 carbon black. The rubber material of this comparative example is recorded as R3.

[0072] Comparative Example 4

[0073] The rubber material of this comparative example is composed of the following raw materials in parts by weight: 100 parts of PVA resin, 3 parts of organotin stabilizer, 0.8 parts of stearic acid, 10 parts of dioctyl terephthalate, 5 parts of carbon black, and 10 parts of impact modifier CPE. The rubber material of this comparative example is recorded as R4.

[0074] Implementation effect evaluation:

[0075] The following is a detailed test of the rubber materials of Example 1 and Comparative Examples 1-4 to further illustrate the excellent effects achieved by the present invention:

[0076] Figure 1 This is a comparison chart of the compression performance of an impact-resistant and wear-resistant manhole cover rubber material in Example 1 of the present invention and commercially available rubber; the test was conducted using a universal testing machine, and the compression rate was 50%. Figure 1 As shown, the stress at 50% strain of commercially available rubber in the compression cycle test is only approximately 2 MPa, indicating that this material has weak compressive strength and is not suitable for use as a rubber gasket to withstand high pressure and high impact loads. In comparison, the stress at 50% strain of the rubber material in Example 1 is significantly higher than that of commercially available rubber, reaching 14.6 MPa, significantly higher than that of commercially available rubber. After pressure is removed, the rubber material can effectively return to its original state, providing better cushioning and support in actual use, reducing noise caused by external vibration.

[0077] Figure 2 The following is a comparison chart of the tensile properties of an impact-resistant and wear-resistant manhole cover rubber material in Example 1 of the present invention and commercially available rubber; a universal testing machine was used with a tensile rate of 500 mm / min. Figure 2 As shown in the figure, the tensile strength and elongation at break of commercially available rubber gasket materials are significantly lower than those of self-developed rubber. Its tensile strength is only 4.4MPa, and its elongation at break is only 154%. This is because commercially available rubber gaskets are added with a large amount of filling carbon black or other fillers that increase hardness but have no reinforcing effect. The rubber component content is too low, and the mechanical strength is significantly reduced. In comparison, the rubber material of Example 1 is added with 45phr of reinforcing N330 carbon black and 5phr of montmorillonite nanomaterials. The rubber component is appropriate and can significantly improve the mechanical properties of the rubber material. Its tensile strength reaches 20MPa and its elongation at break is 390%.

[0078] Figure 3 The tensile stress-strain curves of the impact-resistant and wear-resistant manhole cover rubber material of Example 1 and commercially available rubber in the present invention are as follows; Figure 3 As shown in FIG. 1 , the toughness of the rubber material of Example 1 of the present invention can reach 33.8 J / cm3, while the toughness of commercially available rubber is only 4.7 J / cm3. 3 Higher toughness means greater impact energy dissipation capacity, so the rubber material of Example 1 has higher impact resistance. Its higher toughness comes from the high tensile strength and elongation of the rubber in a macroscopic sense. From a microscopic perspective, this reflects that the filler network in the self-developed rubber not only plays a good reinforcing role, but also improves the elongation through the energy dissipation generated by the interaction and changes between the filler and the polymer during deformation, as well as within the filler network.

[0079] Figure 4The graph of the height change of the impact-resistant and wear-resistant manhole cover rubber material of Example 1 and the commercially available rubber during 30 days of pressure in the present invention is as follows; Figure 4 As shown, at an initial compression rate of 30%, both the commercially available rubber and the rubber material of Example 1 show an upward trend in height. This is because the longer the compression time, the more difficult it is to recover elasticity. In comparison, the rubber material of Example 1 shows a more gradual upward trend, and the overall height change is significantly smaller. This demonstrates that the rubber material of Example 1 has superior elastic recovery, can essentially return to its original shape even after prolonged compression, and has better creep resistance.

[0080] according to Figure 4 The test results are used to calculate the compression permanent deformation of the two rubber materials when they are compressed for different days, as shown in the following table:

[0081] Table 1 Statistics of permanent compression set

[0082] Compression days 5 10 15 20 25 30 Commercially available rubber 11.4％ 11.5％ 11.5％ 11.8％ 11.9％ 13.4％ Example 1 7.1％ 7.1％ 7.2％ 7.3％ 7.3％ 8.2％

[0083] As shown in Table 1, after 5 days of compression, the compression set of the commercially available rubber was 11.4%, while that of the rubber material of Example 1 was 7.1%. As the compression time increased, the compression set of the commercially available rubber increased to 13.4%, while that of the rubber material of Example 1 was only 8.2%. This result quantitatively demonstrates that the rubber material of Example 1 has superior elastic recovery and creep resistance.

