Method and device for recovering fibers and resin in fiber-reinforced thermoplastic prepreg tape

Abstract

The invention provides a method and a device for recovering fibers and resin in a fiber-reinforced thermoplastic prepreg tape, and belongs to the technical field of thermoplastic composite materials. Placing one end of the fiber-reinforced thermoplastic prepreg tape between a first-stage ultrasonic sound electrode and a roller; the fiber-reinforced thermoplastic prepreg tape is driven by a roller, energy is applied by ultrasonic first-stage sound pole vibration and pressurization, and resin in the prepreg tape is extruded; when the foremost end of the fiber-reinforced thermoplastic prepreg tape reaches the lower end of the ultrasonic second-stage sound electrode, the second-stage ultrasonic sound electrode starts to vibrate, the resin which is not fully extruded is further extruded, and when the foremost end of the fiber-reinforced thermoplastic prepreg tape reaches the lower end of the ultrasonic third-stage sound electrode, the third-stage ultrasonic sound electrode starts to vibrate; the prepreg tape is driven by the conveying belt, and resin is fully extruded out through step-by-step ultrasonic vibration. After the fiber-reinforced thermoplastic prepreg tape is extruded through ultrasonic vibration, the carbon fibers are small in damage, the surfaces of the carbon fibers are clean and smooth, and certain adhesiveness still exists among the carbon fibers.

Description

Technical Field

[0001] The invention relates to the technical field of thermoplastic composite materials, and in particular to a method and a device for recovering fibers and resins in a fiber-reinforced thermoplastic prepreg tape. Background Art

[0002] In view of the significant effect of lightweight in achieving energy conservation and emission reduction, reducing transportation costs, etc., lightweight design has gradually become a common pursuit in the fields of automobile manufacturing, rail transportation, aerospace, etc. Fiber-reinforced thermoplastic composites with thermoplastic resins such as polyetheretherketone, polyphenylene sulfide, polyetherimide, polyamide, polyimide, polysulfone, polypropylene as the matrix and carbon fiber, glass fiber, aramid fiber, etc. as the reinforcement phase have the following advantages: ①Excellent mechanical properties: high specific strength, specific stiffness, specific modulus, excellent toughness, fatigue resistance, impact resistance and fracture toughness; ② High productivity: easy assembly, fast molding, short production cycle, easy to realize automated production; ③ Environmental resistance: There is no environmental or time requirement for storage, it has high tolerance to halogenated hydrocarbons, refrigerants and greases, good resistance to high temperature and corrosion, and good flame retardancy; ④ Fluid resistance and wear resistance: low permeability and moisture absorption, high tolerance to fluids such as seawater, solvents, transmission fluids, and low friction coefficient; ⑤Good weldability: can be repeatedly molded, no solidification reaction during melting-solidification; ⑥Repairable: During repeated molding, polymer chains diffuse and entangle with each other to form a new cross-linked structure, and the performance is not affected by heating and molding times; ⑦ Recyclable: There is no consolidation stage, no large amount of waste is generated, it is easy to recycle with a high recycling rate, and it is green and environmentally friendly.

[0003] Therefore, fiber-reinforced thermoplastic composites have gradually broken the monopoly of traditional thermosetting composites and become a new generation of lightweight materials that are favored and key strategic materials supporting new generation aerospace, automobile manufacturing, energy power, transportation, national defense and military industries and other high-tech fields. With the extensive use of fiber-reinforced thermoplastic composites, recycling and reuse of fiber-reinforced thermoplastic composites after they have completed their service mission has become a problem that fiber-reinforced thermoplastic composites must face. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to apply ultrasonic vibration to a fiber-reinforced thermoplastic prepreg tape by means of ultrasound, melt the prepreg resin by heat, move the prepreg tape relative to the ultrasonic pole and extrude the resin under the pressure of the pole, thereby separating the fiber and the resin.

[0005] The purpose of the present invention is to ensure that after the fiber-reinforced thermoplastic prepreg is extruded through ultrasonic vibration, the carbon fiber is less damaged, the surface of the carbon fiber is clean and smooth, and there is still a certain degree of adhesion between the carbon fibers.

