Device and method for continuously treating aramid fiber filaments through plasma

Abstract

The invention discloses a device and method for continuously treating aramid fiber filaments through plasma, and relates to the field of fiber surface modification. The device mainly comprises a plasma generator, a wire moving mechanism and a gas storage assembly. Wherein the plasma generator is provided with a high-voltage electrode and a ground electrode, and a closed insulating cavity is arranged between the two electrodes. The filament moving mechanism is provided with a filament winding roller assembly, a filament feeding assembly and a filament collecting assembly, and the conveying path of the aramid fiber filaments on the filament winding roller assembly is located on a non-plane. The cavity is connected with an external gas storage assembly through a gas circuit. The plasma generator is combined with non-planar winding conveying, so that the fiber filaments are axially twisted in the filament moving process of the plasma cavity, the directivity influence of plasma is reduced, modification processing is more uniform, the fiber surface activity and the wettability with a composite material matrix can be improved, the interface strength of a composite material is improved, and the service life of the composite material is prolonged. The excellent mechanical property of the aramid fiber is exerted.

Description

Technical Field

[0001] The invention belongs to the field of fiber surface modification, and in particular relates to an aramid fiber plasma modification device and method. Background Art

[0002] Poly(p-phenylene terephthalamide), also known as para-aramid fiber, is a man-made fiber with high elastic modulus and high tensile strength. Its specific strength and specific modulus are 6 times and 3 times that of steel wire respectively. It has outstanding mechanical properties and is widely used in bulletproof, special protective clothing, tires, rubber industrial products, composite materials and other fields. In the field of composite materials, aramid fiber can be used alone or mixed with other fibers as a reinforcement of composite materials to achieve weight reduction and impact resistance.

[0003] However, due to the lack of chemically active groups on the surface of aramid fibers, low polarity, and the smooth surface of the fibers, the surface energy is extremely low. Therefore, the matrix has poor wettability on the aramid surface, and the interface bonding strength between the two is low, which ultimately affects the uniform distribution and transfer of the applied load from the matrix to the load-bearing fibers, reducing the comprehensive mechanical properties of the composite material.

[0004] Plasma modification is a comprehensive modification technology that consists of ions composed of neutral particles and high-energy charged particles. It can be carried out under normal pressure conditions and has the characteristics of no pollution, low energy consumption, and environmental protection. Since plasma modification of the material interface occurs within a thickness range of less than 100 nm from the material surface, it will not affect the bulk characteristics of the fiber, allowing high-performance fibers to be used in high-performance composite materials while maintaining their own excellent performance.

[0005] The essence of plasma modification of fiber interface technology is the process of obtaining free radicals by active particles inducing changes in the polymer surface; the free radicals on the fiber interface can then undergo a series of reactions such as free radical transfer, coupling, cracking and oxidation, forming groups with certain activity on the fiber interface; at the same time, the fiber interface can also be etched by plasma treatment technology to increase the roughness of the fiber surface and improve the surface properties of the fiber. This improves the wettability of the fiber reinforcement and the matrix, thereby improving the interface strength of the composite material and allowing the excellent mechanical properties of aramid fiber to be brought into play. Therefore, plasma modification of fibers has good application prospects.

[0006] At present, the commonly used plasma modification technologies mainly include low-pressure plasma discharge technology. The advantage of this method is that it can produce uniform and stable glow discharge and treat textile materials uniformly. However, the operation of low-pressure plasma requires a complex vacuum system, large equipment investment, complex operation, and is not conducive to industrial large-scale production. Another more common technology is atmospheric pressure dielectric barrier discharge technology, which covers one or two electrodes with an insulating medium, or directly suspends the medium in the discharge space, or fills it with a granular medium. When a certain working gas is filled between the two discharge electrodes, and a voltage of 104~106V is applied between the two electrodes, a 500W~1KW high-frequency or pulse power supply is used to excite the working gas to generate a filamentary discharge plasma; this method has the problem of uneven spatial plasma distribution, especially in the edge area of ​​the plasma generator, resulting in uneven surface treatment of the modified processing, easy burning of fibers and other disadvantages. Therefore, Chinese patent CN114960175A discloses a multi-fiber bundle high-efficiency plasma surface modification device and method, which adopts a cylindrical structure with two electrodes nested, so that the plasma space distribution is more reasonable, suitable for plasma continuous treatment of long fiber filaments. However, the above technical solution still has the problem of plasma movement directionality. Since technical personnel in this field have not yet realized the problem of unidirectional stable transmission of fiber filaments, the surface modification on one side is relatively sufficient, while the modification on the opposite side is insufficient, the problem of uneven treatment still occurs.

