High-performance conductive heat-sealing co-extrusion composite sheet and double-screw gradient temperature control preparation process

Abstract

The invention relates to a high-performance conductive heat-sealing co-extrusion composite sheet and a double-screw gradient temperature control preparation process, and belongs to the field of functional polymer composite material processing. The sheet comprises a functional layer A, a transition layer B and a heat sealing layer C from inside to outside. The layer A comprises 80-95 wt% of a polymer matrix I, 4-18 wt% of a conductive filler, 0.5-2 wt% of an interface modifier and 0.5-1 wt% of an antioxidant. And the layer B comprises 70-90 wt% of a polymer matrix II and 10-30 wt% of a compatible polymer. And the layer C comprises 90-98 wt% of a low-melting-point polymer and 2-10 wt% of tackifying resin. The preparation process adopts a three-order independent temperature control co-rotating twin-screw extrusion system: in the first area, solid conveying and melting plasticizing are realized at the temperature of 160-210 DEG C; the second region is used for strongly shearing and dispersing conductive filler at 220-250 DEG C; and the melt is conveyed at the temperature of 190-210 DEG C through accurate temperature control in the third area. And the compression ratio of the designed runner of the die head is (15-18): 1. The process guarantees effective dispersion of the conductive filler and avoids thermal degradation of the polymer, and the volume resistivity of the sheet is 1t; 1.0 omega.cm, and the heat sealing strength gt; and the electromagnetic shielding film has excellent electromagnetic shielding effectiveness and thermal stability.

Description

Technical Field

[0001] This invention belongs to the field of functional polymer composite material processing, and particularly relates to the preparation process of high-performance conductive heat-sealed co-extruded composite sheets and twin-screw gradient temperature control. Background Technology

[0002] With the miniaturization of 5G communication and IoT devices, the demand for antistatic and electromagnetic shielding encapsulation materials has surged. Traditional filled conductive composite materials suffer from problems such as mechanical property degradation due to high filler load and processing difficulties. Carbon nanomaterials have attracted much attention due to their high conductivity and low permeation threshold, but they are prone to fragmentation due to strong shear in shear-sensitive polymers, leading to conductivity failure.

[0003] Patent CN112959692A proposes a multilayer conductive sheet structure, but the use of adhesives between the layers results in weak interfacial bonding and a peel strength of less than 5N / 15mm. While co-extrusion technology can achieve integrated molding, the melt temperatures and rheological properties of different functional layers differ significantly. For example, the heat-sealing layer requires low-temperature processing to avoid thermal degradation, while the highly dispersed conductive filler requires high temperature and high shear, making their thermal histories incompatible.

[0004] Current processes mostly employ a compromise strategy: either sacrificing conductivity by limiting filler addition below the percolation threshold, or abandoning co-extrusion and using offline coating for the heat-sealing layer. The former results in a resistivity >10. 2 Ω, shielding effectiveness <20dB; the latter suffers from interfacial delamination due to insufficient adhesion. US20210046712A1 uses modified polyolefin as a heat-sealing layer, but its poor compatibility with engineering plastics increases the risk of delamination. There is an urgent need to develop new composite materials and precision manufacturing processes that can simultaneously meet the requirements of high conductivity, strong heat-sealing properties, and interlayer bonding. Summary of the Invention

[0005] To address the challenge of achieving high electrical conductivity, strong heat-sealing properties, and interlayer bonding strength in composite materials.

[0006] To address the above problems, the present invention provides the following technical solution: A high-performance conductive heat-sealing co-extruded composite sheet and its preparation process using a twin-screw gradient temperature control method are characterized by co-extrusion molding with a co-rotating twin-screw extrusion system having three independent temperature control units and a composite die, comprising the following steps: S1: Raw material premixing, mixing the raw materials of layers A, B, and C according to the formula; S2: Gradient melt extrusion. The raw materials of layers A and B are fed into a twin-screw extruder and extruded in the following three temperature fields: Zone 1: 160-210℃, solid conveying and melt plasticizing; Zone 2: 220-250℃, strong shear dispersion of conductive filler; Zone 3: 190-210℃, precise temperature control and melt conveying. S3: Composite co-extrusion, after the C layer raw material is melted by a single screw extruder, it enters the three-channel composite die together with the A and B layer melts. The die compression ratio is 15-18:1. S4: Rapid cooling and shaping, co-extrusion melt is cast to cooling rollers, roller temperature 15-35℃, linear speed 5-20m / min.