[0006] To achieve the purpose of the present invention, the technical solution adopted by the present invention is: a method for recovering fibers and resins in a fiber-reinforced thermoplastic prepreg tape, specifically comprising the following steps: Step 1: Compressing the fiber-reinforced thermoplastic prepreg tape using a first ultrasonic sonotrode; Step 2: applying ultrasonic vibration to the fiber-reinforced thermoplastic prepreg tape through the first ultrasonic sonotrode to melt the resin in the prepreg tape; Step 3: the prepreg tape and the ultrasonic sonotrode move relative to each other parallel to the fiber direction, and the molten resin is squeezed out of the prepreg tape by the first ultrasonic sonotrode; If there is still unmelted resin in the prepreg, preferably, the following steps may be continued: Step 4: the prepreg tape treated by the first ultrasonic sonotrode enters the second ultrasonic sonotrode; Step 5: applying ultrasonic vibration to the prepreg tape treated by the first ultrasonic sonotrode through the second ultrasonic sonotrode, so that the resin that is not completely melted in the prepreg tape treated by the first ultrasonic sonotrode is further melted; Step 6: the prepreg tape treated by the second ultrasonic sonotrode enters the third ultrasonic sonotrode; Step 7: applying ultrasonic vibration to the prepreg tape treated by the first and second ultrasonic sonotrodes through the third ultrasonic sonotrode, so that the resin that is not completely melted in the prepreg tape treated by the first and second ultrasonic sonotrodes is further melted; Step 8: After the prepreg tape has been processed by the first, second and third ultrasonic waves, the first, second and third ultrasonic waves are turned off.

[0007] Furthermore, the fiber-reinforced thermoplastic prepreg tape has a thickness between 0.1 and 0.4 mm.

[0008] Furthermore, the first, second and third ultrasonic acoustic end surface contours are arc-shaped.

[0009] Furthermore, the third ultrasonic sonotrode has an ultrasonic frequency of 15 to 20 kHz, an ultrasonic amplitude of 30 to 50 μm, an applied pressure range of 50 to 200 N, and a relative running speed range of the sonotrode and the prepreg tape of 10 to 50 mm / s.

[0010] Furthermore, the second ultrasonic sonotrode has an ultrasonic frequency of 25 to 30 kHz, an ultrasonic amplitude of 15 to 30 μm, an applied pressure range of 30 to 100 N, and a relative running speed range of the sonotrode and the prepreg tape of 10 to 50 mm / s.

[0011] Furthermore, the first ultrasonic sonotrode has an ultrasonic frequency of 35 to 40 kHz, an ultrasonic amplitude of 5 to 15 μm, an applied pressure range of 10 to 50 N, and a relative running speed range of the sonotrode and the prepreg tape of 10 to 50 mm / s.

[0012] Furthermore, the resin of the fiber-reinforced thermoplastic prepreg tape may be polyetheretherketone, polyphenylene sulfide, polyetherimide, polyamide, polyimide, polysulfone, polypropylene, or other thermoplastic resins.

[0013] Furthermore, the fibers of the fiber-reinforced thermoplastic prepreg tape may be carbon fibers, glass fibers, metal fibers, mineral fibers, plant fibers, and the like.

[0014] The ultrasonic electrodes in the present invention can be set in one group, two groups or more groups according to actual needs. The first ultrasonic electrode, the second ultrasonic electrode and the third ultrasonic electrode in the above technical solution are only for making the above processing steps more clearly represented, and are not a limitation on the number of ultrasonic electrodes.

[0015] To achieve the purpose of the present invention, another technical solution of the present invention is: a device for recovering fibers and resins in a fiber-reinforced thermoplastic prepreg tape, comprising a plurality of ultrasonic poles and supporting devices corresponding to the ultrasonic poles, wherein the fiber-reinforced thermoplastic prepreg tape is arranged between the ultrasonic poles and the supporting device.

