High-adhesion anti-static high-temperature-resistant UV adhesive film and preparation method thereof

Abstract

The invention relates to the field of adhesive film materials, and provides a high-adhesion anti-static high-temperature-resistant UV adhesive film and a preparation method thereof. The adhesive film is prepared from bisphenol A epoxy acrylate, 1, 6-hexanediol diacrylate, modified bismaleimide, a surface modified multistage carbon fiber / carbon nanotube composite filler, a BYK-163 dispersing agent, 1-hydroxycyclohexyl phenyl ketone and benzophenone. The composite filler is subjected to surface modification by adopting a KH-560 silane coupling agent, so that the binding force with a matrix is enhanced. The short carbon fibers and the carbon nanotubes are combined according to a specific mass ratio, a conductive network is optimized, and the anti-static performance is improved. The preparation method comprises the steps of resin premixing, high-shear and ultrasonic synergistic dispersion, vacuum defoaming, slit coating and stepped photocuring, so that the uniformity and excellent heat resistance of the adhesive film are ensured. The UV adhesive film provided by the invention has the characteristics of high adhesive force, excellent anti-static property and high temperature resistance, and is suitable for electronic packaging, optical protection and high-temperature environment gluing application.

Description

Technical Field

[0001] The present invention relates to the field of adhesive film materials, and particularly to a high-adhesion anti-static high-temperature resistant UV adhesive film and a preparation method thereof. Background Art

[0002] In the fields of modern electronic packaging, optical display, flexible circuits, and high-temperature environment adhesive applications, strict requirements are imposed on the performance of UV-curable adhesive films. Among them, high adhesion, anti-static, and high-temperature resistance are the key factors determining whether the adhesive film can meet complex working conditions. In the electronic packaging industry, chip packaging, flexible circuit protection, and optical component fixation require the adhesive film to simultaneously have excellent substrate adhesion to ensure that it does not fail due to peeling or interfacial detachment during long-term use. In addition, with the development of electronic devices towards high-density integration, electrostatic accumulation is likely to cause device damage or even functional failure. Therefore, the anti-static performance of the adhesive film is crucial, and a stable conductive network needs to be formed to effectively release static charges. In high-temperature application scenarios, such as high-power LED packaging, heat-resistant electronic component bonding, and new energy vehicle electronic component fixation, the UV adhesive film needs to have excellent heat stability, maintain mechanical strength and chemical stability in a high-temperature environment, and avoid performance degradation due to thermal degradation or cross-linking structure damage. With the rapid development of 5G communication, aerospace, and high-end manufacturing industries, the demand for UV adhesive films with high adhesion, anti-static, and high-temperature resistance is increasing day by day. The improvement of its performance can not only significantly enhance the reliability and durability of electronic products but also broaden the application range of the adhesive film in extreme environments, promoting the development of a new generation of electronic packaging materials.

[0003] At present, certain progress has been made in the research on UV adhesive films, and improvements have been achieved in high adhesion, anti-static, and high-temperature resistance performance. However, many technical bottlenecks still exist. For example, Chinese Patent No. CN110157323A discloses a wear-resistant photocurable UV anti-static coating and its preparation method, which improves the anti-static performance by adding an anti-static agent. However, in a high-temperature environment, there are still problems such as unstable conductive networks and decreased adhesion caused by thermal expansion mismatch. In addition, another patent with the publication number CN111087918B proposes a high-heat-resistant UV aluminized coating composition and its preparation method. However, due to the relatively high crosslinking density, the brittleness of the material increases, affecting adhesion and flexibility. Although traditional conductive fillers such as carbon nanotubes and graphene can provide certain anti-static capabilities, their uniform dispersion in the photocuring system is poor, prone to agglomeration, resulting in uneven local conductivity. At the same time, the interfacial bonding force between the filler and the resin matrix is insufficient, affecting the final adhesion. On the other hand, the improvement of high-temperature resistance often depends on a resin system with a high crosslinking density, and the increase in crosslinking density usually reduces the flexibility and interfacial adaptability of the material, resulting in a decrease in the adhesion performance of the adhesive film on different substrates. Therefore, how to ensure that the adhesive film has excellent substrate adhesion while taking into account the anti-static and high-temperature resistance characteristics is still the core problem that needs to be solved urgently in the current technology. Summary of the Invention

[0004] (1) Technical problems to be solved

[0005] The purpose of the present invention is to provide a high-adhesion, anti-static, and high-temperature-resistant UV adhesive film and its preparation method to solve the problems of insufficient high adhesion, anti-static, and high-temperature resistance of current UV adhesive films.

[0006] (2) Technical solutions

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A high-adhesion, anti-static, and high-temperature-resistant UV adhesive film comprises the following raw materials in parts by weight: 15 - 30 parts of surface-modified multi-stage carbon fiber / carbon nanotube composite filler, 10 - 20 parts of modified bismaleimide, 0.5 - 1.5 parts of BYK-163 dispersant, 40 - 60 parts of bisphenol A epoxy acrylate, 5.0 - 12.0 parts of 1,6-hexanediol diacrylate, 2.0 - 5.0 parts of 1-hydroxycyclohexyl phenyl ketone, and 0.5 - 1.5 parts of benzophenone.

[0009] The surface-modified multi-stage carbon fiber / carbon nanotube composite filler is obtained by surface-modifying the multi-stage carbon fiber / carbon nanotube composite filler with silane coupling agent KH-560;

[0010] The described multi-stage carbon fiber / carbon nanotube composite filler includes sub-micron scale short carbon fibers and nano-scale carbon nanotubes loaded on the surface of the short carbon fibers;

[0011] The described modified bismaleimide is obtained by modifying bismaleimide 4,4'-diaminodiphenyl ether with polyetheramine D-2000.

[0012] Furthermore, the mass ratio of the short carbon fibers to the carbon nanotubes is (94.5 - 97.5):(5.5 - 2.5).

[0013] Furthermore, the preparation method of the surface-modified multi-stage carbon fiber / carbon nanotube composite filler is as follows: by weight, 1.5 - 2.5 parts of silane coupling agent KH-560 and 97 - 95 parts of absolute ethanol are mixed at 25 - 35 °C with a stirring rate of 200 - 400 rpm to form a hydrolysis solution. After adjusting the pH to 4.0 - 5.0, the hydrolysis reaction is maintained for 60 - 90 min. Subsequently, 10 - 30 parts of the multi-stage carbon fiber / carbon nanotube composite filler are added, and dispersed under ultrasonic power of 300 - 500 W for 30 - 60 min to form a suspension. The suspension is transferred to a high-pressure reactor, heated to 80 - 120 °C at a rate of 2 - 5 °C / min, the pressure is controlled at 0.5 - 1.5 MPa, and nitrogen is continuously introduced for protection. After reacting for 180 - 240 min, the solid and liquid components are separated by a vacuum filtration device. The retained solid product is washed with deionized water until the conductivity of the filtrate ≤ 50 μS / cm. Subsequently, it is treated in a vacuum drying oven at 60 - 80 °C with an air flow rate of 10 - 15 m 3 / h for 120 - 180 min to finally obtain the surface-modified multi-stage carbon fiber / carbon nanotube composite filler.

[0014] Furthermore, the preparation method of the multi-stage carbon fiber / carbon nanotube composite filler is as follows: by weight, with 100 parts of short carbon fibers as the matrix, it is impregnated in 50 - 100 parts of 3+ ferric nitrate ethanol solution with a concentration of 0.05 - 0.15 mol / L, and treated for 30 - 60 min under ultrasonic assistance at 40 - 60 kHz to achieve catalyst loading. Subsequently, it is heated to 700 - 900 °C at a rate of 10 - 15 °C / min in an argon / hydrogen mixed atmosphere with a volume ratio of 9:1 for reduction treatment for 60 - 120 min to form 20 - 50 nm iron catalyst particles. The matrix loaded with the catalyst is transferred to a chemical vapor deposition reactor, and a mixed gas of ethylene / hydrogen / argon with a volume ratio of 1:0.2:(4 - 6) is introduced, the gas flow rate is controlled at 200 - 400 sccm, and carbon nanotubes are grown at a growth temperature of 750 - 850 °C for 30 - 60 min. After the reaction, it is slowly cooled to room temperature at a rate of 5 - 10 °C / min under argon protection to obtain the multi-stage carbon fiber / carbon nanotube composite filler.

[0015] Furthermore, the preparation method of the short carbon fibers is as follows: 9.0 - 12.0 parts of polyacrylonitrile with a molecular weight of 120,000 - 150,000 g / mol and 85 - 95 parts of N,N-dimethylformamide are mixed and treated at 25 - 35°C with a stirring rate of 200 - 400 rpm for 120 - 180 min to form a homogeneous spinning solution. After removing undissolved particles through a 5 - 10 μm precision filter, it is injected into an electrospinning device equipped with a high-voltage electrostatic generator. Continuous electrospinning is carried out under the conditions of a voltage field strength of 15 - 25 kV and a spinning distance of 15 - 25 cm. The obtained primary fiber bundle forms a unidirectional fiber web on a parallel electrode array. The fiber web together with the metal fixture is transferred to an air-circulation heat treatment furnace, and stepwise stabilization treatment is carried out at a heating rate of 3 - 5°C / min from room temperature to 280 - 320°C for 60 - 90 min, with heat preservation for 30 - 50 min at 150 - 160°C, 200 - 210°C, and 250 - 260°C respectively. The stabilized fibers are then transferred to a tube-type carbonization furnace, and programmed carbonization is carried out under the protection of 99.99% high-purity nitrogen with a heating rate of 5 - 10°C / min. In the first stage, non-carbon elements are removed by maintaining at 400 - 600°C for 30 - 60 min. In the second stage, the target temperature of 800 - 1700°C is reached at the same heating rate and maintained for 60 - 90 min to complete the graphitization process. The carbonization product is taken out after being cooled to below 50°C at a cooling rate of 15 - 20°C / min by a forced cooling system, and finally cut into short carbon fibers by an ultrasonic cutting machine.