[0007] In summary, there is a need to improve existing devices and process methods to eliminate or reduce the impact of the aforementioned problems. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a device for continuously treating aramid fiber filaments with plasma, and realizes surface modification of aramid fiber filaments through a highly efficient, continuous and multi-parameter adjustable plasma treatment method.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows: On the one hand, the present invention provides a device for plasma continuous treatment of aramid fiber filaments, which mainly includes a plasma generator, a wire feeding mechanism and a gas storage component; the plasma generator is provided with a high-voltage electrode and a ground electrode, and is characterized in that: a closed cavity is provided between the high-voltage electrode and the ground electrode; an insulating layer is provided on one side of the cavity close to the electrode; the high-voltage electrode is connected to a power supply; and the ground electrode is grounded; The wire-feeding mechanism is provided with a wire winding roller assembly, a wire feeding assembly and a wire collecting assembly; the wire winding roller assembly is located in the cavity, and the conveying path of the aramid fiber filament on the wire winding roller assembly is located on a non-plane; the wire winding roller assembly is connected to the wire feeding assembly and the wire collecting assembly respectively through a feed port and a discharge port provided on the cavity; The cavity is connected to an external gas storage component through a gas path, and working gas is stored in the gas storage component.

[0010] Preferably, the cavity is in a column-ring structure, and the upper and lower end surfaces are both closed by the insulating layer.

[0011] Preferably, the high-voltage electrode is a circular tube structure, which is sleeved on the outside of the cavity; the ground electrode is a column structure, which is vertically arranged at the axis of the high-voltage electrode.

[0012] Preferably, the insulating layer is made of quartz glass; the high-voltage electrode and the ground electrode are both integrally formed of metal copper.

[0013] Preferably, the power supply is a pulse power supply and is provided with a voltage regulating device; the output power of the pulse power supply ranges from 10W to 1000W, the pulse frequency ranges from 10kHz to 100kHz, the pulse width is 1μs to 100μs, and the pulse amplitude is 10mA to 10A.

[0014] Preferably, the wire winding roller assembly includes a plurality of fixed pulley groups distributed along the circumference of the cavity; the aramid fiber filaments are wound around each fixed pulley group along a zigzag path.

[0015] Preferably, the wire feeding assembly and the wire collecting assembly both include a guiding mechanism and a winding mechanism; the guiding mechanism is provided with a plurality of wire feeding wheels and is connected to a braking mechanism and / or a driving mechanism; the winding mechanism is provided with a winding roller and is connected to a braking mechanism and / or a driving mechanism.

[0016] Preferably, when the working gas density is less than the air density, an air inlet is provided at the upper portion of the cavity, and is connected to the gas storage assembly through the gas path, and the discharge port and the feed port are both located at the lower portion of the cavity; When the working gas density is greater than the air density, an air inlet is provided at the lower portion of the cavity and is connected to the gas storage assembly through the gas path, and the discharge port and the feed port are both located at the upper portion of the cavity.

[0017] Preferably, the gas storage assembly includes a gas cylinder and a gas flow meter, the gas cylinder is provided with a pressure reducer or a pressure regulating valve; the gas flow meter is connected in series to the gas path.

[0018] On the other hand, the present invention also provides a method for continuously treating the surface modification of aramid fiber filaments based on the above device, comprising the following steps: First, the aramid fiber filaments of the wire feeding assembly are introduced into the cavity through the feed port, and are wound around the wire winding roller assembly, and then connected to the wire collecting assembly through the discharge port; S1. Open the gas storage assembly, adjust the gas flow rate range to 0.1 L / min ~10 L / min, and start the power supply after the working gas fills the cavity; S2. Adjust the power supply parameters so that the power spectrum density in the cavity is within 5 W / cm 3 -80W / cm 3 , and maintain the gas flow rate range of 0.1 L / min ~10L / min; S3, start the wire feeding assembly and the wire collecting assembly, and adjust the fiber filament wire running speed range to 15 cm / s~100 cm / s, and the wire running time range in the cavity to 6s~40s.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The device for continuous plasma treatment of aramid fiber filaments described in the present invention can achieve continuous surface modification of aramid fiber filaments. Combined with non-planar winding transportation, the fiber filaments are subjected to axial twisting during the wire feeding process in the plasma cavity, thereby reducing the directional influence of the plasma, making the modification process more uniform, improving the surface activity of the fiber and the wettability with the composite material matrix, improving the interface strength of the composite material, and allowing the excellent mechanical properties of the aramid fiber to be brought into play. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the device for plasma continuous treatment of aramid fiber filaments of the present invention.