[0016] Preferably, the supporting device is a roller, and the roller corresponds to the ultrasonic sonotrode, so that the roller and the ultrasonic sonotrode press the fiber-reinforced thermoplastic prepreg tape and realize the movement of the fiber-reinforced thermoplastic prepreg tape in parallel to the fiber direction.

[0017] Further preferably, the supporting device is a processing platform, the ultrasonic sonotrode is arranged above the processing platform, and the ultrasonic sonotrode moves in a direction parallel to the fibers of the fiber-reinforced thermoplastic prepreg tape.

[0018] Compared with the prior art, the present invention achieves the following technical effects: (1) Compared with the loss of fiber sizing agent caused by heat treatment, the ultrasonic vibration heat input of the present invention is used to melt the resin and extrude the resin by applying pressure and relative movement. After the resin is extruded, the fibers of the carbon fiber prepreg tape have good adhesion, high integrity, and low loss of fiber sizing agent; (2) Ultrasonic vibration heat input melts the resin. The vibration heat generated is slightly higher than the crystallization temperature. The surface of the sonotrode is smooth, so the carbon fiber is less worn, avoiding the wear of the carbon fiber caused by high temperature and mechanical friction, and ensuring the good strength of the recycled carbon fiber. (3) Due to the vibration and high pressure applied by the ultrasonic equipment, the surface of the recycled fiber is cleaner and there is less resin residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] For ease of explanation, the present invention is described in detail with reference to the following specific embodiments and the accompanying drawings.

[0020] Figure 1 Schematic diagram of the fiber reinforced thermoplastic prepreg recycling method in Example 1 and Example 2.

[0021] Figure 2 Schematic diagram of the fiber reinforced thermoplastic prepreg tape recycling method in Example 3.

[0022] In the figure: 1. first ultrasonic sonotrode; 2. second ultrasonic sonotrode; 3. third ultrasonic sonotrode; 4. first roller; 5. second roller; 6. third roller; 7. fiber-reinforced thermoplastic prepreg tape; 8. resin extruded by the first ultrasonic sonotrode; 9. resin extruded by the second ultrasonic sonotrode; 10. resin extruded by the third ultrasonic sonotrode; 11. fiber; 12. processing platform. DETAILED DESCRIPTION

[0023] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments; in the following description, specific details such as specific configurations are provided only to help fully understand the embodiments of the present invention. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention.

[0024] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0025] Example 1 A method for recycling fibers and resin from a fiber-reinforced thermoplastic prepreg tape comprises the following steps: Step 1: Compressing a carbon fiber reinforced polyetheretherketone (CF / PEEK) prepreg tape using a first ultrasonic sonotrode 1; Step 2: applying ultrasonic vibration to the fiber-reinforced thermoplastic prepreg tape 7 (carbon fiber-reinforced polyetheretherketone prepreg tape) through the first ultrasonic sonotrode 1 to melt the resin in the thermoplastic prepreg tape. The first ultrasonic sonotrode 1 has an ultrasonic frequency of 20 kHz, a sonotrode pressure of 170 N, and an amplitude of 40 μm. Step 3: Set the linear speed of rollers 4, 5, and 6 to 30 mm / s, and the CF / PEEK prepreg tape moves parallel to the fiber direction. The resin extruded by the first ultrasonic sonotrode 1 (resin 8 extruded by the first ultrasonic sonotrode) accumulates on the rear side of the first ultrasonic sonotrode 1 (the movement direction of the prepreg tape is specified to be forward).

