A high temperature resistant and corrosion resistant rubber material and a method of making

Abstract

The application relates to the technical field of rubber materials, and discloses a high-temperature-resistant and corrosion-resistant rubber material and a preparation method, which is formed by co-extrusion vulcanization compounding of A layer rubber and B layer rubber. The A layer rubber is used as an anti-corrosion barrier layer, and is prepared by using ethylene-propylene-diene rubber, unmodified hydrotalcite and a sulfur vulcanization system; the B layer rubber is used as a high-temperature-resistant and high-strength layer, and is prepared by using ethylene-propylene-diene rubber, zinc methacrylate, liquid reactive carrier masterbatch and a peroxide vulcanization system; the liquid reactive carrier masterbatch is in the form of dry powder and is prepared by physically adsorbing liquid maleic anhydride grafted polybutadiene on the surface of fumed silica; in the preparation process, the extrusion temperature of the B layer rubber is higher than that of the A layer rubber, and the temperature difference is used to drive the directional migration of the liquid active component to the bonding interface. The application effectively solves the problem of interface co-vulcanization difficulty of the sulfur and peroxide heterogeneous vulcanization system, and endows the rubber material with excellent interlayer peeling strength, high-temperature-resistant and aging resistance and chemical corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of rubber materials technology, specifically to a high-temperature resistant and corrosion-resistant rubber material and its preparation method. Background Technology

[0002] Rubber waterstops, as crucial waterproofing barriers at concrete deformation joints and expansion joints, are widely used in infrastructure construction such as tunnels, subways, dams, and underground utility tunnels. As engineering projects extend into deeper underground spaces and geologically complex areas, such as deep-buried long tunnels, deep-well mines, and underground engineering in geothermal active areas, their service environments exhibit characteristics of both high geothermal activity and strong corrosion. In these special environments, ambient temperatures are often maintained at high levels for extended periods (e.g., rock temperatures in some high-geothermal tunnels can reach 60-90℃), and groundwater contains high concentrations of chloride and sulfate ions. Therefore, rubber waterstop materials must possess both high-temperature aging resistance and excellent chemical corrosion resistance.

[0003] A single-formulation ethylene propylene diene monomer (EPDM) rubber cannot simultaneously meet the above stringent requirements. Traditional waterstops mostly use sulfur vulcanization systems, which have good physical and mechanical properties, high tear strength, and good barrier properties to the medium. However, in high geothermal environments, the bond energy of sulfur crosslinking bonds (polysulfide bonds) is low, making them prone to thermal decomposition or excessive crosslinking, leading to material hardening, brittleness, and even loss of waterproofing ability. While EPDM using peroxide vulcanization systems has excellent high-temperature resistance and compression set resistance, making it suitable for resisting geothermal aging, its tear resistance is relatively weak, and it is difficult to balance the flexibility required for waterproof sealing with the strength required for construction and installation when used alone.

[0004] To combine the advantages of both, high-performance waterstops can be prepared using a multi-layer composite co-extrusion process, for example, by combining an aging-resistant layer with a high-strength layer. However, when sulfur-cured and peroxide-cured rubber compounds are combined, the fundamental differences in their curing mechanisms, reaction rates, and crosslinking bond types make it difficult for the two compounds to form an effective co-crosslinking network at the interface during co-extrusion curing. This interfacial incompatibility leads to low interlayer peel strength in the waterstop, making it highly susceptible to interlayer separation under the high shear forces or hydrostatic pressure generated by tunnel settlement or slab slippage. This results in water leakage failure due to interfacial peeling, seriously threatening engineering safety.

[0005] To further enhance the mechanical properties and interfacial adhesion of the high-temperature resistant strong layer, functional liquid additives (such as liquid polybutadiene derivatives) are often added to the formulation design. These high-viscosity liquid additives are difficult to disperse in traditional open or closed rubber mixing processes, which can easily cause the rubber compound to slip and stick to the rollers. It is also difficult to accurately control their distribution in the rubber compound. If added directly, the liquid additives are often unevenly dispersed and cannot effectively accumulate at the key heterogeneous rubber compound interface to play a bridging role. This also poses a challenge to the stability of continuous production in the factory. In addition, in high-pressure groundwater environments, although traditional rubber barrier layers can block water molecules, they cannot completely block the penetration and migration of chloride ions. These penetrating chloride ions will gradually erode the internal reinforcing structure of the rubber or the metal components connected to the waterstop, undermining the integrity of the waterstop system from the inside. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a high-temperature resistant and corrosion-resistant rubber material and its preparation method. It solves the problems of difficult interfacial co-vulcanization and poor interlayer bonding when dissimilar rubber compounds of sulfur vulcanization system and peroxide vulcanization system are co-extruded. At the same time, it overcomes the problems that a single rubber compound cannot simultaneously achieve high-temperature resistance and corrosion resistance, as well as the poor dispersion uniformity of high-viscosity liquid functional additives in rubber compounding.

[0007] In a first aspect, the present invention provides a high-temperature resistant and corrosion-resistant rubber material, which adopts the following technical solution:

[0008] A high-temperature resistant and corrosion-resistant rubber material, comprising A-layer rubber compound and B-layer rubber compound through co-extrusion vulcanization compound molding, including:

[0009] Layer A, serving as an anti-corrosion barrier layer, is composed of the following components in parts by weight: 100 parts EPDM rubber; 60-70 parts quick-pressing black; 5-8 parts unmodified hydrotalcite; 10-15 parts naphthenic oil; 3-5 parts zinc oxide; 1-2 parts stearic acid; 0.5-0.8 parts insoluble sulfur; 1.8-2.3 parts vulcanization accelerator; and 0.3-0.5 parts scorch inhibitor.

[0010] Preferably, unmodified hydrotalcite is used to capture permeated chloride ions; the sulfidation accelerator is a combination of accelerator CZ and accelerator TMTD, and the amount of accelerator CZ is 1.2-1.5 parts, and the amount of accelerator TMTD is 0.6-0.8 parts.

[0011] Preferably, unmodified hydrotalcite refers to hydrotalcite whose surface and interlayer have not been coated or modified by stearic acid, oleic acid, silane coupling agent, titanate coupling agent or other organic surfactants. It retains abundant surface-active hydroxyl groups and open interlayer ion exchange channels, which can chemically react with acid anhydride groups and effectively exchange chloride ions. It is preferably a magnesium aluminum carbonate type layered bimetallic hydroxide.

[0012] Layer B, serving as a high-temperature resistant high-strength layer, is composed of the following components in parts by weight: 100 parts EPDM rubber; 20-25 parts zinc methacrylate; 20-30 parts calcined kaolin; 2-8 parts fumed silica; 7-15 parts liquid reactive carrier masterbatch; 2-4 parts high-temperature resistant pigment; 4.0-5.0 parts peroxide vulcanizing agent; 1.5-2.0 parts vulcanizing aid; and 0.5-1.0 parts antioxidant.

[0013] Preferably, the liquid reactive carrier masterbatch is formed by the adsorption of liquid maleic anhydride-grafted polybutadiene on the surface of fumed silica. During the co-extrusion process, the liquid maleic anhydride-grafted polybutadiene in the B layer compound is enriched at the interface between the A layer compound and the B layer compound.

[0014] Preferably, the peroxide vulcanizing agent is dicumyl peroxide; preferably, the vulcanizing aid is N,N'-m-phenylenebismaleimide; preferably, the antioxidant is 2,6-di-tert-butyl-4-methylphenol; preferably, the high-temperature resistant pigment is nickel antimony titanium yellow, CAS number 8007-18-9.

[0015] By adopting the above technical solution, the present invention solves the interfacial adhesion problem between the A-layer and B-layer adhesives by utilizing the physical loading and thermal release mechanism of liquid maleic anhydride-grafted polybutadiene.

