High performance inner fluorine and outer silicon rubber tube suitable for high temperature environment

Abstract

The application relates to the technical field of rubber tube manufacturing, and discloses a high-performance inner-fluorine outer-silicon rubber tube suitable for high-temperature environments, which comprises an inner layer, the inner layer is a high-temperature-resistant fluorine rubber layer containing a silicone-modified fatty acid condensate, and is used for improving the lubricity and anti-sticking performance of the inner wall of the rubber tube; a reinforcing layer, the reinforcing layer is coated on the outer circumferential surface of the inner layer, and the reinforcing layer is a composite reinforcing structure formed by aramid web cloth and double-sided calendered fluorine rubber; a transition adhesive layer, the transition adhesive layer is arranged between the reinforcing layer and an outer layer, and is used for realizing chemical bonding between the fluorine rubber and the silicone rubber; and the outer layer is a high-temperature-resistant silicone rubber layer. Through the technical scheme, the problems that the existing inner-fluorine outer-silicon rubber tube is prone to sticking with metal connecting pieces in a high-temperature environment, the bonding force between the fluorine rubber layer and the silicone rubber layer is insufficient, the rubber tube is prone to delamination, delayering and bulging during long-term use, and the structural stability is poor are solved.

Description

Technical Field

[0001] This invention relates to the field of hose manufacturing technology, and more specifically, to high-performance inner fluoropolymer and outer silicone hoses suitable for high-temperature environments. Background Technology

[0002] Fluoropolymer-inner-silicone-outer hoses, combining the media resistance of fluororubber with the heat resistance, flexibility, and external protection of silicone rubber, are widely used in high-temperature engine pipelines, hot air delivery pipelines, chemical equipment connection pipelines, and other fluid transport systems operating in prolonged high-temperature environments. These hoses typically use an inner fluororubber layer that directly contacts the steel pipe or the transported medium, while the outer silicone rubber layer provides external environmental protection and flexible cushioning. As equipment operating temperatures, operating durations, and the frequency of disassembly and maintenance increase, these hoses not only need good high-temperature stability but also require excellent interfacial bonding and disassembly performance under long-term thermal cycling, pressure fluctuations, and assembly clamping conditions.

[0003] Existing fluororubber inner and silicone outer tubing still has certain shortcomings under long-term high-temperature environments. On the one hand, the inner fluororubber layer is prone to sticking to the connecting steel pipe under high-temperature compression, requiring significant external force for disassembly. This can easily cause tearing of the inner wall of the tubing, residual adhesive on the surface of the connectors, or damage to the pipeline, affecting subsequent maintenance and reassembly. On the other hand, fluororubber and silicone rubber are elastomer materials of different systems, with differences in polarity, crosslinking system, and interfacial compatibility. After conventional composite molding, the interlayer bonding force is insufficient, and under high-temperature aging, repeated bending, or pressure impact conditions, problems such as delamination, peeling, and bulging are prone to occur, leading to a decrease in the sealing reliability and structural stability of the tubing.

[0004] Therefore, it is necessary to provide a high-performance inner fluoropolymer outer silicone tubing that can simultaneously solve the problems of high-temperature adhesion and interlayer separation. Summary of the Invention

[0005] To overcome the above-mentioned defects, the present invention provides a high-performance inner fluorine and outer silicone tube suitable for high-temperature environments, which solves the problems of existing inner fluorine and outer silicone tubes being prone to sticking to metal connectors in high-temperature environments, insufficient bonding between the fluorine rubber layer and the silicone rubber layer, easy delamination, peeling, bulging and poor structural stability during long-term use.

[0006] According to one aspect, at least one embodiment of the present invention provides a high-performance inner fluoropolymer and outer silicone tubing suitable for high-temperature environments, comprising, from the inside to the outside, the following: The inner layer is a high-temperature resistant fluororubber layer that extends continuously along the axial direction of the tube to form a tubular structure. Organosilicon-modified fatty acid condensates are dispersed in the fluororubber matrix of the inner layer to improve the surface lubricity and anti-adhesion properties of the inner layer, so that the inner layer does not stick to the metal connector in a high-temperature environment. A reinforcing layer is wrapped around the outer peripheral surface of the inner layer. The reinforcing layer is a composite reinforcing structure formed by double-sided calendering of aramid mesh and fluororubber. Both sides of the aramid mesh are covered with fluororubber to form an integrated reinforcing sheet. A transition adhesive layer is disposed between the reinforcing layer and the outer layer to achieve chemical bonding between the fluororubber layer and the silicone rubber layer; The outer layer is a silicone rubber layer that covers the outer peripheral surface of the transition adhesive layer; The inner layer, reinforcing layer, transition adhesive layer and outer layer are manually wound together, then integrally molded by high-temperature vulcanization, and then subjected to high-temperature stabilization post-treatment to form an integrated composite pipe body that is resistant to sticking and delamination.

