An erosion-resistant EPDM insulation material with good adhesion properties and its preparation method

Abstract

This invention provides an erosion-resistant EPDM insulation material with good adhesion properties and its preparation method. The EPDM insulation material comprises the following components by weight: 100 parts EPDM rubber, 15-40 parts reinforcing filler, 5-15 parts organic fiber, 5-10 parts inorganic fiber, 2-5 parts organic flame retardant, 3-10 parts inorganic flame retardant, 1-5 parts charring component, 5-10 parts plasticizer, 1-5 parts activator, 0.02-0.5 parts charring accelerator, 1-5 parts vulcanization accelerator, and 1-5 parts vulcanizing agent. The preparation method adopts a multi-stage mixing process. This invention can improve the uniformity of the material system and address the problem of poor mechanical properties in erosion-resistant materials; it can utilize the energy during dynamic ablation to form a dense, erosion-resistant carbonized layer on the material surface using the carbon nucleation and growth mechanism, thereby improving the material's poor erosion resistance; it can reduce the inorganic-organic raw material interface, enhance material fusion, improve the interfacial tension imbalance between the material and the substrate, and improve interfacial adhesion.

Description

Technical Field

[0001] This invention belongs to the field of aerospace thermal protection materials technology, specifically relating to an erosion-resistant EPDM thermal insulation material with good adhesion properties and its preparation method. Background Technology

[0002] Ethylene propylene diene monomer (EPDM) insulation materials are mainly used in the cylinder sections and end caps of solid rocket engines to provide thermal protection for the inner walls of the engine casing and the propellant erosion areas. This protects the solid rocket engines from high-temperature ablation and erosion by high-pressure airflow and dense particles during operation, thus ensuring the reliable operation of the solid rocket engines. Improving the high-temperature ablation and particle erosion resistance of insulation materials is currently a key research focus.

[0003] However, EPDM insulation materials have relatively weak polarity and weak adhesion interfaces with metals, composite materials, and propellants. Once debonded, it can lead to uneven temperature fields inside the engine, runaway operation, and material burn-through, causing catastrophic accidents. Therefore, improving the adhesion strength and reliability of insulation materials to various interfaces is a hot topic of concern.

[0004] Existing literature reports researchers have attempted to improve the ablation resistance of thermal insulation materials by increasing the content of ablation-resistant fillers, using blends of organic and inorganic fibers, and blending with inorganic flame retardants. Alternatively, they have added carbon nanotubes to the materials, utilizing the principle of carbon deposition to form a good ablation carbonized layer during the ablation process, thereby improving the material's erosion resistance. Interface treatment, base adhesive modification (such as introducing acrylates to improve interfacial polarity), and filler or fiber surface modification have been used to optimize the interfacial adhesion of thermal insulation materials. However, these methods increase the Mooney viscosity and processing complexity of the materials, degrade their mechanical properties, and fail to achieve effective synergy among the raw materials.

[0005] Chinese patent CN201911274442.4 discloses a modified carbon nanotube-reinforced EPDM rubber thermal insulation material and its preparation method. It employs a vapor deposition pretreatment method to form a protective layer on the outside of the carbon nanotubes, thereby reducing the thermal conductivity of the insulation material, the thermal conductivity of the carbonized layer, and the carbonization ablation rate of the material. However, it does not take measures to improve the overall synergistic coupling of the material, resulting in a still relatively high carbonization ablation rate (0.166 mm / s) and high Mooney viscosity.

[0006] This patent application is filed to address the shortcomings of existing technologies. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an erosion-resistant EPDM insulation material with good adhesion properties and its preparation method. This invention can improve the uniformity of the material system and improve the problem of poor mechanical properties of erosion-resistant materials; it can utilize the energy in the dynamic ablation process and the carbon nucleation and growth mechanism to form a dense erosion-resistant carbonized layer on the material surface, thereby improving the problem of poor erosion resistance; it can reduce the inorganic-organic raw material interface, improve the material fusion, improve the problem of interfacial tension imbalance between the material and the substrate, and improve interfacial adhesion.

[0008] This invention provides the following technical solution:

[0009] This invention provides an erosion-resistant EPDM insulation material with good adhesion properties, comprising the following components by weight: 100 parts EPDM rubber, 15-40 parts reinforcing filler, 5-15 parts organic fiber, 5-10 parts inorganic fiber, 2-5 parts organic flame retardant, 3-10 parts inorganic flame retardant, 1-5 parts charring component, 5-10 parts plasticizer, 1-5 parts activator, 0.02-0.5 parts charring accelerator, 1-5 parts accelerator, and 1-5 parts vulcanizing agent.