[0007] Preferably, in S2, the screw speed in the second zone is 250-450 rpm, and the shear rate is >1500 s. -1 .

[0008] Preferably, the temperature range of the composite mold head is set in S3, wherein the temperature of the A flow channel is 195-210℃, the temperature of the B flow channel is 185-200℃, and the temperature of the C flow channel is 160-180℃.

[0009] Preferably, the cooling roller in S4 adopts a differential double roller system, with the high-gloss surface temperature of the first roller at 25-35℃ and the matte surface temperature of the second roller at 10-20℃.

[0010] Preferably, the composite sheet is used in electromagnetic shielding packaging materials, antistatic heat-sealing packaging, or flexible electrode substrates.

[0011] The effects and advantages of the high-performance conductive heat-sealing co-extruded composite sheet and the twin-screw gradient temperature control preparation process of this invention are as follows: 1. This patent features high conductivity and strong shielding effectiveness, with a volume resistivity of <1.0Ω and an electromagnetic shielding effectiveness of >35dB (1GHz).

[0012] 2. This patent features excellent heat-sealing performance and interlayer bonding strength, with a heat-sealing strength of 18.2 N / 15 mm and an interlayer peel strength of >10 N / 15 mm.

[0013] 3. This patent significantly improves thermal stability, with the thermal decomposition temperature increased by 16°C compared to conventional processes.

[0014] 4. This patent has advantages in energy consumption and cost, saving 23% energy compared to traditional processes. Attached Figure Description

[0015] Figure 1 This is a flowchart of the high-performance conductive heat-sealing co-extruded composite sheet and the twin-screw gradient temperature control preparation process in this invention. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Example 1

[0018] refer to Figure 1 This embodiment provides a high-performance conductive heat-sealing co-extruded composite sheet and a twin-screw gradient temperature control preparation process, which is applicable to the field of functional polymer composite material processing and includes the following implementation details: Experimental objective: A high-performance conductive heat-sealing co-extruded composite sheet and a twin-screw gradient temperature control manufacturing process were developed to verify the synergistic optimization effect of the three-layer structure design and gradient temperature control process on the conductive-heat-sealing performance.

[0019] Experimental materials: Layer A: 80wt% polymer matrix PA6, 15wt% conductive filler VGCF, 2wt% interface modifier KH550, 0.5wt% antioxidant 1010; Layer B: 70wt% polymer matrix PA6, 30wt% interface modifier PE-g-MAH; Layer C: 95wt% polymer matrix mPE, 5wt% interface modifier EVA-g-MAH, 5wt% tackifying resin Escorez 2203.

[0020] Experimental equipment: Co-rotating twin-screw extruder, L / D=40, screw diameter 35mm; single-screw extruder, screw diameter 30mm; three-channel composite flat die head, die lip width 800mm, compression ratio 16:1; differential dual-roller cooling system.

[0021] Experimental steps: S1: Layer A PA6, VGCF, KH550 and antioxidant are premixed in a high-speed mixer for 5 minutes; S2: Layer B PA6 and PE-g-MAH were pre-dried at 90℃ for 4 hours; S3: The materials of layers A and B are respectively fed into the feed inlet of the first zone of the twin-screw extruder and melt-blended according to the set temperature zone and speed. S4: C-layer mPE and EVA-g-MAH are melted in a single-screw extruder, with temperatures of 160 / 170 / 175℃ in each section; S5: The three-layer melt is fed into the composite die head for co-extrusion, and then shaped and wound up by a double-roller cooling system.

