Carbon fiber combined high polymer material microporous pipe and forming method

Abstract

The invention provides a carbon fiber combined high polymer material microporous pipe and a forming method, and relates to the technical field of plastic forming. The carbon fiber combined high polymer material micropore pipe sequentially comprises a surface layer, a middle layer and an inner layer from outside to inside, the surface layer is of a composite structure of PTFE and CNT, the middle layer is formed by implanting a carbon fiber bundle coated with prepreg liquid into a PTFE base body in the vertical direction, the inner layer is a glass fiber woven mesh impregnated with PTFE emulsion, and the pore size of the surface layer, the pore size of the middle layer and the pore size of the inner layer are gradually increased. The forming method of the carbon fiber combined high polymer material microporous pipe comprises the steps of preparing the surface layer, preparing the middle layer and preparing the inner layer, then compounding the surface layer, the middle layer and the inner layer, performing thermal forming, and finally performing quenching. The shear strength of the microporous pipe is improved, and the porosity is not affected.

Description

Technical Field

[0001] The invention relates to the technical field of plastic molding, and in particular to a carbon fiber combined polymer material microporous tube and a molding method thereof. Background Art

[0002] Microporous tubes are a type of material that achieves precision filtration with a porous structure. Currently, microporous tubes have low shear strength and are easy to break. If their strength is to be increased, their porosity will decrease. Summary of the Invention

[0003] The purpose of the present invention is to develop a carbon fiber combined polymer material microporous tube and a molding method thereof, which can improve the shear strength of the microporous tube and will not affect the porosity.

[0004] The present invention is achieved through the following technical solutions:

[0005] A carbon fiber composite polymer microporous tube comprises, from the outside to the inside, a surface layer, a middle layer and an inner layer. The surface layer is a composite structure of PTFE and CNT. The middle layer is formed by vertically implanting carbon fiber bundles coated with prepreg into a PTFE matrix. The inner layer is a glass fiber woven mesh impregnated with PTFE emulsion. The pore sizes of the surface layer, middle layer and inner layer gradually increase.

[0006] A method for forming a carbon fiber combined polymer material microporous tube comprises preparing a surface layer, an intermediate layer and an inner layer, then compounding and thermoforming the surface layer, the intermediate layer and the inner layer, and finally quenching.

[0007] Optionally, the surface layer preparation includes mixing PTFE dispersed resin with CNT, calendering the mixture into a film, and then stretching the mixture longitudinally and transversely.

[0008] Optionally, the intermediate layer preparation includes calendering a PTFE dispersion resin into a PTFE matrix, laser drilling the PTFE matrix, and then placing the prepreg carbon fiber bundle into a mold, and preheating the PTFE matrix so that the prepreg carbon fiber bundle is vertically inserted into the pores of the PTFE matrix;

[0009] The pre-impregnated carbon fiber bundle is prepared by pre-impregnating the carbon fiber bundle with a pre-impregnated liquid and then drying the pre-impregnated liquid. The pre-impregnated liquid is prepared by ultrasonically mixing PTFE dispersion, CNT, silane coupling agent and ethanol.

[0010] Optionally, the prepreg carbon fiber bundle is heated to 200±10° C. in a mold before being inserted into the PTFE matrix.

[0011] Optionally, the mold blowing gas blows the pre-impregnated carbon fiber bundles into the pores of the PTFE matrix.

[0012] Optionally, before the prepreg carbon fiber bundle is inserted into the PTFE matrix, high-voltage positive corona ionization is used to generate positive ions attached to the prepreg carbon fiber bundle, and then the prepreg carbon fiber bundle and the PTFE matrix are placed in an electric field, with the prepreg carbon fiber bundle located on the side close to the positive pole of the electric field and the PTFE matrix located on the side close to the negative pole of the electric field, and the prepreg carbon fiber bundle is driven to be inserted into the PTFE matrix by the electric field force.

[0013] Optionally, the inner layer preparation includes rolling a glass fiber braided mesh tube impregnated with PTFE emulsion and sheathing it on a core shaft, and curing it by hot air;

[0014] The steps of compounding the surface layer, the middle layer and the inner layer include:

[0015] Winding the middle layer around the inner layer, and then wrapping the outer layer around the middle layer to form a composite tube;

[0016] For hot pressing composite, one or more side rollers are set on the side of the core shaft. The side rollers apply pressure to the composite tube on the core shaft. The rotation of the side rollers and the core shaft drives the composite tube to rotate. During the hot pressing composite process, the temperature is controlled at 80°C, the pressure applied by the side rollers is 0.8Mpa, and the hot pressing composite time is 5 minutes.