[0010] This invention addresses the technical challenge of poor integration between inorganic flame retardants and EPDM adhesives by adding organic flame retardants. The combination of macromolecular organic flame retardants and inorganic flame retardants results in good integration with the base adhesive and minimizes precipitation. By controlling the appropriate proportions of each component in the formulation, the material achieves good fusion and cross-linking, realizing coupling between components and promoting synergistic effects during ablation. The formulation combination forms a three-dimensional flexible carbonized layer and a well-integrated primary layer, solving problems such as incomplete cross-linking leading to small molecule precipitation and stress caused by uneven internal structure, thus improving interlayer bonding and interfacial adhesion strength. The addition of carbonization promoters facilitates the formation of graphene, carbon nanowires, silicon carbide whiskers, and other structures, with short fibers composited with long fibers, enhancing the strength of the ablated carbonized layer and the integration between the carbonized layer and the base adhesive.

[0011] Furthermore, in the above materials, the reinforcing filler is one or more of the following: fumed silica, precipitated silica, activated carbon black, calcium carbonate, talc, and clay.

[0012] Furthermore, in the above materials, the organic fiber is one or more of aramid fiber, polyphenylene sulfide fiber, phenolic fiber, carbon fiber, and polyimide fiber; the inorganic fiber is one or more of quartz fiber, aluminum silicate fiber, basalt fiber, mullite fiber, and silicon carbide fiber.

[0013] Furthermore, the organic fibers include organic fibers of three sizes: 0.1-0.5 mm, 0.5-1 mm, and 1-3 mm, wherein the organic fibers of 0.1-0.5 mm comprise 2-5 parts, the organic fibers of 0.5-1 mm comprise 2-5 parts, and the organic fibers of 1-3 mm comprise 1-5 parts; the inorganic fibers include inorganic fibers of three sizes: 0.1-0.5 mm, 0.5-1 mm, and 1-3 mm, wherein the inorganic fibers of 0.1-0.5 mm comprise 1-2 parts, the inorganic fibers of 0.5-1 mm comprise 3-5 parts, and the inorganic fibers of 1-3 mm comprise 1-3 parts.

[0014] Furthermore, in the above materials, the organic flame retardant is one or more of the following: ammonium polyphosphate, decabromodiphenyl ether, hexachlorocyclotriphosphazene, and phosphate ester; the inorganic flame retardant is one or more of the following: aluminum hydroxide, magnesium hydroxide, zinc borate, barium sulfate, and antimony trioxide.

[0015] Furthermore, in the above materials, the carbon-forming components are one or more combinations of carbon fibers, carbon nanotubes, silicon carbide, and graphene.

[0016] Furthermore, in the above materials, the plasticizer is one or a combination of two or more of liquid paraffin, dioctyl sebate, aromatic hydrocarbon oil, and cycloalkane oil.

[0017] Furthermore, in the above materials, the activator is one or more of the following: calcium oxide, zinc oxide, magnesium oxide, stearic acid, zinc stearate, triethanolamine, and polyethylene glycol.

[0018] Furthermore, in the above materials, the carbonization promoter is one or a combination of two or more of tin oxide, nickel oxide, lanthanum oxide, tungsten oxide, and molybdenum oxide.

[0019] Furthermore, in the above materials, the vulcanization accelerator is one or a combination of two or more of dicaprolactam disulfide, zinc dibenzyl dithiocarbamate, and tetrabenzyl thiuram disulfide.

[0020] Furthermore, in the above materials, the vulcanizing agent is one or more of sulfur, dicumyl peroxide, and bis(tert-butylperoxide)benzene.

[0021] This invention also provides a method for preparing the above-mentioned erosion-resistant EPDM insulation material with good adhesion, comprising the following steps:

[0022] S1. Fuse all fibers with 10-30 parts of EPDM rubber to make a masterbatch;

[0023] S2. Add the masterbatch to the internal mixer, break it up, add the remaining EPDM rubber and mix well. Add the reinforcing filler, organic and inorganic flame retardants, carbon-forming components, activators, and carbon-forming accelerators in small amounts several times to ensure that the EPDM rubber is fully dispersed with the reinforcing filler, organic and inorganic flame retardants, carbon-forming components, activators, and carbon-forming accelerators. Turn off the water cooling system of the internal mixer to allow the chamber to heat up rapidly and promote the rapid agglomeration of the rubber compound. Then turn on the water cooling system to keep the chamber heating up slowly and stir the rubber agglomerates thoroughly. Discharge the rubber and let it dry to room temperature.