[0021] Figure 2 It is a schematic diagram of the structure in which aramid fiber filaments are pulled back and forth by the winding rollers in the cavity.

[0022] Figure 3 This is a top view of the electrode, cavity and wire winding roller structure.

[0023] In the figure: 1. Aramid fiber filament; 2. Wire winding roller assembly; 3. Ground electrode; 4. High voltage electrode; 5. Wire feeding assembly; 6. Wire collecting assembly; 7. Gas flow meter; 8. Gas cylinder; 9. Cavity; 10. Power supply; 11. Voltage regulating device. Implementation

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] The present invention provides a device for continuous plasma treatment of aramid fiber filaments. In a specific embodiment, Figure 1 As shown, it mainly includes a plasma generator, a wire feeding mechanism and a gas storage component.

[0032] Among them, the plasma generator of this embodiment is provided with a high-voltage electrode 4 and a ground electrode 3. The high-voltage electrode 4 is a copper cylindrical structure with upper and lower openings, and is formed by an integrated molding process, which is connected to a power supply 10; preferably, the power supply 10 is a pulse power supply, and is provided with a voltage regulator 11. The input end of the power supply 10 is connected to the industrial frequency AC power supply, and the output end is connected to the input end of the voltage regulator 11 through a wire or cable, and a control signal line. The output end of the voltage regulator 11 is connected to the high-voltage electrode 4 by a high-voltage cable, and the cable and the high-voltage electrode 4 are fixed by screws. The setting parameters of the power supply 10 are: the output power range is 10W~1000W, the pulse frequency range is 10kHz~100kHz, the pulse width is 1μs~100μs, and the pulse amplitude is 10mA~10A.

[0033] The ground electrode 3 is an integrally formed copper column, the lower end of which is grounded and located at the axis of the high-voltage electrode 4. The cylindrical ring space between the two electrodes is the cavity 9 of the plasma generator, which is designed to be sealed with an insulating layer of quartz glass due to insulation requirements. The insulating layer is a cylindrical structure with closed upper and lower ends, and the outer wall is embedded in the high-voltage electrode 4. A hollow cylindrical structure is provided at the inner axis, and the ground electrode 3 is coaxially placed. The lead-out portion of the ground electrode 3 from the cavity 9 is connected and sealed to the cavity 9 port using a threaded joint.

[0034] As shown in the figure, the wire feeding mechanism is provided with a wire winding roller assembly 2, a wire feeding assembly 5 and a wire collecting assembly 6. Figure 2 , 3 As shown, the winding roller assembly 2 is located in the cavity, and the conveying path of the aramid fiber filaments on the winding roller assembly is located on a non-plane; preferably, in this embodiment, the winding roller assembly 2 is composed of multiple groups of fixed pulleys, and is evenly distributed along the circumference of the cavity 9, specifically, 9 fixed pulleys are evenly distributed above the cavity 9, and 8 fixed pulleys are evenly distributed below the cavity 9. Figure 3 As shown in the top view, the upper and lower fixed pulleys are arranged in a circumferentially staggered manner, and as shown in Figure 2 As shown, the upper fixed pulley axis is located on the same spatial plane (the plane where the upper dotted line is located in the figure), and the lower fixed pulley axis is also located on the same spatial plane (the plane where the lower dotted line is located in the figure). The aramid fiber filament 1 is guided by the winding roller assembly 2 to and fro between the upper and lower ends of the cavity, taking a zigzag conveying path ( Figure 3The path of the aramid fiber filament 1 in the cavity 9 is a circular path when viewed from above, and a total of 9 round trips are made to ensure the uniformity of the plasma treatment and the treatment time requirements. Moreover, since the path of the aramid fiber filament 1 in the cavity 9 is a curved surface that is approximately circular, the folded wire in the superimposed curved surface causes the aramid fiber filament 1 to be twisted along the axial direction during the transportation process, so that different peripheral side sections can be directed toward the high-voltage electrode 4, thereby making the surface modification of the filament more uniform and obtaining better processing effects with limited device volume and processing times. Furthermore, considering the integrity of the side wall of the cavity 9, each fixed pulley support seat in this embodiment is fixed to the inner wall of the cavity 9 by bonding.