[0017] Optionally, the hot forming is performed by charging the composite tube into a furnace for step sintering, and the step sintering steps include:

[0018] During step 1 sintering, the heating rate was controlled at 5°C / min, and the temperature was raised to 150°C and then kept at this temperature for 30 minutes. During this process, nitrogen was introduced into the furnace to remove the residual solvent.

[0019] During step 2 sintering, the heating rate was controlled at 10°C / min, and the temperature was raised to 280°C and then kept at that temperature for 20 minutes. During this process, the furnace was sealed and pressurized, and the nitrogen pressure in the furnace was 0.3 MPa.

[0020] During step 3 sintering, the heating rate was controlled at 5°C / min, and the temperature was kept at 380°C for 20 minutes. During this process, the furnace was sealed and pressurized, and the nitrogen pressure in the furnace was 0.1 MPa.

[0021] Optionally, the quenching is liquid nitrogen quenching, the cooling rate is greater than 100°C / s, and the temperature is maintained at -50°C for 5 minutes.

[0022] The beneficial effects of the present invention are:

[0023] The microporous tube is designed with a gradient pore size, which gradually increases from the outside to the inside. The surface layer realizes precision filtration, and the middle and inner layers have high flux for rapid flow diversion to avoid clogging. Fluoropolymer makes the microporous tube highly corrosion-resistant, and the addition of CNT improves its low-temperature toughness. The pre-impregnated carbon fiber bundles are chemically bonded through the pre-impregnation liquid to avoid interface peeling. The carbon fiber bundles are vertically and evenly implanted into the middle layer, breaking through the current limitation that carbon fibers can only be arranged horizontally, improving the Z-direction strength (thickness direction), greatly improving the shear strength, and improving the structural strength of the microporous tube without sacrificing porosity. The PTFE is fully melted through step sintering without damaging the carbon fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] Figure 1 It is a template structure diagram;

[0026] Figure 2 This is a diagram of the internal structure of the nozzle.

[0027] Figure numerals: 1. template; 2. nozzle; 3. air path; 4. air chamber; 5. energized metal plate; 6. corona needle; 7. control groove. DETAILED DESCRIPTION

[0028] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be regarded as illustrative in nature and not restrictive.

[0029] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] The present invention discloses a carbon fiber composite polymer microporous tube, which comprises a surface layer, a middle layer and an inner layer from the outside to the inside. The surface layer is a composite structure of PTFE (polytetrafluoroethylene) and CNT (carbon nanotube), the middle layer is formed by carbon fiber bundles coated with prepreg liquid and implanted into a PTFE matrix in a vertical direction, and the inner layer is a glass fiber woven mesh impregnated with PTFE emulsion. The pore sizes of the surface layer, the middle layer and the inner layer gradually increase.

[0031] The forming method of the carbon fiber composite polymer microporous tube includes preparing a surface layer, an intermediate layer and an inner layer, then compounding and thermoforming the surface layer, the intermediate layer and the inner layer, and finally quenching with liquid nitrogen.

[0032] The surface preparation includes the following steps:

[0033] After mixing PTFE dispersion resin with CNTs, the film is calendered and then stretched in both the longitudinal and transverse directions. Longitudinal stretching orients the molecular chains along the stretching direction, elongating the amorphous regions to form fibrous "fibrils." Transverse stretching separates the fibrils laterally, with the crystalline regions acting as "nodes." This fibril-node structure forms micropores. Fibrils are stretched fibrous PTFE bundles with a diameter of approximately 50–200 nm. Nodes are unstretched PTFE crystalline regions that serve as connecting points. Pores are the three-dimensional network gaps between the fibrils and nodes.

[0034] The middle layer preparation involves calendering PTFE dispersion resin into a PTFE matrix and then vertically inserting pre-impregnated carbon fiber bundles into the PTFE matrix.

[0035] The preimpregnated carbon fiber bundle is prepared by preimpregnating the carbon fiber bundle with a preimpregnated liquid and then drying the preimpregnated liquid, wherein the preimpregnated liquid is prepared by ultrasonically mixing PTFE dispersion, CNT, silane coupling agent and ethanol.

[0036] Before the pre-impregnated carbon fiber bundle is inserted into the PTFE matrix, the PTFE matrix is ​​firstly laser-drilled, and the holes are evenly distributed on the PTFE matrix.

