A braided pultrusion process for corrosion-resistant composite pipe

Abstract

A kind of braiding pultrusion process of corrosion-resistant composite pipe, the main part of composite pipe is polymer material, at least one layer of carbon fiber material is attached to the surface of polymer material, which is braided into shape;The form of rotary extrusion is used to attach carbon fiber material to the surface of polymer material, and the form of impregnating carbon fiber is also used, which can reduce the angle bending and position movement of carbon fiber due to mutual friction during direct braiding process, and when subsequent melting and re-shaping, the re-melting of epoxy resin can strengthen the connection strength between pipe and carbon fiber and carbon fiber, so as to better play the role of structural strength improvement of carbon fiber, and prevent cracks between them during subsequent use.

Description

Technical Field

[0001] This invention relates to a braided pultrusion molding process for corrosion-resistant composite pipes. Background Technology

[0002] With the gradual development of carbon fiber raw materials, applying carbon fiber to the production of existing plastic polymer pipes to increase the impact resistance of pipes has become a new development direction in the industry.

[0003] Currently, the processing technology of plastic polymer pipes mainly uses extrusion molding for high-speed, uninterrupted production. Its main competitive advantage in processing costs lies in its extremely high production efficiency, which is far higher than that of pipes made of other materials. Furthermore, due to advancements in plastic polymer materials, its quality and strength are gradually approaching those of metal pipes.

[0004] However, after introducing carbon fiber, the existing winding molding methods are all intermittent processes, which greatly affect production efficiency. Furthermore, during downtime, some raw materials are wasted at the plastic extruder, requiring readjustment of the extruder. This results in a significant increase in production costs.

[0005] In addition, some researchers have applied 0° coverage to carbon fibers, which does not require weaving and can cover the surface with carbon fibers. However, this method has very limited strength. Furthermore, how to combine the generally accepted optimal weaving angle of 45° with extrusion molding remains one of the technical challenges in the industry.

[0006] Therefore, the main problem to be solved at present is how to achieve a seamless production process for 45° carbon fiber braiding, so as to meet the requirements of braiding extrusion molding of polymer plastic pipes. Summary of the Invention

[0007] The purpose of this invention is to provide a braided pultrusion molding process for corrosion-resistant composite pipes, which solves the problems of continuous production and low bonding strength in the prior art.

[0008] A braided pultrusion molding process for a corrosion-resistant composite pipe, wherein the main body of the composite pipe is made of polymer material, and the surface of the polymer material is coated with at least one layer of braided carbon fiber material.

[0009] To ensure continuous production and improve bonding strength, attaching carbon fiber material to the surface of the polymer material includes the following steps:

[0010] S1. Powdered epoxy resin material is adsorbed onto the surface of filamentous carbon fiber material by electrostatic adsorption.

[0011] S2. After attachment, immerse the material in molten epoxy resin to melt a layer of epoxy resin onto the surface of the single-strand carbon fiber material.

[0012] S3. Set up an inlet with a certain temperature. The inlet will shape the epoxy resin material on the surface. After the shaping is completed, it will be cooled and shaped.

[0013] S4. A heating device is installed at the discharge port of the pipe extruder to uniformly heat the surface of the prepared pipe.

[0014] S5. The rear end of the heating device is equipped with multiple rotating devices arranged in sequence. The multiple rotating devices are divided into two operating states: working and waiting. The rotating devices in operation will sequentially wind the filamentous carbon fibers with epoxy resin layer attached to the surface of the pipe.

[0015] S6. After attaching carbon fiber, heat it to melt and reshape the epoxy resin on the surface.

[0016] To achieve weaving effects or provide weaving capabilities at different angles, multiple rotating devices employ both forward and reverse winding methods. These two winding methods are combined to create the weaving pattern on the surface. Each rotating device uses only one strand of carbon fiber material. Using a single strand ensures that only one strand is attached to each rotating device at a time, thus allowing for easier control over the weaving pattern.

[0017] Furthermore, to ensure the yarn has a certain shaping ability, the shape of the insertion point can be circular, semi-circular, Ω-shaped, or square. Among these, circular yarns have the optimal surface resin content, while irregularly shaped yarns will improve the subsequent molding effect and the connection strength between them. In actual production, a circular shape is generally used to reduce friction while increasing the resin content.