[0007] For example, in the high-performance inner fluorinated and outer silicone tube suitable for high-temperature environments provided by at least one embodiment of the present invention, the amount of the organosilicon-modified fatty acid condensate added to the inner fluororubber matrix is ​​1% to 2% of the mass of the fluororubber. The organosilicon-modified fatty acid condensate continuously migrates to the inner wall surface of the inner layer under high-temperature conditions to form a dynamic lubricating film layer, so that the dynamic friction coefficient of the inner wall surface of the inner layer is lower than the dynamic friction coefficient when it is not added.

[0008] For example, in the high-performance inner fluoropolymer and outer silicone tube suitable for high-temperature environments provided by at least one embodiment of the present invention, the fluororubber of the inner layer is a high-temperature resistant fluororubber compound. The formulation system of the fluororubber compound also includes a heat-resistant stabilizer and a reinforcing filler. The heat-resistant stabilizer is used to inhibit the thermo-oxidative aging and degradation of the fluororubber during long-term use at high temperatures, and the reinforcing filler is used to improve the mechanical strength and wear resistance of the inner layer.

[0009] For example, in the high-performance inner fluoropolymer and outer silicone tubing suitable for high-temperature environments provided by at least one embodiment of the present invention, the aramid mesh in the reinforcing layer is a high-temperature resistant meta-aramid fiber woven mesh. The warp and weft threads of the aramid mesh interweave to form a grid skeleton structure. Both sides of the grid skeleton structure are calendered and coated with fluororubber, so that the fluororubber penetrates into the mesh and forms a through-type locking structure with the fluororubber coating on both sides. The reinforcing layer provides radial pressure resistance and axial tensile strength for the tubing.

[0010] For example, in the high-performance inner fluoropolymer and outer silicone tubing suitable for high-temperature environments provided by at least one embodiment of the present invention, the transition adhesive layer is a bifunctional coupling agent coating layer containing organosilicon functional groups and fluorine functional groups. The fluorine functional groups of the bifunctional coupling agent form chemical bonds with the fluororubber of the reinforcing layer, and the organosilicon functional groups of the bifunctional coupling agent form chemical bonds with the silicone rubber of the outer layer, thereby establishing a chemical bridge between the fluororubber layer and the silicone rubber layer and achieving high-strength interlayer bonding.

[0011] For example, in the high-performance inner fluorine outer silicone tube suitable for high-temperature environments provided by at least one embodiment of the present invention, the outer silicone rubber is high-temperature resistant methyl vinyl silicone rubber, the outer silicone rubber matrix contains heat-resistant reinforcing filler and tear-resistant agent, the outer layer provides thermal insulation and mechanical protection for the composite tube body in high-temperature environments, and the outer surface of the outer layer forms a smooth and dense protective surface after vulcanization.

[0012] For example, in the high-performance inner fluorine outer silicone tube suitable for high-temperature environments provided by at least one embodiment of the present invention, the high-temperature stabilization post-treatment is as follows: the vulcanized tube is placed in a high-temperature environment for heat treatment in an unconstrained free state, the temperature of the heat treatment is not lower than the working temperature of the tube, and the heat treatment is used to eliminate residual stress inside the tube body, increase the crosslinking density of each layer and enhance the bonding strength of the interlayer interface.

[0013] For example, in the high-performance inner fluoropolymer and outer silicone tubing suitable for high-temperature environments provided by at least one embodiment of the present invention, the inner wall surface of the inner layer is provided with an anti-adhesion functional gradient layer. The anti-adhesion functional gradient layer is formed by the enrichment of the organosilicon-modified fatty acid condensate into the inner wall surface during vulcanization and post-treatment. The concentration of the organosilicon-modified fatty acid condensate in the anti-adhesion functional gradient layer gradually decreases from the inner wall surface to the outer surface, so that the inner wall surface has durable low surface energy and lubrication properties.