[0037] The prepreg carbon fiber bundle is placed in an implantation device for implantation into a PTFE matrix. The PTFE matrix is ​​preheated to 160-180° C. before the prepreg carbon fiber bundle is implanted. The implantation device includes a material tray for accommodating the prepreg carbon fiber bundle. The material tray is provided with a vibration motor to enable it to vibrate.

[0038] Implantable devices also include Figure 1 The template 1 shown is used as a mold to accommodate the prepreg carbon fiber bundles. The bottom of the template 1 is covered with several Figure 2 The nozzle 2 shown has a position corresponding to the position of the laser-drilled hole on the PTFE substrate;

[0039] The upper portion of the nozzle 2 is truncated cone-shaped, and the lower portion of the nozzle 2 is cylindrical. The large diameter end of the upper portion of the nozzle 2 is connected to the template 1. The upper and lower portions of the nozzle 2 are coaxially connected. The inner diameter of the lower portion of the nozzle 2 is slightly larger than the outer diameter of the carbon fiber bundle.

[0040] A cylindrical control groove 7 is provided in the template 1 above the nozzle 2. The control groove 7 is coaxially connected to the interior of the nozzle 2. A plurality of air paths 3 are evenly connected on the side walls of the control groove 7. The plurality of air paths 3 are connected to the control groove 7 at equal intervals in the circumferential direction of the control groove 7. The air path 3 includes a vertical section, an inclined section is connected to the bottom of the vertical section, the lower end of the inclined section is connected to the vertical section, and the high end of the inclined section is connected to the control groove 7. An air chamber 4 is also provided in the template 1 above the control groove 7. The vertical section of the air path 3 is connected to the air chamber 4. Through the air chamber 4, gas can be sprayed from the air path 3 into the control groove 7 or the control groove 7 can be sucked under negative pressure;

[0041] A powered metal plate 5 is provided on the top of the control slot 7, and a corona needle 6 is provided on the side wall of the control slot 7;

[0042] The implant device also includes a heated metal plate and a grounded metal plate;

[0043] The prepreg carbon fiber bundle is placed on the material tray. The vibration motor vibrates the material tray, and the template 1 runs onto the material tray. The air chamber 4 and several air paths 3 suction the control groove 7 and the nozzle 2, so that the prepreg carbon fiber bundle is sucked into the nozzle 2. In this process, the vibration of the material tray makes the prepreg carbon fiber bundle vibrate and finally can be smoothly sucked into the nozzle 2.

[0044] After the prepreg carbon fiber bundle is sucked into the nozzle 2, the template 1 leaves the material tray, and the suction flow of the control groove 7 and the nozzle 2 is reduced to ensure that the prepreg carbon fiber bundle does not fall out of the nozzle 2. Then, the heated metal plate is moved below the nozzle 2, and the distance between the heated metal plate and the nozzle 2 is adjusted so that the distance between the top surface of the heated metal plate and the energized metal plate 5 is adapted to the length of the prepreg carbon fiber bundle. The distance between the top surface of the heated metal plate and the energized metal plate 5 is slightly smaller than the length of the prepreg carbon fiber bundle, ensuring that both ends of the prepreg carbon fiber bundle are in contact with the heated metal plate and the energized metal plate 5 respectively. The energized metal plate 5 and the heated metal plate are energized to generate a current flowing through the prepreg carbon fiber bundle, and the prepreg carbon fiber bundle is heated to 200±10°C by Joule heat.

[0045] After the prepreg carbon fiber bundle is heated, the energized metal plate 5 is powered off, the heated metal plate moves to separate from the bottom of the nozzle 2, and the template 1 moves to above the PTFE matrix. At this time, the PTFE matrix is ​​placed on the grounded metal plate. Then the high-voltage positive corona ionization of the corona needle 6 produces positive ions attached to the prepreg carbon fiber bundle, so that the prepreg carbon fiber bundle as a whole has a net positive charge. After ensuring that the nozzle 2 corresponds to the hole on the PTFE matrix, the energized metal plate 5 is connected to a high-voltage DC power supply. At this time, the energized metal plate 5 serves as the positive electrode and the grounded metal plate serves as the negative electrode to generate an electric field. The prepreg carbon fiber bundle is driven by the electric field force to be injected into the hole of the PTFE matrix. When the energized metal plate 5 is powered on, the air chamber 4 stops pumping and passes through the gas. Chamber 4 injects gas with a certain pressure into the air path 3 and the control groove 7. The gas flows downward from the control groove 7 into the nozzle 2 and is finally ejected, generating thrust to push the prepreg carbon fiber bundle. After the airflow is ejected from the nozzle 2, it will impact the hole on the PTFE matrix, causing it to instantly produce a small elastic expansion, which is beneficial to the implantation of the prepreg carbon fiber bundle. After the prepreg carbon fiber bundle is implanted, the hole elastically recovers. The implantation of the prepreg carbon fiber bundle is mainly driven by pneumatic blowing and supplemented by electric field force. Under the joint promotion of pneumatic blowing and electric field force, the prepreg carbon fiber bundle is implanted into the hole opened in advance by the laser. The prepreg carbon fiber bundle is heated before being implanted into the hole, optimizing the interface compatibility and thermal stress distribution of PTFE, significantly improving the implantation efficiency and composite quality;

