High-elasticity anti-corrosion rubber sealing strip for elevator landing door and preparation method of high-elasticity anti-corrosion rubber sealing strip

Abstract

The invention discloses a high-elasticity anti-corrosion rubber sealing strip for an elevator landing door and a preparation method of the high-elasticity anti-corrosion rubber sealing strip, and relates to the technical field of rubber sealing strips, the high-elasticity anti-corrosion rubber sealing strip comprises a main body structure and an outer covering protection layer, the main body structure is composed of EPDM rubber and fluororubber according to the mixing ratio of 9: 1-8: 2, the EPDM rubber meets the GB / T14657 standard, the fluororubber meets the GB / T6560 standard, and the outer covering protection layer is arranged between the EPDM rubber and the fluororubber. The mixture of the EPDM rubber and the fluororubber is in a homogeneous non-layering state before vulcanization. By designing a matrix composite system formed by mixing EPDM rubber and fluororubber, a matrix material with high elasticity and high resistance is formed, and the problems that a traditional single rubber sealing strip is prone to aging and insufficient in elasticity in high-frequency vibration and corrosion environments and cannot meet the high-performance requirement of an elevator landing door for a sealing material are solved. The service life of the sealing strip is obviously prolonged, and the sealing reliability and safety of the elevator landing door are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber seals, and specifically to a highly elastic anti-corrosion rubber seal for elevator landing doors and a preparation method thereof. Background Art

[0002] With the popularization of elevator applications and the continuous increase in operating frequencies, the elevator landing door sealing strips made of traditional single materials can no longer meet the requirements of modern elevators for high elasticity, corrosion resistance, and long-term stable sealing performance. Existing products are prone to problems such as sealing failure, cracking, and early aging in high-frequency vibration, temperature fluctuations, and harsh corrosion environments, seriously affecting elevator operation safety and maintenance costs.

[0003] Patent CN117209888B discloses a polypropylene plastic seal containing marine essence. The above patent realizes the improvement of the low-temperature embrittlement phenomenon, has a wide range of application fields, large toughness, strong rigidity, a high melt index, and a high qualified product rate.

[0004] The above patent uses modified nitrile rubber as a toughening agent to improve the low-temperature embrittlement phenomenon, has a wide range of application fields, large toughness, strong rigidity, a high melt index, and a high qualified product rate, and will not break even after long-term use. However, the seals disclosed in the above patent are prone to problems such as sealing failure, cracking, and early aging in high-frequency vibration, temperature fluctuations, and harsh corrosion environments.

[0005] Therefore, this application proposes a highly elastic anti-corrosion rubber seal for elevator landing doors with high elasticity and high resistance and a preparation method thereof. Summary of the Invention

[0006] The purpose of the present invention is to provide a highly elastic anti-corrosion rubber seal for elevator landing doors and a preparation method thereof, so as to solve the technical problems of sealing failure, cracking, and early aging easily occurring in high-frequency vibration, temperature fluctuations, and harsh corrosion environments as mentioned in the above background art.

[0007] To achieve the above purpose, the present invention provides the following technical solution: A highly elastic anti-corrosion rubber seal for elevator landing doors includes a main structure and an outer protective layer. The main structure is composed of EPDM rubber and fluororubber with a mixing ratio of 9:1 to 8:2. The EPDM rubber complies with the GB / T14657 standard, and the fluororubber complies with the GB / T6560 standard. The mixture of EPDM rubber and fluororubber is in a homogeneous and non-stratified state before vulcanization; The pre-homogenization process is adopted during the mixing process to ensure no stratification or phase separation before internal mixing.

[0008] Preferably, nano-silica after ball milling treatment is added to the main structure. The particle size of the nano-silica is controlled between 20 and 50 nanometers, the specific surface area is greater than or equal to 150 m2 / g, the incorporation amount is 3% to 5% of the weight of the main structure, and the nano-silica is dispersed and treated during the mixing process until there is no obvious agglomeration state.

[0009] Preferably, zinc phosphate powder after ultrafine grinding treatment is added to the main structure. The average particle size of the zinc phosphate powder is less than 10 microns, the incorporation amount is 2% to 4% of the weight of the main structure. The zinc phosphate is Zn3(PO4)2·4H2O and is used after being dried to a moisture content of less than 1%.

[0010] Preferably, the outer protective layer is a PTFE film with a thickness of 20 to 50 microns, and is subjected to plasma surface activation treatment before application. The activation conditions are a power of 100 W and a treatment time of 30 seconds, so that the surface roughness Ra of the PTFE film is controlled within the range of 0.8 to 1.2 microns.