[0084] The hardness of commercially available rubber and the rubber material of Example 1 was tested, and the test results are shown in the following table:

[0085] Table 2 Shore hardness of rubber materials

[0086] sample Commercially available rubber Example 1 Hardness (Shore A) 85 71

[0087] As can be seen from the table above, the hardness of the commercially available rubber is 85, while the hardness of the rubber material of Example 1 is 71. The hardness of the rubber material of Example 1 falls within the medium hardness range, allowing for significant compression deformation, which is crucial for impact resistance. Sufficient deformation ensures adequate energy dissipation. The higher hardness of the commercially available rubber is due to its high filler content. Excessive filler content not only results in lower mechanical properties but also results in less deformation under the same impact load, resulting in reduced impact resistance.

[0088] Figure 5 This is a comparison chart of the tensile strength of an impact-resistant and wear-resistant manhole cover rubber material in Example 1 of the present invention and commercially available rubber after 30 days of equivalent impact; Figure 5It can be seen that the average tensile strength of the commercially available rubber is only 0.4 MPa after 30 days of simulated impact experiment. Among them, several samples have been directly broken by impact. This shows that the commercially available ordinary rubber gasket is difficult to meet the use requirements of the working road conditions of the manhole cover. In contrast, the rubber material of Example 1 has good impact resistance. After 30 days of impact experiment, its tensile strength can still remain at about 19 MPa. Its excellent impact resistance is due to the resistance and dissipation of the tough filler network in the rubber matrix to the impact force.

[0089] Figure 6 In the present application, the variation of dynamic stiffness of the anti-impact and wear-resistant manhole cover rubber material of Example 1 and the commercially available rubber with equivalent impact time is shown in the graph. The dynamic stiffness reflects the ability of the test piece to resist deformation, and the change of its value with impact time also reflects the impact resistance of the test piece. The sinusoidal wave load or sinusoidal wave deformation is applied to the test sample reaching the impact time on the fatigue testing machine, and the time domain waveforms of the load and deformation are recorded. From this waveform, the load amplitude P0, the deformation amplitude X0, the period T and the phase difference Δt (the time difference between the maximum load and the maximum displacement) can be obtained. The dynamic stiffness K is calculated by the following formula d :

[0090] K d = P0 / X0

[0091] In the formula, P0 is the load amplitude, in kilonewtons (kN); X0 is the deformation amplitude, in millimeters (mm).

[0092] It can be seen from Figure 6 that the dynamic stiffness of the commercially available rubber is relatively low and decreases rapidly with impact time; while the dynamic stiffness of the rubber material of Example 1 is relatively high and decreases slowly. This result also shows that the rubber material of Example 1 has good impact resistance.

[0093] Figure 7 In the present application, the variation of rubber stress with loading cycle number during dynamic cyclic loading of the anti-impact and wear-resistant manhole cover rubber material of Example 1 and the commercially available rubber is shown in the graph. From Figure 7 it can be seen that the stress attenuation of the commercially available rubber starts at 1.3 million cycles. While the attenuation starting cycle number of the rubber material of Example 1 can reach 4.5 million. This shows that the rubber material of Example 1 has significantly excellent fatigue resistance.

[0094] Figure 8 In the present application, the variation of crack propagation rate with loading cycle number of the anti-impact and wear-resistant manhole cover rubber material of Example 1 and the commercially available rubber is shown in the graph. From Figure 8As can be seen in the figure, the crack growth test was conducted on rectangular specimens with a length, width, and thickness of 90mm, 25mm, and 2mm, respectively, and an initial pre-cut of 5mm. The experiment was conducted on a Metrivib crack growth tester. Through displacement control, the machine output was adjusted to a sine wave with an amplitude of 9mm and a frequency of 3Hz, and cyclic stress in tensile mode was applied to the specimens. The stress ratio R was fixed at 0. The experiment was stopped every 5000 cycles and the crack length was recorded. Figure 8 The crack growth rate data shown in Table 3 can be obtained.