[0016] Furthermore, the parameters of the ultrasonic cutting machine include: an ultrasonic frequency of 20 - 40 kHz, an output power of 200 - 400 W, a cutting speed of 0.5 - 1.5 m / min, a tool head amplitude of 10 - 50 μm, a pressure of the compressed air cooling system of 0.2 - 0.5 MPa, a fiber fixture pressure of 5 - 10 N, a cutting gap of 50 - 150 μm, and a working pressure of the supporting negative pressure dust removal system of 0.05 - 0.1 MPa.

[0017] Furthermore, the average diameter of the short carbon fibers is 200 - 650 nm; the average length is 2.0 - 3.5 μm;

[0018] Furthermore, the average diameter of the carbon nanotubes is 10 - 50 nm; the average length is 250 - 650 nm.

[0019] The design of the present invention using surface-modified multi-stage carbon fiber / carbon nanotube composite fillers is mainly used to enhance the high adhesion, anti-static and high-temperature resistance properties of materials. The core lies in through reasonable structural design and surface modification processes, enabling the components to form a tight combination at the microscale, achieving a synergistic effect, and thus significantly improving the comprehensive properties of the materials. The preparation process of short carbon fibers ensures their stable microstructure. Through electrospinning, stabilization treatment and high-temperature carbonization, a carbon fiber skeleton with high purity and high crystallinity is formed, providing an excellent substrate for the construction of subsequent multi-stage structures. On this basis, a catalyst is loaded with an iron nitrate ethanol solution and subjected to high-temperature reduction treatment, so that nano-scale iron catalyst particles are evenly distributed on the surface of the short carbon fibers, providing active sites for the subsequent growth of carbon nanotubes. By chemical vapor deposition, the ratio of ethylene to hydrogen / inert gas is regulated, and carbon nanotubes are evenly grown on the carbon fiber surface to form a multi-stage structure, making the composite filler have a higher specific surface area and more excellent interfacial bonding ability. Further, the multi-stage carbon fiber / carbon nanotube composite filler is surface-modified with silane coupling agent KH-560. Active functional groups are introduced through hydrolysis reaction, and under ultrasonic and high-temperature and high-pressure conditions, the directional adsorption and chemical bonding of the coupling agent on the carbon material surface are promoted, thereby enhancing the polarity and interfacial interaction force of the filler, and improving its dispersibility and compatibility in the matrix. This modification process not only optimizes the interfacial characteristics of the filler, but also further enhances its stability and conductivity in high-temperature environments. The synergistic effect among the components is the key to improving the performance of the present invention: short carbon fibers provide mechanical strength and high-temperature stability, carbon nanotubes endow the material with excellent electrical conductivity and toughening effect, and the surface modification of silane coupling agent effectively improves the interfacial compatibility of the filler, ensuring its uniform distribution and tight combination in the composite material system. Finally, this composite filler not only shows excellent performance in enhancing the adhesion of the matrix material, but also performs outstandingly in anti-static and high-temperature resistance properties, and can meet the application requirements under harsh environmental conditions.

[0020] Further, the preparation method of the modified bismaleimide is as follows: by weight, 15.0 - 22.0 parts of bismaleimide and 30 - 45 parts of 1,6-hexanediol diacrylate are added into a reaction vessel, then 3.5 - 4.5 parts of 4,4'-diaminodiphenyl ether and 35 - 45 parts of polyetheramine D-2000 are further added. The temperature is raised to 70 - 90 °C at a stirring rate of 300 - 500 rpm at a rate of 2 - 5 °C / min and maintained for 20 - 40 min until the resin is completely dissolved. Subsequently, the temperature is raised to 140 - 150 °C at a heating rate of 5 - 10 °C / min, and stirred at a constant temperature for 60 - 90 min. After the reaction is completed, it is naturally cooled to room temperature to obtain the modified bismaleimide.

[0021] The design of the present invention using modified bismaleimide is mainly used to enhance the high adhesion, anti-static and high-temperature resistance properties of the reinforcing material. By reasonably selecting bismaleimide, 1,6-hexanediol diacrylate, 4,4'-diaminodiphenyl ether and polyetheramine D-2000, and combining with an optimized synthesis process, the obtained modified bismaleimide exhibits excellent characteristics in terms of molecular structure and interfacial interaction, thereby endowing the target material with better comprehensive properties. Bismaleimide, as the matrix resin, provides excellent heat resistance and mechanical strength, while the introduction of 1,6-hexanediol diacrylate improves the flexibility and processing performance of the system, making it easier to form in subsequent applications and enhancing the interfacial bonding ability. In addition, the addition of 4,4'-diaminodiphenyl ether introduces amide bonds in the molecular structure, which helps to improve the heat resistance and toughness of the material, while enhancing the crosslinking density of the resin to ensure its excellent stability in high-temperature environments. The role of polyetheramine D-2000 is particularly crucial. Its long-chain flexible structure can effectively adjust the internal stress of the system, enabling the material to exhibit more excellent adhesion and impact toughness while maintaining high heat resistance, improving the interfacial compatibility at the same time, reducing the brittleness of the material during use, and enhancing its fatigue resistance. During the synthesis process, through reasonable temperature and stirring control, it is ensured that each component reacts fully and is uniformly dispersed, making the molecular structure of the modified bismaleimide more uniform and further improving its comprehensive properties. The synergistic effect among the components is the core of the technical solution of the present invention. Bismaleimide provides a rigid skeleton, 1,6-hexanediol diacrylate optimizes the flexibility, 4,4'-diaminodiphenyl ether enhances the heat resistance and crosslinking degree, while polyetheramine D-2000 plays a key role in improving the adhesion and mechanical strength. Finally, the obtained modified bismaleimide exhibits excellent characteristics in terms of high adhesion, anti-static and high-temperature resistance, and can meet the application requirements in harsh environments.

[0022] The present invention also discloses a preparation method of a high-adhesion, anti-static and high-temperature resistant UV adhesive film, comprising the following steps:

[0023] S1. Add bisphenol A epoxy acrylate, 1,6-hexanediol diacrylate and modified bismaleimide into a vacuum reactor equipped with a double planetary stirrer. Under the protection of nitrogen inert gas, mix at a stirring rate of 300 - 500 rpm, control the temperature in the reactor at 40 - 60 °C, continuously stir for 30 - 60 min, and then cool down to 25 - 35 °C at a rate of 2 - 5 °C / min to form a homogeneous resin premix;

[0024] S2. The surface-modified multi-stage carbon fiber / carbon nanotube composite filler and BYK-163 dispersant are added to the resin premix in three times, with an interval of 5-10 minutes each time. Primary dispersion is carried out using a high-shear disperser at a rotational speed of 1500-3000 rpm, controlling the material temperature ≤50°C. Subsequently, it is switched to the ultrasonic-mechanical synergistic dispersion mode, and treated for 60-90 minutes under the conditions of ultrasonic power of 400-600 W, frequency of 40-60 kHz and mechanical stirring of 200-400 rpm to obtain a uniformly dispersed glue solution;

[0025] S3. 1-Hydroxycyclohexyl phenyl ketone and benzophenone are sequentially added to the uniformly dispersed glue solution, and mixed at a stirring rate of 300-500 rpm for 20-40 minutes under light-shielded conditions. During the mixing process, the system temperature is maintained at 25-35°C, and degassing treatment is carried out for 30-60 minutes through a vacuum degassing device at a vacuum degree of -0.08 to -0.10 MPa;

[0026] S4. The glue solution is coated on the surface of the substrate using a slot coater, controlling the wet film thickness at 50-200 μm and the coating rate at 0.5-2.0 m / min. After coating, the substrate is transferred to the leveling area and left standing for 5-15 minutes at 30-50°C; A stepped photocuring process is used for curing, and a high-adhesion antistatic high-temperature resistant UV glue film is obtained after curing.

[0027] Further, the stepped photocuring process in step S4 includes: First, primary curing is carried out using a mercury lamp array with a main wavelength of 365 nm in a nitrogen protection atmosphere with an oxygen concentration of less than 100 ppm, controlling the light intensity at 80-120 mW / cm 2 、irradiation time of 30-60 seconds to form a gel-like network; Subsequently, the light intensity is increased to 150-200 mW / cm 2 , and continuous curing is carried out for 60-120 seconds to eliminate the interfacial oxygen inhibition effect; Finally, heating is carried out at 80-100°C for 20-40 minutes to complete the curing.