[0046] After the prepreg carbon fiber bundle is implanted into the PTFE matrix, cooling gas is sprayed toward the hole of the PTFE matrix below through the air chamber 4, the air path 3, the control groove 7 and the nozzle 2. The cooling gas is dry nitrogen with a temperature of 5 to 15°C. The cooling gas pressure is significantly lower than the gas pressure when the prepreg carbon fiber bundle is sprayed. The implantation location of the prepreg carbon fiber bundle in the PTFE matrix is ​​cooled, causing the PTFE to shrink and wrap the prepreg carbon fiber bundle tightly, inhibiting the growth of the lamellae, controlling the crystallinity, inhibiting the thermal residual stress, locking the position of the prepreg carbon fiber bundle, ensuring the implantation accuracy, and preventing the thermal decomposition of the PTFE.

[0047] The inner layer preparation includes winding a glass fiber braided mesh impregnated with PTFE emulsion into a tube and sleeved onto a core shaft, and then curing the tube by hot air to form an inner layer tube blank.

[0048] The steps for compounding the surface layer, middle layer and inner layer are as follows:

[0049] The middle layer is wrapped around the inner tube blank, and then the outer layer is covered on the middle layer to form a composite tube, which is then hot-pressed and laminated. One or more side rollers are set on the side of the mandrel. The side rollers apply pressure to the composite tube on the mandrel, and the rotation of the side rollers and the mandrel drives the composite tube to rotate. During the hot-pressing and laminating process, the temperature is controlled at 80°C, the pressure applied by the side rollers is 0.8 MPa, and the hot-pressing and laminating time is 5 minutes.

[0050] After hot pressing and lamination, hot forming is carried out by loading the composite tube into a furnace for step sintering. The step sintering steps include:

[0051] During step 1 sintering, the solvent is removed, the initial shape is fixed, and the internal stress is eliminated. The heating rate is controlled at 5°C / min to avoid interlayer delamination caused by thermal stress. The temperature is raised to 150°C and then kept at this temperature for 30 minutes. During this process, nitrogen is introduced into the furnace to remove residual solvents (such as ethanol and water vapor).

[0052] During step 2 sintering, the semi-sintered interface is bonded to form a microporous prototype, the nodes are partially melted, and initial bonding occurs. The heating rate is controlled at 10°C / min, and the PTFE crystallization zone (200–260°C) is quickly passed through to avoid recrystallization. The temperature is raised to 280°C and then kept at this temperature for 20 minutes. During this process, the furnace is sealed and pressurized, and the nitrogen pressure in the furnace is 0.3 MPa.

[0053] During step 3 sintering, the whole sintering is completed, the pores are fixed by full melting, and the pores are stable. The heating rate is controlled at 5°C / min, and the temperature is kept at 380°C for 20 minutes. During this process, the furnace is sealed and pressurized, and the nitrogen pressure in the furnace is 0.1 MPa.

[0054] After step sintering, the composite tube is quenched in liquid nitrogen with a cooling rate greater than 100°C / s, skipping the PTFE crystallization temperature zone (310–300°C) to form an amorphous structure and avoid crystallization destroying the pores. It is kept at -50°C for 5 minutes to eliminate the temperature gradient stress. The porosity retention rate is greater than 99%. After completing liquid nitrogen quenching, a carbon fiber composite polymer microporous tube is obtained.

[0055] The above embodiments are only preferred embodiments of the present invention and are not limitations on the technical solutions of the present invention. Any technical solution that can be implemented on the basis of the above embodiments without creative work should be deemed to fall within the scope of protection of the patent of the present invention.