[0011] Preferably, stainless steel reinforcing ribs are provided at the inner edge of the main structure. The stainless steel material used complies with the GB / T20878 standard, the cross-sectional shape is rectangular or I-shaped, the width is 1.5 to 3 mm, the thickness is 0.3 to 0.5 mm, and the installation position is 2 to 3 mm inward from the edge center line and is fixed in the main rubber through an embedding structure; The processing technology adopts the embedding blending method to ensure that the reinforcing ribs are located 2 to 3 mm inward from the edge center line of the rubber matrix, and the embedding depth and position are precisely controlled by the mold preset.

[0012] Preferably, a peroxide vulcanizing agent is incorporated into the EPDM rubber and fluororubber mixture before vulcanization, and the incorporation amount is 1% to 2% of the weight of the mixture, and it is vulcanized at 150°C to 170°C and 1.0 to 2.0 MPa for 25 to 35 minutes during the vulcanization process to form a uniform three-dimensional cross-linked network structure.

[0013] Preferably, when the PTFE film is compounded with the main structure during the co-extrusion process, an interfacial modifier is used. The interfacial modifier is selected from polymers containing active carboxyl or amino groups, and the incorporation amount is 0.5% to 1% of the surface area of the PTFE film, so that a continuous physical embedding and chemical bond interface is formed between the PTFE film and the main structure during the co-extrusion molding process, and the thickness of the chemical bond interface is controlled within 5 to 10 microns.

[0014] Preferably, the seal is a multi-layer composite structure, and a transition layer is provided between the main structure and the outer protective layer. The transition layer is composed of a mixture of EPDM rubber and an interfacial modifier, with a thickness of 2 to 5 microns, and is continuously formed with the main structure and the PTFE protective layer during the co-extrusion molding.

[0015] Preferably, the preparation method includes the following steps: S1. Raw material ratio: Accurately weigh EPDM rubber, fluororubber, ball-milled nano-silica, ultrafinely pulverized zinc phosphate, anti-aging agent, plasticizer, and peroxide vulcanizing agent. The weight ratio of EPDM rubber to fluororubber is 9:1 to 8:2, and the dosages of nano-silica and zinc phosphate are 3% - 5% and 2% - 4% respectively; S2. High-shear mixing: Mix the raw materials in a twin-screw internal mixer at a temperature of 120°C - 140°C for 8 - 12 minutes to ensure that all raw materials are fully and evenly dispersed. At the same time, monitor the mixing temperature and rotation speed in real time to avoid overheating; S3. Preheating and co-basing: After preheating the uniformly mixed rubber mixture to 90°C - 110°C, use a co-extruder to synchronously feed the preheated rubber mixture and the PTFE film treated by plasma and coated with an interfacial modifier into a co-extrusion die. The die size is precisely controlled according to the design requirements to form a semi-finished seal with a composite cross-sectional size; S4. Vulcanization and curing: Place the co-extruded semi-finished product in a vulcanization die and vulcanize it at a temperature of 150°C - 170°C and a pressure of 1.0 - 2.0 MPa. The vulcanization time is controlled within 25 - 35 minutes to ensure the formation of a uniformly cross-linked three-dimensional structure; S5. Post-treatment: After vulcanization, clean the surface of the semi-finished seal, perform dimensional stability treatment using a hot air shaping device, and cut and trim it according to the predetermined size to obtain the final product.