[0024] S3. The material obtained in step S2 is put into a mixer and broken into flocculent form. Then, vulcanization accelerator and vulcanizing agent are added to mix it evenly in a dispersed state. As the temperature of the chamber rises, the rubber compound slowly forms clumps. After mixing for 1-3 minutes, plasticizer is added to break the clumps into flocculent form again and disperse them evenly. At this time, the water cooling system is turned off to allow the temperature in the chamber to rise rapidly and promote the rapid clumping of the rubber compound. Then, the water cooling system is turned on again to keep the temperature in the chamber rising slowly and the clumps are thoroughly stirred evenly. The rubber is then discharged, sheeted, and dried to room temperature to obtain the EPDM insulation material.

[0025] This solution employs a multi-stage mixing method, following the order of adding base rubber → fiber and base rubber fusion material → powder filler → liquid plasticizer, first dry mixing and then blending, to improve the uniform distribution of each component in the base rubber.

[0026] This solution reduces the amount of char-forming components and adds a char-forming accelerator that accelerates carbon deposition to form a dense carbonized layer, thus fully leveraging the ablation-improving function of char-forming components with a small amount of char-forming components. Combined with optimized mixing process measures, it improves the uniformity of the mixing of rubber and fillers, enhances heating flow, and reduces the Mooney viscosity of the material. Through fiber premixing and optimized mixing process parameters, the fibers and carbon nanotubes are more uniformly dispersed in the base rubber, eliminating the mechanical property degradation caused by uneven stress. This solution does not require surface modification of carbon nanotubes; it only improves the micro-interface of the material by optimizing the type and amount of fillers and the mixing process, resulting in a uniform distribution and effective synergy of raw materials, thus reducing the complexity of the process.

[0027] The present invention has the following beneficial effects:

[0028] 1. This invention can effectively improve the adhesion, ablation resistance, and erosion resistance of thermal insulation materials, solving the problem of poor process performance of current erosion-resistant thermal insulation materials; through reasonable formulation combination, a three-dimensional flexible carbonized layer and a well-integrated original layer can be formed, solving problems such as incomplete cross-linking leading to small molecule precipitation and uneven internal structure causing stress, thereby improving interlayer bonding force and interfacial adhesion strength; by adding a carbonization promoter, a protective layer is dynamically formed during the ablation process, and this protective layer is resistant to high temperature and temperature shock, transition changes, and forms a good bond with the original layer; by utilizing the nucleation and pinning effect of short fiber pulp during thermal pyrolysis, the strength and density of the carbonized layer are improved, and by using the compounding of long and short fibers, a flexible, three-dimensional carbonized layer structure is formed;

[0029] 2. By adding organic flame retardants, this invention can improve the problems caused by the moisture absorption of inorganic flame retardants, such as decreased mechanical properties, increased ablation rate, and bulging and curling of the ablation and carbonization layer. It also improves the cohesion of the base adhesive, improves the molding process performance, and avoids precipitation.

[0030] 3. The preparation process of the present invention can make each component uniformly dispersed in the base adhesive, which synergistically enhances the material design and the prepared thermal insulation material has excellent comprehensive performance. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 These are the apparent images of the carbonized layer after oxy-acetylene ablation of the samples prepared in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention.

[0033] Figure 2 This is a SEM image of the carbonized layer of the sample prepared in Example 1 of the present invention;

[0034] Figure 3 This is a SEM image of the carbonized layer of the sample prepared in Comparative Example 1 of the present invention.

[0035] Figure 4 This is a SEM image of the carbonized layer of the sample prepared in Comparative Example 2 of the present invention.

[0036] Figure 5 This is a SEM image of the carbonized layer of the sample prepared in Comparative Example 3 of the present invention.

[0037] Figure 6 The images show the appearance of the vulcanized sheets of the samples prepared in Example 1 and Comparative Example 3 of this invention.

[0038] Figure 7 The fiber distribution of raw material sheets prepared in Example 1 and Comparative Example 4 before the addition of carbon nanotubes is shown.

[0039] Figure 8 This is a schematic diagram of the raw rubber structure before vulcanization (left) and a schematic diagram of the original layer of the insulation material after vulcanization (right).

[0040] Figure 9 The fiber distribution and morphology between the original layer and the carbonized layer of the sample after ablation in Example 1 of this invention;

[0041] Figure 10 This describes the morphology of the three-dimensional flexible carbonized layer formed after ablation of the sample in Example 1 of this invention.

[0042] Figure 11 This is a morphology diagram of the carbonized layer after ablation of the sample in Example 1 of the present invention;

[0043] Figure 12 This is a schematic diagram of the test specimen showing the adhesion and separation of raw and cooked material sheets according to the present invention;

[0044] Figure 13 The diagram on the left shows the adhesion test results between the carbonized layer and the original layer of this invention, and the schematic diagram on the right shows the apparatus.