Claims

1. A carbon fiber combined with polymer material microporous tube, characterized in that: From the outside to the inside, it includes a surface layer, a middle layer and an inner layer. The surface layer is a composite structure of PTFE and CNT. The middle layer is formed by carbon fiber bundles coated with pre-impregnation liquid and implanted into a PTFE matrix in a vertical direction. The inner layer is a glass fiber woven mesh impregnated with PTFE emulsion. The pore sizes of the surface layer, middle layer and inner layer gradually increase.

2. A method for forming a carbon fiber combined polymer microporous tube according to claim 1, characterized in that: The process includes preparation of the surface layer, the middle layer and the inner layer, and then compounding and thermoforming the surface layer, the middle layer and the inner layer, and finally quenching.

3. The method for forming a carbon fiber combined polymer microporous tube according to claim 2, characterized in that: The surface layer preparation includes mixing PTFE dispersed resin and CNT, rolling to form a film, and then stretching in the longitudinal and transverse directions.

4. The method for forming a carbon fiber combined polymer microporous tube according to claim 2, characterized in that: The intermediate layer preparation includes calendering a PTFE dispersion resin into a PTFE matrix, laser drilling the PTFE matrix, placing a prepreg carbon fiber bundle in a mold, and preheating the PTFE matrix so that the prepreg carbon fiber bundle is vertically inserted into the pores of the PTFE matrix; The pre-impregnated carbon fiber bundle is prepared by pre-impregnating the carbon fiber bundle with a pre-impregnated liquid and then drying the pre-impregnated liquid. The pre-impregnated liquid is prepared by ultrasonically mixing PTFE dispersion, CNT, silane coupling agent and ethanol.

5. The method for forming a carbon fiber combined polymer microporous tube according to claim 4, characterized in that: The pre-impregnated carbon fiber bundle is heated to 200±10° C. in a mold before being inserted into the PTFE matrix.

6. The method for forming a carbon fiber combined polymer microporous tube according to claim 4, characterized in that: The mold blowing gas blows the pre-impregnated carbon fiber bundles into the pores of the PTFE matrix.

7. The method for forming a carbon fiber combined polymer microporous tube according to claim 4, characterized in that: Before the prepreg carbon fiber bundle is inserted into the PTFE matrix, high-voltage positive corona ionization is used to generate positive ions attached to the prepreg carbon fiber bundle. Then, the prepreg carbon fiber bundle and the PTFE matrix are placed in an electric field, with the prepreg carbon fiber bundle located on the side close to the positive electrode of the electric field and the PTFE matrix located on the side close to the negative electrode of the electric field. The prepreg carbon fiber bundle is driven to be inserted into the PTFE matrix by the electric field force.

8. The method for forming a carbon fiber combined polymer microporous tube according to any one of claims 2 to 7, characterized in that: The inner layer preparation includes rolling a glass fiber braided mesh tube impregnated with PTFE emulsion and sheathing it on a core shaft, and curing it by hot air; The steps of compounding the surface layer, the middle layer and the inner layer include: Winding the middle layer around the inner layer, and then wrapping the outer layer around the middle layer to form a composite tube; For hot pressing composite, one or more side rollers are set on the side of the core shaft. The side rollers apply pressure to the composite tube on the core shaft. The rotation of the side rollers and the core shaft drives the composite tube to rotate. During the hot pressing composite process, the temperature is controlled at 80°C, the pressure applied by the side rollers is 0.8Mpa, and the hot pressing composite time is 5 minutes.

9. The method for forming a carbon fiber combined polymer microporous tube according to claim 8, characterized in that: The hot forming is carried out by charging the composite tube into a furnace for step sintering. The step sintering steps include: During step 1 sintering, the heating rate was controlled at 5°C / min, and the temperature was raised to 150°C and then kept at this temperature for 30 minutes. During this process, nitrogen was introduced into the furnace to remove the residual solvent. During step 2 sintering, the heating rate was controlled at 10°C / min, and the temperature was raised to 280°C and then kept at that temperature for 20 minutes. During this process, the furnace was sealed and pressurized, and the nitrogen pressure in the furnace was 0.3 MPa. During step 3 sintering, the heating rate was controlled at 5°C / min, and the temperature was kept at 380°C for 20 minutes. During this process, the furnace was sealed and pressurized, and the nitrogen pressure in the furnace was 0.1 MPa.

10. The method for forming a carbon fiber combined polymer microporous tube according to claim 9, characterized in that: The quenching is liquid nitrogen quenching, the cooling rate is greater than 100°C / s, and the temperature is maintained at -50°C for 5 minutes.

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