[0016] On the one hand, by using fumed silica with a high specific surface area as a physical carrier, liquid maleic anhydride-grafted polybutadiene with high reactivity is adsorbed in its pore structure, protecting the liquid component from premature consumption during the mixing stage. On the other hand, under the high temperature and high shear of extrusion and vulcanization, the physical adsorption balance is broken, and the liquid maleic anhydride-grafted polybutadiene can be released from the surface of fumed silica.

[0017] On the other hand, the liquid maleic anhydride-grafted polybutadiene molecular chain contains double bonds and anhydride groups. The double bonds participate in the peroxide crosslinking reaction of the B layer rubber compound, while the anhydride groups undergo physical adsorption or chemical bonding with the polar components in the A layer rubber compound, thereby constructing a chemical transition layer between the sulfur vulcanization interface and the peroxide vulcanization interface and improving the interlayer peel strength.

[0018] By adopting the above technical solution, carbonate ions between the unmodified hydrotalcite layers can undergo ion exchange reactions with chloride ions that have penetrated into the rubber interior, fixing the chloride ions between the hydrotalcite layers and thus blocking the penetration path of corrosive media, thereby improving the material's chemical corrosion resistance. Accelerator CZ is used in conjunction with TMTD, utilizing the delayed-action properties of CZ to balance the rapid reaction characteristics of TMTD, ensuring both vulcanization efficiency and preventing scorching of the A-layer compound during extrusion.

[0019] By adopting the above technical solution, zinc methacrylate is polymerized in situ under the initiation of peroxide to generate polyzinc methacrylate or grafted onto the molecular chain of EPDM rubber to form an ionic cluster cross-linked structure. This ionic bond has better thermal stability than ordinary sulfur bond, giving the B layer rubber compound excellent heat aging resistance and high temperature modulus.

[0020] Preferably, the liquid reactive carrier masterbatch is in the form of a clump-free dry powder, wherein the mass ratio of liquid maleic anhydride-grafted polybutadiene to fumed silica is 1:(2.5-4).

[0021] By adopting the above technical solution and controlling the liquid-solid ratio within this range, it is possible to ensure that the fumed silica fully adsorbs the liquid components, prevent the masterbatch from clumping or seeping oil, and at the same time ensure that the masterbatch contains a sufficient amount of high-concentration active components per unit weight, providing a material basis for subsequent interfacial thickening.

[0022] Secondly, this invention provides a method for preparing a high-temperature resistant and corrosion-resistant rubber material, employing the following technical solution:

[0023] A method for preparing the above-mentioned high-temperature resistant and corrosion-resistant rubber material includes the following steps:

[0024] S1. After mixing EPDM rubber, unmodified hydrotalcite, zinc oxide and stearic acid, add fast extrusion black and naphthenic oil, continue mixing and discharge the rubber, and after cooling, add insoluble sulfur, vulcanization accelerator and anti-scorching agent for thin-passing to obtain layer A rubber compound.

[0025] S2. After mixing EPDM rubber, zinc methacrylate, calcined kaolin, high-temperature resistant pigment and fumed silica, add liquid reactive carrier masterbatch, mix and discharge the mixture, and after cooling, add peroxide vulcanizing agent, vulcanizing aid and antioxidant for thin-passing to obtain layer B rubber compound.

[0026] S3. Add the A-layer rubber compound obtained in step S1 and the B-layer rubber compound obtained in step S2 into the two barrels of the double compound extruder, and extrude them together at the compounding head to obtain a rubber strip;

[0027] S4. The rubber strips obtained in step S3 are vulcanized sequentially through a microwave vulcanization section and a hot air vulcanization section to obtain the finished product.

[0028] Preferably, during the process of adding the A-layer rubber compound and the B-layer rubber compound to the two barrels of the twin compound extruder, the temperature of the metering zone of the A-layer rubber compound extruder barrel is controlled at 70-80℃, and the temperature of the B-layer rubber compound extruder barrel metering zone is controlled at 95-105℃.

[0029] By adopting the above technical solution, this invention utilizes a non-isothermal field to induce the directional migration of active components. By setting the extrusion temperature of the B layer rubber compound to be higher than that of the A layer rubber compound, the matrix viscosity of the B layer rubber compound at the die head junction decreases, and the thermal motion of the liquid maleic anhydride-grafted polybutadiene molecules inside it intensifies. Under the combined drive of the shear flow field and temperature gradient, the liquid maleic anhydride-grafted polybutadiene spontaneously migrates to the phase interface with a higher shear rate and lower flow resistance. During the subsequent vulcanization process, it reacts with the rubber compounds on both sides, thereby achieving the bonding of the A layer rubber compound and the B layer rubber compound.

[0030] Preferably, the pre-preparation method of the liquid reactive carrier masterbatch is as follows: fumed silica is put into a high-speed mixer, heated to 55℃-65℃, and stirred at a speed of 750-850 rpm. Liquid maleic anhydride grafted polybutadiene, preheated to 55℃-65℃, is sprayed onto the surface of fumed silica through an atomizing nozzle. After spraying, the speed is increased to 1000-1500 rpm, and mixing continues for 3-8 minutes. The liquid components are physically adsorbed and dispersed by shear force. After cooling, a dry powder masterbatch is obtained.

[0031] By adopting the above technical solution, the process of combining heated spraying with variable frequency high-speed shearing reduces the viscosity of the liquid component, making it easier to penetrate into the nanoscale pores of fumed silica. The high-speed shearing force breaks up the agglomerates, ensuring that the liquid component is uniformly coated on the carrier surface at the microscale, forming a stable dry powder system.

[0032] Preferably, in step S1, the glue discharge temperature is 145-150℃.

[0033] Preferably, in step S2, the glue discharge temperature is 120-130℃.

[0034] By adopting the above technical solution, the A layer rubber compound is a sulfur system, and the higher discharge temperature is beneficial to the dispersion of fillers and the plasticization of raw rubber; the B layer rubber compound contains highly reactive liquid reactive carrier masterbatch and zinc methacrylate, and controlling the lower discharge temperature can effectively prevent the active groups from pre-crosslinking during the mixing stage, and retain their reactivity until the extrusion vulcanization stage.

[0035] Preferably, in step S3, the temperature of the microwave vulcanization section is 140-160℃ and the time is 60-90 s; the temperature of the hot air vulcanization section is 170-180℃ and the time is 10-15 min.

[0036] This invention provides a high-temperature resistant and corrosion-resistant rubber material and its preparation method, which has the following beneficial effects:

[0037] 1. This invention solves the problem of difficult interfacial co-vulcanization between sulfur vulcanization and peroxide vulcanization systems by introducing a liquid reactive carrier masterbatch and combining it with a non-isothermal co-extrusion process. The temperature gradient drives the accumulation of liquid maleic anhydride-grafted polybutadiene in the B-layer rubber compound at the interface. After the release of this active component, the double bonds on its molecular chain participate in the peroxide crosslinking of the B-layer rubber compound, and the anhydride groups bond with the polar components of the A-layer rubber compound, forming a chemical bond at the interface and improving the adhesion strength between the A-layer and B-layer rubber compounds.

[0038] 2. This invention employs a functionally layered composite structure, effectively balancing the dual performance requirements of high-temperature resistance and corrosion resistance. Layer A acts as a barrier layer, utilizing the interlayer ion exchange characteristics of unmodified hydrotalcite to capture permeated chloride ions and block the inward diffusion of corrosive media. Layer B acts as a reinforcing layer, employing a zinc methacrylate-peroxide vulcanization system. The in-situ generated ion cluster cross-linking structure endows the material with excellent high-temperature modulus and heat aging resistance, thereby enabling the overall material to maintain long-term service stability under high-temperature and corrosive media conditions.