[0014] According to another aspect, at least one embodiment of the present invention also provides a method for preparing a high-performance inner fluorine and outer silicone tubing suitable for high-temperature environments, comprising the following steps: S1. Inner layer preparation: The high-temperature resistant fluororubber compound containing organosilicon-modified fatty acid condensate is made into a tubular inner layer preform by calendering or extrusion. S2. Preparation of reinforcing layer: Aramid mesh is subjected to double-sided calendering fluororubber treatment, so that fluororubber can penetrate and cover both sides of the aramid mesh at the same time to obtain a double-sided composite reinforcing sheet. S3. Transition adhesive layer coating: A bifunctional coupling agent is coated on the outer surface of the reinforcing layer blank to form a transition adhesive layer; S4. Composite molding: The reinforcing sheet is wrapped around the outer periphery of the inner layer blank by manual winding, and then a silicone rubber outer layer sheet is wrapped around the outside of the transition adhesive layer to form a composite tube blank. S5. Vulcanization and shaping: The composite tube blank is placed on the mandrel and sent into the vulcanization equipment for high-temperature vulcanization, so that the layers can be chemically cross-linked and bonded. After vulcanization is completed, the tube is demolded to obtain the vulcanized tube body. S6. High-temperature stabilization post-treatment: The vulcanized pipe body is subjected to free-state heat treatment in a high-temperature environment not lower than the service temperature to eliminate internal stress and improve cross-linking density and interlayer bonding force to obtain the finished rubber hose.

[0015] For example, in the preparation method provided by at least one embodiment of the present invention, in step S5, the high-temperature vulcanization adopts a segmented heating vulcanization process, including a pre-pressure stage for exhaust, a pre-vulcanization stage, and a complete vulcanization stage performed sequentially; the pre-pressure stage for exhaust makes each layer of the composite tube blank tightly bonded and exhausts the residual gas between the layers; the pre-vulcanization stage for preliminary cross-linking and shaping of each layer; the complete vulcanization stage for achieving sufficient chemical cross-linking between each layer; in step S6, the duration of the high-temperature stabilization post-treatment is not less than 4 hours, and the treatment temperature matches the design operating temperature of the hose.

[0016] The beneficial effects of the embodiments of the present invention are as follows: 1. In this invention, by adding an organosilicon-modified fatty acid condensate to the inner fluororubber matrix, it migrates to the inner wall surface during vulcanization and high-temperature stabilization to form an anti-adhesion functional gradient layer or a dynamic lubricating film layer. This reduces the surface energy and frictional resistance of the inner wall surface, and decreases adhesion between the inner fluororubber and metal connectors under high-temperature compression. Therefore, the hose maintains good disassembly even after prolonged exposure to high temperatures, preventing tearing of the inner wall, residual adhesive, or damage to the connecting pipes due to adhesion during disassembly, thus improving pipeline maintenance convenience and reassembly reliability.

[0017] 2. In this invention, a composite reinforced structure is formed by double-sided calendering of aramid mesh with fluororubber, and a transitional adhesive layer formed by a bifunctional coupling agent is set between the fluororubber reinforcing layer and the silicone rubber outer layer. This transforms the conventional physical bonding between the fluororubber layer and the silicone rubber layer into an interfacial bond with chemical bridging, significantly reducing the risk of delamination, peeling, and bulging during high-temperature aging, pressure fluctuations, and bending. Simultaneously, the segmented temperature-increasing vulcanization process reduces residual gas between layers and promotes full cross-linking of each layer. The high-temperature stabilization post-treatment further eliminates internal stress, increases cross-linking density and interlayer bonding strength, enabling the hose to maintain good structural stability, pressure resistance, and service life under long-term high-temperature environments. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit the invention.

[0019] In this document, "inner layer" refers to the side of the hose closest to the medium flow channel or the outer wall of the connector during use, and "outer layer" refers to the side furthest from the medium flow channel and in contact with the external environment. Terms such as "covering," "adhering," "composite," and "connection" should be interpreted broadly. For example, they can refer to direct contact forming a connection, or a connection formed through an intermediate transition layer; they can refer to pre-composite bonding in an uncured state, or further chemical cross-linking during the curing process. Those skilled in the art can understand the meaning of these terms in this invention based on the specific circumstances.