[0095] Table 3 Statistics of crack growth characteristics of rubber materials

[0096]

[0097]

[0098] As shown in Table 3, the average crack growth rate of commercially available rubber is 1.3×10 -4 mm / cycle, which is significantly higher than the 7.3×10 -5 mm / cycle. There are two main reasons for this. On the one hand, the rubber material of Example 1 has a reinforcing and toughening filler network composed of reinforcing carbon black and montmorillonite, and there is good interface bonding between the filler and the rubber matrix. Therefore, the expansion of cracks can be significantly inhibited; on the other hand, the strain-induced crystallization property of natural rubber can also significantly inhibit the expansion of cracks. This is because the crystals generated by strain induction of natural rubber are highly oriented along the loading direction and perpendicular to the crack tip, so they can play a role in preventing crack expansion. In this study, montmorillonite can significantly enhance the strain-induced crystallization property of natural rubber materials, so the ability to resist crack growth is significantly improved.

[0099] Figure 9 Schematic diagram of the inhibitory effect of a network of impact-resistant and wear-resistant manhole cover rubber material and commercially available rubber filler on crack propagation in Example 1 of the present invention; Figure 9 As shown in a, although the filler content of commercially available rubber materials is high, the interfacial interaction is low and there is no obvious reinforcement effect, so the cracks propagate quickly and are easily broken when impacted. Figure 9 The filler shown in b has good interface bonding and obvious reinforcing effect. Through the interface bonding and the action of the bonding glue, a filler network is formed, which plays a good role in inhibiting crack propagation.

[0100] The materials were aged at 70°C for 72 hours, and the hardness, tensile strength, and compressive strength of the materials were compared. The experimental results are shown in Tables 4 and 5:

[0101] Table 4 Comparison of tensile strength before and after aging treatment

[0102] serial number Commercially available rubber Example 1 Tensile strength before aging (MPa) 4.4 20 Tensile strength after aging (MPa) 3.8 19.2 Tensile strength change rate 13.6％ 4％

[0103] Table 5 Comparison of compressive strength before and after aging treatment

[0104] serial number Commercially available rubber Example 1 Compressive strength before aging (MPa) 51 55 Compression strength after aging (MPa) 42 51.5 Compression strength change rate 17.6％ 6.4％

[0105] As can be seen from Tables 4 and 5, the tensile strength and compressive strength of commercially available rubbers show a more pronounced decrease under the effects of thermal oxidative aging, while the rubber material of Example 1 shows a relatively low rate of decline. This is because thermal oxidative aging primarily causes the destruction of double bonds and sulfur crosslinking structures in the rubber. The addition of montmorillonite can inhibit the diffusion of oxygen molecules, while a good filler network can also inhibit aging reactions from the surface to the interior to a certain extent. In addition, an antioxidant that resists thermal oxidative aging and fatigue-induced heat aging is added to the rubber formula. Therefore, the rubber material of Example 1 has better aging resistance.

[0106] Figure 10 Schematic diagram of the change in rubber Akron abrasion loss of an impact-resistant and wear-resistant manhole cover rubber material of Example 1 and a commercially available rubber as a function of carbon black content in the present invention; Figure 10 As shown, with the increase of carbon black dosage, the wear of rubber shows a downward trend and the wear resistance increases. In comparison, the rubber material of Example 1 has a significantly lower wear, indicating that its wear resistance is better. When the carbon black dosage of the rubber material of Example 1 reaches 50phr, the wear of the rubber material of Example 1 increases slightly, indicating that the carbon black dosage is too large and the wear resistance is reduced. This is because the carbon black dosage is too large, the agglomeration phenomenon is serious, the mechanical properties are reduced, and from a microscopic point of view, the wear damage of the rubber at the wear surface position is more serious, so the wear resistance is reduced. Commercially available rubber has a large wear rate because of the large amount of carbon black added and the weak reinforcing effect of carbon black.

[0107] Figure 11 This is a schematic diagram of the effect of different types of carbon black on the wear groove width of the rubber material of Example 1 in the present invention; the test uses a scanning electron microscope to observe the microscopic texture of the wear surface and analyze the wear groove width. The larger the wear groove width, the higher the wear amount. Figure 11 As can be seen, N220 carbon black has the smallest wear mark width, while N770 carbon black has the largest wear mark width among carbon black-filled natural rubbers. Unfilled natural rubber experiences greater wear than filled natural rubber. This is because N220 carbon black has the smallest carbon black ions and the best reinforcing effect, while N770 carbon black has larger ions and a lower reinforcing effect, making it a semi-reinforcing carbon black. However, while N220 carbon black has a good reinforcing effect, it also generates the most heat. Therefore, in the present invention, N330 carbon black was selected for its excellent wear resistance, high reinforcing effect, and moderate heat generation.