[0016] Preferably, the preparation method further includes the following steps: S31. The plasma treatment parameters of the PTFE film are a power of 100 W and a treatment time of 30 seconds, which increases the surface energy of the PTFE film to 30 - 50 mJ / m2, and through the synergistic effect of the interfacial modifier during the co-extrusion process, realizes the continuous co-extrusion and adhesion of the PTFE film and the rubber main structure; S41. Adopt a segmented heating technique to set independent vulcanization temperature curves for the main structure and the outer protective layer respectively to ensure that each layer reaches the optimal cross-linking density and composite effect.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention designs a matrix composite system mixed with EPDM rubber and fluororubber, forming a matrix material with both high elasticity and high resistance, solving the problems that traditional single-rubber seals are prone to aging, lack of elasticity, and cannot meet the high-performance requirements of elevator landing door seal materials in high-frequency vibration and corrosive environments, significantly extending the service life of the seal, and improving the sealing reliability and safety of elevator landing doors; 2. The present invention optimizes the microstructure and crosslinking density of the rubber matrix by designing an additive-assisted system with nano-silica and zinc phosphate powders, improves the anti-aging and anti-corrosion properties of the material, solves the problems of cracking, aging and insufficient anti-corrosion ability that occur in traditional rubber materials during long-term use, and significantly enhances the physical and mechanical properties and environmental adaptability of the rubber seal; 3. The present invention ensures the firm bonding of the PTFE film to the rubber matrix by designing a PTFE outer protective layer interface modification co-extrusion technology, forms a stable and continuous composite structure, overcomes the problems of poor bonding and easy peeling between the traditional PTFE film and the rubber, improves the wear resistance, anti-corrosion and anti-peeling properties of the seal, and enhances the long-term stability of the product under harsh working conditions; 4. The present invention realizes the continuous composite of multi-layer materials during co-extrusion and vulcanization by designing a multi-layer composite structure and a segmented vulcanization process. Each layer reaches the optimal crosslinking density and composite effect, solves the problems of uneven crosslinking and poor interfacial bonding during the vulcanization process of different material layers, ensures the stability, sealing performance and anti-aging performance of the overall structure of the seal, and improves the reliability of the product under high temperature, high pressure and vibration conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of the preparation process of the present invention; Figure 2 is a schematic diagram of the seal fatigue cycle test curve of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0021] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, terms such as "installation", "equipped with", "connection", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] Please refer to Figure 1 , an embodiment provided by the present invention: a highly elastic anti-corrosion rubber seal for an elevator landing door, including a main structure and an outer protective layer. The main structure is composed of EPDM rubber and fluororubber with a mixing ratio of 9:1 to 8:2. The EPDM rubber complies with the GB / T14657 standard, and the fluororubber complies with the GB / T6560 standard. The mixture of EPDM rubber and fluororubber is in a homogeneous and non-stratified state before vulcanization; The mixing process adopts a pre-homogenization process to ensure no stratification or phase separation before internal mixing; Nano-silica after ball milling treatment is added to the main structure. The particle size of the nano-silica is controlled between 20 and 50 nanometers, the specific surface area is greater than or equal to 150 m2 / g, and the incorporation amount is 3% to 5% of the weight of the main structure. And the nano-silica is dispersed during the mixing process to a state without obvious agglomeration; Zinc phosphate powder after ultrafine pulverization treatment is added to the main structure. The average particle size of the zinc phosphate powder is less than 10 microns, and the incorporation amount is 2% to 4% of the weight of the main structure. The zinc phosphate is Zn3(PO4)2·4H2O, and it is used after being dried to a moisture content of less than 1%; Furthermore, EPDM rubber compliant with the GB / T14657 standard and fluororubber compliant with the GB / T6560 standard are selected and pre-formulated according to a weight ratio of 9:1. To prevent stratification, a low-speed stirring device is used to perform pre-homogenization treatment on the EPDM and fluororubber to ensure that the mixture is in a homogeneous and non-stratified state before entering the internal mixer; Nano-silica after ball milling treatment is selected and added at 4% of the weight of the mixture. Through ultrasonic dispersion or a high-shear pre-dispersion process, it has no obvious agglomeration state in the rubber mixture; Zn3(PO4)2·4H2O is selected, first ultrasonically pulverized to make its average particle size less than 10 microns, and the powder is dried to ensure that the moisture content is lower than 1%, and then added at 3% of the weight of the mixture to ensure uniform dispersion during the mixing process.