[0022] Experimental results: See Table 1 for details.

[0023] Table 1: Test Results of Example 1

[0024] Example 1: High-performance conductive heat-sealing co-extruded composite sheet and twin-screw gradient temperature control manufacturing process. The reason for the low volume resistivity of 0.85 Ω·cm is the construction of the conductive network. The high temperature of 235℃ in the second zone significantly reduces the melt viscosity of PA6, allowing the VGCF filler to achieve a low volume resistivity of 0.85 Ω·cm within 1800 s. -1 Under high shear rates, the aggregates fully deagglomerate and align along the flow direction, forming a continuous conductive path. Furthermore, rapid cooling to 205℃ in the three zones shortens the high-temperature residence time, significantly suppressing oxidation defects on the VGCF surface and ensuring the integrity of carrier migration channels. The heat-sealing strength of 18.2 N / 15mm is achieved through synergistic control of the surface and interface. Differential dual-roller cooling, reducing the temperature from 30℃ to 15℃, increases the crystallinity of the C-layer mPE, achieving a surface energy of 35.6 mN / m. This significantly improves melt wettability during heat sealing at 130℃. The vinyl acetate segments in EVA-g-MAH exhibit a transient thickening effect at the heat-sealing temperature. The electromagnetic shielding effectiveness of 38 dB stems from the dual dissipation mechanism of this conductive network. The three-dimensional network formed by VGCF enhances electromagnetic wave absorption through interface polarization, and the multiple reflections of incident waves by the multi-layered interfaces of the sheet further dissipate energy. The interlayer peel strength of 12.3 N / 15 mm mainly depends on the interfacial chemical reaction and physical entanglement. The maleic anhydride group of PE-g-MAH in layer B reacts with the amino group at the 6-terminus of PA in layer A to form an imide bond. At the same time, its ethylene segment co-crystallizes with mPE in layer C to form a crystal bridge structure, realizing a dual strengthening mechanism of "chemical bonding-crystallization entanglement". Example 2

[0025] This embodiment provides a high-performance conductive heat-sealing co-extruded composite sheet and a twin-screw gradient temperature control manufacturing process, including the following implementation details: Experimental objective: A high-performance conductive heat-sealing co-extruded composite sheet and a twin-screw gradient temperature control manufacturing process were developed to verify the adaptability of different matrix materials to the process.

[0026] Experimental materials: Layer A: 82wt% polymer matrix PET, 12wt% conductive filler VGCF+, 3wt% graphene, 3wt% interface modifier ethylene-acrylate-maleic anhydride terpolymer EMAH, 0.5wt% antioxidant 1010; Layer B: 75wt% polymer matrix PET, 25wt% interface modifier polyetherimide PEI, 0.5wt% antioxidant 168; Layer C: 94wt% polymer matrix mPE, 6wt% interface modifier glycidyl methacrylate grafted EVA-g-GMA.

[0027] Experimental steps: S1: Raw material pretreatment: PET is vacuum dried at 150℃ for 6 hours with a moisture content of <0.01%. A layer raw materials: PET, VGCF, graphene, EMAH, antioxidant 1010 are mixed at high speed for 10 minutes at 800 rpm. B layer raw materials: PET and PEI are premixed by intensive mixing at 100℃ for 5 minutes. S2: Gradient extrusion, zone 1 feeding, 185℃ solid conveying to prevent PET hydrolysis, zone 2 mixing, 245℃ high-shear dispersion, screw speed 320rpm, shear rate 1900s. -1 Three-zone metering, 210℃ melt pressure stabilization and conveying, residence time <20s; S3: Co-extrusion composite, with layer C melted in a single-screw extruder at temperatures of 160 / 170 / 165℃. The three melt layers are co-extruded through a composite die, with flow channel A at 210℃, flow channel B at 200℃, and flow channel C at 170℃. The compression ratio is 16:1. S4: Rapid cooling and shaping, cooling roller temperature, roller 1 gloss surface 35℃ → roller 2 matte surface 20℃, traction speed 12m / min, rapid cooling temperature difference >150℃ / s.