[0026] Example 2 The other steps are the same as those in Example 1, except that the following steps are also included: Step 4: the prepreg tape treated by the first ultrasonic sonotrode 1 enters the second ultrasonic sonotrode 2; Step 5: applying ultrasonic vibration to the prepreg tape treated by the first ultrasonic sonotrode 1 through the second ultrasonic sonotrode 2, so that the resin that is not completely melted in the prepreg tape treated by the first ultrasonic sonotrode 1 is further melted, and the resin extruded by the second ultrasonic sonotrode 2 (resin 9 extruded by the second ultrasonic sonotrode) is accumulated on the rear side of the second ultrasonic sonotrode 2; the second ultrasonic sonotrode 2 uses an ultrasonic frequency of 30 kHz, a sonotrode pressure of 100 N, and an amplitude of 20 μm; Step 6: the prepreg tape treated by the second ultrasonic sonotrode 2 enters the third ultrasonic sonotrode 3; Step 7: applying ultrasonic vibration to the prepreg tape treated by the first ultrasonic sonotrode 1 and the second ultrasonic sonotrode 2 through the third ultrasonic sonotrode 3, so that the resin that is not completely melted in the prepreg tape treated by the first ultrasonic sonotrode 1 and the second ultrasonic sonotrode 2 is further melted, and the resin extruded by the third ultrasonic sonotrode 3 (resin 10 extruded by the third ultrasonic sonotrode) is accumulated on the rear side of the third ultrasonic sonotrode 3; the third ultrasonic sonotrode 3 uses an ultrasonic frequency of 40 kHz, a sonotrode pressure of 50N, and an amplitude of 10 μm; Step 8: After the carbon fiber reinforced polyetheretherketone prepreg tape is processed by the first ultrasonic sonotrode 1, the second ultrasonic sonotrode 2, and the third ultrasonic sonotrode 3, the ultrasonic wave is stopped. The resin extruded by the first ultrasonic sonotrode 1, the resin extruded by the second ultrasonic sonotrode 2, and the resin extruded by the third ultrasonic sonotrode 3 are taken out respectively to obtain resin; the fiber is obtained at the front side of the third ultrasonic sonotrode 3, thereby realizing the separation of the fiber and the resin.

[0027] Example 3 A simplified method for recycling fibers and resin from fiber-reinforced thermoplastic prepreg tapes comprises the following steps: Step 1: Lay the fiber-reinforced thermoplastic prepreg tape 7 (carbon fiber reinforced nylon 6 (CF / PA6) prepreg tape) flat on the processing platform 12 and fix it, place the first ultrasonic sonotrode 1 above a section of the CF / PA6 prepreg tape, program along the direction of the carbon fibers in the CF / PA6, determine the starting point and end point of the ultrasonic action, and the starting point and end point should both be on the CF / PA6 prepreg tape, not exceeding the two ends of the prepreg tape, and formulate a motion trajectory; Step 2: Select the ultrasonic frequency to 20 kHz, set the ultrasonic trigger pressure to 150 N, the sonotrode pressure to 150 N, and the amplitude to 30 μm; Step 3: Move the first ultrasonic sonotrode 1 to the starting point of action, apply sonotrode pressure to the trigger pressure, and start to output ultrasonic vibration. At the same time, the first ultrasonic sonotrode 1 moves along the fiber direction of the prepreg tape at a speed of 40 mm / s, and the molten resin is squeezed out of the prepreg tape by the sonotrode and accumulates in front of the first ultrasonic sonotrode 1; Step 4: After the first ultrasonic sonotrode 1 moves to the end point of action, the ultrasonic wave is turned off and the first ultrasonic sonotrode 1 is lifted. The front side of the first ultrasonic sonotrode 1 is the extruded resin, and the rear side of the sonotrode is the carbon fiber (fiber 11), thereby achieving separation and recovery of the fiber and the resin.

[0028] Those skilled in the art to which the present application belongs may make various modifications or additions to the specific embodiments described or replace them in a similar manner, but they will not deviate from the inventive concept of the present application or exceed the scope defined by the attached claims.

Claims

1. A method for recovering fibers and resins from fiber-reinforced thermoplastic prepreg tapes, characterized in that: The specific steps include: Step 1: Compressing the fiber-reinforced thermoplastic prepreg tape using a first ultrasonic sonotrode; Step 2: applying ultrasonic vibration to the fiber-reinforced thermoplastic prepreg tape through the first ultrasonic sonotrode to melt the resin in the prepreg tape; Step 3: The prepreg tape and the ultrasonic sonotrode move relative to each other parallel to the fiber direction, and the molten resin is squeezed out of the prepreg tape by the first ultrasonic sonotrode.