[0023] Please refer to Figure 1, an embodiment provided by the present invention: a highly elastic anti-corrosion rubber seal for an elevator landing door, wherein the outer protective layer is a layer of PTFE film, the thickness of the PTFE film is 20 - 50 microns, and it is subjected to plasma surface activation treatment before application. The activation conditions are a power of 100W and a treatment time of 30 seconds, so that the surface roughness Ra of the PTFE film is controlled within the range of 0.8 - 1.2 microns; Stainless steel reinforcing ribs are provided at the inner edge of the main body structure. The stainless steel material used complies with the GB / T20878 standard. The cross-sectional shape is rectangular or I-shaped, the width is 1.5 - 3 mm, the thickness is 0.3 - 0.5 mm, and the installation position is 2 - 3 mm inward from the edge center line, and it is fixed in the main body rubber through an embedding structure; The processing technology adopts the embedding blending method to ensure that the reinforcing ribs are located 2 - 3 mm inward from the edge center line of the rubber matrix. The embedding depth and position are precisely controlled through mold presetting; Furthermore, a PTFE film with a thickness of 30 microns is selected. The film material meets the relevant standard requirements. The film is placed in a plasma treatment device, the set power is 100W, and the treatment time is 30 seconds; during the treatment, air or oxygen is used as the working gas to produce a micron-level concavo-convex structure on the PTFE surface. After treatment, it is detected with a surface roughness measuring instrument to ensure that the surface roughness Ra is controlled within the range of 0.8 - 1.2 microns. This treatment effectively improves the surface energy of the film, which is beneficial for subsequent physical embedding and chemical bonding with the rubber matrix; The stainless steel sheet is subjected to surface cleaning and necessary rust prevention treatments such as phosphating or coating with a special adhesive to improve its bonding performance with the rubber. Special positioning grooves or recesses are preset in the designed mold to fix the position of the reinforcing ribs. According to the design requirements, the reinforcing ribs are installed on the inner edge of the rubber matrix, and the specific position is 2 - 3 mm inward from the edge center line. This offset is precisely controlled by the built-in positioning device of the mold to ensure that the reinforcing ribs do not drift in position during the mixing process; In the high-shear internal mixing stage, first, the EPDM and fluororubber mixture is formed into a homogeneous and non-stratified rubber compound through a pre-homogenization process. The "embedding blending method" is adopted, that is, before the rubber mixture enters the co-extrusion mold, through automatic or manual operation, the pretreated stainless steel reinforcing ribs are placed in the predetermined positioning grooves of the mold, so that when the reinforcing ribs come into contact with the rubber mixture, they can be synchronously wrapped in the rubber matrix. The embedding depth and position are precisely controlled within the range of 2 - 3 mm inward from the edge center line through mold presetting accuracy. During the co-extrusion process, the rubber mixture flows around the reinforcing ribs and fully coats its surface to ensure that the reinforcing ribs are fixed inside the rubber, and its edge forms a continuous composite body with no obvious interface defects with the overall seal structure.

[0024] Please refer to Figure 1 and Figure 2, an embodiment provided by the present invention: a highly elastic anti-corrosion rubber seal for elevator landing doors, wherein a peroxide vulcanizing agent is incorporated into the EPDM rubber and fluororubber mixture before vulcanization, and the incorporation amount is 1% - 2% of the weight of the mixture, and it is vulcanized at 150°C - 170°C and 1.0 - 2.0 MPa for 25 - 35 minutes during the vulcanization process to form a uniform three-dimensional cross-linked network structure; During the co-extrusion process of the PTFE film when it is compounded with the main structure, an interfacial modifier is used. The interfacial modifier is selected from polymers containing active carboxyl or amino groups, and the incorporation amount is 0.5% - 1% of the surface area of the PTFE film, so that a continuous physical embedding and chemical bond interface is formed between the PTFE film and the main structure during the co-extrusion molding process, and the thickness of the chemical bond interface is controlled within 5 - 10 microns; Furthermore, EPDM rubber conforming to the GB / T14657 standard and fluororubber conforming to the GB / T6560 standard are mixed in a predetermined ratio to ensure that the mixture is homogeneous and non-stratified before vulcanization. A commercially available peroxide vulcanizing agent is selected, and the incorporation amount is controlled to be 1% - 2% of the weight of the matrix rubber mixture. It is selected from polymers containing active carboxyl or amino groups, such as acrylic acid modified polymers, and the incorporation amount is 0.5% - 1% of the surface area of the PTFE film; In a twin-screw internal mixer, the EPDM and fluororubber mixture and a predetermined amount of peroxide vulcanizing agent are kneaded at a temperature of 120°C - 130°C for 8 - 12 minutes to ensure that the vulcanizing agent is evenly dispersed and does not cause pre-crosslinking phenomenon. The kneaded rubber mixture is preheated to 90°C - 110°C to improve fluidity and facilitate subsequent co-extrusion molding. The semi-finished product after co-extrusion molding is placed in a vulcanization mold, the mold temperature is set at 150°C - 170°C, and a pressure of 1.0 - 2.0 MPa is applied. Under these conditions, the vulcanization time is controlled within 25 - 35 minutes to ensure that the peroxide vulcanizing agent fully acts on the mixture to form a uniform three-dimensional cross-linked network structure and strong chemical bonds are formed between rubber molecules; after the curing is completed, the temperature of the product is rapidly reduced through a cooling module to ensure the stability of the cross-linked structure; Select a PTFE film with a thickness of 30 microns. First, it is subjected to plasma treatment with the treatment conditions set as a power of 100 W and a treatment time of 30 seconds to ensure that the surface roughness Ra of the film reaches 0.8 - 1.2 microns. In the co - extrusion process, first, the plasma - treated PTFE film is transported into the fixed groove of the co - extrusion die. At the same time, a pre - prepared interfacial modifier is evenly coated on the surface of the PTFE film, and its dosage is 0.5% - 1% of the film surface area. This modifier can be a polymer solution containing active carboxyl or amino groups. After being evenly sprayed or dip - coated, it is left to dry naturally until a uniform film is formed on the film surface. The pre - heated rubber mixture and the PTFE film treated with the modifier enter the co - extrusion die synchronously. The die design ensures that a continuous composite layer is formed between the rubber mixture and the PTFE film in the contact area. During the co - extrusion process, due to the presence of the modifier, a continuous physical embedding and partial chemical bonding interface are formed between the PTFE film and the rubber matrix at the interface. The thickness of this interface is precisely controlled within 5 - 10 microns through die parameters and flow control; Use cross - link density testing and scanning electron microscopy to detect the three - dimensional cross - link network inside the vulcanized rubber to confirm whether the dosage of the vulcanizing agent and the vulcanization conditions meet the requirements of uniform cross - linking. Use cross - section observation, transmission electron microscopy, or tensile peel test to detect the interfacial structure between the PTFE film and the rubber matrix to ensure that the interface thickness is within 5 - 10 microns and confirm that the physical embedding and chemical bonding effects are good.