[0039] 3. The liquid reactive carrier masterbatch technology provided by this invention improves the processability of high-viscosity liquid additives. By physically adsorbing the liquid components onto the surface of fumed silica and converting them into dry powder, the sticking to rollers and uneven dispersion phenomena caused by direct addition of traditional liquid additives are avoided, ensuring accurate metering and uniform distribution of active components. Combined with microwave and hot air segmented vulcanization processes, the rubber compound is heated evenly inside and out, effectively avoiding defects such as incomplete vulcanization or appearance deformation in thick-walled products, and improving the dimensional accuracy and physical property consistency of finished products. Attached Figure Description

[0040] Figure 1 This is a comparison diagram of the interfacial peel strength at room temperature and high temperature of the present invention;

[0041] Figure 2 This is a graph showing the thermal stability retention rate of the interfacial bonding strength in this invention.

[0042] Figure 3 This is a graph showing the change in interfacial bonding strength under non-isothermal conditions according to the present invention;

[0043] Figure 4 This is a characterization diagram of the interfacial crosslinking density of the present invention. Detailed Implementation

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the preparation examples, examples, comparative examples, and test examples. 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.

[0045] Preparation Example 1:

[0046] This preparation example provides a method for preparing a liquid reactive carrier masterbatch. Based on the principle of porous adsorption, the masterbatch utilizes the physical adsorption of fumed silica to convert the liquid component into a dry powder form. In this preparation example, the mass ratio of liquid maleic anhydride-grafted polybutadiene to fumed silica is 1:3. The specific preparation steps are as follows:

[0047] (1) 300 parts by weight of fumed silica are put into a high-speed mixer with a heating jacket and a spray device. The stirring paddle is started and the speed is set to 800 rpm. At the same time, hot water is introduced into the jacket to heat the material in the mixing chamber and maintain the temperature at 60°C, so that the fumed silica is fluidized and preheated.

[0048] (2) 100 parts by weight of liquid maleic anhydride grafted polybutadiene is preheated to 60°C to reduce viscosity, and then pumped into the atomizing nozzle through a metering pump to atomize the liquid into micron-sized droplets and sprayed evenly onto the surface of high-speed rotating fumed silica powder at a suitable flow rate.

[0049] (3) After spraying, increase the stirring speed to 1200 rpm and continue mixing for 5 min. Use the shear force generated by the high speed to break the droplet aggregation, and promote the liquid maleic anhydride grafted polybutadiene to be physically adsorbed and locked by the pore depth of the gas phase silica surface through capillary action to form a coating structure.

[0050] (4) Stop stirring, discharge the material, and allow it to cool naturally to room temperature. After inspection, it is confirmed to be a free-flowing white dry powder without lumps. Seal and package it for later use.

[0051] Preparation Example 2:

[0052] This preparation example provides a method for preparing a liquid reactive carrier masterbatch, which differs from Preparation Example 1 only in the ratio of raw materials. In this preparation example, the mass ratio of liquid maleic anhydride-grafted polybutadiene to fumed silica is 1:2.5. The specific preparation steps are as follows:

[0053] (1) 250 parts by weight of fumed silica were put into a high-speed mixer, the speed was set to 800 rpm, and the material temperature was controlled to 60℃.

[0054] (2) 100 parts by weight of preheated liquid maleic anhydride grafted polybutadiene are evenly sprayed onto the surface of fumed silica through an atomizing nozzle.

[0055] (3) After spraying, increase the speed to 1500 rpm and continue mixing for 8 minutes to ensure that the material remains dry and dispersed under a high liquid-solid ratio by using high shear force.

[0056] (4) Discharge, cool, and seal for later use.

[0057] Preparation Example 3:

[0058] This preparation example provides a method for preparing a liquid reactive carrier masterbatch, which differs from Preparation Example 1 only in the ratio of raw materials. In this preparation example, the mass ratio of liquid maleic anhydride-grafted polybutadiene to fumed silica is 1:4. The specific preparation steps are as follows:

[0059] (1) 400 parts by weight of fumed silica were put into a high-speed mixer, the speed was set to 800 rpm, and the material temperature was controlled at 60℃;

[0060] (2) 100 parts by weight of preheated liquid maleic anhydride grafted polybutadiene are evenly sprayed onto the surface of fumed silica through an atomizing nozzle.

[0061] (3) After spraying, increase the rotation speed to 1000 rpm and continue mixing for 3 minutes;

[0062] (4) Discharge, cool, and seal for later use.

[0063] Example 1:

[0064] This embodiment provides a high-temperature resistant and corrosion-resistant rubber material and its preparation method. The rubber material is formed by co-extrusion and vulcanization of layer A and layer B rubber.

[0065] Layer A is composed of the following components in parts by weight: 100 parts EPDM rubber; 65 parts fast-pressing black N550; 6 parts unmodified hydrotalcite; 15 parts naphthenic oil; 4 parts zinc oxide; 1.5 parts stearic acid; 0.6 parts insoluble sulfur; 2.1 parts vulcanization accelerator (specifically composed of 1.4 parts accelerator CZ and 0.7 parts accelerator TMTD) and 0.4 parts scorch inhibitor.

[0066] Among them, unmodified hydrotalcite refers to hydrotalcite whose surface and interlayer have not been coated or modified by stearic acid, oleic acid, silane coupling agent, titanate coupling agent or other organic surfactants, preferably magnesium aluminum carbonate type layered bimetallic hydroxide.

[0067] Layer B is composed of the following components in parts by weight: 100 parts EPDM rubber; 22 parts zinc methacrylate (ZDMA); 25 parts calcined kaolin; 5 parts fumed silica; 12 parts liquid reactive carrier masterbatch obtained in Preparation Example 1; 3 parts high-temperature resistant pigment; 4.5 parts peroxide vulcanizing agent (specifically dicumyl peroxide, DCP); 1.8 parts vulcanizing aid (specifically N,N'-m-phenylenebismaleimide, HVA-2); and 0.8 parts antioxidant (specifically 2,6-di-tert-butyl-4-methylphenol, BHT).

[0068] The preparation method includes the following steps:

[0069] (1) A layer rubber compound mixing: Add EPDM rubber, unmodified hydrotalcite, zinc oxide and stearic acid from the A layer rubber compound formula to the internal mixer and mix at 65 rpm for 90 s; add fast extrusion black N550 and naphthenic oil, and continue mixing until the rubber is discharged at 145℃; after cooling, add insoluble sulfur, accelerator CZ, accelerator TMTD and anti-scorching agent on the open mill, roll temperature 55℃, pass through the thin mill 5 times and then stop the sheet;

[0070] (2) B-layer rubber compound mixing: Add EPDM rubber, ZDMA, calcined kaolin, fumed silica and high-temperature resistant pigments from the B-layer rubber compound formula to a mixer and mix at 45 rpm for 60 s; add the liquid reactive carrier masterbatch obtained in Preparation Example 1 and continue mixing until the rubber is discharged at 125°C; after cooling, add DCP, HVA-2 and BHT to the open mill, control the roller temperature at 45°C, and after passing through the mill 5 times, the sheet is removed and left to rest.

[0071] (3) Co-extrusion molding: A double compound extruder is used to merge and extrude at the compound die head to obtain a rubber strip. The temperature of the metering zone of the A layer extruder barrel is set to 80℃ and the temperature of the metering zone of the B layer extruder barrel is set to 100℃.

[0072] (4) Vulcanization: The extruded rubber strip enters the microwave vulcanization section at a temperature of 150°C for 90 seconds; then it enters the hot air vulcanization section at a temperature of 170°C for 12 minutes to obtain the finished product.

[0073] Example 2:

[0074] This embodiment provides a high-temperature resistant and corrosion-resistant rubber material and its preparation method. The rubber material is formed by co-extrusion and vulcanization of layer A and layer B rubber.