[0028] The design of the present invention using a high-adhesion antistatic high-temperature resistant UV adhesive film is mainly used to enhance the mechanical strength, electrical stability and heat resistance of materials. By precisely selecting bisphenol A epoxy acrylate, 1,6-hexanediol diacrylate and modified bismaleimide as the resin matrix, and combining the synergistic reinforcement effect of surface-modified multi-level carbon fiber / carbon nanotube composite fillers, the resulting UV adhesive film exhibits excellent characteristics in terms of microstructure, interfacial bonding and overall physical and chemical properties. The composition of the resin matrix is optimized to have both excellent heat resistance brought by high crosslinking density and appropriate flexibility, thereby enhancing adhesion and interfacial bonding strength. Bisphenol A epoxy acrylate imparts good mechanical properties and chemical stability to the system, while the introduction of 1,6-hexanediol diacrylate effectively reduces the internal stress after curing, improving the ductility and crack resistance of the material. The addition of modified bismaleimide not only enhances the high-temperature resistance performance, but also improves the solvent resistance and thermal aging stability of the system, enabling the adhesive film to maintain excellent performance during long-term use. The addition of surface-modified multi-level carbon fiber / carbon nanotube composite fillers further improves the electrical conductivity and mechanical strength of the material. Its nanoscale structure provides a high specific surface area, forming a uniformly distributed conductive network during the photocuring process, thereby effectively reducing the surface resistance and achieving the antistatic function. At the same time, the action of BYK-163 dispersant ensures the uniform dispersion of the fillers in the resin matrix, avoids agglomeration phenomena, improves the interfacial bonding quality, and further optimizes the adhesion performance and durability of the UV adhesive film. During the preparation process, through the combination of double planetary stirring, high-shear dispersion and ultrasonic-mechanical synergistic dispersion technology, the components are fully mixed to form a stable and uniform glue solution, thereby ensuring the structural uniformity and performance stability after final curing. In addition, a photoinitiator system of 1-hydroxycyclohexyl phenyl ketone and benzophenone is used and mixed under light-shielding and vacuum degassing conditions to effectively remove the residual bubbles and solvent volatiles in the system, ensuring the denseness and transparency of the adhesive film after photocuring. During the UV curing process, the application of a stepped photocuring strategy further optimizes the curing quality of the adhesive film. In the primary curing stage, a gel-like network is formed in a low-oxygen environment, effectively enhancing the initial adhesion; then, by increasing the light intensity, the interfacial oxygen inhibition effect is eliminated, making the curing reaction more complete; the final heat treatment step further promotes the increase of crosslinking density, strengthening the temperature resistance performance and mechanical strength of the UV adhesive film. The synergistic effect among the components is the key to improving the performance of the UV adhesive film in the present invention. The resin matrix provides the basic adhesion and heat resistance, the multi-level carbon fiber / carbon nanotube composite fillers endow it with electrical conductivity and toughening functions, the dispersant ensures the uniformity of the fillers, and the combination of the photoinitiator system and the stepped curing process ultimately guarantees the stability and efficient curing of the adhesive film. Finally, the high-adhesion antistatic high-temperature resistant UV adhesive film prepared by the present invention can still maintain excellent adhesion performance, electrical stability and heat resistance under complex environmental conditions, meeting the application requirements of high-performance electronic packaging and optical bonding, etc.

[0029] (3) Beneficial technical effects

[0030] 1. Through the synergistic effect of short carbon fibers, carbon nanotubes, and silane coupling agent, the present invention achieves a significant improvement in high adhesion, anti-static, and high-temperature resistance performance. The optimized surface modification process ensures the uniform dispersion and tight combination of the fillers in the matrix. Compared with the prior art, the mechanical strength, conductive stability, and heat resistance of the material are improved, which is widely applicable to high-demand electronic packaging and structural reinforcement fields, promoting the development of high-performance composite materials.

[0031] 2. By optimizing the bismaleimide matrix and introducing 1,6-hexanediol diacrylate, 4,4'-diaminodiphenyl ether, and polyetheramine D-2000, the present invention realizes the synergistic improvement of high adhesion, anti-static, and high-temperature resistance performance. Compared with the prior art, the toughness, heat resistance, and interfacial bonding force of the material are significantly enhanced, while the internal stress is reduced, and the long-term use stability is improved. It is widely applicable to electronic packaging and structural bonding under high-temperature environments, promoting the development of high-performance resin materials.

[0032] 3. By optimizing the resin matrix, introducing surface-modified multi-level carbon fiber / carbon nanotube composite fillers, and adopting a stepped photocuring process, the present invention realizes the synergistic improvement of high adhesion, anti-static, and high-temperature resistance performance. Compared with the prior art, the mechanical strength, electrical stability, and durability of the material are significantly enhanced, while the internal stress is reduced, the interfacial bonding quality and curing efficiency are improved, and the failure problem of traditional UV adhesive films in high-temperature, high-humidity, and electrostatic-sensitive environments is avoided. It is widely applicable to fields such as electronic packaging and optical bonding, promoting the development of high-performance adhesive materials. Description of the Drawings

[0033] Figure 1 It is the morphology diagram of the short carbon fibers prepared in Example 1 of the present invention.

[0034] Figure 2 It is the morphology diagram of the multi-level carbon fiber / carbon nanotube composite fillers prepared in Example 1 of the present invention.

[0035] Figure 3 It is the XRD phase analysis diagram of the multi-level carbon fiber / carbon nanotube composite fillers prepared in Example 1 of the present invention. Detailed Embodiments

[0036] To make the objectives, 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 with reference to the accompanying drawings in the embodiments of the present invention.

[0037] Example 1

[0038] A high-adhesion anti-static and high-temperature resistant UV adhesive film, comprising the following raw materials in parts by weight: 15 parts of surface-modified multi-stage carbon fiber / carbon nanotube composite filler, 10 parts of modified bismaleimide, 0.5 part of BYK-163 dispersant, 40 parts of bisphenol A epoxy acrylate, 5.0 parts of 1,6-hexanediol diacrylate, 2.0 parts of 1-hydroxycyclohexyl phenyl ketone, and 0.5 part of benzophenone.

[0039] The surface-modified multi-stage carbon fiber / carbon nanotube composite filler is obtained by surface-modifying the multi-stage carbon fiber / carbon nanotube composite filler with silane coupling agent KH-560; the multi-stage carbon fiber / carbon nanotube composite filler includes submicron-scale short carbon fibers and nano-scale carbon nanotubes supported on the surface of the short carbon fibers; the modified bismaleimide is obtained by modifying bismaleimide 4,4'-diaminodiphenyl ether with polyetheramine D-2000.

[0040] In this embodiment, the mass ratio of the short carbon fibers to the carbon nanotubes is 97.5:2.5.

[0041] The preparation method of the surface-modified multi-stage carbon fiber / carbon nanotube composite filler in this embodiment is as follows: in parts by weight, 1.5 parts of silane coupling agent KH-560 and 97 parts of absolute ethanol are mixed at 25 °C with a stirring rate of 200 rpm to form a hydrolysis solution. After adjusting the pH to 4.0, the hydrolysis reaction is maintained for 60 min. Subsequently, 10 parts of the multi-stage carbon fiber / carbon nanotube composite filler are added, and dispersion treatment is carried out for 30 min under the condition of an ultrasonic power of 300 W to form a suspension. The suspension is transferred to a high-pressure reaction kettle, heated to 80 °C at a rate of 2 °C / min, the pressure is controlled at 0.5 MPa, and nitrogen is continuously introduced for protection. After reacting for 180 min, the solid-liquid components are separated by a vacuum filtration device. The remaining solid product is washed with deionized water until the conductivity of the filtrate ≤ 50 μS / cm. Subsequently, it is treated in a vacuum drying oven at 60 °C with an air flow rate of 10 m 3 / h for 120 min to finally obtain the surface-modified multi-stage carbon fiber / carbon nanotube composite filler.

[0042] The preparation method of the multi-stage carbon fiber / carbon nanotube composite filler in this embodiment is as follows: in parts by weight, 100 parts of short carbon fibers are used as the matrix, and it is impregnated in 50 parts of Fe 3+In a ferric nitrate ethanol solution with a concentration of 0.05 mol / L, catalyst loading was achieved by treating for 30 min under the assistance of 40 kHz ultrasonic waves. Subsequently, reduction treatment was carried out at a heating rate of 10 °C / min to 700 °C for 60 min in an argon / hydrogen mixed atmosphere with a volume ratio of 9:1 to form 20 nm iron catalyst particles. The substrate carrying the catalyst was transferred to a chemical vapor deposition reactor, and a mixed gas of ethylene / hydrogen / argon with a volume ratio of 1:0.2:4 was introduced. The gas flow rate was controlled at 200 sccm, and carbon nanotubes were grown at a growth temperature of 750 °C for 30 min. After the reaction ended, it was slowly cooled to room temperature at a rate of 5 °C / min under argon protection to obtain a multi-stage carbon fiber / carbon nanotube composite filler.