[0018] To ensure rapid impregnation of carbon fibers by the epoxy resin system within a short time, reactive epoxy resin diluents, such as 1,4-butanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and bisphenol A polyoxyethylene ether, were blended with commonly used liquid bisphenol A type epoxy resins (such as E-51 and E-53) to obtain a low-viscosity epoxy resin system. Simultaneously, to ensure good mechanical properties of the resin matrix, multifunctional epoxy compounds with rigid structures (such as triglycidyl isocyanurate) were added to increase the crosslinking density of the cured resin. The effects of diluent structure and dosage on the viscosity of the epoxy resin system were tested using a rotational rheometer; the advancing contact angle at the interface between the resin system and carbon fiber was analyzed using a surface / interfacial tensiometer; the thermodynamic adhesion work between the resin system and carbon fiber was calculated using the Young-Dupre method; and the effects of diluent structure and dosage on the wettability and impregnation rate of the epoxy resin system and carbon fiber were investigated.

[0019] To ensure the efficient and continuous operation of the braiding-pultrusion process, a rapid-curing resin system was prepared by mixing an anionic catalytic curing agent (imidazolium curing agent) with epoxy resin. Imidazole compounds possess tertiary amine nitrogen atoms, which can initiate anionic chain polymerization of epoxy groups, resulting in rapid curing.

[0020] However, commonly used imidazole compounds have high room temperature curing activity, short process pot life after mixing with epoxy resin, and rapid increase in resin viscosity, making it difficult for the resin to impregnate the fiber in the later stage; in addition, the curing exothermic system of ordinary imidazole is intense, and "core burning" is likely to occur when preparing thicker products.

[0021] Therefore, ordinary imidazole curing agents are passivated to reduce reactivity, improve process controllability, and ensure product quality. The proposed approach is to introduce electron-withdrawing and steric hindrance groups (such as triazine rings, triazine trione rings, phosphaphenanthrene groups, and cyclotriphosphazene groups) into the molecular structure of ordinary imidazole compounds through molecular design. This reduces the nucleophilicity of the imidazole ring, passivates the room-temperature curing activity of imidazole, extends the pot life of the resin system, and ensures it meets molding requirements.

[0022] The viscosity of the resin system as a function of time and temperature was studied using a rotational rheometer, and the pot life of the resin system at a certain temperature was determined. The curing exothermic behavior of the resin system was studied using variable temperature / constant temperature differential scanning calorimetry (DSC), and the thermodynamic parameters of the curing reaction (such as curing exothermic temperature and curing exothermic heat) were obtained. The kinetic parameters of the curing reaction (such as activation energy, frequency factor, and reaction rate constant) were calculated using the Arrhenius equation and the Kissinger equation, and a curing kinetic model was established.

[0023] Furthermore, a 0° pultrusion attachment method can be added, in which the innermost filamentous carbon fibers are attached to the surface of the tube through synchronous pultrusion.

[0024] The benefits of adding this step are as follows: The inner and outer layers are reinforced with high-strength fibers (fibers in the ±45° direction), and the middle layer is reinforced with high-modulus fibers (fibers in the 0° direction). Through modular design, this structure ensures that the composite shaft tube possesses excellent axial stiffness, circumferential strength, and torsional resistance. Specifically, the high-modulus carbon fiber in the 0° direction primarily provides axial stiffness, while the high-strength carbon fiber in the ±45° direction primarily provides torsional resistance and circumferential strength. Based on the actual application requirements of the product, the number of layers, fiber orientation, and thickness of the multilayer structure can be further optimized to prepare high-stiffness, high-strength composite shaft tubes.

[0025] The layered structure of the aforementioned composite pipe, from the inside out, consists of a base layer of plastic polymer, extruded filamentous carbon fibers arranged at 0° parallel to the center line of the base layer, and braided carbon fibers arranged at 45° parallel to the center line of the base layer, wherein epoxy resin material is filled between the braided carbon fibers.