[0020] In this invention, unless otherwise explicitly specified and limited, the first layer is located "outer periphery" or "outer side" of the second layer, which may include direct contact between the first and second layers, or may include the presence of an adhesive layer, transition layer, or other functional layer between them. The terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0021] Example 1

[0022] This embodiment provides a high-performance inner fluororubber and outer silicone tubing suitable for high-temperature environments, comprising an inner layer, a reinforcing layer, a transition adhesive layer, and an outer layer arranged sequentially from the inside to the outside. The inner layer is a high-temperature resistant fluororubber layer that extends continuously along the tubing axis to form a tubular structure, used for direct contact with metal connectors or the conveying medium during tubing use. Organosilicon-modified fatty acid condensates are dispersed in the fluororubber matrix of the inner layer. These organosilicon-modified fatty acid condensates improve the lubricity and low surface energy characteristics of the inner wall surface of the inner layer, thereby reducing the adhesion tendency between the inner layer and the metal connector under high-temperature compression.

[0023] In this embodiment, the amount of organosilicon-modified fatty acid condensate added to the inner fluororubber matrix is ​​preferably 1% to 2% of the fluororubber mass, more preferably about 1.4%. This addition ratio can ensure the mechanical properties and high-temperature resistance of the fluororubber matrix while providing good anti-adhesion effect to the inner wall surface of the inner layer. When the addition amount is too low, the improvement effect on the lubrication of the inner layer surface is not obvious; when the addition amount is too high, it may affect the crosslinking stability and mechanical strength of the fluororubber matrix. Therefore, controlling the organosilicon-modified fatty acid condensate within the above range can achieve a good balance between anti-adhesion performance and overall material strength.

[0024] During the vulcanization and high-temperature stabilization post-treatment, the organosilicon-modified fatty acid condensate can be moderately enriched into the inner wall surface of the inner layer under thermal action, forming an anti-adhesion functional gradient layer on the inner wall surface. The concentration of the organosilicon-modified fatty acid condensate in this functional gradient layer gradually decreases from the inner wall surface outwards, thus the inner wall surface has strong low surface energy and lubrication properties, while the inner layer still retains the original high-temperature resistance and mechanical support properties of the fluororubber matrix.

[0025] In this embodiment, the inner fluororubber layer also includes a heat-resistant stabilizer and reinforcing filler. The heat-resistant stabilizer includes one or more of magnesium oxide, calcium hydroxide, and hydrotalcite, preferably a compound system of magnesium oxide and calcium hydroxide. Magnesium oxide and calcium hydroxide can absorb or neutralize acidic substances generated in the system during the high-temperature vulcanization and long-term thermal aging of the fluororubber, reducing the risk of degradation of the fluororubber molecular chains under high-temperature conditions. Hydrotalcite can further improve the thermal stability and processing stability of the fluororubber system, thereby reducing the occurrence of hardening, cracking, or decreased elasticity of the inner layer during long-term high-temperature use.

[0026] The reinforcing filler includes one or more of carbon black, silica, calcium silicate, and barium sulfate, preferably a compound system of carbon black and silica. Carbon black can improve the tensile strength, abrasion resistance, and tear resistance of the fluororubber inner layer; silica can improve the structural density and compressive deformation resistance of the fluororubber inner layer; calcium silicate and barium sulfate can improve the dimensional stability and processing performance of the inner layer. Through the combination of heat stabilizer and reinforcing filler, the inner layer can simultaneously maintain good heat aging resistance, mechanical strength, and anti-sticking properties under high temperature conditions.

[0027] Example 2

[0028] Based on Example 1, this example further illustrates the structure of the reinforcing layer and the transition adhesive layer. The reinforcing layer covers the outer peripheral surface of the inner layer and is a composite reinforcing structure formed by double-sided calendered fluororubber of aramid mesh. The aramid mesh is preferably a high-temperature resistant meta-aramid fiber woven mesh, with its warp and weft threads interwoven to form a grid skeleton structure. The aramid mesh itself has high strength and good heat resistance, which can improve the tensile strength, pressure resistance, and dimensional stability of the hose under high-temperature working conditions.

[0029] During the double-sided calendering process, fluororubber is pressed in from both sides of the aramid mesh, allowing it to penetrate into the mesh openings and form a through-type interlocking structure with the fluororubber coatings on both sides of the mesh. This structure ensures that the aramid mesh is not only covered by the fluororubber surface but also forms an interlocking bond with the fluororubber in the mesh area, thereby reducing the risk of relative slippage between the aramid mesh and the rubber matrix under pressure, tension, or bending conditions.

[0030] A transition adhesive layer is disposed between the reinforcing layer and the outer layer. Since the outer surface of the reinforcing layer is primarily a fluororubber system, while the outer layer is a silicone rubber system, the interfacial bonding strength is easily insufficient when the two are directly laminated. Therefore, in this embodiment, a transition adhesive layer is disposed between them. The transition adhesive layer is preferably a bifunctional coupling agent coating layer containing both organosilicon and fluorine functional groups. The fluorine functional groups can form chemical bonds with the fluororubber in the reinforcing layer, and the organosilicon functional groups can form chemical bonds with the silicone rubber in the outer layer.