[0075] Layer A is composed of the following components in parts by weight: 100 parts EPDM rubber; 60 parts fast-pressing black N550; 5 parts unmodified hydrotalcite; 10 parts naphthenic oil; 3 parts zinc oxide; 1 part stearic acid; 0.5 parts insoluble sulfur; 1.8 parts vulcanization accelerator (specifically composed of 1.2 parts accelerator CZ and 0.6 parts accelerator TMTD) and 0.3 parts scorch inhibitor.

[0076] Layer B is composed of the following components in parts by weight: 100 parts EPDM rubber; 20 parts zinc methacrylate (ZDMA); 20 parts calcined kaolin; 8 parts fumed silica; 7 parts liquid reactive carrier masterbatch obtained in Preparation Example 2; 2 parts high-temperature resistant pigment; 4.0 parts peroxide vulcanizing agent (specifically dicumyl peroxide, DCP); 1.5 parts vulcanizing aid (specifically N,N'-m-phenylenebismaleimide, HVA-2); and 0.5 parts antioxidant (specifically 2,6-di-tert-butyl-4-methylphenol, BHT).

[0077] The preparation method includes the following steps:

[0078] (1) A layer rubber compound mixing: The difference from Example 1 is that the discharge temperature is controlled at 145℃;

[0079] (2) B layer rubber compound mixing: The difference from Example 1 is that the discharge temperature is controlled at 120℃;

[0080] (3) Co-extrusion molding: The difference from Example 1 is that the temperature of the metering zone of the extruder barrel of the A layer rubber compound is 75°C, and the temperature of the metering zone of the extruder barrel of the B layer rubber compound is 95°C.

[0081] (4) Vulcanization: The difference from Example 1 is that the microwave vulcanization section temperature is 140℃ and the time is 90 s; the hot air vulcanization section temperature is 170℃ and the time is 15 min.

[0082] Example 3:

[0083] This embodiment provides a high-temperature resistant and corrosion-resistant rubber material and its preparation method. The rubber material is formed by co-extrusion and vulcanization of layer A and layer B rubber.

[0084] Layer A is composed of the following components in parts by weight: 100 parts EPDM rubber; 70 parts fast-pressing black N550; 8 parts unmodified hydrotalcite; 15 parts naphthenic oil; 5 parts zinc oxide; 2 parts stearic acid; 0.8 parts insoluble sulfur; 2.3 parts vulcanization accelerator (specifically composed of 1.5 parts accelerator CZ and 0.8 parts accelerator TMTD) and 0.5 parts scorch inhibitor.

[0085] Layer B is composed of the following components in parts by weight: 100 parts EPDM rubber; 25 parts zinc methacrylate (ZDMA); 30 parts calcined kaolin; 2 parts fumed silica; 15 parts liquid reactive carrier masterbatch obtained in Preparation Example 3; 4 parts high-temperature resistant pigment; 5.0 parts peroxide vulcanizing agent (specifically dicumyl peroxide, DCP); 2.0 parts vulcanizing aid (specifically N,N'-m-phenylenebismaleimide, HVA-2); and 1.0 part antioxidant (specifically 2,6-di-tert-butyl-4-methylphenol, BHT).

[0086] The preparation method includes the following steps:

[0087] (1) A layer rubber compound mixing: The difference from Example 1 is that the discharge temperature is controlled at 150℃;

[0088] (2) B layer rubber compound mixing: The difference from Example 1 is that the discharge temperature is controlled at 130℃;

[0089] (3) Co-extrusion molding: The difference from Example 1 is that the temperature of the metering zone of the extruder barrel in layer A is 80°C, and the temperature of the metering zone of the extruder barrel in layer B is 105°C.

[0090] (4) Vulcanization: The difference from Example 1 is that the microwave vulcanization section is 160°C for 60 s and the hot air vulcanization section is 180°C for 10 min.

[0091] Example 4:

[0092] This embodiment provides a high-temperature resistant and corrosion-resistant rubber material and its preparation method. The formulation is exactly the same as that in Example 1, and the preparation method includes the following steps:

[0093] (1) A layer rubber compound mixing: Same as in Example 1;

[0094] (2) B-layer rubber compound mixing: Same as in Example 1;

[0095] (3) Co-extrusion molding: The difference from Example 1 is that the temperature of the metering zone of the extruder barrel of layer A is set to 70°C and the temperature of the metering zone of the extruder barrel of layer B is set to 95°C.

[0096] (4) Vulcanization: Same as in Example 1.

[0097] Example 5:

[0098] This embodiment provides a high-temperature resistant and corrosion-resistant rubber material and its preparation method. The formulation is exactly the same as that in Example 1, and the preparation method includes the following steps:

[0099] (1) A layer rubber compound mixing: Same as in Example 1;

[0100] (2) B-layer rubber compound mixing: Same as in Example 1;

[0101] (3) Co-extrusion molding: The difference from Example 1 is that the temperature of the metering zone of the extruder barrel of layer A is set to 80°C and the temperature of the metering zone of the extruder barrel of layer B is set to 105°C.

[0102] (4) Vulcanization: Same as in Example 1.

[0103] Comparative Example 1:

[0104] Compared with Example 1, the difference is that 6 parts of unmodified hydrotalcite in the A layer compound formulation are replaced with an equal amount of stearic acid surface-modified hydrotalcite (surface-active hydroxyl groups are blocked), and the rest are the same.

[0105] Comparative Example 2:

[0106] Compared with Example 1, the difference is that the liquid reactive carrier masterbatch obtained in Preparation Example 1 is not used in the B layer rubber compound formulation. Instead, 9 parts of fumed silica and 3 parts of solid maleic anhydride-grafted EPDM rubber (grafting rate 1.0 wt%) are added directly to replace the liquid maleic anhydride-grafted polybutadiene. All other aspects are the same.

[0107] Comparative Example 3:

[0108] Compared to Example 1, the difference is that the B layer compound formulation does not contain 1.8 parts of N,N'-m-phenylenebismaleimide (HVA-2), while all other aspects are the same.

[0109] Comparative Example 4:

[0110] Compared with Example 1, the difference is that in step (3) of the preparation method, the temperature of the metering zone of the B-layer extruder barrel is set to 80°C.

[0111] Comparative Example 5:

[0112] Compared with Example 1, the difference is that the B layer rubber compound formulation does not contain 22 parts of zinc methacrylate (ZDMA), but is replaced with 30 parts of fast-pressing black N550, and the vulcanization system is changed to the same sulfur vulcanization system as the A layer.

[0113] Comparative Example 6:

[0114] Compared with Example 1, the difference is that the B layer adhesive formulation does not contain 12 parts of liquid reactive carrier masterbatch, but only 9 parts of fumed silica are added.

[0115] Test Example 1:

[0116] refer to Figure 1 and Figure 2 This test case compares the interfacial peel strength under normal temperature and high temperature environments.

[0117] Experimental steps:

[0118] The co-extruded vulcanized rubber strips prepared in Example 1, Comparative Example 2 and Comparative Example 6 were selected as test objects. Long strips with a width of 25.0 mm and a length of 150 mm were cut, and 50 mm non-adhesive areas were reserved at both ends of the sample for clamping. Five parallel samples were prepared for each formulation.

[0119] The sample was conditioned in a standard laboratory environment for 24 hours to eliminate internal stress during the preparation process.

[0120] The test was conducted according to the T-peel method specified in GB / T 532-2008 "Determination of Adhesion Strength between Vulcanized Rubber or Thermoplastic Rubber and Fabric".

[0121] First, a peel strength test was conducted at an ambient temperature of 23℃ with a tensile speed of 100 mm / min. The average force value of the sample within the effective peel length at 23℃ was recorded, and the peel strength was calculated.