[0025] Please refer to Figure 1 , an embodiment provided by the present invention: a highly elastic anti - corrosion rubber seal for elevator landing doors. The seal is a multi - layer composite structure, and a transition layer is provided between the main structure and the outer protective layer. The transition layer is composed of a mixture of EPDM rubber and an interfacial modifier, with a thickness of 2 - 5 microns, and is continuously formed with the main structure and the PTFE protective layer during co - extrusion molding; Furthermore, the multi - layer co - extrusion device is equipped with three raw material conveying channels. Channel A conveys the rubber mixture of the main structure, Channel B is dedicated to the transition layer material, that is, the mixture of EPDM rubber and the interfacial modifier, and Channel C conveys the pre - treated PTFE film, which is continuously supplied in the form of a coil. A three - layer co - extrusion die design is adopted, and a precise separation structure is provided inside the die to ensure that the three layers of materials are continuously laminated at the die outlet, and the transition layer is seamlessly butt - jointed between the main structure and the PTFE protective layer, and its inter - layer thickness is precisely controlled within the range of 2 - 5 microns by the die slit; Preheat the main structure rubber mixture of Channel A to 90°C - 110°C to improve fluidity. The transition layer mixture in Channel B is also controlled within a similar temperature range to ensure material viscosity matching. The PTFE film in Channel C maintains a stable supply state. In the coextrusion die, first, the main structure layer is extruded from Channel A. Then, the transition layer is evenly covered on the surface of Layer A through Channel B. The die slit is precisely set so that the thickness of the transition layer is fixed at 2 - 5 microns. Finally, the PTFE film supplied by Channel C is smoothly covered on the transition layer, and the two are continuously formed during the coextrusion process to form an integral composite structure. After extrusion, the three-layer composite material is cooled and solidified through a cooling tank to ensure tight bonding between layers and a smooth interface without delamination.