[0045] Figure 14 The diagram on the left shows the test results for the destructive force of the carbonized layer of this invention, and the schematic diagram on the right shows the apparatus. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Example 1

[0048] Weigh the raw materials: 100 parts of EPDM rubber, 15 parts of silica, 5 parts of aramid fiber (1 part of 0.1-0.5mm fiber, 3 parts of 0.5-1mm fiber, and 1 part of 1-3mm fiber), 5 parts of quartz fiber (1 part of 0.1-0.5mm fiber, 3 parts of 0.5-1mm fiber, and 1 part of 1-3mm fiber), 4 parts of ammonium polyphosphate, 3 parts of aluminum hydroxide, 1 part of carbon nanotubes, 5 parts of liquid paraffin, 1 part of calcium oxide, 0.02 parts of tin oxide, 1 part of dicaprolactam disulfide, and 1 part of sulfur.

[0049] The specific preparation method steps are as follows:

[0050] S1. Fibers are blended with 15 parts of base rubber (ethylene propylene diene monomer rubber) to form a masterbatch;

[0051] S2. Add the masterbatch to the internal mixer, break it up, add the remaining base rubber and mix well. Add the powder (reinforcing filler, organic and inorganic flame retardants, carbon-forming components, activators, and carbon-forming accelerators) in 3 batches. Stir the base rubber and powder in a broken state for 1 minute, then turn off the water cooling system of the internal mixer to rapidly raise the temperature in the chamber to 50°C. Then turn on the water cooling system (constant temperature 20°C) to keep the temperature in the chamber rising slowly. Stir the rubber clumps thoroughly and evenly. When the chamber temperature reaches 110°C, remove the rubber and let it cool to room temperature.

[0052] S3. The material obtained in step S2 is put into a mixer and broken into flocculent form. Then, an accelerator and a vulcanizing agent are added. The mixture is stirred in a dispersed state for 1 minute. As the temperature of the chamber rises to 50°C, the rubber compound forms clumps. After mixing for 1 minute, liquid paraffin is added to break the clumps into flocculent form again. The mixture is stirred for 1 minute. The water cooling system is then turned off, and the temperature of the chamber is rapidly raised to 50°C. After the rubber compound forms clumps, the water cooling system is turned on again (constant temperature 20°C) to maintain a slow temperature rise in the chamber. The clumps are thoroughly mixed. When the temperature of the chamber reaches 80°C, the rubber is discharged, sheeted, and dried to room temperature to obtain the EPDM insulation material.

[0053] Example 2

[0054] Weigh the raw materials: 100 parts of EPDM rubber, 40 parts of talc powder, 15 parts of polyphenylene sulfide fiber (including 5 parts of 0.1-0.5mm fiber, 5 parts of 0.5-1mm fiber, and 5 parts of 1-3mm fiber), 10 parts of mullite fiber (including 2 parts of 0.1-0.5mm fiber, 5 parts of 0.5-1mm fiber, and 3 parts of 1-3mm fiber), 5 parts of decabromodiphenyl ether, 5 parts of magnesium hydroxide, 5 parts of graphene, 10 parts of aromatic hydrocarbon oil, 5 parts of zinc oxide, 0.5 parts of lanthanum oxide, 5 parts of zinc dibenzyl dithiocarbamate, and 5 parts of dicumyl peroxide.

[0055] The specific preparation method steps are as follows:

[0056] S1. Fibers are blended with 30 parts of base rubber (ethylene propylene diene monomer rubber) to form a masterbatch;

[0057] S2. Add the masterbatch to the internal mixer, break it up, add the remaining base rubber and mix well. Add the powder in 5 batches, and stir the base rubber and powder in a broken state for 3 minutes. Then turn off the water cooling system of the internal mixer and let the temperature in the chamber rise rapidly to 55°C. Then turn on the water cooling system (constant temperature 25°C) and let the temperature in the chamber rise slowly. Stir the rubber clumps thoroughly and evenly. When the temperature in the chamber reaches 115°C, remove the rubber and let it dry to room temperature.

[0058] S3. The material obtained in step S2 is put into a mixer and broken into flocculent form. Then, accelerator and vulcanizing agent are added. The mixture is stirred in a dispersed state for 2 minutes. As the temperature of the chamber rises to 55°C, the rubber compound forms clumps. After mixing for 1 minute, liquid paraffin is added to break the clumps into flocculent form again. The mixture is stirred for 2 minutes. The water cooling system is turned off, and the temperature in the chamber is rapidly raised to 55°C. After the rubber compound forms clumps, the water cooling system is turned on again (constant temperature 25°C) to keep the temperature in the chamber rising slowly. The clumps are thoroughly mixed. When the temperature of the chamber reaches 85°C, the rubber is discharged, sheeted, and dried to room temperature to obtain the EPDM insulation material.