[0108] Figure 12The present invention, the comparative example 1-4 rubber material compression performance comparison diagram; the test compression rate is 20%, from Figure 12 As can be seen, R2 and R4 exhibit higher stresses, both around 60 MPa, indicating that these two materials possess superior static compressive strength. R1 and R3 exhibit lower strain after elastic recovery, indicating greater elasticity. This allows them to better recover to their original state after pressure is removed, providing improved cushioning and support in actual use, reducing noise generated by external vibrations. All four rubber materials exhibit excessive compressive stress. This is due to the high hardness of the selected rubber, resulting in less impact deformation during actual use, making it difficult to laminate with materials such as cord fabric. This hinders impact energy dissipation and, in turn, increases the impact energy received.

[0109] Figure 13 The height change diagram of the rubber materials of Comparative Examples 1-4 during 30 days of compression in the present invention; the initial compression rate is 30%, from Figure 13 As can be seen from the table, although the heights of R2 and R3 show a downward trend, they are more gradual than those of R1 and R4, indicating that R2 and R3 have good elastic recovery capabilities and can basically return to their original shape even under prolonged pressure. In Table 10, the compression set rates of R2 and R3 are also significantly lower than those of the other two. Overall, using PVC as the base material produces a large compression set, which is prone to plastic deformation and is not suitable for long-term durability. Nitrile rubber as the base material has a smaller compression set, but its impact resistance and tensile strength are not as good as the aforementioned natural rubber-based rubber materials.

[0110] Figure 14 The tensile properties comparison diagram of the rubber materials of Comparative Examples 1-4 in the present invention; Figure 14 It can be seen that R2 and R3 have greater tensile strength, but their elongation at break is lower than that of R1 and R4. This indicates that R2 and R3 materials have a higher ability to resist deformation and breakage when subjected to tensile loads, which is directly related to the durability and safety of the materials in practical applications. R1 and R4 rubbers have better extensibility. This property allows the materials to better adapt to external forces, reducing the possibility of breakage and being less likely to rupture when under pressure. The following table shows the comparative data of the tensile stress of the rubber materials of Comparative Examples 1-4:

[0111] Table 6 Comparative data of the tensile stress of the rubber materials of Comparative Examples 1-4

[0112]

[0113] From the table above, we can see that the stresses generated by rubbers R2 and R3 at different tensile growth rates are higher than those of R1 and R4, indicating that they have higher mechanical strength. In addition, the fracture growth rate of R3 is higher than that of R2, indicating better overall performance.

[0114] Figure 15 The toughness comparison diagram of the rubber materials of Comparative Examples 1-4 in the present invention; Figure 15 As can be seen from the figure, R3 rubber has the best toughness, far higher than the other three. Only when the fracture strength and fracture growth rate of the material are high, the toughness of the material will be good, indicating that R3 is a rubber with good comprehensive performance. High tensile strength and elongation bring high impact resistance. However, compared with the rubber material of Example 1, which is as high as 33.8J / cm 3 Compared with the toughness of the above four rubber materials, the toughness is too low, resulting in too low energy dissipation due to impact, which is not enough to withstand the larger impact from various heavy vehicles and is easily damaged by impact.

[0115] Figure 16 The toughness comparison diagram of the rubber materials of Comparative Examples 1-4 in the present invention; Figure 16 As can be seen, the static stiffness of the rubber materials in Comparative Examples 1-4 decreased after multiple impacts. R3 had the highest initial static stiffness, indicating good impact resistance. Even after multiple impacts, it maintained good stiffness. This indicates that the materials have good impact resistance, but still not as good as Example 1.