[0026] Please refer to Figure 1 , an embodiment provided by the present invention: A preparation method of a high-elastic anti-corrosion rubber seal for an elevator landing door, comprising the following steps: S1. Raw material ratio: Accurately weigh EPDM rubber, fluororubber, ball-milled nano-silica, ultra-finely pulverized zinc phosphate, anti-aging agent, plasticizer, and peroxide vulcanizing agent. The weight ratio of EPDM rubber to fluororubber is 9:1 - 8:2, and the dosages of nano-silica and zinc phosphate are 3% - 5% and 2% - 4% respectively; S2. High-shear mixing: Mix the raw materials in a twin-screw internal mixer at a temperature of 120°C - 140°C for 8 - 12 minutes to ensure that all raw materials are fully and evenly dispersed. At the same time, monitor the mixing temperature and rotation speed in real time to avoid overheating; S3. Preheating and coextrusion: After preheating the uniformly mixed rubber mixture to 90°C - 110°C, use a coextrusion machine to synchronously feed the preheated rubber mixture and the PTFE film treated by plasma and coated with an interface modifier into the coextrusion die. The die size is precisely controlled according to the design requirements to form a semi-finished seal with a composite cross-sectional size; S4. Vulcanization and curing: Place the coextruded semi-finished product in a vulcanization die and vulcanize it at a temperature of 150°C - 170°C and a pressure of 1.0 - 2.0 MPa. The vulcanization time is controlled within 25 - 35 minutes to ensure the formation of a uniformly cross-linked three-dimensional structure; S5. Post-treatment: After vulcanization, clean the surface of the seal semi-finished product, perform size stabilization treatment using a hot air shaping device, and cut and trim it according to the predetermined size to obtain the final product; S31. The plasma treatment parameters of the PTFE film are a power of 100 W and a treatment time of 30 seconds, which increases the surface energy of the PTFE film to 30 - 50 mJ / m2, and through the synergistic effect of the interface modifier during the coextrusion process, continuous coextrusion adhesion of the PTFE film and the rubber main structure is achieved; S41. Adopt the segmented heating technology to set independent vulcanization temperature curves for the main structure and the outer protective layer respectively, ensuring that each layer reaches the optimal crosslinking density and composite effect; Furthermore, S1. EPDM rubber and fluororubber are in a weight ratio of 9:1 or other ratios within the range of 8:2. The selected rubbers all meet the standards of GB / T14657 and GB / T6560. The nano-silica treated by ball milling has a particle size controlled within 20 - 50 nanometers and a specific surface area ≥ 150 m² / g, and its incorporation amount is set to 4% of the weight of the matrix rubber mixture. The zinc phosphate powder after ultrafine pulverization has a moisture content < 1% after drying and an average particle size < 10 microns, and its incorporation amount is 3% of the weight of the matrix rubber mixture. Antioxidants and plasticizers are added according to a predetermined formula to ensure that the rubber system has excellent aging resistance and flexibility during the subsequent vulcanization process. The incorporation amount of the peroxide vulcanizing agent is controlled within 1% - 2% of the weight of the matrix mixture to ensure the formation of a uniform crosslinked network after vulcanization; S2. Feed all the raw materials weighed in S1 into a twin-screw internal mixer, set the mixing temperature at 120°C - 140°C, and control the mixing time within 8 - 12 minutes. During the mixing process, monitor the temperature and rotation speed in the mixer in real time to prevent pre-crosslinking or local over-vulcanization caused by overheating; at the same time, ensure that the nano-silica and zinc phosphate are evenly dispersed in the rubber matrix without obvious agglomeration, and obtain a homogeneous and non-layered rubber mixture; S3. Preheat the homogeneous rubber mixture obtained in S2 to 90°C - 110°C to improve fluidity and molding effect. At the same time, take a roll of PTFE film with a thickness of 20 - 50 microns, first perform pretreatment in a special plasma treatment equipment, and set the treatment conditions as a power of 100W and a treatment time of 30 seconds, so that the surface energy of the PTFE film is increased to 30 - 50 mJ / m² and its surface roughness Ra reaches 0.8 - 1.2 microns. Coat an interfacial modifier: evenly coat a polymer containing active carboxyl or amino groups on the PTFE film to ensure that the modifier layer is uniform and has high compatibility with the rubber matrix after drying. Use a co-extrusion machine to synchronously feed the preheated rubber mixture and the PTFE film treated by plasma and coated with an interfacial modifier into the co-extrusion die. The design dimensions of the die are precisely controlled so that the two form a continuous and composite cross-sectional structure in the die, and obtain a semi-finished seal. In the pretreatment stage of the PTFE film, the plasma treatment parameters are a power of 100W and a time of 30 seconds, which increases the surface energy of the film to 30 - 50 mJ / m². After coating the interfacial modifier, a continuous composite interface is formed between the PTFE film and the rubber main structure through the co-extrusion process, and the interface thickness is precisely controlled within 5 - 10 microns to ensure long-term anti-peeling and aging resistance; S4. Feed the co-extruded semi-finished product into a vulcanization mold and adopt segmented heating technology: set independent vulcanization temperature curves for the main structure and the outer protective layer respectively to ensure that each layer reaches the optimal crosslinking density and composite effect. During vulcanization, set the vulcanization temperature at 150°C to 170°C, the vulcanization pressure at 1.0 to 2.0 MPa, and control the vulcanization time within 25 to 35 minutes. During this process, the peroxide vulcanizing agent fully acts to form a uniform three-dimensional crosslinked network structure. At the same time, ensure that physical embedding and partial chemical bonding are achieved between the PTFE film and the rubber matrix under the synergistic effect of the interfacial modifier, with the interface being continuous and the thickness controlled within 5 to 10 microns. The segmented heating technology is adopted in the vulcanization mold to set independent vulcanization temperature curves for the main structure and the outer protective layer respectively. This process ensures that different material layers reach their respective optimal crosslinking densities during vulcanization, enhances the overall composite effect, and ensures that the seal has a uniform three-dimensional crosslinked network and a stable composite interface under high temperature and high pressure. S5. After vulcanization, clean the surface of the seal semi-finished product to remove residual vulcanization by-products, use hot air shaping equipment for dimensional stability treatment to ensure that the dimensions of all parts of the product meet the design requirements, and cut and trim according to the predetermined dimensions to obtain the final product. Comprehensive performance test of the seal: Test items and conditions: 1. Tensile strength and elongation test: According to ISO37 standard, adopt a tensile rate of 500 mm / min and a gauge length of 100 mm. 2. Fatigue cycle test: Simulate the opening and closing cycle of the elevator landing door, conduct 5000 repeated cycles, and test the change of elastic retention rate at room temperature. 3. Salt spray corrosion test: Conduct a 72-hour salt spray corrosion test in a 5% NaCl solution, and observe the appearance change and the degradation of mechanical properties. 4. Interface peel strength test: Conduct an interface peel test according to ASTM D1876 standard to test the peel strength between the PTFE film and the rubber matrix, with the unit of N / mm. Description of test results: The test results show that both the tensile strength and elongation of the seal meet the requirements of high elasticity and large deformation tolerance for elevator landing door sealing. The high elastic retention rate after 5000 cycles indicates that the seal can still maintain excellent sealing performance under frequent use conditions. After 72 hours of salt spray test, the seal has no obvious cracks and performance degradation, showing good corrosion resistance and aging resistance. The peel strength between the PTFE film and the rubber matrix reaches 2.3 N / mm, indicating that the interface has achieved firm bonding through the coextrusion process with the interface modifier, effectively preventing interlayer separation. Test result chart