[0059] Example 3

[0060] Weigh the raw materials: 100 parts of EPDM rubber, 25 parts of talc powder, 10 parts of polyimide fiber (including 2 parts of 0.1-0.5mm fiber, 4 parts of 0.5-1mm fiber, and 4 parts of 1-3mm fiber), 5 parts of mullite fiber (including 1 part of 0.1-0.5mm fiber, 3 parts of 0.5-1mm fiber, and 1 part of 1-3mm fiber), 5 parts of decabromodiphenyl ether, 3 parts of magnesium hydroxide, 3 parts of graphene, 7 parts of aromatic hydrocarbon oil, 3 parts of zinc oxide, 0.3 parts of lanthanum oxide, 3 parts of zinc dibenzyl dithiocarbamate, and 3 parts of dicumyl peroxide.

[0061] The specific preparation method steps are as follows:

[0062] S1. Fibers are blended with 20 parts of base rubber (ethylene propylene diene monomer rubber) to form a masterbatch;

[0063] S2. Add the masterbatch to the internal mixer, break it up, add the remaining base rubber and mix well. Add the powder in 4 batches, and stir the base rubber and powder in a broken state for 2 minutes. Then turn off the water cooling system of the internal mixer to rapidly raise the temperature in the chamber to 50°C. Then turn on the water cooling system (constant temperature 20°C) to keep the temperature in the chamber rising slowly. Stir the rubber clumps thoroughly and evenly. When the temperature in the chamber reaches 110°C, remove the rubber and let it dry to room temperature.

[0064] S3. The material obtained in step S2 is put into a mixer and broken into flocculent state. Then, accelerator and vulcanizing agent are added. The mixture is stirred in a dispersed state for 1.5 minutes. As the temperature of the chamber rises to 50°C, the rubber compound forms clumps. After mixing for 1 minute, liquid paraffin is added to break the clumps into flocculent state again. The mixture is stirred for 1.5 minutes. The water cooling system is turned off, and the temperature of the chamber is rapidly raised to 50°C. After the rubber compound forms clumps, the water cooling system is turned on again (constant temperature 20°C) to keep the temperature of the chamber rising slowly. The clumps are thoroughly stirred and evenly mixed. When the temperature of the chamber reaches 80°C, the rubber is discharged, sheeted, and dried to room temperature to obtain the EPDM insulation material.

[0065] Comparative Example 1

[0066] The only difference was the absence of a carbonization accelerator; the quality of other raw materials and the process steps were the same as in Example 1.

[0067] Comparative Example 2

[0068] The only difference was the absence of fiber length blending (the dimensions of both aramid fiber and quartz fiber were 0.1~0.5mm), while the quality of other raw materials and process steps were the same as in Example 1.

[0069] Comparative Example 3

[0070] The only difference is that the combination of organic and inorganic flame retardants was not included (only aluminum hydroxide was added), while the quality of other raw materials and process steps were the same as in Example 1.

[0071] Comparative Example 4

[0072] The raw material ratio is the same as in Example 1, but a multi-stage mixing process is not used. The specific preparation method steps are as follows:

[0073] S1. Blend the fiber with 15 parts of base glue to make a masterbatch;

[0074] S2. Add the masterbatch and the remaining base rubber into the internal mixer and stir for 5 minutes. Add the powder and stir for another 5 minutes. After stirring the rubber mass thoroughly, remove the rubber from the mixer when the chamber temperature reaches 110-115℃ and let it cool to room temperature.

[0075] S3. Put the material obtained in step S2 into a mixer, stir for 3 minutes, add accelerator and vulcanizing agent, stir for 2 minutes, add liquid paraffin, stir for 5 minutes, and when the chamber temperature reaches 80-85℃, dispense the adhesive, sheet it out, and let it dry to room temperature to obtain EPDM insulation material.

[0076] The materials prepared in Examples 1-3 and Comparative Example 1 were tested for various properties (tensile strength, elongation at break, oxyacetylene ablation rate, raw-cure bond pull-off strength, Mooney viscosity, adhesion between the carbonized layer and the original layer, and carbonized layer destructive force). The results are shown in Table 1. Higher tensile strength and elongation at break indicate better mechanical properties of the material; lower oxyacetylene ablation rate indicates better ablation resistance; higher raw-cure bond pull-off strength indicates better adhesion; lower Mooney viscosity indicates better flowability and processing performance; higher adhesion between the carbonized layer and the original layer, and greater carbonized layer destructive force, indicate better erosion resistance of the carbonized layer formed after ablation.