[0122] Subsequently, a hot peel test was performed. The ambient temperature was raised to 120°C and held for 30 minutes. The sample was clamped in a fixture and preheated at 120°C for 10 minutes to ensure the temperature balance inside and outside the sample. The tensile program was started while maintaining the ambient temperature at 120°C, and the tensile speed was maintained at 100 mm / min. The average force value and the characteristics of the fracture surface (interfacial failure or cohesive failure) were recorded.

[0123] High temperature retention rate = (peel strength at 120℃ / peel strength at 23℃) × 100%.

[0124] The test data is shown in Table 1.

[0125] Table 1 Peel strength and high temperature retention

[0126] Sample number Peel strength at 23℃ (N / mm) Peel strength at 120℃ (N / mm) High-temperature retention rate (%) Damage mode (120℃) Example 1 8.42 5.76 68.4 B-layer bulk cracking (cohesive failure) Comparative Example 2 4.15 0.68 16.4 Interface flat separation Comparative Example 6 1.83 0.21 11.5 Interface flat separation

[0127] As shown in Table 1, although the values ​​of Example 1 decreased at high temperatures, its high-temperature retention rate was relatively high. The peel strength at 120°C of Comparative Examples 2 and 6 decreased significantly, indicating that their interface connection failed catastrophically at high temperatures. This proves that it is impossible to build a heat-resistant interface by relying solely on physical diffusion (Comparative Example 6) or restricted solid grafting (Comparative Example 2), while the chemical bonding mechanism of Example 1 successfully constructed a high-temperature resistant molecular solder joint.

[0128] Based on the data in Table 1, the interface mechanism of this technical solution can be inferred as follows:

[0129] Figure 1In Example 1, the fracture surface at 120°C showed cohesive failure of the B-layer rubber compound, strongly supporting the formation of interfacial chemical bonds. In contrast, in Comparative Example 6, due to the lack of active carriers and reactive groups, the interlayer bonding mainly relied on the physical diffusion of molecular chains during vulcanization. This physical entanglement is more sensitive to temperature, as shown in... Figure 1 As shown, when the temperature rises to 120℃, the thermal motion of polymer chain segments intensifies, leading to deentanglement and instantaneous loss of interfacial strength (only 0.21 N / mm). Figure 2 The relatively low high-temperature retention rate is clear evidence of physical connection failure. Although solid grafted polymers were introduced in Comparative Example 2, the high density of connection points could not be established due to the difficulty of solid macromolecules migrating in the melt and the lack of liquid carrier wetting. As a result, its mechanical behavior at high temperature showed similar failure characteristics to Comparative Example 6.

[0130] The reason why Example 1 can be achieved Figure 2 The high retention rate shown is primarily due to the directional migration of liquid maleic anhydride-grafted polybutadiene during the non-isothermal co-extrusion process. During the initial vulcanization phase, the anhydride groups enriched at the interface undergo ring-opening esterification with the hydroxyl groups on the surface of the unmodified hydrotalcite in layer A, forming ester bonds with excellent heat resistance. Simultaneously, the double bonds of the liquid polybutadiene backbone participate in the cross-linking network on both sides. This chemical bonding, with bond energy exceeding that of intermolecular forces, does not break due to chain segment relaxation at 120°C, thus maintaining high interfacial strength.

[0131] Test Example 2:

[0132] refer to Figure 3 and Figure 4 This test example examines the interfacial physical and mechanical properties and solvent swelling behavior of samples under different temperature differences.

[0133] Experimental steps:

[0134] The vulcanized rubber strips of Example 1, Example 4, Example 5 and Comparative Example 4 were selected as test objects.

[0135] T-type peel test specimens were prepared according to GB / T 532-2008 "Determination of Adhesion Strength between Vulcanized Rubber or Thermoplastic Rubber and Fabric". Five specimens were taken from each group and the peel strength was tested at 23℃. The average peel force was recorded.

[0136] The crosslinking density of the interface layer was characterized by the swelling method. In accordance with GB / T 2941-2006 "General Procedures for Sample Preparation and Conditioning of Rubber Physical Test Methods", a precision slicer was used to prepare thin sheet samples with a thickness of 0.5±0.05 mm at the interface of each group of samples.

[0137] Referring to the immersion weighing method in GB / T 1690-2010 "Determination of Liquid Resistance of Vulcanized Rubber or Thermoplastic Rubber", accurately weigh the initial mass (m0) of the sample and completely immerse it in excess toluene solvent. Immerse it in a constant temperature environment of 23±2 ℃ in the dark for 72 h until swelling equilibrium is reached. Remove the sample, quickly blot off the residual solvent on the surface with filter paper, and immediately place it in a weighing bottle to weigh the swollen mass (m1). Calculate the mass swelling rate Q according to the formula Q=(m1-m0) / m0×100%. The swelling rate is negatively correlated with the crosslinking density; that is, the more active components participate in the reaction and the denser the network, the lower the swelling rate.

[0138] The test data is shown in Table 2.

[0139] Table 2. Interfacial properties and swelling data under different extrusion temperature differences

[0140] Sample number B-layer rubber compound extrusion temperature (°C) Temperature difference (ΔT ℃) Peel strength (N / mm) Mass swelling rate Q (%) Comparative Example 4 80 0 3.42 365.2 Example 4 95 25 6.18 288.4 Example 1 100 20 8.35 232.1 Example 5 105 25 8.67 224.8

[0141] By comparing the test data of Comparative Example 4, Example 4, Example 1 and Example 5, it can be found that as the extrusion temperature of the B layer rubber compound gradually increases and the temperature gradient between the A layer rubber compound and the B layer rubber compound is established, the interfacial peel strength shows an obvious upward trend. Its value increases from 3.42 N / mm during isothermal extrusion in Comparative Example 4 to 8.67 N / mm in Example 5.

[0142] Based on the data in Table 2, the mechanism of action of this technical solution is speculated as follows: Due to the high temperature and strong shear of the B layer rubber, the physical adsorption equilibrium on the surface of the fumed silica is broken, and the liquid maleic anhydride-grafted polybutadiene undergoes forced desorption. Its viscosity is much lower than that of the highly filled EPDM matrix in the B layer, which can form an immiscible system of high viscosity matrix and low viscosity dispersed phase in the flow field. In the co-extrusion channel, the low viscosity component will spontaneously migrate to the region with the highest shear rate (i.e., the channel wall or the interface between the two phases) to form a lubricating layer to reduce the frictional resistance of the overall flow. Therefore, the liquid maleic anhydride-grafted polybutadiene tends to precipitate outward from the B layer bulk. When liquid maleic anhydride-grafted polybutadiene migrates to the interface between layer A and layer B, the low temperature, high viscosity, and restricted molecular chain movement of layer A prevent the liquid maleic anhydride-grafted polybutadiene from quickly penetrating deep into layer A. Its diffusion coefficient decreases abruptly at the interface, which acts as a cold wall. This freezes and intercepts the continuously flowing liquid maleic anhydride-grafted polybutadiene from layer B, forcing it to accumulate and form a micron-thick enrichment layer. The unmodified hydrotalcite dispersed in layer A contains a large number of surface polar hydroxyl groups, while the migrating liquid rubber carries highly reactive anhydride groups. The thermodynamic affinity between these strong polar groups further induces directional adsorption of liquid molecules at the interface, anchoring them to the hydrotalcite surface and preventing lateral loss under extrusion pressure. Ultimately, under the synergistic effect of rheological migration, thermal barrier effect and chemical affinity, the active components released by the liquid reactive carrier masterbatch are precisely enriched at a high concentration at the interface between layer A and layer B, thus constructing a pre-reactive interface layer.

[0143] Will Figure 4 and Figure 3 The combined analysis shows that the downward slope of the swelling rate curve and the upward trend of the peel strength histogram are highly negatively correlated. This confirms at the microscopic level that with the enhancement of the non-isothermal driving force, more liquid active molecules are enriched and cross-linked at the interface, thereby reducing the swelling rate and improving the macroscopic strength.