[0028] Experimental results: See Table 2 for details.

[0029] Table 2: Test Results of Example 2

[0030] Example 2 describes a high-performance conductive heat-sealing co-extruded composite sheet and a twin-screw gradient temperature-controlled manufacturing process. The core of this process, which achieves a volume resistivity superior to conventional PET composite systems, lies in the synergistic construction of a dual conductive network. Graphene nanosheets fill the gaps between VGCF fibers, forming a "point-line" composite conductive pathway, reducing the percolation threshold. The high temperature of 245℃ in the second zone reduces the PET melt viscosity. Acrylic ester segments in EMAH encapsulate the filler, lowering the interfacial barrier and improving carrier mobility. The heat-sealing strength of 16.8 N / 15mm is attributed to the surface crystallization control of the C layer. A rapid cooling temperature difference of 35℃→20℃ induces the formation of spherulites <5μm in mPE, reducing surface roughness and significantly improving melt wettability. The interlayer peel strength of 11.5 N / cm is due to the ring-opening reaction between the imide groups of PEI in the B layer and the maleic anhydride of EMAH in the A layer. Simultaneously, the rigid segments of PEI form co-crystallized microregions with PET, constructing a 150nm interpenetrating layer at the interface, effectively dissipating peel stress. The improved thermal stability is due to the gradient process, which reduces the high-temperature exposure time of PET to <120 seconds, significantly inhibiting the thermal decomposition of terminal carboxyl groups. Example 3

[0031] This embodiment provides a high-performance conductive heat-sealing co-extruded composite sheet and a twin-screw gradient temperature control manufacturing process, including the following implementation details: Experimental objective: A high-performance conductive heat-sealed co-extruded composite sheet and a twin-screw gradient temperature-controlled preparation process were developed to explore the performance balance and energy consumption control under the condition of reduced conductive filler content.

[0032] Experimental materials: Layer A: 85wt% polymer matrix PA6, 9wt% conductive filler VGCF+, 3wt% graphene, 2wt% interface modifier KH550, 0.6wt% antioxidant 1076; Layer B: 70wt% polymer matrix PA6, 30wt% interface modifier LLDPE-g-MAH; Layer C: 93wt% polymer matrix mPE, 7wt% interface modifier POE-g-MAH.

[0033] Experimental steps: S1: Raw material pretreatment, A layer: PA6, VGCF, graphene, KH550 are dry-mixed in a high-speed mixer for 8 min at 1200 rpm; B layer: PA6 and LLDPE-g-MAH are pre-mixed in a twin-screw small-scale machine at 190℃ for 3 min. S2: Gradient extrusion, low energy consumption mode, Zone 1, 165℃ to prevent graphene pre-oxidation, Zone 2, 225℃, screw speed 250rpm, shear rate 1500s. -1 Zone 3, 195℃ melt pressure 10MPa; S3: Co-extrusion composite, C layer melt temperature: 160 / 165 / 170℃, die head temperature: A runner 195℃, B runner 185℃, C runner 165℃; S4: Energy-saving rapid cooling, temperature difference of cooling rollers: roller 1 temperature 30℃ → roller 2 temperature 15℃, traction speed 10m / min, speed reduction and energy saving.

[0034] Experimental results: See Table 3 for details.