[0077] Table 1. Performance results of materials prepared in Examples 1-3 and Comparative Examples 1-4

[0078] Test Standards Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 <![CDATA[Mooney viscosity M l (1 + 4)]]> GB / T 1232 56 65 60 57 65 58 67 Tensile strength / MPa GB / T 528-2009 8.0 10.5 9.0 7.5 8.5 8.6 8.0 Elongation at break / % GB / T 528-2009 380% 300% 350% 400% 360% 290% 280% Raw and cooked bond pull strength / MPa QJ 2038.1A-2004 3.5 3.8 3.6 3.2 2.3 2.1 2.5 Oxyacetylene line ablation rate / mm / s GJB 323A-1996 0.045 0.021 0.035 0.060 0.055 0.070 0.060 Adhesion between carbonized layer and original layer / N / 22 28 26 20 18 15 12 Carbide layer destructive force / N / 80 90 85 60 75 70 58

[0079] As shown in Table 1, compared with Example 1, the Mooney viscosity and mechanical properties of the sample without the added charring accelerator (Comparative Example 1) remained largely unchanged, the raw-to-cooked pull strength decreased slightly, but the linear ablation rate increased significantly. Furthermore, the adhesion and destructive force between the carbonized layer and the original layer decreased, and the erosion resistance of the carbonized layer deteriorated. This indicates that the charring accelerator significantly affects the ablation resistance and erosion resistance of the material.

[0080] Compared to Example 1, the Mooney viscosity of the sample without fiber blending (Comparative Example 2) increased significantly, while the mechanical properties remained largely unchanged. The pull-off strength between raw and cooked layers decreased, and the adhesion and destructive force between the carbonized layer and the original layer both decreased. The erosion resistance of the carbonized layer also deteriorated. This indicates that fiber blending significantly affects the Mooney viscosity, adhesive properties, and erosion resistance of the material.

[0081] Compared to Example 1, the Mooney viscosity of the sample without flame retardant formulation (Comparative Example 3) remained relatively unchanged, but the elongation at break decreased significantly, the raw-to-cure pull strength decreased, and the adhesion and destructive force between the carbonized layer and the original layer both decreased, while the erosion resistance of the carbonized layer deteriorated. This indicates that flame retardant formulation significantly affects the Mooney viscosity, adhesion, and erosion resistance of the material.

[0082] Compared to Example 1, the sample without segmented mixing process (Comparative Example 4) showed a significantly increased Mooney viscosity, a significantly decreased elongation at break, a reduced raw-to-cooked pull strength, and decreased adhesion and destructive force between the carbonized layer and the original layer. The erosion resistance of the carbonized layer also deteriorated. This indicates that the segmented mixing process significantly affects the Mooney viscosity, mechanical properties, adhesive properties, and erosion resistance of the material.

[0083] Compared with Example 1, Examples 2 and 3 have different fiber content and types, flame retardant content and types, vulcanization systems, etc. Therefore, their mechanical properties, Mooney viscosity, bonding properties, ablation resistance and erosion resistance fluctuate, but their overall performance is better than that of the comparative sample.

[0084] The present invention requires that the material have a Mooney viscosity ≤ 65, tensile strength ≥ 7.5 MPa, elongation at break ≥ 300%, raw-cure bond pull strength ≥ 3.0 MPa, oxyacetylene ablation rate ≤ 0.05 mm / s, adhesion between the carbonized layer and the original layer ≥ 20 N, and carbonized layer destructive force ≥ 80 N, which can be considered to have good comprehensive performance.

[0085] See Figure 1 The carbonized layer of the sample in Example 1 was intact and not easily damaged, while the carbonized layer of the sample in Comparative Example 1 (without carbon accelerator) was easily damaged, and the carbonized layer of the sample in Comparative Example 2 (without fiber size matching) was easily delaminated.

[0086] See Figure 2 As can be seen, the sample prepared in Example 1 formed a dense, multi-sized fiber-interwoven three-dimensional carbonized layer structure; see also Figure 3It can be seen that the sample without added carbon accelerator only formed a relatively loose carbonized layer structure; see also Figure 4 It is evident that samples with mismatched fiber sizes did not form a well-defined three-dimensional carbonized layer structure; see also Figure 5 It can be seen that the sample without flame retardant compounding did not form a good three-dimensional carbonized layer structure;

[0087] Figure 6 The images show the appearance of the vulcanized flakes of the samples prepared in Example 1 and Comparative Example 3 of this invention. As can be seen from the figures, the sample without flame retardant compounding has more precipitates on its surface, indicating that the internal filler has poor compatibility.

[0088] Figure 7 The figure shows the fiber distribution of raw material sheets in Example 1 and Comparative Example 4 before the addition of carbon nanotubes (to facilitate observation of fiber dispersion). As can be seen from the figure, the fiber distribution inside the sample without segmented mixing process is uneven, and there is a lot of fiber agglomeration.