[0043] The preparation method of the short carbon fibers in this example is as follows: 9.0 parts of polyacrylonitrile with a molecular weight of 120,000 g / mol and 85 parts of N,N-dimethylformamide were mixed and treated at 25 °C with a stirring rate of 200 rpm for 120 min to form a homogeneous spinning solution. After removing undissolved particles through a 5 μm precision filter, it was injected into an electrospinning device equipped with a high-voltage electrostatic generator. Continuous electrospinning was carried out under the conditions of a voltage field strength of 15 kV and a spinning distance of 15 cm. The obtained primary fiber bundle formed a unidirectional fiber web on a parallel electrode array. The fiber web together with the metal fixture was transferred to an air-circulation heat treatment furnace, and stepwise stabilization treatment was carried out at a heating rate of 3 °C / min from room temperature to 280 °C for 60 min, with insulation for 30 min at 150 °C, 200 °C, and 250 °C respectively. The stabilized fibers were then transferred to a tube-type carbonization furnace, and programmed carbonization was carried out at a heating rate of 5 °C / min under the protection of 99.99% high-purity nitrogen. In the first stage, non-carbon elements were removed by maintaining at 400 °C for 30 min. In the second stage, the target temperature of 800 °C was reached at the same heating rate and maintained for 60 min to complete the graphitization process. The carbonized product was taken out after being cooled to below 50 °C at a rate of 15 °C / min by a forced cooling system. Finally, short carbon fibers were prepared by an ultrasonic cutting machine. The parameters of the ultrasonic cutting machine include: ultrasonic frequency of 20 kHz, output power of 200 W, cutting speed of 0.5 m / min, tool head amplitude of 10 μm, pressure of the compressed air cooling system of 0.2 MPa, pressure of the fiber fixture of 5 N, cutting gap of 50 μm, and working pressure of the supporting negative pressure dust removal system of 0.05 MPa.

[0044] The average diameter of the short carbon fibers in this example is 200 nm; the average length is 2.0 μm; the average diameter of the carbon nanotubes is 10 nm; the average length is 250 nm.

[0045] The preparation method of the modified bismaleimide in this embodiment is as follows: by weight, 15.0 parts of bismaleimide and 30 parts of 1,6 - hexanediol diacrylate are added into a reaction vessel, then 3.5 parts of 4,4'-diaminodiphenyl ether and 35 parts of polyetheramine D - 2000 are further added. The temperature is raised to 70 °C at a rate of 2 °C / min under a stirring rate of 300 rpm and maintained for 20 min until the resin is completely dissolved. Subsequently, the temperature is raised to 140 °C at a heating rate of 5 °C / min, and stirred at a constant temperature for 60 min. After the reaction, it is naturally cooled to room temperature to obtain the modified bismaleimide.

[0046] The preparation method of a high - adhesion antistatic high - temperature - resistant UV adhesive film in this embodiment includes the following steps:

[0047] S1. Bisphenol A epoxy acrylate, 1,6 - hexanediol diacrylate and the modified bismaleimide are added into a vacuum reaction kettle equipped with a double - planetary stirrer. Under the protection of nitrogen inert gas, they are mixed at a stirring rate of 300 rpm, the temperature in the kettle is controlled at 40 °C, and stirred continuously for 30 min. Subsequently, the temperature is decreased to 25 °C at a rate of 2 °C / min to form a homogeneous resin premix.

[0048] S2. The surface - modified multi - level carbon fiber / carbon nanotube composite filler and BYK - 163 dispersant are added into the resin premix in three times, with an interval of 5 min each time. Primary dispersion is carried out at a speed of 1500 rpm using a high - shear disperser, and the material temperature is controlled ≤50 °C. Subsequently, it is switched to the ultrasonic - mechanical synergistic dispersion mode, and treated for 60 min under the conditions of an ultrasonic power of 400 W, a frequency of 40 kHz and a mechanical stirring of 200 rpm to obtain a uniformly dispersed glue solution.

[0049] S3. 1 - Hydroxycyclohexyl phenyl ketone and benzophenone are successively added to the uniformly dispersed glue solution, and mixed at a stirring rate of 300 rpm for 20 min under light - shielding conditions. The temperature of the system is maintained at 25 °C during the mixing process, and degassing treatment is carried out for 30 min through a vacuum degassing device at a vacuum degree of - 0.08 MPa.

[0050] S4. The glue solution is coated on the surface of the substrate using a slot coater, controlling the wet film thickness at 50 μm and the coating rate at 0.5 m / min. After coating, the substrate is transferred to the leveling area and left to stand for 5 min at 30 °C. A stepped light - curing process is used for curing, and a high - adhesion antistatic high - temperature - resistant UV adhesive film is obtained after curing. The stepped light - curing process includes: first, primary curing is carried out using a mercury lamp array with a main wavelength of 365 nm under a nitrogen - protection atmosphere with an oxygen concentration of less than 100 ppm, controlling the light intensity at 80 mW / cm 2 and the irradiation time at 30 seconds to form a gel - like network; subsequently, the light intensity is increased to 150 mW / cm 2, cure continuously for 60 seconds to eliminate the interfacial oxygen inhibition polymerization effect; finally, complete the curing by heating at 80 °C for 20 minutes.

[0051] It is composed of Figure 1 It can be seen that the short carbon fibers prepared in Example 1 of the present invention have a uniform diameter and good dispersibility, indicating that its preparation process can effectively control the fiber size and ensure the stability of its morphology. Figure 2 It further shows that high-density and uniformly distributed carbon nanotubes have successfully grown on the surface of the short carbon fibers, forming a stable multi-level structure, which helps to increase the specific surface area and interfacial bonding ability of the filler. Figure 3 The XRD analysis results show that the obtained composite filler has diffraction peaks of typical carbon materials, proving that it has a good degree of graphitization. At the same time, no obvious residual peaks of Fe catalyst are observed, indicating that the catalyst has been basically removed, further verifying the effectiveness of the preparation method of the present invention. In summary, the present invention has successfully prepared a multi-level carbon fiber / carbon nanotube composite filler with high adhesion, anti-static and high temperature resistance, which has a stable structure, uniform growth of carbon nanotubes, and good crystallinity, and can meet the application requirements of high-performance composite materials.

[0052] Example 2

[0053] A high-adhesion, anti-static and high-temperature-resistant UV adhesive film, comprising the following raw materials in parts by weight: 20 parts of surface-modified multi-level carbon fiber / carbon nanotube composite filler, 13 parts of modified bismaleimide, 0.8 part of BYK-163 dispersant, 46 parts of bisphenol A epoxy acrylate, 7.1 parts of 1,6-hexanediol diacrylate, 2.9 parts of 1-hydroxycyclohexyl phenyl ketone, and 0.8 part of benzophenone.

[0054] The surface-modified multi-level carbon fiber / carbon nanotube composite filler is obtained by surface modification of the multi-level carbon fiber / carbon nanotube composite filler with silane coupling agent KH-560; the multi-level carbon fiber / carbon nanotube composite filler includes sub-micron-scale short carbon fibers and nano-scale carbon nanotubes supported on the surface of the short carbon fibers; the modified bismaleimide is obtained by modifying bismaleimide 4,4'-diaminodiphenyl ether with polyetheramine D-2000.

[0055] In this example, the mass ratio of the short carbon fibers to the carbon nanotubes is 96.5:3.5.

[0056] The preparation method of the surface-modified multi-stage carbon fiber / carbon nanotube composite filler in this embodiment is as follows: by weight, 1.8 parts of silane coupling agent KH-560 and 96 parts of absolute ethanol are mixed at 28 °C with a stirring rate of 260 rpm to form a hydrolysis solution. After adjusting the pH to 4.3, the hydrolysis reaction is maintained for 69 min. Then, 16 parts of the multi-stage carbon fiber / carbon nanotube composite filler are added, and dispersion treatment is carried out for 39 min under the condition of an ultrasonic power of 360 W to form a suspension. The suspension is transferred to a high-pressure reactor, heated to 92 °C at a rate of 3 °C / min, the pressure is controlled at 0.8 MPa, and nitrogen is continuously introduced for protection. After reacting for 198 min, the solid and liquid components are separated by a vacuum filtration device. The retained solid product is washed with deionized water until the conductivity of the filtrate ≤ 50 μS / cm. Then, it is treated in a vacuum drying oven at 66 °C with an air flow rate of 12 m 3 / h for 138 min to finally obtain the surface-modified multi-stage carbon fiber / carbon nanotube composite filler.

[0057] The preparation method of the multi-stage carbon fiber / carbon nanotube composite filler in this embodiment is as follows: by weight, 100 parts of short carbon fibers are used as the matrix, and it is impregnated in 65 parts of Fe 3+ in an iron nitrate ethanol solution with a concentration of 0.08 mol / L, and catalyst loading is achieved by treating for 39 min under the assistance of 46 kHz ultrasonic waves. Then, it is heated to 760 °C at a rate of 12 °C / min in an argon / hydrogen mixed atmosphere with a volume ratio of 9:1 for reduction treatment for 78 min to form 29 nm iron catalyst particles. The matrix carrying the catalyst is transferred to a chemical vapor deposition reactor, and a mixed gas of ethylene / hydrogen / argon with a volume ratio of 1:0.2:4.6 is introduced, and the gas flow rate is controlled at 260 sccm. Carbon nanotubes are grown at a growth temperature of 780 °C for 39 min. After the reaction, it is slowly cooled to room temperature at a rate of 7 °C / min under argon protection to obtain the multi-stage carbon fiber / carbon nanotube composite filler.

