A flexible bendable composite pipe supported by spring winding with ePTFE membrane, its preparation method and application

Abstract

This invention discloses a flexible, bendable composite pipe with spring support for ePTFE membrane winding, its preparation method, and its applications. The composite pipe includes a spring support body; multiple layers of ePTFE expanded polytetrafluoroethylene (ePTFE) membrane wound around the outer surface of the spring support body; the multiple ePTFE membranes are crystalline-linked by a hot-melt sintering process to form fluorocarbon bonds, thus combining the multiple ePTFE membranes with the spring support body to form a composite pipe wall structure. This structure solves the problems of collapse and loosening caused by the softness and deformation of single-layer ePTFE membranes, endowing the pipe with good tensile strength, flexible bending characteristics, and air permeability / filtration functions due to the microporous structure of ePTFE. The pipe is resistant to chemical corrosion and has a wide temperature adaptability range, making it suitable for industrial fluid transport and filtration systems requiring flexible conveying, pressure balance, or the infiltration / emission of specific gases. The preparation method mainly includes winding and hot-melt sintering processes within a specific temperature range.

Description

Technical Field

[0001] This invention relates to the field of composite pipes for fluid transport and filtration, and in particular to a flexible, bendable composite pipe with spring support for ePTFE membrane winding, its preparation method, and its application. Background Technology

[0002] Due to its unique microporous network structure, ePTFE membranes possess excellent air permeability, chemical inertness, resistance to high and low temperatures, and low surface energy, and have been widely used in gas filtration, liquid purification, medical protection, and breathable and waterproof applications. Traditionally, ePTFE membranes are typically used in the form of planar films or simple linings.

[0003] However, when applied to fluid transport or filtration in pipeline configurations, a single ePTFE membrane, due to its inherent softness and low mechanical strength, struggles to maintain the pipeline's shape stability under pressure. Over time, it is prone to collapse, loosening, and wrinkling, which not only affects the appearance of the pipeline system but also severely reduces its filtration efficiency, air permeability uniformity, and flow channel stability, limiting its application in dynamic or pressure fluid systems requiring structural strength and shape retention.

[0004] In existing technologies, there are solutions that use rigid pipes lined with or covered with ePTFE membranes, but such structures often sacrifice the flexibility of the pipes and are difficult to adapt to complex working conditions that require bending and pipe laying. Summary of the Invention

[0005] The main technical problem solved by this invention is to provide a composite pipe structure that can maintain the excellent functional properties of ePTFE membrane while also having good mechanical strength, shape retention and flexible bending ability.

[0006] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide a flexible bendable composite pipe with spring support for ePTFE membrane winding, comprising: a spring support body; multiple layers of ePTFE expanded polytetrafluoroethylene membrane, wound on the outer surface of the spring support body; the multiple layers of ePTFE membrane are connected by fluorocarbon bond crystallization through a hot melt sintering process, so that the multiple layers of ePTFE membrane and the spring support body are combined to form a composite pipe wall structure.

[0007] In a preferred embodiment of the present invention, the spring support is a helical spring or a braided spring structure to provide different radial support forces and flexibility characteristics.

[0008] In a preferred embodiment of the present invention, the spring support is made of a polymer, including polyethylene, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene propylene copolymer, perfluoroalkyl, polyimide, polyetheretherketone, nylon or stainless steel, to adapt to different chemical environments and temperature requirements.

[0009] In a preferred embodiment of the present invention, the ePTFE membrane has a uniform and dense microporous network structure with micropore diameters between 0.1 micrometers and 30 micrometers, which is the basis for realizing functions such as precision filtration and air permeability.

[0010] In a preferred embodiment of the present invention, the ePTFE membrane is wound with at least one layer, and the specific number of layers is determined according to the fluid transport pressure, flow rate and air permeability parameters that the composite pipeline needs to withstand.

[0011] In a preferred embodiment of the present invention, the spring support is a hollow structure, so that the composite pipeline as a whole has a fluid transport channel.

[0012] Another technical solution adopted by the present invention is: providing a method for preparing a flexible, bendable composite pipe with spring support for ePTFE membrane winding, comprising the following steps:

[0013] S1: Prepare the spring support and ePTFE membrane;

[0014] S2: The ePTFE membrane is wound around the outer surface of the spring support to form a multi-layer winding structure;

[0015] S3: The wound tube is subjected to hot melt sintering treatment, so that the layers of the ePTFE membrane are firmly connected through fluorocarbon bond crystallization;

[0016] S4: Test the air permeability and pressure resistance of the sintered composite pipes to ensure product qualification.

[0017] In a preferred embodiment of the present invention, the temperature of the hot melt sintering treatment in step S3 is 340°C to 360°C, and the temperature is maintained for 0.5 to 1 hour.

[0018] Another technical solution adopted by the present invention is to provide an application of the composite pipe as a filtration or conveying pipe.