[0089] Figure 8 The diagram shows the raw rubber structure before vulcanization (left) and the original layer of the insulation material after vulcanization (right). As can be seen from the diagram, the present invention uses the combination and compounding of the components and multi-stage mixing process to make the components uniformly dispersed and well integrated in the material, and the crosslinking points are more evenly distributed after vulcanization.

[0090] Figure 9 This image shows the fiber distribution and morphology between the original layer and the carbonized layer of the sample after ablation. Figure 10 This shows the fiber morphology of the sample after ablation. Figure 11 The figure shows the morphology of the carbonized layer after ablation of the sample of this invention. As can be seen from the figure, this invention, by adding compounded organic and inorganic fibers, forms multi-scale fibers during the mixing process, which interweave to form a three-dimensional network structure in the insulation material. During the ablation process, some fibers undergo pyrolysis and carbonization and become anchored in the carbonized layer, while some fibers do not carbonize but combine with the original layer, thus forming a three-dimensional flexible carbonized structure. At the same time, under high-temperature ablation conditions, the carbon-forming components in the material rapidly form a dense carbonized layer under the action of compounded flame retardants and carbonization promoters, filling the large pores formed during the carbonization and pyrolysis of the insulation material. The synergistic effect of these two processes promotes the formation of a three-dimensional flexible network carbonized layer.

[0091] Figure 12-14 Table 1 shows the schematic diagrams illustrating the testing methods for the adhesion between the carbonized layer and the original layer, as well as the destructive force of the carbonized layer. Figure 12 This is a schematic diagram of a test specimen showing the adhesion and separation of raw and cooked material sheets according to the present invention. Figure 13 The diagram on the left shows the adhesion test results between the carbonized layer and the original layer of this invention, and the schematic diagram on the right shows the apparatus. Figure 14 The diagram on the left shows the test results for the destructive force of the carbonized layer of this invention, and the schematic diagram on the right shows the apparatus.

[0092] In summary, this invention can effectively improve the adhesion, ablation resistance, and erosion resistance of thermal insulation materials, solving the problem of poor process performance of current erosion-resistant thermal insulation materials. Through a reasonable formulation combination, a three-dimensional flexible carbonized layer and a well-integrated primary layer can be formed, solving problems such as incomplete cross-linking leading to small molecule precipitation and stress caused by uneven internal structure, thus improving interlayer bonding and interfacial adhesion strength. The addition of a carbonization promoter enables the dynamic formation of a protective layer during ablation, and this protective layer is resistant to high temperatures and temperature shocks, exhibits smooth transitions, and forms a good bond with the primary layer. The nucleation and pinning effect during the thermal pyrolysis of short fiber pulp enhances the strength and density of the carbonized layer, and the combination of long and short fibers forms a flexible, three-dimensional carbonized layer structure.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A washout resistant ethylene-propylene-diene terpolymer insulation having good adhesion properties, characterized in that, The ternary ethylene propylene rubber 100 parts by weight, reinforcing filler 15-40 parts, organic fiber 5-15 parts, inorganic fiber 5-10 parts, organic flame retardant 2-5 parts, inorganic flame retardant 3-10 parts, carbon component 1-5 parts, plasticizer 5-10 parts, activator 1-5 parts, carbonation accelerator 0.02-0.5 parts, vulcanization accelerator 1-5 parts, vulcanizing agent 1-5 parts; The organic fiber includes three sizes of organic fibers of 0.1-0.5mm, 0.5-1mm and 1-3mm, wherein the organic fiber of 0.1-0.5mm is 2-5 parts, the organic fiber of 0.5-1mm is 2-5 parts, and the organic fiber of 1-3mm is 1-5 parts; the inorganic fiber includes three sizes of inorganic fibers of 0.1-0.5mm, 0.5-1mm and 1-3mm, wherein the inorganic fiber of 0.1-0.5mm is 1-2 parts, the inorganic fiber of 0.5-1mm is 3-5 parts, and the inorganic fiber of 1-3mm is 1-3 parts; the carbonation accelerator is one or more than two combinations of tin oxide, nickel oxide, lanthanum oxide, cerium oxide, tungsten oxide and molybdenum oxide; The preparation method of the anti-erosion ternary ethylene propylene heat insulating material comprises the following steps: S1, melt all the fibers with 10-30 parts of ternary ethylene propylene rubber to make a masterbatch; S2, put the masterbatch into the internal mixer, disperse and then mix the remaining ternary ethylene propylene rubber, a small amount of reinforcing filler, organic and inorganic flame retardant, carbon component, activator and carbonation accelerator, so that the ternary ethylene propylene rubber and the reinforcing filler, organic and inorganic flame retardant, carbon component, activator and carbonation accelerator are fully dispersed, the water cooling system of the internal mixer is closed to rapidly heat the chamber, so that the rubber compound is quickly formed into a mass, then the water cooling system is opened to keep the chamber slowly heated, the rubber mass is fully stirred and uniformly distributed, the rubber is discharged and cooled to room temperature; S3, put the material obtained in step S2 into the internal mixer, disperse into flocculation, then add the accelerator and vulcanizing agent, mix them in a dispersed state, the rubber mass slowly forms a mass as the temperature of the chamber rises, then add the plasticizer after 1-3 minutes of mixing, disperse the rubber mass into flocculation again, fully disperse and mix, then close the water cooling system to rapidly heat the chamber, so that the rubber compound is quickly formed into a mass, then open the water cooling system again to keep the chamber slowly heated, fully stir and mix the rubber mass, discharge the rubber, cut it into sheets, cool to room temperature, and the ternary ethylene propylene heat insulating material is obtained.