[0035] The wire winding roller assembly 2 is connected to the wire feeding assembly 5 and the wire collecting assembly 6 respectively through the feed port and the discharge port arranged on the cavity. Preferably, in the present embodiment, the wire feeding assembly 5 and the wire collecting assembly 6 both include a guiding mechanism and a winding mechanism. Among them, the guiding mechanism is two opposing wire wheels or guide rollers, which are used to guide the aramid fiber filaments 1 to pass through the feed port without contact. The winding mechanism is provided with a winding roller, which is used to wind the aramid fiber filaments 1, wherein the winding roller of the wire feeding assembly 5 is used to release the wire, and the winding roller of the wire collecting assembly 6 is used to collect the wire. Since a single or single strand of fiber filament is subjected to less tension, an adjustable speed motor is configured on both winding rollers as a driving mechanism, and is equipped with a braking mechanism to avoid unilateral pulling causing the fiber filaments to break, and the motor rotation speed range is 1-12r / min.

[0036] The cavity 9 is connected to an external gas storage component through an air path, and the gas storage component stores working gas. Preferably, considering that the inlet and outlet ports cannot be installed with completely closed sealing components, in order to make the working gas better fill the cavity 9 and reduce leakage, it is necessary to design the inlet and outlet structure according to the type of working gas. The existing types of working gases include oxygen, nitrogen, argon, helium, etc. Since the density of some gases is greater than that of air and some is less than that of air, the design is as follows: 1. When the density of the selected working gas is less than the density of air, an air inlet is provided at the upper part of the cavity 9 and connected to the gas storage assembly through an air path, and the discharge port and the feed port are both located at the lower part of the cavity 9; 2. When the density of the selected working gas is greater than the density of air, an air inlet is provided at the lower part of the cavity 9 and connected to the gas storage assembly through an air path, and the discharge port and the feed port are both located at the upper part of the cavity.

[0037] In this embodiment, considering the convenience of taking and releasing the wire, the working gas is designed to have a density less than that of air, and the upper opening of the cavity 9 is set as an air inlet, which is connected to the air storage component through an air path; and the discharge port and the feed port are both located at the lower part of the cavity 9.

[0038] Preferably, Figure 1As shown, the gas storage assembly of this embodiment includes a gas cylinder 8 and a gas flow meter 7. The gas cylinder 8 has a volume range of 10 to 50 L and is also provided with a pressure reducer or a pressure regulating valve for reducing the gas pressure and controlling the gas flow. The gas flow meter 7 is located on the gas path and is used to monitor and adjust the gas flow. The outlet end of the gas flow meter 7 is sealed and connected to the cavity 9 through a joint and an O-ring.

[0039] The present invention also provides a method for continuously treating the surface modification of aramid fiber filaments based on the above device, comprising the following steps: First, ensure that all components of the device (such as high-voltage electrode, ground electrode, quartz glass cavity, wire winding roller, wire feeding and wire collecting assembly, pulse power supply, voltage regulating device, gas cylinder and gas flow meter) have been properly installed and connected. Introduce the aramid fiber filament of the wire feeding assembly into the cavity through the feed port, and wind it around the wire winding roller assembly, and then connect it to the wire collecting assembly through the discharge port; S1. Open the gas storage assembly, select the type and proportion of air, oxygen, argon and other gases according to the processing requirements, and start the power supply after the working gas fills the cavity; S2. Adjust the power supply parameters so that the power spectrum density in the cavity is within 5 W / cm 3 -80W / cm 3 , and maintain the gas flow rate range of 0.1 L / min ~10L / min; S3, start the wire feeding assembly and the wire collecting assembly, and adjust the fiber filament wire speed range to 15cm / s~100cm / s, and the wire time range in the cavity to 6s~40s At the same time, various parameters in the treatment process, including plasma morphology, fiber surface state, etc., are monitored, and necessary adjustments and optimizations are made based on experimental and research results.