[0026] Furthermore, the device is designed to include a ring-shaped rotating support. The pipe to be processed passes through the middle of the ring-shaped rotating support. The inner surface of the ring-shaped rotating support is provided with an outlet for filamentous carbon fibers. When the rotating support rotates, the filamentous carbon fibers are wrapped around the outer surface of the pipe. The position and angle of the filamentous carbon fibers are limited by multiple limiting rollers. The diameter of the pipe to be processed is 2-100mm.

[0027] Beneficial effects: By using multiple rotating devices for compensatory weaving, multiple layers of carbon fiber can be woven or pultruded on the pipe, thereby giving the pipe a certain structural strength. Compared with the existing weaving method, the combination of multiple rotating devices can ensure the continuity of processing through the relay between the rotating devices.

[0028] In addition, impregnating the carbon fiber can reduce the bending and displacement of the carbon fiber due to mutual friction during the direct weaving process. Furthermore, during the subsequent melting and reshaping, the epoxy resin is remelted, which can strengthen the connection between the pipe and the carbon fiber, as well as between the carbon fibers. This better leverages the structural strength enhancement effect of the carbon fiber and prevents cracks from forming between them during subsequent use. Attached Figure Description

[0029] Figure 1 It is a comparison chart of the two existing mainstream weaving angles;

[0030] Figure 2 This is a process flow diagram for braided pultrusion molding;

[0031] Figure 3 It is a multi-layered weaving structure;

[0032] The markings in the diagram are as follows: 1. Thread winding drum; 2. Electrostatic adsorption device; 3. Rotating device; 4. Extruder. Detailed Implementation

[0033] To better understand the purpose, structure, and function of this invention, the following detailed description, in conjunction with the accompanying drawings, provides an explanation of the braiding pultrusion molding process for a corrosion-resistant composite pipe according to this invention.

[0034] Example 1, preparation as follows Figure 3 The diagram illustrates a multi-layered braided structure, comprising inner and outer layers reinforced with high-strength fibers (fibers in the ±45° direction), and a middle layer reinforced with high-modulus fibers (fibers in the 0° direction). Through unit design and finite element simulation, the optimized structure ensures the composite shaft tube possesses excellent axial stiffness, circumferential strength, and torsional resistance. Specifically, the high-modulus carbon fiber in the 0° direction primarily provides axial stiffness, while the high-strength carbon fiber in the ±45° direction primarily provides torsional resistance and circumferential strength.

[0035] The preparation steps are as follows:

[0036] S1. The filamentous carbon fiber material is electrostatically adsorbed onto the surface of the powdered epoxy resin material. An anionic catalytic curing agent is added to the powdered epoxy resin. The anionic catalytic curing agent is a passivated imidazole curing agent. The passivation method is to use a triazine ring, a triazine trione ring, a phosphaphenanthrene group, or a cyclotriphosphazene group to actively passivate the imidazole ring.

[0037] S2. After attachment, the material is immersed in molten epoxy resin. A layer of epoxy resin is melted onto the surface of the single-strand filamentous carbon fiber material. The molten epoxy resin contains epoxy resin diluent, liquid bisphenol A type epoxy resin, and a multifunctional epoxy compound. The epoxy resin diluent is one or a mixture of 1,4-butanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and bisphenol A polyoxyethylene ether. The liquid bisphenol A type epoxy resin is one or a mixture of E-51 and E-53. The multifunctional epoxy compound is triglycidyl isocyanurate.

[0038] S3. Set up an inlet with a certain temperature. The inlet will shape the epoxy resin material on the surface. After the shaping is completed, it will be cooled and shaped.

[0039] S4. A heating device is installed at the discharge port of the pipe extruder to uniformly heat the surface of the prepared pipe.

[0040] S5. The rear end of the heating device is equipped with six rotating devices arranged in sequence. The six rotating devices are divided into upper and lower groups, such as... Figure 2As shown, the top three are 45-degree forward weaving, 0-degree extrusion, and 45-degree forward weaving (the spare rotating device is not shown), and the bottom three are 45-degree reverse weaving, 0-degree extrusion, and 45-degree reverse weaving (the spare rotating device is not shown). Only one strand of carbon fiber material is set on each rotating device.

[0041] S6. After attaching carbon fiber, heat it to melt and reshape the epoxy resin on the surface.