[0058] The preparation method of the short carbon fibers in this embodiment is as follows: 9.9 parts of polyacrylonitrile with a molecular weight of 129,000 g / mol and 88 parts of N,N-dimethylformamide are mixed and processed at 28 °C with a stirring rate of 260 rpm for 138 min to form a homogeneous spinning solution. After removing undissolved particles through a 7-μm precision filter, it is injected into an electrospinning device equipped with a high-voltage electrostatic generator. Continuous electrospinning is carried out under the conditions of a voltage field strength of 18 kV and a spinning distance of 18 cm. The as-spun fiber bundle forms a unidirectional fiber web on a parallel electrode array. The fiber web together with the metal fixture is transferred to an air-circulation heat treatment furnace, and stepwise stabilization treatment is carried out at a heating rate of 4 °C / min from room temperature to 292 °C for 69 min, with heat preservation for 36 min at 153 °C, 203 °C, and 253 °C respectively. The stabilized fibers are then transferred to a tubular carbonization furnace, and programmed carbonization is carried out under the protection of 99.99% high-purity nitrogen with a heating rate of 7 °C / min. In the first stage, non-carbon elements are removed by maintaining at 460 °C for 39 min. In the second stage, it is heated to the target temperature of 1070 °C at the same heating rate and maintained for 69 min to complete the graphitization process. The carbonized product is taken out after being cooled to below 50 °C at a cooling rate of 17 °C / min by a forced cooling system. Finally, short-cut carbon fibers are prepared by an ultrasonic cutting machine. The parameters of the ultrasonic cutting machine include: ultrasonic frequency of 26 kHz, output power of 260 W, cutting speed of 0.8 m / min, tool head amplitude of 22 μm, pressure of the compressed air cooling system of 0.3 MPa, fiber fixture pressure of 7 N, cutting gap of 80 μm, and working pressure of the supporting negative pressure dust removal system of 0.07 MPa.

[0059] The average diameter of the short carbon fibers in this embodiment is 650 nm; the average length is 3.5 μm; the average diameter of the carbon nanotubes is 50 nm; the average length is 650 nm.

[0060] The preparation method of the modified bismaleimide in this embodiment is as follows: By weight, 17.1 parts of bismaleimide and 35 parts of 1,6-hexanediol diacrylate are added to a reaction vessel, and then 3.8 parts of 4,4'-diaminodiphenyl ether and 38 parts of polyetheramine D-2000 are further added. It is heated to 76 °C at a rate of 3 °C / min with a stirring rate of 360 rpm and maintained for 26 min until the resin is completely dissolved. Subsequently, it is heated to 143 °C at a heating rate of 7 °C / min and stirred at a constant temperature for 69 min. After the reaction ends, it is naturally cooled to room temperature to obtain the modified bismaleimide.

[0061] The preparation method of a high-adhesion, anti-static, high-temperature-resistant UV adhesive film in this embodiment includes the following steps:

[0062] S1. Add bisphenol A epoxy acrylate, 1,6 - hexanediol diacrylate and modified bismaleimide into a vacuum reactor equipped with a double - planetary stirrer. Under the protection of nitrogen inert gas, mix at a stirring rate of 360 rpm, control the temperature in the reactor at 46 °C, continuously stir for 39 min, and then cool down to 28 °C at a rate of 3 °C / min to form a homogeneous resin premix;

[0063] S2. Add the surface - modified multi - level carbon fiber / carbon nanotube composite filler and BYK - 163 dispersant into the resin premix in three times, with an interval of 7 min each time. Use a high - shear disperser to conduct primary dispersion at a rotation speed of 1950 rpm, control the material temperature ≤ 50 °C, and then switch to the ultrasonic - mechanical synergistic dispersion mode. Treat for 69 min under the conditions of an ultrasonic power of 460 W, a frequency of 46 kHz and a mechanical stirring of 260 rpm to obtain a uniformly dispersed adhesive solution;

[0064] S3. Add 1 - hydroxycyclohexyl phenyl ketone and benzophenone to the uniformly dispersed adhesive solution in sequence. Mix at a stirring rate of 360 rpm under light - shielding conditions for 26 min. Maintain the system temperature at 28 °C during the mixing process, and conduct degassing treatment for 39 min through a vacuum degassing device at a vacuum degree of - 0.09 MPa;

[0065] S4. Use a slot coater to coat the adhesive solution on the surface of the substrate, control the wet film thickness at 95 μm, the coating rate at 0.9 m / min. After coating, transfer the substrate to the leveling area and let it stand at 36 °C for 8 min; Cure using a step - type photocuring process to obtain a high - adhesion anti - static high - temperature resistant UV adhesive film after curing. The step - type photocuring process includes: First, use a mercury lamp array with a main wavelength of 365 nm to conduct primary curing in a nitrogen - protected atmosphere with an oxygen concentration of less than 100 ppm, control the light intensity at 92 mW / cm 2 and the irradiation time at 39 s to form a gel - like network; Subsequently, increase the light intensity to 165 mW / cm 2 , continuously cure for 78 s to eliminate the interfacial oxygen inhibition effect; Finally, complete the curing by heating at 86 °C for 26 min.

[0066] Example 3

[0067] A high - adhesion anti - static high - temperature resistant UV adhesive film, comprising the following raw materials in parts by weight: 24 parts of surface - modified multi - level carbon fiber / carbon nanotube composite filler, 16 parts of modified bismaleimide, 1.1 parts of BYK - 163 dispersant, 52 parts of bisphenol A epoxy acrylate, 9.2 parts of 1,6 - hexanediol diacrylate, 3.8 parts of 1 - hydroxycyclohexyl phenyl ketone, and 1.1 parts of benzophenone.

[0068] The surface-modified multi-stage carbon fiber / carbon nanotube composite filler is obtained by surface-modifying the multi-stage carbon fiber / carbon nanotube composite filler with the silane coupling agent KH-560; the multi-stage carbon fiber / carbon nanotube composite filler includes sub-micron scale short carbon fibers and nano-scale carbon nanotubes supported on the surface of the short carbon fibers;

[0069] The modified bismaleimide is obtained by modifying bismaleimide 4,4'-diaminodiphenyl ether with polyetheramine D-2000.

[0070] In this example, the mass ratio of short carbon fibers to carbon nanotubes is 94.5:5.5.

[0071] The preparation method of the surface-modified multi-stage carbon fiber / carbon nanotube composite filler in this example is as follows: by weight, 2.1 parts of the silane coupling agent KH-560 and 96 parts of absolute ethanol are mixed at 31 °C with a stirring rate of 320 rpm to form a hydrolysis solution. After adjusting the pH to 4.6, the hydrolysis reaction is maintained for 78 min. Subsequently, 22 parts of the multi-stage carbon fiber / carbon nanotube composite filler are added, and the dispersion treatment is carried out for 48 min under the condition of an ultrasonic power of 420 W to form a suspension. The suspension is transferred to a high-pressure reactor, heated to 104 °C at a rate of 4 °C / min, the pressure is controlled at 1.1 MPa, and nitrogen is continuously introduced for protection. After reacting for 216 min, the solid-liquid components are separated by a vacuum filtration device. The remaining solid product is washed with deionized water until the conductivity of the filtrate ≤ 50 μS / cm. Subsequently, it is treated in a vacuum drying oven at 72 °C with an air flow rate of 13 m 3 / h for 156 min to finally obtain the surface-modified multi-stage carbon fiber / carbon nanotube composite filler.

[0072] The preparation method of the multi-stage carbon fiber / carbon nanotube composite filler in this example is as follows: by weight, taking 100 parts of short carbon fibers as the matrix, it is impregnated in 80 parts of Fe 3+ The iron nitrate ethanol solution with a concentration of 0.11 mol / L is treated for 48 min under the assistance of 52 kHz ultrasonic waves to achieve catalyst loading. Subsequently, it is heated to 820 °C at a rate of 13 °C / min in an argon / hydrogen mixed atmosphere with a volume ratio of 9:1 for 96 min for reduction treatment to form 38 nm iron catalyst particles. The matrix carrying the catalyst is transferred to a chemical vapor deposition reactor, and a mixed gas of ethylene / hydrogen / argon with a volume ratio of 1:0.2:5.2 is introduced, the gas flow rate is controlled at 320 sccm, and the carbon nanotubes are grown at a growth temperature of 810 °C for 48 min. After the reaction, it is slowly cooled to room temperature at a rate of 8 °C / min under argon protection to obtain the multi-stage carbon fiber / carbon nanotube composite filler.