[0031] Through the bridging effect of the aforementioned bifunctional coupling agent, a chemical bonding interface is formed between the fluororubber reinforcing layer and the silicone rubber outer layer. Compared with traditional composite methods that rely solely on material softening and bonding or mechanical pressing, this chemically bridging interface can significantly improve the interlayer peel strength, making the hose less prone to delamination, peeling, and bulging under long-term high temperature, repeated bending, and pressure impact conditions.

[0032] Example 3

[0033] Based on Example 1 or Example 2, this example further illustrates the overall performance of the outer layer and the composite tube. The outer layer is a silicone rubber layer, covering the outer periphery of the transition adhesive layer. The outer layer is preferably made of high-temperature resistant methyl vinyl silicone rubber, which has good heat resistance, flexibility and adaptability to the external environment. It can form a protective layer on the outside of the tube, reducing the impact of external heat sources, friction, oil stains and assembly clamping on the internal structure.

[0034] The outer silicone rubber matrix contains heat-resistant reinforcing fillers and tear-resistant agents. The heat-resistant reinforcing fillers include one or more of fumed silica, precipitated silica, alumina, titanium dioxide, and silica powder, preferably a compound system of fumed silica and alumina. Fumed silica significantly improves the tensile strength, resilience, and resistance to compression set of the silicone rubber outer layer; alumina improves the heat resistance and thermal conductivity uniformity of the outer layer, reducing thermal damage caused by localized high temperatures; titanium dioxide and silica powder improve the aging resistance, dimensional stability, and surface density of the outer layer. With the addition of these heat-resistant reinforcing fillers, the outer layer can maintain good strength and morphological stability even under long-term high-temperature conditions.

[0035] The tear-resistant additive includes one or more of vinyl MQ silicone resin, hydroxyl silicone oil, hydrogen-containing silicone oil, and silane coupling agents, preferably a compound system of vinyl MQ silicone resin and hydroxyl silicone oil. Vinyl MQ silicone resin can form a resin reinforcing phase in the silicone rubber crosslinking network, improving the tear strength and crack propagation resistance of the outer layer; hydroxyl silicone oil can improve the dispersibility of silica in silicone rubber and reduce local stress concentration caused by filler agglomeration; hydrogen-containing silicone oil can participate in the silicone rubber crosslinking reaction, improving the integrity of the outer layer network structure; and silane coupling agents can enhance the interfacial bonding between the filler and the silicone rubber matrix. Through the combination of the tear-resistant additive and the heat-resistant reinforcing filler, the outer layer is less prone to tearing, cracking, or surface damage during installation, disassembly, bending, and contact with pipe clamps.

[0036] In this embodiment, the outer layer, after vulcanization, forms a smooth and dense external protective surface. This external protective surface reduces the adhesion of oil, dust, and external media, and reduces surface wear during hose assembly. The inner layer, reinforcing layer, transition adhesive layer, and outer layer are composite molded to form an integrated composite tube. The inner layer provides high-temperature resistance, media resistance, and anti-adhesion properties; the reinforcing layer provides pressure resistance, tensile strength, and structural support properties; the transition adhesive layer improves the interfacial bonding strength between the fluororubber system and the silicone rubber system; and the outer layer provides heat protection and mechanical protection. The functional division between each layer is clear, and the overall structure is formed through vulcanization crosslinking and chemical bridging, enabling the hose to possess high-temperature anti-adhesion, anti-delamination, pressure resistance, and long-term stable performance.

[0037] Example 4

[0038] This embodiment provides a method for preparing a high-performance inner fluorine and outer silicone tubing suitable for high-temperature environments, used to prepare the tubing described in any one of Embodiments 1 to 3, comprising the following steps: First, the inner layer is compounded and the inner layer preform is prepared. High-temperature fluororubber, silicone-modified fatty acid condensate, heat stabilizer, reinforcing filler, and conventional vulcanization aids are added to a Banbury mixer or open mill for compounding to obtain a high-temperature fluororubber compound. The silicone-modified fatty acid condensate is used to improve the lubricity and anti-sticking properties of the inner layer. The heat stabilizer includes one or more of magnesium oxide, calcium hydroxide, and hydrotalcite, preferably a mixture of magnesium oxide and calcium hydroxide, used to absorb or neutralize acidic substances generated during high-temperature vulcanization and long-term thermal aging of the fluororubber, reducing the risk of thermal degradation of the fluororubber molecular chains. The reinforcing filler includes one or more of carbon black, silica, calcium silicate, and barium sulfate, preferably a mixture of carbon black and silica, used to improve the tensile strength, wear resistance, structural density, and compressive deformation resistance of the inner layer. After compounding, the high-temperature fluororubber compound is formed into a tubular inner layer preform by calendering or extrusion, ensuring continuous axial molding and a smooth inner wall.