[0019] In a preferred embodiment of the present invention, the application is any of the following:

[0020] a) Used as an exhaust pipe for pure substance fluids in a filtration system;

[0021] b) Gas filtration ducts used in ventilation systems for cleanrooms in the semiconductor industry to intercept particles as small as 0.1 micrometers;

[0022] c) Precision liquid filtration pipes used for corrosive media in the chemical industry;

[0023] d) Used as a non-polluting fluid transport pipeline for food, beverages, or oil products;

[0024] e) Used as industrial pipelines for transporting corrosive gases.

[0025] The beneficial effects of this invention are: the spring support body of this invention gives the pipeline good resistance to radial collapse and shape retention, while the outer sintered ePTFE membrane provides chemical protection and functional interface. The combination of the two enables the pipeline to work under certain pressure and to be flexibly bent for installation, adapting to complex pipeline layouts.

[0026] This invention utilizes a hot-melt sintering process to firmly bond the membrane layers while essentially preserving the original microporous structure of the ePTFE material, thereby fully retaining its high air permeability, precise filtration capability, excellent chemical stability, and wide temperature range tolerance.

[0027] This composite pipeline can not only be used for the transportation and filtration of conventional corrosive fluids, but its unique breathable membrane wall has also opened up new applications in new processes such as in-situ gas addition and online gas removal, realizing the functional upgrade of pipelines from "passive transmission" to "active process treatment". Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0029] Figure 1 This is a schematic diagram of a preferred embodiment of the flexible, bendable composite pipe supported by a spring for ePTFE membrane winding according to the present invention;

[0030] Figure 2 This is a schematic diagram of the typical microstructure (SEM) of an ePTFE expanded polytetrafluoroethylene membrane. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0033] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0034] In the description of this invention, it should be noted that the terms "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0035] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] In this invention, unless otherwise expressly specified and limited, "above or below" a first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on" the first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] Please see Figure 1 and Figure 2 The embodiments of the present invention include:

[0038] Example 1:

[0039] A method for preparing a flexible, bendable composite pipe with spring support for ePTFE membrane winding includes the following steps:

[0040] S1: Prepare a stainless steel helical spring as the spring support 1. Prepare an ePTFE membrane 2 with an average pore size of 1.0 μm and a thickness of 0.15 mm, whose microporous structure is uniform and dense.

[0041] S2: Cut the ePTFE membrane into strips. With a 50% overlap, spirally wind the strips onto the outer surface of the spring support 1, for a total of 3 layers. The number of layers is determined based on the target pressure resistance (0.5MPa).

[0042] S3: Place the winding in a sintering furnace and hold at 350°C for 40 minutes, followed by a programmed cooling process. This process allows the ePTFE layers to crystallize and firmly connect through fluorocarbon bonds, thus bonding with the spring.

[0043] S4: After cooling, the pipe shows no leakage under 0.6MPa water pressure and can be bent to a radius of curvature 8 times the pipe diameter. The air permeability test is passed.

[0044] This embodiment verifies that a composite pipe with strength, flexibility, and breathability can be formed by using a stainless steel helical spring as support and an ePTFE membrane with specific parameters after winding and sintering at a specific temperature.

[0045] Example 2:

[0046] A method for preparing a flexible, bendable composite pipe with spring support for ePTFE membrane winding includes the following steps:

[0047] S1: Prepare a helical spring made of PFA material as the support body 1. Prepare an ePTFE membrane 2 with an average pore size of 0.5μm and a thickness of 0.1mm.

[0048] S2: The ePTFE membrane is spirally wound onto the spring with a 55% overlap rate, for a total of 5 layers, to improve durability and filtration accuracy in corrosive environments.

[0049] S3: Place the wound material in a sintering furnace and sinter at 345℃ for 1 hour. PFA material is morphologically stable at this temperature and can bond well with the ePTFE membrane.

[0050] S4: After cooling, the pipeline exhibits excellent resistance to hydrofluoric acid corrosion, withstands pressure up to 0.4MPa, and its air permeability meets the requirements for filtration of 0.1-micron particles.

[0051] This embodiment demonstrates the feasibility of using fluoropolymer (PFA) springs and achieves higher corrosion resistance and precision filtration requirements by increasing the number of winding layers.

[0052] Example 3:

[0053] A method for preparing a flexible, bendable composite pipe with spring support for ePTFE membrane winding includes the following steps:

[0054] S1: A mesh spring tube woven from PTFE filaments is used as the support 1. An air-permeable ePTFE membrane 2 with an average pore size of 5.0 μm and a thickness of only 0.05 mm is selected.

[0055] S2: The ePTFE membrane is wound with a 60% overlap rate using precise tension control to form an extremely thin functional layer, aiming to achieve maximum air permeability and flexibility.

[0056] S3: Place the winding body in a sintering furnace and sinter at 350°C for 0.5 hours.

[0057] S4: After cooling, the resulting pipe is extremely flexible and can be bent tightly, making it suitable for gas circuits in dynamic equipment. It withstands pressure up to 0.15 MPa and has extremely high gas permeability.

[0058] This embodiment verifies that an ultra-flexible pipe can be achieved by using a braided spring structure and single-layer winding, which is suitable for scenarios with extremely high flexibility requirements.