[0073] The preparation method of the short carbon fibers in this embodiment is as follows: 10.8 parts of polyacrylonitrile with a molecular weight of 138,000 g / mol and 91 parts of N,N-dimethylformamide are mixed and processed at 31 °C with a stirring rate of 320 rpm for 156 min to form a homogeneous spinning solution. After removing undissolved particles through an 8-μm precision filter, it is injected into an electrospinning device equipped with a high-voltage electrostatic generator. Continuous electrospinning is carried out under the conditions of a voltage field strength of 21 kV and a spinning distance of 21 cm. The obtained as-spun fiber bundles form a uniaxially oriented fiber web on a parallel electrode array. The fiber web together with the metal fixture is transferred to an air-circulation heat treatment furnace, and stepwise stabilization treatment is carried out at a heating rate of 4 °C / min from room temperature to 304 °C for 78 min, with heat preservation for 42 min at 156 °C, 206 °C, and 256 °C respectively. The stabilized fibers are then transferred to a tube-type carbonization furnace and subjected to programmed carbonization under the protection of 99.99% high-purity nitrogen with a heating rate of 8 °C / min. In the first stage, non-carbon elements are removed by maintaining at 520 °C for 48 min. In the second stage, it is heated to the target temperature of 1340 °C at the same heating rate and held for 78 min to complete the graphitization process. The carbonized product is taken out after being cooled to below 50 °C at a cooling rate of 18 °C / min by a forced cooling system, and finally prepared into short carbon fibers through an ultrasonic cutting machine. The parameters of the ultrasonic cutting machine include: ultrasonic frequency of 32 kHz, output power of 320 W, cutting speed of 1.1 m / min, tool head amplitude of 34 μm, pressure of the compressed air cooling system of 0.4 MPa, fiber fixture pressure of 8 N, cutting gap of 110 μm, and working pressure of the supporting negative pressure dust removal system of 0.08 MPa.

[0074] The average diameter of the short carbon fibers in this embodiment is 470 nm; the average length is 2.9 μm; the average diameter of the carbon nanotubes is 34 nm; the average length is 490 nm.

[0075] The preparation method of the modified bismaleimide in this embodiment is as follows: By weight, 19.2 parts of bismaleimide and 39 parts of 1,6-hexanediol diacrylate are added to a reaction vessel, and then 4.1 parts of 4,4'-diaminodiphenyl ether and 41 parts of polyetheramine D-2000 are further added. It is heated to 82 °C at a rate of 4 °C / min with a stirring rate of 420 rpm and held for 32 min until the resin is completely dissolved. Subsequently, it is heated to 146 °C at a heating rate of 8 °C / min and stirred at a constant temperature for 78 min. After the reaction ends, it is naturally cooled to room temperature to obtain the modified bismaleimide.

[0076] The preparation method of a high-adhesion anti-static high-temperature resistant UV adhesive film in this embodiment includes the following steps:

[0077] S1. Add bisphenol A epoxy acrylate, 1,6 - hexanediol diacrylate and modified bismaleimide into a vacuum reactor equipped with a double - planetary stirrer. Under the protection of nitrogen inert gas, mix at a stirring rate of 500 rpm, control the temperature in the kettle at 60 °C, and continuously stir for 60 min. Then cool down to 35 °C at a rate of 5 °C / min to form a homogeneous resin premix;

[0078] S2. Add the surface - modified multi - stage carbon fiber / carbon nanotube composite filler and BYK - 163 dispersant into the resin premix in three portions, with an interval of 10 min each time. Use a high - shear disperser to conduct primary dispersion at a rotational speed of 3000 rpm, control the material temperature ≤50 °C. Then switch to the ultrasonic - mechanical synergistic dispersion mode, and process for 90 min under the conditions of an ultrasonic power of 600 W, a frequency of 60 kHz and a mechanical stirring of 400 rpm to obtain a uniformly dispersed adhesive solution;

[0079] S3. Add 1 - hydroxycyclohexyl phenyl ketone and benzophenone into the uniformly dispersed adhesive solution in sequence. Mix at a stirring rate of 500 rpm under light - shielding conditions for 40 min. During the mixing process, maintain the system temperature at 35 °C, and conduct degassing treatment for 60 min through a vacuum degassing device at a vacuum degree of - 0.10 MPa;

[0080] S4. Use a slot coater to coat the adhesive solution on the surface of the substrate, control the wet film thickness at 200 μm, the coating rate at 2.0 m / min. After coating, transfer the substrate to the leveling area and let it stand for 15 min at 50 °C. Adopt a stepped photocuring process for curing to obtain a high - adhesion antistatic high - temperature - resistant UV adhesive film after curing. The stepped photocuring process includes: First, use a mercury lamp array with a main wavelength of 365 nm to conduct primary curing in a nitrogen - protected atmosphere with an oxygen concentration of less than 100 ppm, control the light intensity at 120 mW / cm 2 and the irradiation time at 60 seconds to form a gel - like network; Then increase the light intensity to 200 mW / cm 2 , and continuously cure for 120 seconds to eliminate the interfacial oxygen inhibition effect; Finally, complete the curing by heating at 100 °C for 40 minutes.

[0081] Example 4

[0082] A high - adhesion antistatic high - temperature - resistant UV adhesive film, comprising the following raw materials in parts by weight: 30 parts of surface - modified multi - stage carbon fiber / carbon nanotube composite filler, 20 parts of modified bismaleimide, 1.5 parts of BYK - 163 dispersant, 60 parts of bisphenol A epoxy acrylate, 12.0 parts of 1,6 - hexanediol diacrylate, 5.0 parts of 1 - hydroxycyclohexyl phenyl ketone, and 1.5 parts of benzophenone.

[0083] The surface-modified multi-level carbon fiber / carbon nanotube composite filler is obtained by surface-modifying the multi-level carbon fiber / carbon nanotube composite filler with the silane coupling agent KH-560; the multi-level carbon fiber / carbon nanotube composite filler includes sub-micron scale short carbon fibers and nano-scale carbon nanotubes loaded on the surface of the short carbon fibers; the modified bismaleimide is obtained by modifying bismaleimide 4,4'-diaminodiphenyl ether with polyetheramine D-2000.

[0084] In this embodiment, the mass ratio of the short carbon fibers to the carbon nanotubes is 96:4.0.

[0085] The preparation method of the surface-modified multi-level carbon fiber / carbon nanotube composite filler in this embodiment is as follows: by weight, 2.5 parts of the silane coupling agent KH-560 and 95 parts of absolute ethanol are mixed at 35°C with a stirring rate of 400 rpm to form a hydrolysis solution. After adjusting the pH to 5.0, the hydrolysis reaction is maintained for 90 min. Subsequently, 30 parts of the multi-level carbon fiber / carbon nanotube composite filler are added, and dispersion treatment is carried out for 60 min under the condition of an ultrasonic power of 500 W to form a suspension. The suspension is transferred to a high-pressure reactor, heated to 120°C at a rate of 5°C / min, the pressure is controlled at 1.5 MPa, and nitrogen is continuously introduced for protection. After reacting for 240 min, the solid-liquid components are separated by a vacuum filtration device. The retained solid product is washed with deionized water until the conductivity of the filtrate ≤ 50 μS / cm. Subsequently, it is treated in a vacuum drying oven at 80°C with an air flow rate of 15 m 3 / h for 180 min to finally obtain the surface-modified multi-level carbon fiber / carbon nanotube composite filler.

[0086] The preparation method of the multi-level carbon fiber / carbon nanotube composite filler in this embodiment is as follows: by weight, 100 parts of short carbon fibers are used as the matrix, and it is impregnated in 100 parts of Fe 3+ in an ethanol solution of ferric nitrate with a concentration of 0.15 mol / L, and catalyst loading is achieved by treating for 60 min under ultrasonic assistance at 60 kHz. Subsequently, reduction treatment is carried out at a rate of 15°C / min to 900°C for 120 min in an argon / hydrogen mixed atmosphere with a volume ratio of 9:1 to form 50 nm iron catalyst particles. The matrix carrying the catalyst is transferred to a chemical vapor deposition reactor, and a mixed gas of ethylene / hydrogen / argon with a volume ratio of 1:0.2:6 is introduced, the gas flow rate is controlled at 400 sccm, and carbon nanotube growth is maintained for 60 min at a growth temperature of 850°C. After the reaction, it is slowly cooled to room temperature at a rate of 10°C / min under argon protection to obtain the multi-level carbon fiber / carbon nanotube composite filler.

[0087] The preparation method of the short carbon fibers in this embodiment is as follows: 12.0 parts of polyacrylonitrile with a molecular weight of 150,000 g / mol and 95 parts of N,N-dimethylformamide are mixed and treated at 35 °C with a stirring rate of 400 rpm for 180 min to form a homogeneous spinning solution. After removing undissolved particles through a 10-μm precision filter, it is injected into an electrospinning device equipped with a high-voltage electrostatic generator. Continuous electrospinning is carried out under the conditions of a voltage field strength of 25 kV and a spinning distance of 25 cm. The as-spun fiber bundles form a uniaxially oriented fiber web on a parallel electrode array. The fiber web together with the metal fixture is transferred to an air-circulation heat treatment furnace, and stepwise stabilization treatment is carried out at a heating rate of 5 °C / min from room temperature to 320 °C for 90 min, with insulation for 50 min at 160 °C, 210 °C, and 260 °C respectively. The stabilized fibers are then transferred to a tube-type carbonization furnace, and programmed carbonization is carried out under the protection of 99.99% high-purity nitrogen at a heating rate of 10 °C / min. In the first stage, non-carbon elements are removed by maintaining at 600 °C for 60 min. In the second stage, the target temperature of 1700 °C is reached at the same heating rate and maintained for 90 min to complete the graphitization process. The carbonized product is taken out after being cooled to below 50 °C at a cooling rate of 20 °C / min by a forced cooling system, and finally, short-cut carbon fibers are prepared by an ultrasonic cutting machine. The parameters of the ultrasonic cutting machine include: ultrasonic frequency of 40 kHz, output power of 400 W, cutting speed of 1.5 m / min, tool head amplitude of 50 μm, pressure of the compressed air cooling system of 0.5 MPa, fiber fixture pressure of 10 N, cutting gap of 150 μm, and working pressure of the supporting negative-pressure dust removal system of 0.1 MPa.