[0042] Example 2, omitting the pultruded layer (0° direction fiber), the six rotating devices are divided into upper and lower groups, as follows: Figure 2 As shown, the top three are 45-degree forward weaves and two spare 45-degree forward weaves, while the bottom three are 45-degree reverse weaves and two spare 45-degree reverse weaves. Only one strand of carbon fiber material is used on each rotating device. The rest of the structure is the same as in Example 1.

[0043] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the guidance of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A braided pultrusion molding process for a corrosion-resistant composite pipe, wherein the main body of the composite pipe is made of polymer material, and the surface of the polymer material is coated with at least one layer of braided carbon fiber material; Its features are, Attaching carbon fiber material to the surface of a polymer material includes the following steps: S1. Powdered epoxy resin material is adsorbed onto the surface of filamentous carbon fiber material by electrostatic adsorption. S2. After attachment, immerse the material in molten epoxy resin to melt a layer of epoxy resin onto the surface of the single-strand carbon fiber material. S3. Set up an inlet with a certain temperature. The inlet will shape the epoxy resin material on the surface. After the shaping is completed, it will be cooled and shaped. S4. A heating device is installed at the discharge port of the pipe extruder to uniformly heat the surface of the prepared pipe. S5. The rear end of the heating device is equipped with multiple rotating devices arranged in sequence. The multiple rotating devices are divided into two operating states: working and waiting. The rotating devices in operation will sequentially wind the filamentous carbon fibers with epoxy resin layer attached to the surface of the pipe. S6. After attaching carbon fiber, heat it to melt and reshape the epoxy resin on the surface.

2. The braided pultrusion molding process for a corrosion-resistant composite pipe according to claim 1, characterized in that, Multiple rotating devices include two types of angle winding: forward angle winding and reverse angle winding. After the two angle winding methods are combined, they are woven into the surface. Only one strand of carbon fiber material is set on a single rotating device.

3. The braided pultrusion molding process for a corrosion-resistant composite pipe according to claim 1, characterized in that, The opening can be circular, semi-circular, Ω-shaped, or square.

4. The braided pultrusion molding process for a corrosion-resistant composite pipe according to claim 1, characterized in that, The molten epoxy resin comprises an epoxy resin diluent, liquid bisphenol A type epoxy resin, and a multifunctional epoxy compound. The epoxy resin diluent is one or a mixture of 1,4-butanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and bisphenol A polyoxyethylene ether. The liquid bisphenol A type epoxy resin is one or a mixture of E-51 and E-53. The multifunctional epoxy compound is triglycidyl isocyanurate.

5. The braided pultrusion molding process for a corrosion-resistant composite pipe according to claim 1, characterized in that, The powdered epoxy resin is adsorbed onto the carbon fiber surface by electrostatic adsorption. An anionic catalytic curing agent is added to the powdered epoxy resin. The anionic catalytic curing agent is a passivated imidazole curing agent. The passivation method is to use triazine ring, phosphenanthrene group or cyclotriphosphazene group to actively passivate the imidazole ring.

6. The braided pultrusion molding process for a corrosion-resistant composite pipe according to claim 1, characterized in that, The innermost filamentous carbon fibers are attached to the surface of the tube through synchronous pultrusion.

7. The braided pultrusion molding process for a corrosion-resistant composite pipe according to claim 6, characterized in that, The composite pipe has a layered structure from the inside out, consisting of a base layer of plastic polymer, extruded filamentous carbon fibers arranged at 0° parallel to the center line of the base layer, and braided carbon fibers arranged at 45° parallel to the center line of the base layer, with epoxy resin material filling the spaces between the braided carbon fibers.

8. The braided pultrusion molding process for a corrosion-resistant composite pipe according to any one of claims 1-7, characterized in that, The rotating device includes an annular rotating support. The pipe to be processed passes through the middle of the annular rotating support. The inner surface of the annular rotating support is provided with an outlet for filamentous carbon fibers. When the rotating support rotates, the filamentous carbon fibers are wrapped around the outer surface of the pipe. The position and angle of the filamentous carbon fibers are limited by multiple limiting rollers.

9. The braided pultrusion molding process for a corrosion-resistant composite pipe according to claim 8, characterized in that, The diameter of the pipe to be treated is 2-100mm.

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