[0040] After being treated by the plasma generator, the various active particles generated by the plasma etch and oxidize the surface, which can change the structure, morphology, chemical and physical properties of the fiber surface and improve the wettability with the resin. The performance changes include the following aspects: 1. The increase in the O element content on the fiber surface produces more polar functional groups, which improves the polarity and chemical activity of the fiber surface, helps to improve the wettability of the fiber surface, and enhances the adhesion between the fiber and the matrix. 2. The roughness of the fiber surface is improved. For example, under an oxygen atmosphere and a pulse power output power of 200W, the fiber surface roughness Ra gradually increases with the increase in treatment time. 3. The dynamic contact angle and surface free energy of the fiber are improved, and the wettability with the resin is better, and the interlayer shear strength of its epoxy resin composite material is improved. Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A device for continuous plasma treatment of aramid fiber filaments, comprising a plasma generator, a wire feeding mechanism and a gas storage assembly; the plasma generator is provided with a high voltage electrode and a ground electrode, characterized in that: A closed cavity is provided between the high-voltage electrode and the ground electrode; an insulating layer is provided on the electrode side of the cavity; the high-voltage electrode is connected to a power source; and the ground electrode is grounded; The wire-feeding mechanism is provided with a wire winding roller assembly, a wire feeding assembly and a wire collecting assembly; the wire winding roller assembly is located in the cavity, and the conveying path of the aramid fiber filament on the wire winding roller assembly is located on a non-plane; the wire winding roller assembly is connected to the wire feeding assembly and the wire collecting assembly respectively through a feed port and a discharge port provided on the cavity; The cavity is connected to an external gas storage component through a gas path, and working gas is stored in the gas storage component.

2. The device for continuous plasma treatment of aramid fiber filaments according to claim 1, characterized in that: The cavity is in a column-ring structure, and the upper and lower end surfaces are both closed by the insulating layer.

3. The device for continuous plasma treatment of aramid fiber filaments according to claim 2, characterized in that: The high-voltage electrode is a circular tube structure, which is sleeved on the outside of the cavity; the ground electrode is a column structure, which is vertically arranged at the axis of the high-voltage electrode.

4. The device for continuous plasma treatment of aramid fiber filaments according to claim 3, characterized in that: The insulating layer is made of quartz glass; the high-voltage electrode and the ground electrode are both integrally formed of metal copper.

5. The device for continuous plasma treatment of aramid fiber filaments according to claim 1, characterized in that: The power supply is a pulse power supply and is provided with a voltage regulating device; the output power of the pulse power supply ranges from 10W to 1000W, the pulse frequency ranges from 10kHz to 100kHz, the pulse width ranges from 1μs to 100μs, and the pulse amplitude ranges from 10mA to 10A.

6. The device for continuous plasma treatment of aramid fiber filaments according to any one of claims 1 to 5, characterized in that: The winding roller assembly comprises a plurality of fixed pulley groups, which are distributed along the circumference of the cavity; the aramid fiber filaments are wound around each fixed pulley group along a zigzag path.

7. The device for continuous plasma treatment of aramid fiber filaments according to claim 1, characterized in that: The wire feeding assembly and the wire collecting assembly both include a guiding mechanism and a winding mechanism; the guiding mechanism is provided with a plurality of wire feeding wheels and is connected to a braking mechanism and / or a driving mechanism; the winding mechanism is provided with a winding roller and is connected to a braking mechanism and / or a driving mechanism.

8. The device for continuous plasma treatment of aramid fiber filaments according to claim 1, characterized in that: When the working gas density is less than the air density, an air inlet is provided at the upper portion of the cavity, and is connected to the gas storage assembly through the gas path, and the discharge port and the feed port are both located at the lower portion of the cavity; When the working gas density is greater than the air density, an air inlet is provided at the lower portion of the cavity and is connected to the gas storage assembly through the gas path, and the discharge port and the feed port are both located at the upper portion of the cavity.

9. The device for continuous plasma treatment of aramid fiber filaments according to claim 7, characterized in that: The gas storage assembly comprises a gas cylinder and a gas flow meter, wherein the gas cylinder is provided with a pressure reducer or a pressure regulating valve; and the gas flow meter is connected in series to the gas path.

10. A method for continuously treating the surface modification of aramid fiber filaments using the device according to any one of claims 1 to 9, comprising the following steps: First, the aramid fiber filaments of the wire feeding assembly are introduced into the cavity through the feed port, and are wound around the wire winding roller assembly, and then connected to the wire collecting assembly through the discharge port; S1, open the gas storage assembly, and start the power supply after the working gas fills the cavity; S2. Adjust the power supply parameters so that the power spectrum density in the cavity is within 5 W / cm 3 -80W / cm 3 , and maintain the gas flow rate range of 0.1 L / min ~10L / min; S3, start the wire feeding assembly and the wire collecting assembly, and adjust the fiber filament wire running speed range to 15 cm / s~100 cm / s, and the wire running time range in the cavity to 6s~40s.

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