[0116] The rubber materials of Comparative Examples 1-4 were subjected to thermal oxidative aging tests. The test conditions were aging at 70°C for 72 hours and the hardness, tensile strength, and compressive strength were compared. The results are shown in Tables 7-8:

[0117] Table 7 Comparison of tensile strength before and after aging treatment

[0118] serial number R1 R2 R3 R4 Tensile strength before aging (MPa) 1.72 2.50 4.57 1.44 Tensile strength after aging (MPa) 1.44 2.23 4.14 1.15 Tensile strength change rate 16.32％ 10.58％ 9.50％ 20.17％

[0119] Table 8 Comparison of compressive strength before and after aging treatment

[0120] serial number R1 R2 R3 R4 Compressive strength before aging (MPa) 50.61 63.68 46.56 60.63 Compression strength after aging (MPa) 43.80 58.35 42.68 50.76 Compression strength change rate 13.45％ 8.37％ 8.33％ 16.29％

[0121] Tables 7-8 show that the tensile strength of the four materials decreased to varying degrees after aging, with R3 experiencing the smallest decrease at 9.50% and R4 experiencing the largest decrease at 20.17%. From the perspective of tensile properties, R3 exhibits relatively better aging resistance. Table 8 analyzes the compressive strength of the four materials before and after aging, revealing that R3 exhibits a relatively small decrease in strength, while R4 exhibits a greater decrease. While R3 exhibits better aging resistance, it is still inferior to that of Example 1.

[0122] Figure 17 Schematic diagram of the change of volume wear of the rubber material of Comparative Example 3 with the amount of carbon black and particle size in the present invention; Figure 17 It can be seen that with the increase of carbon black dosage, the wear of rubber tends to decrease and the wear resistance increases; with the decrease of carbon black particle size, the wear gradually decreases, that is, using carbon black with larger particle size can obtain better wear resistance at a smaller dosage.

[0123] Figure 18 This is a morphology diagram of the wear surface of the rubber material of Comparative Example 3 in the present invention. From the perspective of the wear surface morphology, the direction of the R3 wear mark is parallel to the direction of the friction force, the grinding is granular, and the gap between the wear marks is wide, which belongs to wear and abrasion. After adding carbon black, the wear surface morphology of the material has not changed, but the gap between the wear marks is significantly reduced, and as the particle size of the added carbon black increases, the wear marks gradually become coarser, and the wear resistance also decreases. Therefore, the wear resistance of the rubber material of Example 1, especially the initial wear resistance, is significantly better than that of Comparative Examples 1-4. At the same time, the wear resistance of PVC and nitrile rubber materials changes more significantly with the increase of the amount of carbon black added.

[0124] In summary, the rubber material of the present invention has excellent mechanical properties. At 50% strain, the stress reaches 14.6MPa, which is significantly higher than the 2MPa of commercially available rubber. This shows that it has stronger compressive resistance under high pressure or high impact loads. After the pressure is unloaded, it can recover to its original state well, provide better cushioning and support effects, and reduce vibration and noise. The tensile strength is as high as 20MPa, far exceeding the 4.4MPa of commercially available rubber. The elongation at break is 390%, significantly better than the 154% of commercially available rubber. The toughness is 33.8J / cm 3 , significantly higher than the 4.7J / cm of commercially available rubber 3 High toughness means better impact energy dissipation and enhanced impact resistance. The addition of 45 phr of reinforcing N330 carbon black and 5 phr of montmorillonite nanomaterial effectively enhances the material's mechanical properties. The filler network enhances the rubber's strength and toughness, while also improving the material's deformation capacity through energy dissipation mechanisms.

[0125] The rubber material of this invention can withstand significant pressure and quickly return to its original shape, ensuring that manhole covers resist deformation under high loads or strong impacts, thereby extending their service life and safety. Its excellent compressive resistance and high toughness effectively absorb vibration and impact, reducing noise generated by manhole covers during traffic and improving the quality of the urban environment. Its high toughness enables the material to withstand and distribute the instantaneous impact forces borne by manhole covers, reducing the risk of material damage.

[0126] The rubber material of the present invention has excellent elastic recovery ability and creep resistance. After 30 days of pressure, the compression permanent deformation rate of the rubber material of the present invention is only 8.2%, which is significantly lower than the 13.4% of commercially available rubber. Even under long-term pressure, its shape changes little and it can better maintain its original shape. Scanning electron microscopy shows that the cross-section of the rubber material of the present invention is rough and uneven, showing typical toughness fracture characteristics. The cross-section of commercially available rubber is smooth and has brittle fracture characteristics, indicating that its impact resistance is relatively low. The low compression permanent deformation rate of the rubber material of the present invention enables it to maintain a stable shape after long-term load bearing, avoid displacement and settlement of the manhole cover, and extend its service life. The medium hardness and good toughness enable it to absorb and disperse impact energy when bearing traffic loads, reduce the risk of material damage, and improve the impact resistance of the manhole cover. The excellent creep resistance ensures that the manhole cover rubber is not prone to permanent deformation under long-term pressure, maintaining its original functionality and safety.