2. The method for recycling fibers and resins in fiber-reinforced thermoplastic prepreg tape according to claim 1, characterized in that: The following steps are also included: Step 4: the prepreg tape treated by the first ultrasonic sonotrode enters the second ultrasonic sonotrode; Step 5: applying ultrasonic vibration to the prepreg tape treated by the first ultrasonic sonotrode through the second ultrasonic sonotrode, so that the resin that is not completely melted in the prepreg tape treated by the first ultrasonic sonotrode is further melted; Step 6: the prepreg tape treated by the second ultrasonic sonotrode enters the third ultrasonic sonotrode; Step 7: applying ultrasonic vibration to the prepreg tape treated by the first and second ultrasonic sonotrodes through the third ultrasonic sonotrode, so that the resin that is not completely melted in the prepreg tape treated by the first and second ultrasonic sonotrodes is further melted; Step 8: After the prepreg tape has been processed by the first, second and third ultrasonic waves, the first, second and third ultrasonic waves are turned off.

3. A method for recycling fibers and resins in a fiber-reinforced thermoplastic prepreg tape according to claim 1 or 2, characterized in that: The fiber-reinforced thermoplastic prepreg tape has a thickness between 0.1 and 0.4 mm.

4. The method for recycling fibers and resins in a fiber-reinforced thermoplastic prepreg tape according to claim 2, characterized in that: The first, second and third ultrasonic sound end end surfaces are in arc shape.

5. The method for recycling fibers and resins in fiber-reinforced thermoplastic prepreg tapes according to claim 2, characterized in that: The third ultrasonic sonotrode has an ultrasonic frequency of 15 to 20 kHz, an ultrasonic amplitude of 30 to 50 μm, an applied pressure range of 50 to 200 N, and a relative running speed range of 10 to 50 mm / s between the sonotrode and the prepreg tape; The second ultrasonic sonotrode has an ultrasonic frequency of 25 to 30 kHz, an ultrasonic amplitude of 15 to 30 μm, an applied pressure range of 30 to 100 N, and a relative running speed range of the sonotrode and the prepreg tape of 10 to 50 mm / s; The first ultrasonic sonotrode has an ultrasonic frequency of 35 to 40 kHz, an ultrasonic amplitude of 5 to 15 μm, an applied pressure range of 10 to 50 N, and a relative running speed range of the sonotrode and the prepreg tape of 10 to 50 mm / s.

6. The method for recycling fibers and resins in fiber-reinforced thermoplastic prepreg tape according to claim 2, characterized in that: The resin of the fiber-reinforced thermoplastic prepreg is a thermoplastic resin, which is any one of polyetheretherketone, polyphenylene sulfide, polyetherimide, polyamide, polyimide, polysulfone and polypropylene.

7. The method for recycling fibers and resins in fiber-reinforced thermoplastic prepreg tapes according to claim 2, characterized in that: The fiber of the fiber-reinforced thermoplastic prepreg tape is any one of carbon fiber, glass fiber, metal fiber, mineral fiber and plant fiber.

8. A device for recovering fibers and resins in fiber-reinforced thermoplastic prepreg tapes, characterized in that: It comprises a plurality of ultrasonic sonic poles and supporting devices corresponding to the ultrasonic sonic poles, and the fiber-reinforced thermoplastic prepreg tape is arranged between the ultrasonic sonic poles and the supporting devices.

9. The device for recovering fibers and resins in fiber-reinforced thermoplastic prepreg tape according to claim 8, characterized in that: The supporting device is a roller, which corresponds to the ultrasonic sonotrode, so that the roller and the ultrasonic sonotrode press the fiber-reinforced thermoplastic prepreg tape and realize the movement of the fiber-reinforced thermoplastic prepreg tape in parallel to the fiber direction.

10. The device for recovering fibers and resins in fiber-reinforced thermoplastic prepreg tape according to claim 8, characterized in that: The supporting device is a processing platform, and the ultrasonic sonotrode is arranged above the processing platform. The ultrasonic sonotrode moves in a direction parallel to the fiber direction of the fiber-reinforced thermoplastic prepreg tape.

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