Nanofiber-reinforced super-thick PTFE composite molded board and lamination molding process thereof

Abstract

The invention relates to the technical field of composite molded boards, in particular to a nanofiber-reinforced super-thick PTFE composite molded board which comprises the following components in percentage by weight: a matrix material: 70-85% of PTFE resin; nanofiber reinforcement: 5%-15% of PI nanofibers and 2%-8% of modified carbon nanotubes; functional additives: 3%-10% of fluorinated graphene and 1%-5% of nano SiO2; and a processing aid: 0.5%-2% of hydroxypropyl methyl cellulose ether and 1%-3% of ammonium perfluorooctanoate. The invention relates to a lamination forming process of a nanofiber-reinforced super-thick PTFE (Polytetrafluoroethylene) composite molded board. The lamination forming process comprises the following steps: step 1, pretreating nanofibers; step 2, mixing and pre-pressing; and step 3, designing a laminated structure. The gradient lamination design is combined with surface layer-core layer function differentiation, and the problem that the interlayer peeling strength of a traditional PTFE plate is low is solved.

Description

Technical Field

[0001] This invention relates to the field of composite molding technology, and in particular to nanofiber reinforced ultra-thick PTFE composite molding plates and their lamination molding process. Background Technology

[0002] Polytetrafluoroethylene (PTFE) is widely used in aerospace, chemical corrosion protection, and electronic insulation due to its extremely low coefficient of friction (0.04), high temperature resistance (-200~260℃), and chemical corrosion resistance (resistant to strong acids, strong alkalis, and organic solvents). However, its inherent defects, such as low mechanical strength (tensile strength only 25-30MPa), poor creep resistance (creep rate of 2.5% at 200℃), and weak interlayer bonding, limit its application in ultra-thick structural components (such as plates over 50mm).

[0003] Demand for ultra-thick substrates: In fields such as semiconductor equipment and high-power electronic packaging, PTFE substrates with a thickness of ≥50mm are required to withstand extreme operating conditions (such as high-frequency electromagnetic fields and high-pressure corrosion environments).

[0004] Current status of enhancement technology: Existing technologies improve mechanical properties by filling with glass fibers, carbon nanotubes, etc., but there are problems such as uneven dispersion of fillers, interlayer thermal stress cracking, and insufficient interfacial bonding.

[0005] Lamination process challenges:

[0006] Traditional PTFE lamination processes use a single temperature-pressure curve (e.g., 380℃ / 10MPa), resulting in an interlayer bubble residual rate >5% and large differences in thermal shrinkage rates (linear expansion coefficient reaches 50-100ppm / ℃). Furthermore, the lack of gradient structure design in ultra-thick sheets leads to a mismatch between the core and surface properties, easily causing interlayer delamination (peel strength <5N / cm). Summary of the Invention

[0007] The purpose of this invention is to provide a nanofiber-reinforced ultra-thick PTFE composite molded plate and its lamination process to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a nanofiber-reinforced ultra-thick PTFE composite molded plate, comprising the following components in percentage:

[0009] Matrix material: 70%-85% PTFE resin;

[0010] Nanofiber reinforcement: 5%-15% PI nanofibers, 2%-8% modified carbon nanotubes;

[0011] Functional additives: 3%-10% fluorinated graphene, 1%-5% nano-SiO2;

[0012] Processing aids: 0.5%-2% hydroxypropyl methylcellulose ether, 1%-3% perfluorooctanoic acid ammonium.

[0013] Preferably, the PTFE resin has a bimodal molecular weight, and the fluorinated graphene has a particle size of 30nm-50nm.

[0014] The lamination process for nanofiber-reinforced ultra-thick PTFE composite molded sheets includes the following steps:

[0015] Step 1: Nanofiber pretreatment;

[0016] Step 2: Mixing and Pre-compression;

[0017] Step 3: Laminated structure design;

[0018] Step 4: Hot pressing;

[0019] Step 5: Post-processing.