[0144] Based on the data in Table 2 and Figure 3 , Figure 4 The test results are analyzed as follows: The temperature gradient in the extrusion process is a key variable determining the interfacial properties, which is evident in... Figure 3 This is reflected in the step-like growth trend. Comparative Example 4, using isothermal co-extrusion, lacks the thermodynamic potential energy to drive the directional movement of liquid components, resulting in random distribution of active molecules, low interfacial reaction rate, and simultaneously... Figure 4 The point corresponding to the highest swelling rate indicates that the interface network is relatively loose.

[0145] Comparing Examples 4 and 1 to 5, it is evident that the increase in the extrusion temperature of layer B and the temperature difference between layers A and B have a decisive impact on interfacial properties. While the temperature difference driving force is enhanced, Figure 3 The peel strength value in the middle increased significantly, while Figure 4 The swelling rate data showed a synchronous decrease, confirming that the enrichment of liquid maleic anhydride-grafted polybutadiene effectively improved the interfacial crosslinking density. Under the dual effects of shear flow field and temperature gradient, the low-viscosity liquid maleic anhydride-grafted polybutadiene, utilizing its temperature-sensitive viscosity characteristics, directionally migrated from the high-temperature, high-shear B-layer of the compound to the relatively low-temperature, low-shear interfacial region, resulting in the enrichment of a large number of active molecules at the interface. The data from Example 1 and Example 5 are similar, indicating that the migration efficiency tends to saturate after reaching a certain temperature threshold, demonstrating that the process has good process performance while ensuring high performance.

[0146] Test Example 3:

[0147] This test case examines the bonding stability of the interface between layer A and layer B of the rubber compound after undergoing a harsh thermo-oxidative aging environment.

[0148] Experimental steps:

[0149] The co-extruded vulcanized products prepared in Examples 1-5 and Comparative Examples 1-6 were selected, and T-type peel test specimens conforming to the requirements of GB / T 532-2008 "Determination of Adhesion Strength between Vulcanized Rubber or Thermoplastic Rubber and Fabrics" were cut. Ten parallel specimens were prepared for each formulation, of which 5 were used for initial performance testing and 5 were used for post-aging testing.

[0150] After the initial group of samples were conditioned for 24 hours under standard conditions, a tensile testing machine was used to perform a peel test at a speed of 100 mm / min, and the average value of the initial peel strength and the failure mode were recorded.

[0151] Referring to GB / T 3512 "Accelerated Aging and Heat Resistance Test of Vulcanized Rubber or Thermoplastic Rubber in Hot Air", the aged samples were suspended in a forced-ventilation thermal aging chamber, and the aging conditions were set at 150℃ for 168 h to simulate the degradation of materials under long-term high-temperature service.

[0152] After the aging cycle is completed, the sample is taken out and allowed to cool in a standard environment for 24 hours. The aged sample is then subjected to a peel test at a tensile speed of 100 mm / min, and the peel strength after aging is recorded.

[0153] Calculate the strength retention rate and observe the failure mode after aging.

[0154] The test data is shown in Table 3.

[0155] Table 3 Comparison of peel strength of each group of samples before and after hot air aging

[0156] Sample number Initial peel strength (N / mm) Peel strength after aging (150℃×168 h) (N / mm) Strength retention rate (%) Post-aging damage modes Example 1 8.42 6.15 73.0 B-layer cohesion failure Example 2 7.85 5.43 69.2 B-layer cohesion failure Example 3 8.91 6.58 73.8 B-layer cohesion failure Example 4 6.18 4.02 65.0 Hybrid destruction (partial interface) Example 5 8.67 6.24 72.0 B-layer cohesion failure Comparative Example 1 5.23 1.84 35.2 Interface flat separation Comparative Example 3 3.12 0.45 14.4 Interface flat separation Comparative Example 5 8.10 3.89 48.0 B-layer hardening brittle fracture Comparative Example 6 1.83 0.15 8.2 Interface flat separation

[0157] As shown in Table 3, after aging at 150℃ for 168 h, the peel strength of Examples 1-3 and Example 5 remained above 5.4 N / mm, and the failure mode was cohesive failure of the B layer. This indicates that the interfacial bonding strength was always higher than the strength of the rubber body, and the interfacial structure showed high stability in a thermo-oxidative environment.

[0158] Comparative Example 1 used stearic acid-modified hydrotalcite, whose surface active hydroxyl groups were covered and blocked by organic molecules. Although the initial peel strength (5.23 N / mm) was acceptable, it quickly dropped to 1.84 N / mm after aging, with a retention rate of only 35.2%, indicating that the interface only had physical adsorption and could not resist the thermal motion of molecular chains and oxidative degradation at high temperatures.

[0159] Comparative Example 3 almost completely lost its adhesiveness after aging. This is because HVA-2, through a two-way reaction, participates in peroxide crosslinking on one end and connects to the sulfur vulcanization network through Michael addition on the other end, thereby establishing continuous chemical bonds at the interface.

[0160] Although Comparative Example 5 had a high initial strength, it had a low aging retention rate and the failure mode was hardening brittle fracture. This is because the B layer of the comparative example does not contain ZDMA. The heat resistance of the polysulfide bonds is much lower than that of the ionic bonds and carbon-carbon crosslinking bonds formed by ZDMA, which causes the rubber compound to undergo crosslinking hardening and chain breakage after high-temperature aging, thus losing its ability to absorb stress as an elastic transition layer.

[0161] In summary, Example 1, through the synergistic effect of unmodified hydrotalcite, HVA-2, and the ZDMA / DCP system, constructed a stable interface that can resist high-temperature thermo-oxidative aging and maintain high bonding strength.

[0162] Test Example 4:

[0163] This test case demonstrates the resilience and hardness stability of the B-layer compound at high temperatures.

[0164] Experimental steps:

[0165] Uncured compound was prepared separately on a two-roll mill according to the formulations of layer B rubber in Example 1 and Comparative Example 5.

[0166] Referring to GB / T 7759.1-2015 "Determination of compression set of vulcanized rubber or thermoplastic rubber - Part 1: Under normal and high temperature conditions", the compound was molded and vulcanized into a type B cylindrical sample with a diameter of 29.0 mm and a thickness of 12.5 mm using a flat vulcanizing machine. The vulcanization conditions were set to 170℃ × 15 min.

[0167] Select a standard compression clamp and limiter to compress the sample to 75% of its original height (i.e., a compression rate of 25%), tighten the bolts, and then place it in a high-temperature aging chamber.

[0168] Two sets of test conditions were set: the first set was 150℃×24 h, simulating a conventional high-temperature environment; the second set was 175℃×24 h, simulating an extreme overheating environment. Three parallel specimens were tested under each set of conditions. After the test, the clamps were immediately removed from the aging chamber, the bolts were loosened, and the specimens were placed on a wooden board and allowed to recover freely for 30 minutes under standard laboratory conditions. The center height of the specimens after recovery was measured using a thickness gauge, and the compression set was calculated.

[0169] The hardness test was conducted according to GB / T 531.1-2008 "Test Method for Indentation Hardness of Vulcanized Rubber or Thermoplastic Rubber - Part 1: Shore Hardness Tester Method (Shore Hardness)". First, the hardness at 23℃ was tested; then, the sample was preheated in a 150℃ oven for 30 min, quickly removed, and the hot hardness reading was completed within 5 s, recording the hardness change.

[0170] The test data is shown in Table 4.