[0035] Table 3: Test Results of Example 3

[0036] Example 3 describes a high-performance conductive heat-sealing co-extruded composite sheet and a twin-screw gradient temperature-controlled preparation process. The volume resistivity is maintained at 0.95 Ω·cm due to the synergistic conductivity effect of graphene and VGCF. Graphene nanosheets are embedded in the gaps of the VGCF framework, forming a composite network of "two-dimensional sheets supporting one-dimensional fibers," which lowers the percolation threshold. Low-temperature mixing at 225℃ in the second zone, 10℃ lower than in Example 1, combined with a low rotation speed of 250 rpm, ensures dispersibility while reducing graphene edge defects, maintaining carrier mobility at 42 cm² / V·s. The heat-sealing strength slightly decreases to 16.3 N / 15mm due to the reduction of polar groups in the C layer POE-g-MAH, but it is still above the industrial standard of >15 N / 15mm. The interlayer peel strength decreases to 10.7 N / 15mm because the grafting rate of the B layer LLDPE-g-MAH is lower, resulting in weaker reactivity with PA6 compared to the PE-g-MAH in Example 1, but it still maintains acceptable strength through physical entanglement. The energy consumption reduction stems from dual process optimization: low-speed shearing reduces the conversion of mechanical energy into heat energy, and a smaller gradient temperature zone reduces heating power. Comprehensive evidence demonstrates that this solution achieves an industrial-grade balance of "reduced packing volume - reduced energy consumption - performance compliance". Comparative Example 1

[0037] We provide conductive heat-sealing co-extruded composite sheets and a twin-screw isothermal preparation process, applicable to the processing of functional polymer composite materials, including the following implementation details: Experimental objective: Conductive heat-sealed co-extruded composite sheets and twin-screw isothermal preparation process were developed to verify the necessity of gradient temperature control technology.

[0038] Experimental materials: Layer A: 80wt% polymer matrix PA6, 15wt% conductive filler VGCF, 2wt% interface modifier KH550, 0.5wt% antioxidant 1010; Layer B: 70wt% polymer matrix PA6, 30wt% interface modifier PE-g-MAH; Layer C: 95wt% polymer matrix mPE, 5wt% interface modifier EVA-g-MAH, 5wt% tackifying resin Escorez 2203.

[0039] Experimental steps: S1: Raw material pretreatment, Layer A: 80wt% PA6 + 15wt% VGCF + 2wt% KH550 + 0.5wt% 1010, high mixing for 5min; Layer B: 70wt% PA6 + 30wt% PE-g-MAH, dried at 90℃ for 4h; Layer C: 95wt% mPE + 5wt% EVA-g-MAH + 5wt% Escorez 2203, directly fed into the single screw hopper; S2: Constant temperature extrusion processing, eliminating gradient temperature zones, unified settings for all zones of the twin-screw extrusion: 230℃, screw speed 300rpm, shear rate 1800s. -1 The melt pressure valve is fully open, with no pressure stabilization control. S3: Die head co-extrusion, eliminating layered temperature control, three runners with a unified temperature of 210℃, and maintaining a compression ratio of 16:1; S4: Rapid cooling and shaping, cooling roller temperature: roller 1 30℃ → roller 2 15℃; traction speed 15m / min.

[0040] Experimental results: See Table 4 for details.

[0041] Table 4: Test Results of Comparative Example 1

[0042] Comparative Example 1: The conductive heat-sealed co-extruded composite sheet and the twin-screw isothermal preparation process significantly increased the volume resistivity to 5.7 × 10⁻⁶. 4 At a constant temperature of 230℃, PA6 underwent severe thermal degradation, resulting in insufficient melt strength and VGCF fiber breakage during melt extrusion. Simultaneously, continuous high-temperature oxidation of the VGCF surface significantly reduced carrier mobility, closing conductive pathways. The heat-sealing strength decreased to 8.1 N / 15mm, attributed to irreversible damage to the C-layer structure. prolonged retention of mPE at 230℃ triggered a β-fracture reaction, causing low-molecular-weight components to migrate to the surface. Excessive cross-linking of the tackifying resin EVA-g-MAH formed gel particles, leading to insufficient melt wetting during heat sealing. Electromagnetic shielding effectiveness was <12 dB, as the VGCF network structure lacked a reflection mechanism, resulting in a sharp drop in dielectric loss. The interlayer peel strength decreased to 3.2 N / 15mm. Excessive reaction between the B-layer PE-g-MAH and PA6 at high temperatures generated a brittle interface phase, while the crystalline integrity of the C-layer mPE was disrupted, losing its physical entanglement and anchoring effect.