[0020] Preferably, step one, nanofiber pretreatment, includes electrospinning to prepare PI fibers: electrospinning a 20wt% polyimide solution at a voltage of 15kV and a receiving distance of 20cm to obtain a continuous fiber membrane with a diameter of 200-500nm.

[0021] Preferably, step one, nanofiber pretreatment, includes carbon nanotube modification: carbon nanotubes and silver nanopowder are ultrasonically dispersed in ethylene glycol at a ratio of 3:1, spray-dried, and heat-treated at 500°C to form a conductive network.

[0022] Preferably, step two, mixing and pre-compression, includes high-speed shear mixing: PTFE resin, nanofibers and additives are mixed in a twin-screw extruder at an L / D ratio of 30:1, with a temperature gradient of 180°C in the feeding section, 220°C in the mixing section and 200°C in the die head.

[0023] Pre-compression molding: The mixture is cold-compressed into 2mm thin sheets at 10MPa-20MPa and then cut into laminated prepregs.

[0024] Preferably, step three, the laminated structure design, includes gradient lamination:

[0025] The design incorporates a 5-layer structure: surface layer, transition layer, core layer, transition layer, and surface layer.

[0026] Surface layer: 10% fluorinated graphene and 15% PI nanofibers to improve surface wear resistance;

[0027] Core layer: 8% modified nanotubes and 5% nano-SiO2, enhancing creep resistance and dimensional stability;

[0028] Transition layer: 15% PI nanofibers, 8% silver-coated carbon nanotubes, 5% fluorinated graphene, and 3% nano-SiO2.

[0029] Preferably, step four, hot pressing, includes segmented heating:

[0030] First stage: Maintain 180℃ / 10MPa for 30 minutes to allow PTFE to melt and penetrate the fiber gaps;

[0031] Second stage: Maintain at 300℃ / 30MPa for 60 minutes to induce PTFE crystals to align.

[0032] Preferably, step four, hot pressing, includes dynamic pressure compensation: by using a pressure sensor built into the mold to adjust the pressure in real time for fluctuations of ±0.5MPa, interlayer bubbles are eliminated.

[0033] Preferably, step five, the post-processing, includes gradient annealing: cooling to 250°C at a rate of 2°C / min and holding for 1 hour to release residual stress;

[0034] Surface plasma treatment: Ar / O2 mixed gas plasma treatment, power 200W, 5 minutes, to improve coating adhesion.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] Structural innovation: The gradient lamination design, combined with the functional differentiation of the surface and core layers, solves the problem of low interlayer peel strength in traditional PTFE boards.

[0037] Process innovation: Dynamic pressure compensation technology reduces the lamination bubble rate from 5% to 0.1%.

[0038] Material innovation: Silver-coated carbon nanotubes / PI fibers provide synergistic reinforcement, achieving a balance of mechanical, electrical, and temperature resistance properties. Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 The following is a composition table of the nanofiber-reinforced ultra-thick PTFE composite molded plate of the present invention;

[0041] Figure 2 This is a flowchart illustrating the preparation process of the nanofiber-reinforced ultrathick PTFE composite molded plate of the present invention.

[0042] Figure 3 A reference table is provided for the nanofiber-reinforced ultra-thick PTFE composite molding plate of the present invention and the prior art. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Please see Figures 1 to 3 The present invention provides a technical solution:

[0045] Nanofiber reinforced ultra-thick PTFE composite molded sheet, comprising the following percentage components:

[0046] Matrix material: 70%-85% PTFE resin;

[0047] Nanofiber reinforcement: 5%-15% PI nanofibers, 2%-8% modified carbon nanotubes;

[0048] Functional additives: 3%-10% fluorinated graphene, 1%-5% nano-SiO2;

[0049] Processing aids: 0.5%-2% hydroxypropyl methylcellulose ether, 1%-3% perfluorooctanoic acid ammonium.