[0127] The rubber material of the present invention has excellent impact resistance. After 30 days of simulated impact testing, the tensile strength of the rubber material of the present invention is still maintained at about 19 MPa, which is much higher than the 0.4 MPa of commercially available rubber (some samples have been broken). The impact resistance is derived from the absorption and dissipation of impact force by the filler network, which is manifested as higher dynamic stiffness and a slower rate of stiffness decrease. The stress decay starting cycle of the rubber material of the present invention is 4.5 million times, while that of commercially available rubber is only 1.3 million times, and the fatigue resistance is significantly improved. The crack propagation rate of the rubber material of the present invention is 7.3×10-5mm / cycle, which is only about 56% of that of commercially available rubber, showing extremely strong resistance to crack growth. The addition of a filler network composed of reinforcing carbon black and montmorillonite not only enhances the reinforcing and toughening effect of the material, but also significantly improves the ability to inhibit crack propagation. Montmorillonite enhances the strain-induced crystallization ability of natural rubber, causing it to form highly oriented crystals at the crack tip, effectively preventing crack propagation.

[0128] High impact resistance can maintain high strength and stability under long-term traffic impact, avoid material breakage, and ensure the safe operation of manhole covers. Longer stress decay starting cycles mean that the material has a longer life under high-frequency loads, reducing the performance degradation of manhole cover rubber due to fatigue. The low crack propagation rate significantly reduces the risk of cracking of manhole cover rubber under repeated loads, extending service life and reducing maintenance costs. The strain-induced crystallization effect further enhances the crack resistance, enabling it to better adapt to complex working conditions. The high dynamic stiffness and slow decrease in stiffness help the manhole cover rubber maintain shape and function stability when subjected to dynamic loads, thereby improving its efficiency. The reinforced filler network not only enhances the mechanical properties of the material, but also improves durability and stability through interface bonding and energy dissipation mechanisms, making it suitable for use in high-impact and high-fatigue environments of manhole covers.

[0129] The rubber material of the present application has excellent strain-induced crystallization ability. The rubber material of the present application can produce obvious strain-induced crystallization in the bulk part, while the commercially available rubber has almost no obvious crystallization peak. The strong strain-induced crystallization performance effectively improves the crack propagation resistance and delays the material damage process. The filler network of the rubber material of the present application has good interface combination and reinforcement effect, which not only prevents crack propagation, but also significantly improves the overall mechanical properties. Although the commercially available rubber has a high filler content, the interface effect is weak, which cannot form an effective reinforcement effect, resulting in faster crack propagation. The combination of the filler network and the strain-induced crystallization makes the rubber material of the present application have stronger crack propagation resistance at the crack tip and the bulk part. The presence of the combined glue enhances the stability of the filler network, further delaying crack propagation.

[0130] The synergistic effect of strain-induced crystallization and filler network significantly improves the crack resistance, ensuring that the manhole cover rubber is not easy to crack under complex working conditions. Effectively reducing crack propagation and material damage, prolonging the service life and reducing maintenance costs. The filler network enhances the material's resistance to impact force through interface bonding and energy dissipation. Enhance the impact resistance of the manhole cover rubber, adapt to heavy traffic environment, improve safety and reliability. The strain-induced crystallization effect of the rubber material of the present application at the crack tip can effectively prevent crack propagation, and can maintain structural integrity even under high stress. The material is stable under long-term load and repeated impact, and is not easy to fail.

[0131] The advantages of the rubber material of the present application in strain-induced crystallization and filler network design make it significantly better than commercially available rubber in crack propagation resistance and impact resistance. This performance advantage provides the manhole cover rubber with higher stability, durability and safety, and can meet the long-term use requirements under complex traffic conditions, and is an ideal upgrade substitute for commercially available rubber.

[0132] The rubber material of the present application has excellent heat and oxygen aging resistance. The tensile strength and compression strength decrease slightly under heat and oxygen aging conditions, which is significantly better than commercially available rubber. The wear amount of the rubber material of the present application is significantly lower than that of commercially available rubber, indicating that it has stronger wear resistance. The rubber material of the present application uses N330 carbon black, which has wear resistance, reinforcement and moderate heat generation, balancing various properties. This is because the addition of montmorillonite suppresses the diffusion of oxygen molecules and slows down the aging reaction from the surface to the interior. A good filler network structure further enhances the aging resistance. Heat and oxygen aging and fatigue heat aging resistant antioxidants are added to the formula.