[0027] Working principle: Accurately proportion EPDM rubber and fluororubber quantitatively, and add auxiliary agents such as nano-silica treated by ball milling and ultra-finely pulverized zinc phosphate to form a homogeneous rubber mixture. The preheated rubber mixture and the PTFE film treated by plasma and coated with an interface modifier are coextruded synchronously, and multi-layer continuous composite is realized through a precision die; the coextrusion process enables the main structure, transition layer and outer protective layer to be tightly combined in the same forming process, ensuring the formation of a continuous physical embedding and chemical bonding interface between the PTFE film and the rubber matrix, thereby improving the overall wear resistance and corrosion resistance of the product. The semi-finished product formed by coextrusion is cured for the main structure and the outer protective layer respectively by a segmented heating technique in a vulcanization die, vulcanized for 25 - 35 minutes at 150°C - 170°C and a pressure of 1.0 - 2.0 MPa to form a uniform three-dimensional cross-linked network structure; then, through post-treatment processes such as surface cleaning, hot air shaping, cutting and trimming, a highly elastic anti-corrosion rubber seal with stable dimensions, continuous structure and excellent performance is obtained.

[0028] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be regarded as limiting the claimed claims.

Claims

1. A highly elastic anti-corrosion rubber seal for elevator landing doors, comprising a main structure and an outer protective layer, characterized in that: The main body structure is composed of EPDM rubber and fluororubber with a mixing ratio of 9:1 to 8:

2. The EPDM rubber complies with the GB / T14657 standard, and the fluororubber complies with the GB / T6560 standard. The mixture of EPDM rubber and fluororubber is in a homogeneous and non-stratified state before vulcanization; The mixing process adopts a pre-homogenization process to ensure no stratification or phase separation before internal mixing.

2. The high-elasticity anti-corrosion rubber seal for an elevator landing door according to claim 1, wherein: Nanometer silica after ball milling treatment is added to the main body structure. The particle size of the nanometer silica is controlled between 20 and 50 nanometers, the specific surface area is greater than or equal to 150 m2 / g, the incorporation amount is 3% to 5% of the weight of the main body structure, and the nanometer silica is dispersed during the mixing process to a state without obvious agglomeration.

3. The high-elasticity anti-corrosion rubber seal for an elevator landing door according to claim 1, characterized in that: Zinc phosphate powder after ultrafine pulverization treatment is added to the main body structure. The average particle size of the zinc phosphate powder is less than 10 microns, the incorporation amount is 2% to 4% of the weight of the main body structure, the zinc phosphate is Zn3(PO4)2·4H2O, and it is used after being dried to a moisture content of less than 1%.

4. The high-elasticity anti-corrosion rubber seal for elevator landing doors according to claim 1, wherein: The outer protective layer is a layer of PTFE film with a thickness of 20 to 50 microns, and it is subjected to plasma surface activation treatment before application. The activation conditions are a power of 100 W and a treatment time of 30 seconds, so that the surface roughness Ra of the PTFE film is controlled within the range of 0.8 to 1.2 microns.