[0050] The PTFE resin has a bimodal molecular weight, and the fluorinated graphene has a particle size of 30nm-50nm.

[0051] The lamination process for nanofiber-reinforced ultra-thick PTFE composite molded sheets includes the following steps:

[0052] Step 1: Nanofiber pretreatment;

[0053] Step 2: Mixing and Pre-compression;

[0054] Step 3: Laminated structure design;

[0055] Step 4: Hot pressing;

[0056] Step 5: Post-processing.

[0057] Step one, nanofiber pretreatment, includes electrospinning to prepare PI fibers: 20wt% polyimide solution is electrospinned at a voltage of 15kV and a receiving distance of 20cm to obtain a continuous fiber membrane with a diameter of 200-500nm.

[0058] Step one, nanofiber pretreatment, includes carbon nanotube modification: carbon nanotubes and silver nanopowder are ultrasonically dispersed in ethylene glycol at a ratio of 3:1, then spray-dried and heat-treated at 500℃ to form a conductive network.

[0059] Step two, mixing and pre-compression, includes high-speed shear mixing: PTFE resin, nanofibers and additives are mixed in a twin-screw extruder at an L / D ratio of 30:1, with a temperature gradient of 180°C in the feeding section, 220°C in the mixing section and 200°C in the die head.

[0060] Pre-compression molding: The mixture is cold-compressed into 2mm thin sheets at 10MPa-20MPa and then cut into laminated prepregs.

[0061] Step three, the laminated structure design, includes gradient lamination:

[0062] The design incorporates a 5-layer structure: surface layer, transition layer, core layer, transition layer, and surface layer.

[0063] Surface layer: 10% fluorinated graphene and 15% PI nanofibers to improve surface wear resistance;

[0064] Core layer: 8% modified nanotubes and 5% nano-SiO2, enhancing creep resistance and dimensional stability;

[0065] Transition layer: 15% PI nanofibers, 8% silver-coated carbon nanotubes, 5% fluorinated graphene, and 3% nano-SiO2.

[0066] Step four, hot pressing, includes segmented heating:

[0067] First stage: Maintain 180℃ / 10MPa for 30 minutes to allow PTFE melt to penetrate the fiber gaps; promote the penetration of PTFE melt into the fiber gaps and reduce porosity to <0.1%;

[0068] Second stage: Maintain at 300℃ / 30MPa for 60 minutes to induce PTFE crystals to align and PTFE molecular chains to align along the fiber axis, increasing tensile strength to ≥100MPa.

[0069] Step four, hot pressing, includes dynamic pressure compensation: the pressure fluctuates within ±0.5MPa using a built-in pressure sensor in the mold, and the pressure is adjusted in real time to eliminate interlayer bubbles. The press closing speed is dynamically adjusted through a servo hydraulic system to improve density uniformity to ±1%.

[0070] Step five, the post-processing process, includes gradient annealing: cooling to 250°C at a rate of 2°C / min and holding for 1 hour to release residual stress;

[0071] Surface plasma treatment: Ar / O2 mixed gas plasma treatment, power 200W, 5 minutes, to improve coating adhesion.

[0072] Example 1: 15% PI fiber + 10% fluorinated graphene + 3% nano-SiO2, suitable for high-load guide rails;

[0073] Example 2: 8% modified carbon nanotubes + 2% silver powder, suitable for antistatic electronic packaging;

[0074] Example 3: Nano-SiO2 5% + gradient annealing process, suitable for high-temperature valve seals;

[0075] The above solutions, through multi-component synergy and advanced lamination processes, overcome the processing bottleneck of ultra-thick PTFE sheets (thickness > 50 mm) and can be applied to fields such as semiconductor equipment and high-temperature resistant components for aerospace.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A nanofiber-reinforced ultra-thick PTFE composite molded plate, characterized in that: Includes the following percentage components: Matrix material: 70%-85% PTFE resin; Nanofiber reinforcement: 5%-15% PI nanofibers, 2%-8% modified carbon nanotubes; Functional additives: 3%-10% fluorinated graphene, 1%-5% nano-SiO2; Processing aids: 0.5%-2% hydroxypropyl methylcellulose ether, 1%-3% perfluorooctanoic acid ammonium.