[0133] The rubber material of the present application has strong heat-oxidation aging resistance, and can maintain strength and structural integrity under long-term exposure to high-temperature oxidation environment. Therefore, it can reduce the performance decline caused by aging, ensure the long-term stability of the well cover rubber gasket, and reduce the replacement frequency. The rubber material of the present application optimizes the filler design and carbon black selection, enhances the wear resistance of the material and prevents failure due to excessive wear. It provides long-lasting protection against repeated friction between the well cover and the vehicle, extending the service life. The use of N330 carbon black achieves a comprehensive balance of wear resistance, mechanical properties and heat generation, avoiding the degradation of other properties due to excessively high single performance. It meets the multiple needs of well covers in complex traffic environments and improves reliability. The outstanding performance of the rubber material of the present application in terms of aging resistance and wear resistance makes it have significant advantages in the application of well cover rubber gaskets. The optimized filler design and the use of preferred carbon black (N330) achieve a good balance between high performance and stability, ensuring the reliability and durability of the well cover in long-term use, and it is an ideal alternative to commercially available rubber.

[0134] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the inventive concept, several modifications and improvements can be made, which are all within the scope of protection of the present application.

Claims

1. An impact-resistant and wear-resistant manhole cover rubber material, characterized in that: The invention is composed of a rubber mix, nylon cord fabric and rubber-coated steel wire, wherein the rubber mix is ​​composed of the following raw materials in parts by weight: 100 parts of natural rubber, 2-5 parts of zinc oxide, 1-3 parts of stearic acid, 0.5-2 parts of accelerator, 0.5-3 parts of sulfur, 1-2 parts of anti-aging agent, 45-70 parts of carbon black, 1-8 parts of montmorillonite and 2-6 parts of FM coupling agent.

2. The impact-resistant and wear-resistant manhole cover rubber material according to claim 1, characterized in that: The anti-aging agents include anti-aging agent RD and anti-aging agent 4010NA.

3. The impact-resistant and wear-resistant manhole cover rubber material according to claim 2, characterized in that: The weight ratio of the anti-aging agent RD to the anti-aging agent 4010NA in the anti-aging agent is 1:

1.

4. The impact-resistant and wear-resistant manhole cover rubber material according to claim 1, characterized in that: The carbon black is N330 carbon black.

5. The method for preparing an impact-resistant and wear-resistant manhole cover rubber material according to any one of claims 1 to 4, characterized in that: The raw materials of the rubber compound are mixed to obtain a rubber compound strip, which is pressed together with nylon cord fabric and rubber-coated steel wires arranged perpendicularly to each other in a mold and vulcanized at 150° C. for 10 minutes to obtain the impact-resistant and wear-resistant manhole cover rubber material.

6. The method for preparing the impact-resistant and wear-resistant manhole cover rubber material according to claim 5, characterized in that: The specific steps include: S1: After mixing the raw materials according to a set ratio to obtain a rubber mix, the rubber mix is ​​pressed into a 1.5 mm thick film on an open mixing mill, and then cut into 8 mm wide strips for standby use; S2: Cutting the nylon cord fabric into narrow strips with a width of 8 to 9 mm, wherein the nylon thread of the nylon cord fabric has a diameter of 0.5 mm, and setting aside; S3: Cut the rubber-coated steel wire at a 45° angle into narrow strips with a width of 8 to 9 mm. The diameter of each rubber-coated steel wire is 0.32 mm and set aside. S4: The three strip-shaped raw materials cut in steps S1 to S3 are placed layer by layer in a mold in the following order: 1 layer of rubber mix, 2 layers of rubber-coated steel wire, 1 layer of nylon cord fabric, and 2 to 3 layers of rubber mix, wherein the 2 layers of rubber-coated steel wire are placed crosswise at 45 degrees. The placed strips and the mold are pressed on a hot press at room temperature for 2 minutes, and then the strips are removed from the mold to obtain blanks; S5: Preheat the mold on a hot press at 150° C. for 5 minutes, and directly and quickly place the blank into the mold, place the upper and lower cover plates, put it into the hot press, and vulcanize it at 150° C. for 10 minutes to obtain the impact-resistant and wear-resistant manhole cover rubber material.

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