[0088] The average diameter of the short carbon fibers in this embodiment is 335 nm; the average length is 2.5 μm; the average diameter of the carbon nanotubes is 22 nm; the average length is 370 nm.

[0089] The preparation method of the modified bismaleimide in this embodiment is as follows: By weight, 22.0 parts of bismaleimide and 45 parts of 1,6-hexanediol diacrylate are added to a reaction vessel, and then 4.5 parts of 4,4'-diaminodiphenyl ether and 45 parts of polyetheramine D-2000 are further added. It is heated to 90 °C at a rate of 5 °C / min with a stirring rate of 500 rpm and maintained for 40 min until the resin is completely dissolved. Subsequently, it is heated to 150 °C at a heating rate of 10 °C / min and stirred at a constant temperature for 90 min. After the reaction ends, it is naturally cooled to room temperature to obtain the modified bismaleimide.

[0090] The preparation method of a high-adhesion antistatic high-temperature-resistant UV adhesive film in this embodiment includes the following steps:

[0091] S1. Add bisphenol A epoxy acrylate, 1,6 - hexanediol diacrylate and modified bismaleimide into a vacuum reactor equipped with a double - planetary stirrer. Under the protection of nitrogen inert gas, mix at a stirring rate of 420 rpm, control the temperature in the reactor at 52 °C, continuously stir for 48 min, and then cool down to 31 °C at a rate of 4 °C / min to form a homogeneous resin premix;

[0092] S2. Add the surface - modified multi - level carbon fiber / carbon nanotube composite filler and BYK - 163 dispersant into the resin premix in three times, with an interval of 8 min each time. Use a high - shear disperser to conduct primary dispersion at a rotational speed of 2400 rpm, control the material temperature ≤50 °C, and then switch to the ultrasonic - mechanical synergistic dispersion mode. Treat for 78 min under the conditions of an ultrasonic power of 520 W, a frequency of 52 kHz and a mechanical stirring of 320 rpm to obtain a uniformly dispersed adhesive solution;

[0093] S3. Add 1 - hydroxycyclohexyl phenyl ketone and benzophenone to the uniformly dispersed adhesive solution in sequence. Mix at a stirring rate of 420 rpm under light - shielding conditions for 32 min. Maintain the system temperature at 31 °C during the mixing process, and conduct defoaming treatment for 48 min through a vacuum defoaming device at a vacuum degree of - 0.09 MPa;

[0094] S4. Use a slot coater to coat the adhesive solution on the surface of the substrate, control the wet film thickness at 140 μm, the coating rate at 1.4 m / min. After coating, transfer the substrate to the leveling area and let it stand for 11 min at 42 °C; Cure using a step - type photocuring process to obtain a high - adhesion antistatic and high - temperature resistant UV adhesive film. The step - type photocuring process includes: First, use a mercury lamp array with a main wavelength of 365 nm to conduct primary curing in a nitrogen - protected atmosphere with an oxygen concentration less than 100 ppm, control the light intensity at 104 mW / cm 2 、irradiation time at 48 s to form a gel - like network; Subsequently, increase the light intensity to 180 mW / cm 2 , continuously cure for 96 s to eliminate the interfacial oxygen inhibition effect; Finally, complete the curing by heating at 92 °C for 32 min.

[0095] Comparative Example 1

[0096] It is basically the same as Example 1, except that the silane coupling agent KH - 560 is not used for surface modification, resulting in a decrease in the interfacial bonding force between carbon fiber and resin and a decrease in adhesion.

[0097] Comparative Example 2

[0098] It is basically the same as Example 1, except that the concentration of the iron nitrate solution is reduced to 0.01 mol / L, resulting in insufficient Fe 3+ loading, a decrease in the growth density of carbon nanotubes, and ultimately the antistatic performance of the adhesive film is impaired.

[0099] Comparative Example 3

[0100] It is basically the same as Example 1, except that the reaction temperature of the chemical vapor deposition reactor is reduced to 650 °C, resulting in insufficient growth of carbon nanotubes, poor dispersibility, and ultimately reduced heat resistance of the adhesive film.

[0101] Comparative Example 4

[0102] It is basically the same as Example 1, except that 4,4'-diaminodiphenyl ether is not added to the modified bismaleimide, resulting in a decrease in heat resistance.

[0103] Comparative Example 5

[0104] It is basically the same as Example 1, except that the final curing temperature is reduced to 50 °C, resulting in insufficient crosslinking degree and a significant decrease in high-temperature resistance.

[0105] Comparative Example 6

[0106] It is basically the same as Example 1, except that in the preparation process of the short carbon fibers, the voltage field strength of the electrospinning device is 12 kV, which is lower than the range of 15 - 25 kV specified in Claim 5.

[0107] Comparative Example 7

[0108] It is basically the same as Example 1, except that in the preparation process of the short carbon fibers, the target temperature of the second stage of the carbonization stage is 650 °C, which is lower than the target temperature range of 800 - 1700 °C specified in Claim 5.

[0109] Comparative Example 8

[0110] It is basically the same as Example 1, except that the average diameter of the short carbon fibers is 1000 nm, which exceeds the range of 200 - 650 nm specified in Claim 6.

[0111] Comparative Example 9

[0112] It is basically the same as Example 1, except that in step S2, the surface-modified multi-stage carbon fiber / carbon nanotube composite filler and BYK-163 dispersant are all added to the resin premix at one time, rather than added in three times as specified in Claim 9.

[0113] Comparative Example 10

[0114] It is basically the same as Example 1, except that in the stepped photocuring process in step S4, the light intensity of the mercury lamp array is 130 mW / cm 2 , which is higher than the range of 80 - 120 mW / cm 2 specified in Claim 10, resulting in too fast curing of the material and an increase in internal stress.

[0115] Performance test:

[0116] Adhesion test (180° peel test): The 180° peel test was used to evaluate the adhesion of the UV film to the substrate. The UV film was coated on different substrates such as glass, PET, and PI films, and specimens were cut according to the specification of 50 mm × 100 mm. An Instron tensile machine was used to conduct the test at a peel rate of 300 mm / min, and the peel force (N / cm) was recorded. The experiment was repeated 5 times, and the average value was taken to evaluate the adhesion performance of the film on different substrates.

[0117] Antistatic performance test: Referring to ASTM D257-14, a Keithley 6517B high resistance meter was used to measure the surface resistance (Ω / sq) and volume resistance (Ω·cm) of the film. The test environment was controlled at 23°C and 50% RH, the electrode spacing was set at 10 mm, and the test voltage was 100 V. Samples with different conductive filler contents were compared to evaluate their antistatic performance.

[0118] High temperature resistance test (Thermogravimetric analysis TGA): Referring to ASTM E1131-08, a thermogravimetric analyzer (TGA, TA Instruments Q50) was used to evaluate the thermal stability of the film. The test conditions were nitrogen protection (50 mL / min), a heating rate of 10°C / min, and a test temperature range of 25 - 800°C. The 5% mass loss temperature (T 5 %) and 50% mass loss temperature (T 50 %) were recorded to evaluate the thermal degradation behavior of the material.

[0119] The performance of the films of Examples 1 - 4 and Comparative Examples 1 - 10 was summarized in Table 1. It can be seen from Table 1 that the main factors affecting the performance of the UV film include interfacial bonding force, conductive filler loading, carbon nanotube growth conditions, resin modification, curing process, and fiber preparation parameters. The interfacial bonding force is affected by surface modification treatment. If an appropriate silane coupling agent is not used, the bonding force between carbon fiber and resin will decrease, resulting in a decrease in adhesion. The conductive filler loading directly affects the antistatic performance. If Fe 3+Insufficient loading or improper use of the dispersant will lead to a decrease in the growth density of carbon nanotubes or poor dispersibility, resulting in an increase in surface resistance and volume resistance. The growth conditions of carbon nanotubes (such as chemical vapor deposition temperature) determine their structural quality. If the temperature is too low, the growth of carbon nanotubes is insufficient and the heat resistance performance decreases. Resin modification (such as whether to add 4,4'-diaminodiphenyl ether) affects the high-temperature resistance of the adhesive film. Failure to add a suitable modifier will reduce the thermal decomposition temperature in the TGA test. The curing process (such as curing temperature and UV light intensity) determines the degree of crosslinking. If the final curing temperature is too low or the UV light intensity is too high, it will lead to insufficient curing or an increase in internal stress, affecting heat resistance or adhesion. Fiber preparation parameters (such as electrospinning voltage field strength, carbonization temperature, and fiber diameter) affect the structural quality of short carbon fibers. If the voltage field strength or carbonization temperature is insufficient, the conductivity and thermal stability of the carbon fibers will decrease; if the fiber diameter is too large, the interfacial bonding performance will deteriorate, affecting the overall mechanical properties. Generally speaking, these factors interact with each other and jointly determine the adhesion, antistatic performance, and high-temperature resistance of the UV adhesive film.