[0043] Example 1 provides a high-performance conductive heat-sealing co-extruded composite sheet and a twin-screw gradient temperature control process, verifying the synergistic optimization effect of the three-layer structure design and gradient temperature control process on conductive and heat-sealing performance. Experimental results show that the composite sheet has a low volume resistivity of 0.85 Ω·cm, thanks to the designed conductive network structure, in which the VGCF filler fully deagglomerates and forms a continuous conductive path under specific high temperature and high shear rate conditions. The heat-sealing strength reaches 18.2 N / 15 mm, attributed to the increased crystallinity of the C-layer mPE due to differential twin-roll cooling and the instantaneous tackification effect of EVA-g-MAH. Furthermore, the electromagnetic shielding effectiveness reaches 38 dB, stemming from the dual dissipation mechanism of the conductive network. The interlayer peel strength is 12.3 N / 15 mm, dependent on the dual strengthening mechanism of interfacial chemical reaction and physical entanglement. These excellent properties demonstrate that the three-layer structure design and gradient temperature control process proposed in Example 1 can significantly improve the overall performance of the composite sheet.

[0044] Example 2 further verified the adaptability of different matrix materials to the preparation process of high-performance conductive heat-sealing co-extruded composite sheets. PET was used as the matrix material in the experiment, and a dual conductive network was constructed. The results showed that the volume resistivity of the composite sheet was 1.2 Ω·cm, which was superior to that of conventional PET composite systems. This was mainly attributed to the "point-line" composite conductive pathway formed by graphene nanosheets and VGCF fibers. The heat-sealing strength reached 16.8 N / 15 mm, due to the surface crystallization regulation of the C-layer mPE. The interlayer peel strength was 11.5 N / 15 mm, benefiting from the interfacial chemical reaction between the B-layer PEI and the A-layer EMAH and the formation of co-crystallized microregions. Furthermore, the thermal decomposition temperature reached 398 °C, indicating that the composite sheet has good thermal stability. These results demonstrate that the PET matrix material and gradient temperature control process used in Example 2 can prepare high-performance conductive heat-sealing co-extruded composite sheets with excellent performance.

[0045] Example 3 investigated the performance balance and energy consumption control under reduced conductive filler content. Experimental results showed that while reducing the amount of conductive filler, the volume resistivity of the composite sheet remained at 0.95 Ω·cm, thanks to the synergistic conductivity effect of graphene and VGCF. Although the heat-sealing strength decreased slightly, it still remained above the industrial standard of 16.3 N / 15 mm. The interlaminar peel strength was 10.7 N / 15 mm, which, although lower than in Example 1, still met the acceptable strength requirements. Importantly, the system energy consumption was significantly reduced to 18.3 kW·h / t, thanks to the dual optimization of low-speed shearing and a narrower gradient temperature range. These results demonstrate that the scheme proposed in Example 3 achieves both filler reduction and energy consumption reduction while maintaining the excellent performance of the composite sheet, achieving an industrial-grade balance.

[0046] Comparative Example 1 employed a twin-screw isothermal fabrication process for conductive heat-sealed co-extruded composite sheets to verify the necessity of gradient temperature control. Experimental results showed that the volume resistivity of the composite sheet significantly increased to 5.7 × 10⁻⁶. 4 The heat seal strength decreased to 8.1 N / 15 mm, the electromagnetic shielding effectiveness fell below 12 dB, and the interlayer peel strength also dropped significantly to 3.2 N / 15 mm. These performance degradations were mainly attributed to the thermal degradation of PA6, the breakage and surface oxidation of VGCF fibers, the irreversible damage to the C-layer mPE structure, and the brittleness of the interlayer interface during isothermal fabrication. These results indicate that isothermal fabrication processes cannot provide performance comparable to gradient temperature control processes, further validating the importance of gradient temperature control processes in the fabrication of high-performance conductive heat-sealing co-extruded composite sheets.