[0039] Next, the reinforcing layer is prepared. High-temperature resistant aramid mesh is selected as the reinforcing skeleton material, preferably a meta-aramid fiber woven mesh. Fluororubber compound is calendered onto both sides of the aramid mesh, allowing the fluororubber to simultaneously penetrate into the mesh openings from both sides and coat the aramid fibers, thus obtaining a double-sided composite reinforced sheet. Through double-sided calendering, the fluororubber coatings on both sides of the aramid mesh can interpenetrate at the mesh openings, forming a through-type interlocking structure. This improves the interlocking strength between the aramid mesh and the fluororubber, reducing the possibility of fiber slippage or local delamination under high-temperature pressure, tension, or bending conditions.

[0040] Then, a transition adhesive layer treatment is performed. A bifunctional coupling agent is uniformly coated on the outer surface of the double-sided composite reinforcing sheet to form a transition adhesive layer. The bifunctional coupling agent contains fluorinated functional groups that can bond with fluororubber and organosilicon functional groups that can bond with silicone rubber. After coating, the reinforcing sheet is allowed to rest appropriately, allowing the bifunctional coupling agent to form a continuous and uniform interface layer on the outer surface of the reinforcing sheet. This transition adhesive layer forms an interface bond with the fluororubber in the reinforcing layer and the silicone rubber in the outer layer during the subsequent high-temperature vulcanization process, thereby establishing a chemical bridge between the fluororubber system and the silicone rubber system and improving the interlayer bonding strength between the two types of rubber materials.

[0041] Subsequently, the outer layer is compounded and the outer layer sheet is prepared. High-temperature resistant methyl vinyl silicone rubber, heat-resistant reinforcing filler, tear-resistant agent, and vulcanization aid are added to a Banbury mixer or open mill and compounded to obtain the silicone rubber outer layer compound. The heat-resistant reinforcing filler includes one or more of fumed silica, precipitated silica, alumina, titanium dioxide, and silica powder, preferably a compound system of fumed silica and alumina, used to improve the tensile strength, heat resistance, resistance to compression set, and surface density of the outer layer. The tear-resistant agent includes one or more of vinyl MQ silicone resin, hydroxyl silicone oil, hydrogen-containing silicone oil, and silane coupling agent, preferably a compound system of vinyl MQ silicone resin and hydroxyl silicone oil, used to improve the tear strength, crack propagation resistance, and dispersion stability of the filler in the silicone rubber matrix of the silicone rubber outer layer. After compounding, the silicone rubber outer layer compound is calendered into a silicone rubber outer layer sheet.

[0042] Next, composite molding is performed. The tubular inner layer preform is fitted onto the mandrel, or a tubular inner layer preform is directly formed on the outer periphery of the mandrel. Then, the double-sided composite reinforcing sheet is manually wound around the outer periphery of the inner layer preform, ensuring full adhesion between the reinforcing sheet and the inner layer preform. Subsequently, a silicone rubber outer layer sheet is wound around the outside of the transition adhesive layer to form a composite tube preform. During the manual winding process, uniform adhesion between layers should be maintained, and air trapping between layers should be avoided as much as possible, so that the inner layer, reinforcing layer, transition adhesive layer, and outer layer form a stable pre-composite structure before vulcanization.

[0043] Following this, high-temperature vulcanization and shaping are performed. The composite tube blank, along with the mandrel, is fed into the vulcanization equipment for high-temperature vulcanization. High-temperature vulcanization preferably employs a segmented heating vulcanization process, including a sequential venting and pre-compression stage, a pre-vulcanization stage, and a complete vulcanization stage. The venting and pre-compression stage is used to further tighten the layers of the composite tube blank under heat and pressure, and to expel residual gas between layers to reduce bubbles, bulges, and localized voids. The pre-vulcanization stage is used to initially cross-link and shape the inner, reinforcing, and outer layers, maintaining the basic shape of the hose. The complete vulcanization stage is used to fully cross-link the layers and allow the transition adhesive layer to act as a chemical bridge between the fluororubber and silicone rubber, forming a firmly bonded, integrated vulcanized tube body. After vulcanization, the vulcanized tube body is removed from the mandrel.