2. The impact-resistant EPDM thermal insulation material with good adhesion according to claim 1, characterized in that: The reinforcing filler is one or more than two combinations of fumed silica, precipitated silica, activated carbon black, calcium carbonate, talc and clay.

3. The impact-resistant EPDM thermal insulation material with good adhesion according to claim 1, characterized in that: The organic fiber is one or more than two combinations of aramid fiber, polyphenylene sulfide fiber, phenolic fiber and polyimide fiber; the inorganic fiber is one or more than two combinations of quartz fiber, aluminum silicate fiber, basalt fiber, mullite fiber and silicon carbide fiber.

4. The impact-resistant EPDM thermal insulation material with good adhesion according to claim 1, characterized in that: The organic flame retardant is one or more than two combinations of ammonium polyphosphate, decabromodiphenyl ether, hexachlorotriphosphazene and phosphate ester; the inorganic flame retardant is one or more than two combinations of aluminum hydroxide, magnesium hydroxide, zinc borate, barium sulfate and antimony trioxide.

5. The impact-resistant EPDM thermal insulation material with good adhesion according to claim 1, characterized in that: The carbon-forming component is one or a combination of two or more of carbon fiber, carbon nanotube, silicon carbide, and graphene.

6. The impact-resistant EPDM thermal insulation material with good adhesion according to claim 1, characterized in that: The plasticizer is one or a combination of two or more of liquid paraffin, dioctyl adipate, aromatic hydrocarbon oil, and naphthenic oil; and the activator is one or a combination of two or more of calcium oxide, zinc oxide, magnesium oxide, stearic acid, zinc stearate, triethanolamine, and polyethylene glycol.

7. The impact-resistant EPDM thermal insulation material with good adhesion according to claim 1, wherein: The vulcanization accelerator is one or a combination of two or more of dithiocarbonyl diamine, zinc dibenzyl dithiocarbamate, and tetrabenzyl thiuram disulfide; and the vulcanizing agent is one or a combination of two or more of sulfur, dicumyl peroxide, and bis(tert-butyl peroxyisopropyl) benzene.

8. The method of producing the impact-resistant EPDM thermal insulation material having good adhesion according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: S1. Melt all the fibers with 10-30 parts of ethylene-propylene-diene rubber to form a masterbatch; S2. Put the masterbatch into a Banbury mixer, mix well after dispersing, and then add the remaining ethylene-propylene-diene rubber, a small amount of reinforcing filler, organic and inorganic flame retardants, carbon-forming components, activators, and carbon-forming accelerators. Disperse the ethylene-propylene-diene rubber, reinforcing filler, organic and inorganic flame retardants, carbon-forming components, activators, and carbon-forming accelerators. Turn off the water cooling system of the Banbury mixer to quickly raise the temperature in the chamber and promote the rapid formation of the rubber mass. Then turn on the water cooling system to maintain slow temperature rise in the chamber. Mix the rubber mass evenly, discharge the rubber mass, and air dry to room temperature. S3. Put the material obtained in step S2 into a Banbury mixer, disperse into flocculation, and then add accelerators and vulcanizing agents. Mix them evenly in a dispersed state. Slowly form the rubber mass as the temperature in the chamber rises. Add plasticizers after 1-3 minutes of mixing. Disperse the rubber mass into flocculation again, mix evenly, and then turn off the water cooling system to quickly raise the temperature in the chamber and promote the rapid formation of the rubber mass. Then turn on the water cooling system to maintain slow temperature rise in the chamber. Mix the rubber mass evenly, discharge the rubber mass, and air dry to room temperature. Thus, the ethylene-propylene-diene rubber heat insulation material is obtained.

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