5. A highly elastic anti-corrosion rubber seal for an elevator landing door according to claim 1, characterized in that: Stainless steel reinforcing ribs are arranged at the inner edge of the main body structure. The stainless steel material used complies with the GB / T20878 standard, the cross-sectional shape is rectangular or I-shaped, the width is 1.5 to 3 mm, the thickness is 0.3 to 0.5 mm, the installation position is 2 to 3 mm inward from the edge center line, and it is fixed in the main body rubber through an embedding structure; The processing technology adopts an inlay blending method to ensure that the reinforcing ribs are located 2 to 3 mm inward from the edge center line of the rubber matrix. The embedding depth and position are precisely controlled by presetting the mold.

6. The high-elasticity anti-corrosion rubber seal for an elevator landing door according to claim 1, characterized in that: A peroxide vulcanizing agent is incorporated into the mixture of EPDM rubber and fluororubber before vulcanization, and the incorporation amount is 1% to 2% of the weight of the mixture. During the vulcanization process, it is vulcanized at 150°C to 170°C and 1.0 to 2.0 MPa for 25 to 35 minutes to form a uniform three-dimensional cross-linked network structure.

7. The high-elasticity anti-corrosion rubber seal for elevator landing doors according to claim 4, wherein: When the PTFE film is compounded with the main body structure during the co-extrusion process, an interface modifier is used. The interface modifier is selected from polymers containing active carboxyl or amino groups, and the incorporation amount is 0.5% to 1% of the surface area of the PTFE film, so that a continuous physical embedding and chemical bond interface is formed between the PTFE film and the main body structure during the co-extrusion molding process, and the thickness of the chemical bond interface is controlled within 5 to 10 microns.

8. The high-elasticity anti-corrosion rubber seal for an elevator landing door according to claim 1, characterized in that: The seal strip is a multi-layer composite structure. A transition layer is arranged between the main body structure and the outer protective layer. The transition layer is composed of a mixture of EPDM rubber and an interface modifier, with a thickness of 2 to 5 microns, and it is continuously formed with the main body structure and the PTFE protective layer during the co-extrusion molding.

9. A preparation method of a highly elastic anti-corrosion rubber seal for an elevator landing door, applicable to the highly elastic anti-corrosion rubber seal for an elevator landing door according to any one of claims 1-8, characterized in that: The preparation method includes the following steps: S1. Raw material ratio: Accurately weigh EPDM rubber, fluororubber, ball-milled nano-silica, ultrafinely pulverized zinc phosphate, anti-aging agent, plasticizer and peroxide vulcanizing agent. The weight ratio of EPDM rubber to fluororubber is 9:1 to 8:2, and the dosages of nano-silica and zinc phosphate are 3% to 5% and 2% to 4% respectively; S2. High-shear mixing: Mix the raw materials in a twin-screw internal mixer at a temperature of 120°C to 140°C for 8 to 12 minutes to ensure that all raw materials are fully and evenly dispersed. At the same time, monitor the mixing temperature and speed in real time to avoid overheating; S3. Preheating and co-extrusion: After preheating the uniformly mixed rubber mixture to 90°C to 110°C, use a co-extruder to synchronously feed the preheated rubber mixture and the PTFE film treated by plasma and coated with an interfacial modifier into the co-extrusion die. The die size is precisely controlled according to the design requirements to form a semi-finished seal with a composite cross-sectional size; S4. Vulcanization and curing: Place the co-extruded semi-finished product in a vulcanization die and vulcanize it at a temperature of 150°C to 170°C and a pressure of 1.0 to 2.0 MPa. The vulcanization time is controlled within 25 to 35 minutes to ensure the formation of a uniformly cross-linked three-dimensional structure; S5. Post-treatment: After vulcanization, clean the surface of the semi-finished seal, perform dimensional stability treatment with a hot air shaping device, and cut and trim it according to the predetermined size to obtain the final product.

10. The preparation method of a highly elastic anti-corrosion rubber seal for an elevator landing door according to claim 9, characterized in that: The preparation method further includes the following steps: S31. The plasma treatment parameters of the PTFE film are a power of 100 W and a treatment time of 30 seconds, which increases the surface energy of the PTFE film to 30 to 50 mJ / m2, and through the synergistic effect of the interfacial modifier during the co-extrusion process, continuous co-extrusion adhesion of the PTFE film and the rubber main structure is achieved; S41. Adopt a segmented heating technique to set independent vulcanization temperature curves for the main structure and the outer protective layer respectively to ensure the best cross-linking density and composite effect for each layer.

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