[0044] Finally, a high-temperature stabilization post-treatment is performed. The demolded vulcanized tube is placed in a high-temperature environment under unconstrained free conditions for heat treatment. The heat treatment temperature matches the design operating temperature of the hose, and the treatment time is no less than 4 hours. This high-temperature stabilization post-treatment eliminates internal residual stress generated during winding, vulcanization, and cooling of the composite tube, improving the dimensional stability of the tube under high-temperature conditions. It also promotes further stabilization of the cross-linked network of each rubber layer, improving the interlayer interface bonding strength. Simultaneously, it encourages the appropriate enrichment of organosilicon-modified fatty acid condensates in the inner fluororubber layer onto the inner wall surface, forming an anti-adhesion functional gradient layer or dynamic lubricating film layer, thereby improving the smoothness of disassembly and anti-adhesion performance of the hose after high-temperature use. After the above treatment, a high-performance inner fluororubber and outer silicone tube suitable for high-temperature environments is obtained.

[0045] In summary, this application introduces organosilicon-modified fatty acid condensates into the high-temperature resistant fluororubber inner layer, and combines it with an aramid mesh double-sided calendered fluororubber reinforcement structure, a bifunctional coupling agent transition adhesive layer, a high-temperature resistant silicone rubber outer layer, a segmented temperature-increasing vulcanization process, and a high-temperature stabilization post-treatment. This enables the hose to simultaneously possess properties such as high-temperature anti-adhesion, anti-delamination, pressure resistance enhancement, dimensional stability, and long-term reliable use, solving the problems of existing inner fluororubber and outer silicone rubber hoses easily sticking to metal connectors and having weak interlayer bonding under high-temperature environments.

[0046] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A high-performance inner fluoropolymer and outer silicone tubing suitable for high-temperature environments, characterized in that: Including the following, arranged sequentially from the inside out: The inner layer is a high-temperature resistant fluororubber layer that extends continuously along the axial direction of the tube to form a tubular structure. Organosilicon-modified fatty acid condensates are dispersed in the fluororubber matrix of the inner layer to improve the surface lubricity and anti-adhesion properties of the inner layer, so that the inner layer does not stick to the metal connector in a high-temperature environment. A reinforcing layer is wrapped around the outer peripheral surface of the inner layer. The reinforcing layer is a composite reinforcing structure formed by double-sided calendering of aramid mesh and fluororubber. Both sides of the aramid mesh are covered with fluororubber to form an integrated reinforcing sheet. A transition adhesive layer is disposed between the reinforcing layer and the outer layer to achieve chemical bonding between the fluororubber layer and the silicone rubber layer; The outer layer is a silicone rubber layer that covers the outer peripheral surface of the transition adhesive layer; The inner layer, reinforcing layer, transition adhesive layer and outer layer are manually wound together, then integrally molded by high-temperature vulcanization, and then subjected to high-temperature stabilization post-treatment to form an integrated composite pipe body that is resistant to sticking and delamination.

2. The high-performance inner fluorine and outer silicone tubing suitable for high-temperature environments according to claim 1, characterized in that, The amount of the organosilicon-modified fatty acid condensate added to the inner fluororubber matrix is ​​1% to 2% of the mass of the fluororubber. The organosilicon-modified fatty acid condensate continuously migrates to the inner wall surface of the inner layer under high temperature environment to form a dynamic lubricating film layer, so that the dynamic friction coefficient of the inner wall surface of the inner layer is lower than the dynamic friction coefficient when it is not added.

3. The high-performance inner fluoropolymer and outer silicone tubing suitable for high-temperature environments according to claim 1, characterized in that, The inner layer of fluororubber is a high-temperature resistant fluororubber compound. The formulation system of the fluororubber compound also includes a heat-resistant stabilizer and a reinforcing filler. The heat-resistant stabilizer is used to inhibit the thermo-oxidative aging and degradation of the fluororubber during long-term use at high temperatures, and the reinforcing filler is used to improve the mechanical strength and wear resistance of the inner layer.

4. The high-performance inner fluoropolymer and outer silicone tubing suitable for high-temperature environments according to claim 1, characterized in that, The aramid mesh in the reinforcing layer is a high-temperature resistant meta-aramid fiber woven mesh. The warp and weft threads of the aramid mesh interweave to form a grid skeleton structure. Both sides of the grid skeleton structure are calendered and coated with fluororubber, so that the fluororubber penetrates into the mesh and forms a through-type locking structure with the fluororubber coating on both sides. The reinforcing layer provides radial pressure resistance and axial tensile strength for the hose.