[0171] Table 4. High-Temperature Compression Permanent Deformation and Hardness Data of Layer B Rubber Compound

[0172] Sample source Compression set (150℃×24h) (%) Compression set (175℃×24h) (%) 23℃ hardness 150℃ hardness Hardness difference (ΔH) Example 1 (Layer B) 16.2 28.7 73 68 -5 Comparative Example 5 (Layer B) 54.8 81.3 71 52 -19

[0173] As shown in Table 4, the ZDMA / peroxide system represented by Example 1 outperforms the sulfur / carbon black system of Comparative Example 5 in terms of high-temperature resilience. Under the test conditions of 150℃×24 h, the compression set of Example 1 was only 16.2%, indicating that the material retained excellent elasticity under long-term pressure and high temperature. In contrast, the compression set of Comparative Example 5 was as high as 54.8%, indicating that the internal cross-linking network of the material had been damaged and could not be effectively restored. When the temperature was further increased to 175℃, the compression set of Comparative Example 5 reached 81.3%, losing its function as an elastic sealing material, while Example 1 still controlled at 28.7%, showing better resistance to extreme high temperatures.

[0174] Example 1 shows that the hardness at 150℃ is only 5 Shore A less than that at 23℃, exhibiting hot hardness; while Comparative Example 5 shows that the hardness at 150℃ is 19 Shore A less than that at 23℃, exhibiting obvious hot softening.

[0175] The aforementioned performance differences stem from fundamentally different microscopic crosslinking structures. Comparative Example 5 uses a traditional sulfur vulcanization system, resulting in polysulfide bonds with low bond energies (approximately 270 kJ / mol). These bonds are prone to thermal decomposition and network rearrangement above 150°C, leading to irreversible plastic deformation. Example 1 utilizes DCP-initiated in-situ polymerization of ZDMA to construct high-energy carbon-carbon bonds (approximately 350 kJ / mol) as the main crosslinking network. Simultaneously, the ZDMA-generated zinc methacrylate ion clusters form a nanoscale reinforcing phase within the rubber matrix. These ionic bonds exhibit thermal reversibility, and the ion clusters themselves possess high heat resistance, acting as quasi-physical crosslinking points and limiting polymer chain slippage at high temperatures. This dual network structure of covalent and ionic bonds ensures that the B-layer rubber compound maintains high elasticity and high modulus at high temperatures, solving the problems of traditional rubber waterstops being prone to collapse and deformation at high temperatures.

[0176] Test Example 5:

[0177] This test example examines the ability of unmodified hydrotalcite in layer A to block and capture corrosive ions.

[0178] Experimental steps:

[0179] Vulcanized rubber sheets (4 mm thick, with layer A rubber being 1.5 mm and layer B rubber being 2.5 mm) prepared in Example 1 and Comparative Example 1 were selected, and square samples of 150 mm × 150 mm were cut, with 3 samples prepared for each group. Uncorroded layer B rubber from the same batch was also taken as the original control group.

[0180] Prepare an acidic salt spray corrosion solution by adding an appropriate amount of glacial acetic acid to a 5% NaCl solution and adjusting the pH of the solution to 3.0±0.1 to simulate a corrosive environment.

[0181] The sample was fixed on the salt spray chamber support, ensuring that the A layer of rubber was facing upwards, and subjected to a continuous 500-hour acidic salt spray test at 35°C. After the test, the sample was removed, the surface salt was cleaned with deionized water and dried. The A layer of rubber and the interface transition layer were completely removed using a precision delamination machine (or rotary abrasion machine), leaving only the deep layer (less than 0.5 mm from the original interface) of the B layer of rubber.

[0182] The extracted B-layer rubber was cut into dumbbell-shaped tensile specimens, and the tensile strength was tested according to GB / T 528 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber". At the same time, a small amount of rubber was cut into pieces, and the chloride ion content inside the rubber was determined by oxygen bomb combustion-ion chromatography.

[0183] Tensile strength retention rate = (tensile strength after corrosion / tensile strength before corrosion) × 100%.

[0184] The test data is shown in Table 5.

[0185] Table 5 Properties and Chloride Ion Content of Layer B Rubber Compound

[0186] Sample source Tensile strength (MPa) Strength retention rate (%) Chloride ion content (mg / kg) blank sample 18.45 100 <10 Example 1 17.12 92.8 68.5 Comparative Example 1 11.03 59.8 1245.2

[0187] As shown in Table 5, after 500 hours of acidic salt spray corrosion, the tensile strength of layer B in Example 1 remained at 17.12 MPa, with a strength retention rate as high as 92.8%, and the chloride ion content was low (68.5 mg / kg). In contrast, the tensile strength of layer B in Comparative Example 1 decreased to 11.03 MPa, with a strength retention rate of only 59.8%, and the chloride ion content was 1245.2 mg / kg, indicating that a large amount of corrosive media had penetrated layer A and entered layer B.

[0188] The data discrepancies confirm the ion-capturing mechanism of unmodified hydrotalcite in layer A of the rubber compound. The unique lamination structure of hydrotalcite enables the exchangeability of anions between its layers. In Example 1, when chloride ions from the external environment penetrate into layer A of the rubber compound, the unmodified hydrotalcite utilizes its originally weakly bonded carbonate or hydroxide ions between its layers to undergo an ion exchange reaction with the high concentration of chloride ions, firmly fixing the chloride ions between the layers and constructing a defensive barrier that effectively prevents the diffusion of corrosive ions into the internal layer B of the rubber compound. Unmodified hydrotalcite also possesses excellent acid absorption characteristics. When acidic corrosive media penetrate into the rubber, the hydroxide ions on the hydrotalcite layers and the carbonate ions between the layers neutralize the invading acidic ions, thereby adsorbing and fixing the accompanying chloride ions in the interlayer gaps or on the layer surface to maintain charge balance, thus blocking the penetration of corrosive media inward.

[0189] Comparative Example 1 used stearic acid-modified hydrotalcite, which improved dispersibility, but the organic acid molecules covered and blocked the active sites on the surface of the layer, hindering ion exchange channels and rendering it ineffective as an ion trapping agent, serving only as a physical filler. Therefore, chloride and hydrogen ions could rapidly penetrate into the B-layer compound along the interface between the rubber matrix and the filler. Since the B-layer compound uses zinc methacrylate (ZDMA) to construct an ion-crosslinking network, the invading acidic ions would destroy the carboxylic acid-zinc ion clusters, converting them into inactive carboxylic acid groups and zinc salts, leading to the disintegration of the B-layer compound's crosslinking network, macroscopically manifested as a decrease in mechanical strength. The excellent data from Example 1 demonstrates that the A-layer compound designed in this invention not only serves as a physical covering layer but also as a chemical functional layer, effectively ensuring the long-term service stability of the high-performance B-layer compound.

[0190] Test Example 6:

[0191] This test example is based on GB / T 18173.2-2014 "Polymer Waterproof Materials Part 2: Waterstops" and related general rubber testing standards to test the mechanical properties of the rubber materials prepared in Examples 1 to 3.

[0192] Experimental steps:

[0193] The co-extruded vulcanized tapes prepared in Examples 1, 2 and 3 should have a smooth surface without bubbles.

[0194] According to GB / T 528 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber", dumbbell-shaped tensile specimens were cut along the extrusion direction using a type I cutter, with the thickness being the finished product thickness. Five parallel specimens were prepared for each group. The specimens were clamped on an electronic universal testing machine, the tensile speed was set to 500 mm / min, and the test was started until the specimen broke. The maximum tensile force and the gauge length elongation at break were recorded, and the tensile strength and elongation at break were calculated.

[0195] According to GB / T 531.1-2008 "Test method for indentation hardness of vulcanized rubber or thermoplastic rubber - Part 1: Shore hardness tester method (Shore hardness)", the tape is laid flat on a horizontal platform. Using a Shore A hardness tester, five different points are selected on the sample surface (A layer rubber and B layer rubber, and the arithmetic mean of all readings) for measurement. The reading is read 3 seconds after the indenter is pressed in.