2. The nanofiber-reinforced ultra-thick PTFE composite molded plate according to claim 1, characterized in that: The PTFE resin has a bimodal molecular weight, and the fluorinated graphene has a particle size of 30nm-50nm.

3. A lamination process applicable to the nanofiber-reinforced ultra-thick PTFE composite molded plate as described in claim 1, characterized in that: Includes the following steps: Step 1: Nanofiber pretreatment; Step 2: Mixing and Pre-compression; Step 3: Laminated structure design; Step 4: Hot pressing; Step 5: Post-processing.

4. The lamination process for the nanofiber-reinforced ultra-thick PTFE composite molded plate according to claim 3, characterized in that: Step one, nanofiber pretreatment, includes electrospinning to prepare PI fibers: 20wt% polyimide solution is electrospinned at a voltage of 15kV and a receiving distance of 20cm to obtain a continuous fiber membrane with a diameter of 200-500nm.

5. The lamination process for the nanofiber-reinforced ultra-thick PTFE composite molded plate according to claim 3, characterized in that: Step one, nanofiber pretreatment, includes carbon nanotube modification: carbon nanotubes and silver nanopowder are ultrasonically dispersed in ethylene glycol at a ratio of 3:1, then spray-dried and heat-treated at 500℃ to form a conductive network.

6. The lamination process for the nanofiber-reinforced ultra-thick PTFE composite molded plate according to claim 3, characterized in that: Step two, mixing and pre-compression, includes high-speed shear mixing: PTFE resin, nanofibers and additives are mixed in a twin-screw extruder at an L / D ratio of 30:1, with a temperature gradient of 180°C in the feeding section, 220°C in the mixing section and 200°C in the die head. Pre-compression molding: The mixture is cold-compressed into 2mm thin sheets at 10MPa-20MPa and then cut into laminated prepregs.

7. The lamination process for the nanofiber-reinforced ultra-thick PTFE composite molded plate according to claim 3, characterized in that: Step three, the laminated structure design, includes gradient lamination: The design incorporates a 5-layer structure: surface layer, transition layer, core layer, transition layer, and surface layer. Surface layer: 10% fluorinated graphene and 15% PI nanofibers to improve surface wear resistance; Core layer: 8% modified nanotubes and 5% nano-SiO2, enhancing creep resistance and dimensional stability; Transition layer: 15% PI nanofibers, 8% silver-coated carbon nanotubes, 5% fluorinated graphene, and 3% nano-SiO2.

8. The lamination process for the nanofiber-reinforced ultra-thick PTFE composite molded plate according to claim 3, characterized in that: Step four, hot pressing, includes segmented heating: First stage: Maintain 180℃ / 10MPa for 30 minutes to allow PTFE to melt and penetrate the fiber gaps; Second stage: Maintain at 300℃ / 30MPa for 60 minutes to induce PTFE crystals to align.

9. The lamination process for the nanofiber-reinforced ultra-thick PTFE composite molded plate according to claim 3, characterized in that: Step four, hot pressing, includes dynamic pressure compensation: the pressure is adjusted in real time to eliminate interlayer bubbles by using a pressure sensor built into the mold that allows for fluctuations of ±0.5MPa.

10. The lamination process for the nanofiber-reinforced ultra-thick PTFE composite molded plate according to claim 3, characterized in that: Step five, the post-processing process, includes gradient annealing: cooling to 250°C at a rate of 2°C / min and holding for 1 hour to release residual stress; Surface plasma treatment: Ar / O2 mixed gas plasma treatment, power 200W, 5 minutes, to improve coating adhesion.

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