5. The high-performance inner fluoropolymer and outer silicone tubing suitable for high-temperature environments according to claim 1, characterized in that, The transition adhesive layer is a bifunctional coupling agent coating layer containing organosilicon functional groups and fluorine functional groups. The fluorine functional groups of the bifunctional coupling agent form chemical bonds with the fluororubber of the reinforcing layer, and the organosilicon functional groups of the bifunctional coupling agent form chemical bonds with the silicone rubber of the outer layer, thereby establishing a chemical bridge between the fluororubber layer and the silicone rubber layer and achieving high-strength interlayer bonding.

6. The high-performance inner fluoropolymer and outer silicone tubing suitable for high-temperature environments according to claim 1, characterized in that, The outer layer of silicone rubber is high-temperature resistant methyl vinyl silicone rubber. The outer layer of silicone rubber matrix contains heat-resistant reinforcing filler and tear-resistant agent. The outer layer provides thermal insulation and mechanical protection for the composite pipe body in a high-temperature environment. The outer surface of the outer layer forms a smooth and dense protective surface after vulcanization.

7. The high-performance inner fluoropolymer and outer silicone tubing suitable for high-temperature environments according to claim 1, characterized in that, The high-temperature stabilization post-treatment is as follows: the vulcanized rubber hose is placed in a high-temperature environment for heat treatment in an unconstrained free state. The heat treatment temperature is not lower than the working temperature of the rubber hose. The heat treatment is used to eliminate residual stress inside the hose, increase the crosslinking density of each layer, and enhance the bonding strength of the interlayer interface.

8. The high-performance inner fluorine and outer silicone tubing suitable for high-temperature environments according to claim 1, characterized in that, The inner wall surface of the inner layer is provided with an anti-adhesion functional gradient layer. The anti-adhesion functional gradient layer is formed by the enrichment of the organosilicon modified fatty acid condensate into the inner wall surface during the vulcanization and post-treatment process. The concentration of the organosilicon modified fatty acid condensate in the anti-adhesion functional gradient layer gradually decreases from the inner wall surface to the outside, so that the inner wall surface has a long-lasting low surface energy and lubrication properties.

9. A method for preparing a high-performance inner fluorine and outer silicone tubing suitable for high-temperature environments as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Inner layer preparation: The high-temperature resistant fluororubber compound containing organosilicon-modified fatty acid condensate is made into a tubular inner layer preform by calendering or extrusion. S2. Preparation of reinforcing layer: Aramid mesh is subjected to double-sided calendering fluororubber treatment, so that fluororubber can penetrate and cover both sides of the aramid mesh at the same time to obtain a double-sided composite reinforcing sheet. S3. Transition adhesive layer coating: A bifunctional coupling agent is coated on the outer surface of the reinforcing layer blank to form a transition adhesive layer; S4. Composite molding: The reinforcing sheet is wrapped around the outer periphery of the inner layer blank by manual winding, and then a silicone rubber outer layer sheet is wrapped around the outside of the transition adhesive layer to form a composite tube blank. S5. Vulcanization and shaping: The composite tube blank is placed on the mandrel and sent into the vulcanization equipment for high-temperature vulcanization, so that the layers can be chemically cross-linked and bonded. After vulcanization is completed, the tube is demolded to obtain the vulcanized tube body. S6. High-temperature stabilization post-treatment: The vulcanized pipe body is subjected to free-state heat treatment in a high-temperature environment not lower than the service temperature to eliminate internal stress and improve cross-linking density and interlayer bonding force to obtain the finished rubber hose.

10. The preparation method according to claim 9, characterized in that, In step S5, the high-temperature vulcanization adopts a segmented temperature-increasing vulcanization process, including a pre-pressure exhaust stage, a pre-vulcanization stage, and a complete vulcanization stage performed sequentially; the pre-pressure exhaust stage causes the layers of the composite tube blank to adhere tightly and exhaust residual gas between the layers; the pre-vulcanization stage causes the layers to undergo preliminary cross-linking and shaping; and the complete vulcanization stage causes the layers to achieve full chemical cross-linking and bonding. In step S6, the duration of the high-temperature stabilization post-treatment is not less than 4 hours, and the treatment temperature matches the design operating temperature of the hose.