[0196] According to GB / T 1682-2014 "Determination of Low-Temperature Brittleness of Vulcanized Rubber - Single Specimen Method", a single-arm beam impact specimen was prepared, and the failure condition of the specimen under impact at different temperatures was tested in a low-temperature brittleness testing machine to determine the brittleness temperature.

[0197] The test data is shown in Table 6.

[0198] Table 6 Mechanical property data of Examples 1-3

[0199] Testing items Example 1 Example 2 Example 3 Reference Standard Hardness (Shore A) 68 62 75 60±5 Tensile strength (MPa) 16.4 13.9 19.2 ≥10.0 Elongation at break (%) 445 512 378 ≥380 Brittleness temperature (°C) -45 -48 -42 ≤-40 300% constant elongation (MPa) 8.2 5.6 11.5 -

[0200] As shown in Table 6, the tensile strength of Example 2 is 13.9 MPa, the elongation at break is as high as 512%, and the hardness is low. This indicates that under low filler content, the material mainly exhibits the high elasticity characteristics of a rubber matrix. The addition of liquid maleic anhydride grafted polybutadiene plays a certain role in internal plasticization, reduces intermolecular friction, and endows the material with excellent flexibility and low-temperature performance (brittle temperature -48℃), making it suitable for engineering parts with high requirements for deformation adaptability.

[0201] Example 3 exhibits a tensile strength increased to 19.2 MPa and a 300% elongation stress of 11.5 MPa, demonstrating high modulus and high hardness. This is due to the formation of a dense reinforcing network by in-situ generated ion clusters from a high content of ZDMA and a high proportion of carbon black, which restricts the slippage of rubber segments. Although the elongation at break is slightly reduced (378%), it remains within the practical range. This formulation is suitable for environments subjected to high water pressure or high mechanical stress.

[0202] Example 1 demonstrates balanced performance across all aspects, with an optimal match between tensile strength of 16.4 MPa and elongation of 445%. The maleic anhydride-grafted polybutadiene in the liquid reactive carrier masterbatch not only acts as an interfacial coupling agent but also fully participates in the crosslinking network after vulcanization. Therefore, the surface stickiness or mechanical loss caused by the precipitation of traditional low-molecular-weight plasticizers does not occur, indicating that the technical solution of this invention can stably prepare high-performance composite rubber materials within a wide formulation window.

Claims

1. A high-temperature resistant and corrosion-resistant rubber material, characterized in that, The rubber material is formed by co-extrusion vulcanization of layer A and layer B, including: The A-layer rubber compound is made of the following components in parts by weight: 100 parts EPDM rubber; 60-70 parts quick-pressing black; 5-8 parts unmodified hydrotalcite; 10-15 parts naphthenic oil; 3-5 parts zinc oxide; 1-2 parts stearic acid; 0.5-0.8 parts insoluble sulfur; 1.8-2.3 parts vulcanization accelerator; and 0.3-0.5 parts scorch inhibitor. The B-layer rubber compound is made of the following components in parts by weight: 100 parts EPDM rubber; 20-25 parts zinc methacrylate; 20-30 parts calcined kaolin; 2-8 parts fumed silica; 7-15 parts liquid reactive carrier masterbatch; 2-4 parts high-temperature resistant pigment; 4.0-5.0 parts peroxide vulcanizing agent; 1.5-2.0 parts vulcanizing aid; and 0.5-1.0 parts antioxidant. The liquid reactive carrier masterbatch is formed by the adsorption of liquid maleic anhydride-grafted polybutadiene on the surface of fumed silica. During the process of adding the A-layer rubber compound and the B-layer rubber compound to the two barrels of the dual-composite extruder, the temperature of the metering zone of the A-layer rubber compound extruder barrel is controlled at 70-80℃, and the temperature of the B-layer rubber compound extruder barrel metering zone is controlled at 95-105℃. During the co-extrusion process, the liquid maleic anhydride-grafted polybutadiene in the B-layer rubber compound is enriched at the interface between the A-layer rubber compound and the B-layer rubber compound.

2. The high-temperature resistant and corrosion-resistant rubber material according to claim 1, characterized in that, In the A layer of the rubber compound: the unmodified hydrotalcite is used to capture the permeated chloride ions; the vulcanization accelerator is a combination of accelerator CZ and accelerator TMTD, and the weight ratio of accelerator CZ to accelerator TMTD is (1.2-1.5):(0.6-0.8).

3. The high-temperature resistant and corrosion-resistant rubber material according to claim 1, characterized in that, In the B layer compound: zinc methacrylate is an in-situ reinforcing agent; the peroxide vulcanizing agent is dicumyl peroxide; the vulcanization aid is N,N'-m-phenylenebismaleimide; and the antioxidant is 2,6-di-tert-butyl-4-methylphenol.

4. The high-temperature resistant and corrosion-resistant rubber material according to claim 1, characterized in that, In the liquid reactive carrier masterbatch, the mass ratio of liquid maleic anhydride-grafted polybutadiene to fumed silica is 1:(2.5-4); the liquid reactive carrier masterbatch is a dry powder without lumps.

5. A method for preparing a high-temperature resistant and corrosion-resistant rubber material, characterized in that, The preparation of a high-temperature resistant and corrosion-resistant rubber material according to any one of claims 1-4 includes the following steps: S1. After mixing EPDM rubber, unmodified hydrotalcite, zinc oxide and stearic acid, add fast extrusion black and naphthenic oil, continue mixing and discharge the rubber, and after cooling, add insoluble sulfur, vulcanization accelerator and anti-scorching agent for thin-passing to obtain layer A rubber compound. S2. After mixing EPDM rubber, zinc methacrylate, calcined kaolin, high-temperature resistant pigment and fumed silica, add liquid reactive carrier masterbatch, mix and discharge the mixture, and after cooling, add peroxide vulcanizing agent, vulcanizing aid and antioxidant for thin-passing to obtain layer B rubber compound. S3. Add the A-layer rubber compound obtained in step S1 and the B-layer rubber compound obtained in step S2 into the two barrels of the double compound extruder, and extrude them together at the compounding head to obtain a rubber strip; S4. The rubber strip obtained in step S3 is vulcanized sequentially through a microwave vulcanization section and a hot air vulcanization section to obtain the finished product; In step S3, the set temperature of the metering zone of the extruder barrel for layer A rubber compound is 70-80℃, and the set temperature of the metering zone of the extruder barrel for layer B is 95-105℃. The temperature difference is used to drive the liquid components in layer B to migrate to the interface.

6. The method for preparing a high-temperature resistant and corrosion-resistant rubber material according to claim 5, characterized in that, The pre-preparation method of the liquid reactive carrier masterbatch is as follows: Fumed silica is placed in a high-speed mixer and heated to 55℃-65℃. It is stirred at 750-850 rpm. Liquid maleic anhydride grafted polybutadiene, preheated to 55℃-65℃, is sprayed onto the surface of the fumed silica through an atomizing nozzle. After spraying, the speed is increased to 1000-1500 rpm and mixing continues for 3-8 minutes. The liquid components are physically adsorbed and dispersed by shear force. After cooling, a dry powder masterbatch is obtained.

7. The method for preparing a high-temperature resistant and corrosion-resistant rubber material according to claim 5, characterized in that, The glue discharge temperature in step S1 is 145-150℃.

8. The method for preparing a high-temperature resistant and corrosion-resistant rubber material according to claim 5, characterized in that, The glue discharge temperature in step S2 is 120-130℃.

9. The method for preparing a high-temperature resistant and corrosion-resistant rubber material according to claim 5, characterized in that, In step S4, the temperature of the microwave vulcanization section is 140-160℃ and the time is 60-90 s; the temperature of the hot air vulcanization section is 170-180℃ and the time is 10-15 min.

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