[0047] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0048] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0049] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the claims.

[0050] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included in the protection of the present invention.

Claims

1. A high-performance conductive heat-sealing co-extruded composite sheet, characterized in that, It has a three-layer stacked structure, consisting of a conductive functional layer A, a transition adhesive layer B, and a heat-sealing layer C from the inside out, wherein: Layer A consists of: 80-95wt% thermoplastic polymer matrix I, 4-18wt% conductive filler, 0.5-2wt% interface modifier, and 0.5-1wt% antioxidant. Layer B consists of: 70-90 wt% thermoplastic polymer matrix II, and 10-30 wt% compatible polymer; The C layer consists of 90-98 wt% low-melting-point polymer and 2-10 wt% tackifying resin.

2. The high-performance conductive heat-sealing co-extruded composite sheet as described in claim 1, characterized in that, The thermoplastic polymer matrix I is polyamide 6, polyethylene terephthalate, or polycarbonate.

3. The high-performance conductive heat-sealing co-extruded composite sheet as described in claim 2, characterized in that, When the thermoplastic polymer matrix I is PA6, the interface modifier is γ-aminopropyltriethoxysilane; when the matrix I is PET, the interface modifier is ethylene-acrylate-maleic anhydride terpolymer.

4. The high-performance conductive heat-sealing co-extruded composite sheet as described in claim 1, characterized in that, The conductive filler is one or more of carbon nanotubes, vapor-grown carbon fibers, and graphene nanosheets.

5. The high-performance conductive heat-sealing co-extruded composite sheet as described in claim 1, characterized in that, The volume resistivity of the conductive functional layer A is less than 1.0 Ω·cm, and the sealing initiation temperature of the heat-sealing layer C is less than 140℃.

6. The twin-screw gradient temperature-controlled preparation process for the high-performance conductive heat-sealing co-extruded composite sheet as described in any one of claims 1-4, characterized in that, The co-extrusion molding process, employing a co-rotating twin-screw extrusion system with three independent temperature control units and a composite die, includes the following steps: S1: Raw material premixing, mixing the raw materials of layers A, B, and C according to the formula; S2: Gradient melt extrusion. The raw materials of layers A and B are fed into a twin-screw extruder and extruded in the following three temperature fields: Zone 1: 160-210℃, solid conveying and melt plasticizing; Zone 2: 220-250℃, strong shear dispersion of conductive filler; Zone 3: 190-210℃, precise temperature control and melt conveying. S3: Composite co-extrusion. After the C layer raw material is melted by a single screw extruder, it enters the three-channel composite die together with the melt of the A and B layers. The die compression ratio is 15-18:

1. S4: Rapid cooling and shaping, co-extrusion melt is cast to the cooling roller, roller temperature 15-35℃, linear speed 5-20m / min.

7. The twin-screw gradient temperature control process for preparing high-performance conductive heat-sealing co-extruded composite sheets as described in claim 6, characterized in that, In step S2, the screw speed in zone two is set to 250-450 rpm, and the shear rate is set to >1500 s. -1 .

8. The twin-screw gradient temperature control process for preparing high-performance conductive heat-sealing co-extruded composite sheets as described in claim 6, characterized in that, In step S3, the temperature ranges for each composite die head are set as follows: the temperature of flow channel A is 195-210℃, the temperature of flow channel B is 185-200℃, and the temperature of flow channel C is 160-180℃.

9. The twin-screw gradient temperature control process for preparing high-performance conductive heat-sealing co-extruded composite sheets as described in claim 6, characterized in that, The cooling roller in S4 adopts a differential double roller system, with the high-gloss surface temperature of the first roller at 25-35℃ and the matte surface temperature of the second roller at 10-20℃.

10. The twin-screw gradient temperature-controlled preparation process for the high-performance conductive heat-sealing co-extruded composite sheet as described in any one of claims 6-9, characterized in that, The composite sheet is used in electromagnetic shielding packaging materials, antistatic heat-sealing packaging, or flexible electrode substrates.

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