[0059] Example 4:

[0060] The composite pipe prepared in Example 1 was applied to a pure water cleaning system. Pure water was pumped into the composite pipe at a certain flow rate. In the external environment of the pipe, a gas containing a certain concentration of ozone was introduced and allowed to flow around the pipe.

[0061] Because the water pressure inside the pipe is slightly higher than the external ozone gas pressure, and the ePTFE membrane has excellent hydrophobic and aerophilic properties, ozone gas molecules from the external environment, driven by the partial pressure difference, pass through the micropores of the ePTFE membrane in the pipe wall (such as...). Figure 2 The ozone structure shown selectively permeates into the water flow inside the pipe. By adjusting the water flow rate, ozone concentration, and pipe length, stable concentration ozone water can be continuously produced online and directly used in the cleaning process of semiconductor devices, effectively killing microorganisms without leaving chemical residues.

[0062] Example 5:

[0063] In the field of bio-fermentation, the composite pipe prepared by the method of this invention is used to transport fermentation broth containing yeast. During the flow of the fermentation broth within the pipe, carbon dioxide gas is continuously generated.

[0064] Because the fermentation broth flows in a closed loop within the pipe, the generated CO2 will dissolve in the liquid to supersaturation and may aggregate into bubbles. The ePTFE membrane wall of the composite pipe of this invention allows gas molecules to pass through. Driven by the higher partial pressure of CO2 inside the pipe, the dissolved CO2 and microbubbles gradually diffuse into the atmosphere outside the pipe through the micropores of the pipe wall.

[0065] This process enables online, gentle degassing of the fermentation broth during transport, effectively reducing the risk of gas accumulation downstream of the pipeline and avoiding flow instability or pump cavitation problems caused by gas embolism. At the same time, it reduces the intake of dissolved oxygen in the fermentation broth (because the CO2 escape process does not involve violent agitation), which is beneficial for certain anaerobic or microaerobic fermentation processes.

[0066] This process enables online, gentle degassing of the fermentation broth during transport, effectively reducing the risk of gas accumulation downstream of the pipeline and avoiding flow instability or pump cavitation problems caused by gas embolism. At the same time, it reduces the intake of dissolved oxygen in the fermentation broth (because the CO2 escape process does not involve violent agitation), which is beneficial for certain anaerobic or microaerobic fermentation processes.

[0067] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A flexible, bendable composite pipe with spring support for ePTFE membrane winding, characterized in that, include: A spring support; A multilayer ePTFE expanded polytetrafluoroethylene film is wrapped around the outer surface of the spring support body; The multilayer ePTFE membranes are connected by fluorocarbon bonds through a hot-melt sintering process, which combines the multilayer ePTFE membranes with the spring support to form a composite pipe wall structure.

2. The flexible, bendable composite pipe with spring support for ePTFE membrane winding according to claim 1, characterized in that, The spring support is a helical spring or a braided spring structure.

3. The flexible, bendable composite pipe with spring support for ePTFE membrane winding according to claim 1, characterized in that, The spring support is made of one of the following materials: polyethylene, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene propylene copolymer, perfluoroalkyl, polyimide, polyetheretherketone, nylon, or stainless steel.

4. The flexible, bendable composite pipe with spring support for ePTFE membrane winding according to claim 1, characterized in that, The ePTFE membrane has a uniform and dense microporous network structure with micropore diameters ranging from 0.1 micrometers to 30 micrometers.

5. The flexible, bendable composite pipe with spring support for ePTFE membrane winding according to claim 1, characterized in that, The ePTFE membrane has at least one winding layer, and the specific number of layers is determined according to the fluid transport pressure, flow rate and air permeability parameters that the composite pipeline needs to withstand.

6. The flexible, bendable composite pipe with spring support for ePTFE membrane winding according to claim 1, characterized in that, The spring support is a hollow structure, which enables the composite pipeline to have a fluid transport channel.

7. A method for preparing a flexible, bendable composite pipe with spring support for ePTFE membrane winding as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Prepare the spring support and ePTFE membrane; S2: The ePTFE membrane is wound around the outer surface of the spring support to form a multi-layer winding structure; S3: The wound tube is subjected to hot melt sintering treatment, so that the layers of the ePTFE membrane are firmly connected through fluorocarbon bond crystallization; S4: Test the air permeability and pressure resistance of the sintered composite pipe.

8. The method according to claim 7, characterized in that, The temperature of the hot melt sintering treatment in step S3 is 340°C to 360°C, and the holding time is 0.5 to 1 hour.

9. The application of a composite pipe as described in any one of claims 1 to 6 as a filtration or conveying pipe.

10. The application according to claim 9, characterized in that, The application is any one of the following: a) Used as an exhaust pipe for pure substance fluids in a filtration system; b) Gas filtration ducts used in ventilation systems for cleanrooms in the semiconductor industry to intercept particles as small as 0.1 micrometers; c) Precision liquid filtration pipes used for corrosive media in the chemical industry; d) Used as a non-polluting fluid transport pipeline for food, beverages, or oil products; e) Used as industrial pipelines for transporting corrosive gases.

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