[0120] Table 1 Performance aggregation of the adhesive films of Examples 1 to 4 and Comparative Examples 1 to 10

[0121]

[0122]

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that any equivalent structural transformation made under the concept of the present invention by using the content of the specification and drawings of the present invention should be covered by the protection scope of the claims of the present invention.

Claims

1. A high-adhesion antistatic high-temperature resistant UV film, characterized in that: The invention comprises the following raw materials in parts by weight: 15 to 30 parts of surface modified multi-level carbon fiber / carbon nanotube composite filler, 10 to 20 parts of modified bismaleimide, 0.5 to 1.5 parts of BYK-163 dispersant, 40 to 60 parts of bisphenol A epoxy acrylate, 5.0 to 12.0 parts of 1,6-hexanediol diacrylate, 2.0 to 5.0 parts of 1-hydroxycyclohexyl phenyl ketone, and 0.5 to 1.5 parts of benzophenone; The surface-modified multi-level carbon fiber / carbon nanotube composite filler is obtained by surface-modifying the multi-level carbon fiber / carbon nanotube composite filler with a silane coupling agent KH-560; The multi-level carbon fiber / carbon nanotube composite filler comprises submicron-scale short carbon fibers and nanometer-scale carbon nanotubes loaded on the surface of the short carbon fibers; The modified bismaleimide is obtained by modifying bismaleimide 4,4'-diaminodiphenyl ether and polyetheramine D-2000.

2. The high-adhesion antistatic high-temperature resistant UV adhesive film according to claim 1, characterized in that: The mass ratio of the short carbon fibers to the carbon nanotubes is (94.5-97.5):(5.5-2.5).

3. The high-adhesion antistatic high-temperature resistant UV adhesive film according to claim 1, characterized in that: The preparation method of the surface modified multi-level carbon fiber / carbon nanotube composite filler is as follows: by weight, 1.5 to 2.5 parts of silane coupling agent KH-560 and 97 to 95 parts of anhydrous ethanol are mixed at 25 to 35° C. and a stirring rate of 200 to 400 rpm to form a hydrolyzate, the pH is adjusted to 4.0 to 5.0 and the hydrolysis reaction is maintained for 60 to 90 minutes, then 10 to 30 parts of the multi-level carbon fiber / carbon nanotube composite filler are added, and the mixture is stirred at an ultrasonic power of 300 to 400 rpm to form a hydrolyzate. The suspension was dispersed under 500W conditions for 30 to 60 minutes to form a suspension, and the suspension was transferred to a high-pressure reactor, and the temperature was increased to 80 to 120°C at 2 to 5°C / min, and the pressure was controlled to 0.5 to 1.5 MPa and nitrogen was continuously introduced for protection. After reacting for 180 to 240 minutes, the solid and liquid components were separated by a vacuum filtration device, and the retained solid product was washed with deionized water until the filtrate conductivity was ≤50μS / cm, and then dried in a vacuum drying oven at 60 to 80°C for 10 to 15m 3 / h airflow rate for 120 to 180 minutes to finally obtain a surface-modified multi-level carbon fiber / carbon nanotube composite filler.

4. The high-adhesion antistatic high-temperature resistant UV adhesive film according to claim 1, characterized in that: The preparation method of the multi-level carbon fiber / carbon nanotube composite filler is as follows: by weight, 100 parts of short carbon fibers are used as a matrix, and the matrix is ​​immersed in 50 to 100 parts of an ethanol solution of iron nitrate with a Fe3+ concentration of 0.05 to 0.15 mol / L, and treated for 30 to 60 minutes with the assistance of 40 to 60 kHz ultrasonic waves to achieve catalyst loading, and then the temperature is increased to 700 to 900°C at 10 to 15°C / min in an argon / hydrogen mixed atmosphere with a volume ratio of 9:1 for 60 minutes to perform a reduction treatment. The method comprises the following steps: the step of heating the carbon nanotubes for 1 hour and heating the carbon nanotubes for 1 hour; ...

5. The high-adhesion antistatic high-temperature resistant UV adhesive film according to claim 4, characterized in that: The preparation method of the short carbon fiber is as follows: 9.0 to 12.0 parts of polyacrylonitrile with a molecular weight of 120,000 to 150,000 g / mol and 85 to 95 parts of N,N-dimethylformamide are mixed at 25 to 35°C at a stirring rate of 200 to 400 rpm for 120 to 180 minutes to form a homogeneous spinning solution, which is then injected into an electrostatic spinning device equipped with a high-voltage electrostatic generator after removing undissolved particles through a 5 to 10 μm precision filter, and continuously spun under the conditions of a voltage field strength of 15 to 25 kV and a spinning distance of 15 to 25 cm. The resulting primary fiber bundle forms a single-oriented fiber web on a parallel electrode array, and the fiber web is transferred together with a metal clamp to an air circulation heat treatment furnace, and the temperature is raised from room temperature to 300 °C / min. The fiber was then transferred to a tubular carbonization furnace and carbonized at a heating rate of 5 to 10 ° C / min under the protection of 99.99% high-purity nitrogen. The first stage was maintained at 400 to 600 ° C for 30 to 60 minutes to remove non-carbon elements. In the second stage, the temperature was increased to 800 to 1700 ° C at the same heating rate and maintained for 60 to 90 minutes to complete the graphitization process. The carbonized product was cooled to below 50 ° C by a forced cooling system at a temperature of 15 to 20 ° C / min and then taken out, and finally prepared into chopped carbon fiber by an ultrasonic cutting machine.

6. The high-adhesion antistatic high-temperature resistant UV adhesive film according to claim 1, characterized in that: The average diameter of the short carbon fibers is 200-650 nm, and the average length is 2.0-3.5 μm.

7. The high-adhesion antistatic high-temperature resistant UV adhesive film according to claim 1, characterized in that: The average diameter of the carbon nanotubes is 10-50nm; the average length is 250-650nm.

8. The high-adhesion antistatic high-temperature resistant UV adhesive film according to claim 1, characterized in that: The preparation method of the modified bismaleimide is as follows: by weight, 15.0-22.0 parts of bismaleimide and 30-45 parts of 1,6-hexanediol diacrylate are added into a reaction container, and then 3.5-4.5 parts of 4,4'-diaminodiphenyl ether and 35-45 parts of polyetheramine D-2000 are added, and the temperature is raised to 70-90°C at a stirring rate of 2-5°C / min at a stirring rate of 300-500rpm and maintained for 20-40min until the resin is completely dissolved, and then the temperature is raised to 140-150°C at a heating rate of 5-10°C / min, and the temperature is stirred at a constant temperature for 60-90min. After the reaction is completed, the reaction is naturally cooled to room temperature to obtain the modified bismaleimide.

9. The method for preparing a high-adhesion antistatic high-temperature resistant UV adhesive film according to claim 1, comprising the following steps: S1. Add bisphenol A epoxy acrylate, 1,6-hexanediol diacrylate and modified bismaleimide into a vacuum reactor equipped with a double planetary stirrer, mix at a stirring rate of 300-500 rpm under the protection of nitrogen inert gas, control the temperature in the reactor at 40-60° C., continue stirring for 30-60 min, and then cool to 25-35° C. at a rate of 2-5° C. / min to form a homogeneous resin premix; S2. The surface-modified multi-stage carbon fiber / carbon nanotube composite filler and BYK-163 dispersant were added to the resin premix three times, each time with an interval of 5 to 10 minutes, and a high shear disperser was used for primary dispersion at a speed of 1500 to 3000 rpm, and the material temperature was controlled to be ≤50°C, and then switched to the ultrasonic-mechanical synergistic dispersion mode, and the ultrasonic power was 400 to 600 W, the frequency was 40 to 60 kHz, and the mechanical stirring was 200 to 400 rpm. The conditions were treated for 60 to 90 minutes to obtain a uniformly dispersed adhesive solution; S3. 1-hydroxycyclohexyl phenyl ketone and benzophenone were added to the uniformly dispersed glue solution in sequence, and mixed at a stirring rate of 300 to 500 rpm for 20 to 40 min under light-proof conditions, and the system temperature was maintained at 25 to 35 ° C during the mixing process, and the vacuum degassing device was used for degassing for 30 to 60 min at a vacuum degree of -0.08 to -0.10 MPa; S4. Use a slit coater to coat the adhesive on the surface of the substrate, control the wet film thickness to 50-200μm, and the coating rate to 0.5-2.0m / min. After coating, transfer the substrate to the leveling area and let it stand at 30-50℃ for 5-15min. Use a step-by-step light curing process to cure it, and after curing, a high-adhesion, anti-static, and high-temperature resistant UV adhesive film is obtained.

10. The method for preparing a high-adhesion antistatic high-temperature resistant UV adhesive film according to claim 9, characterized in that: The step-by-step light curing process in step S4 includes: firstly, using a mercury lamp array with a main wavelength of 365 nm to perform primary curing in a nitrogen protective atmosphere with an oxygen concentration of less than 100 ppm, and controlling the light intensity to 80-120 mW / cm 2 , irradiation time 30 to 60 seconds, forming a gel network; then increase the light intensity to 150 to 200 mW / cm 2 , continue curing for 60 to 120 seconds to eliminate the interfacial oxygen inhibition effect; finally, heat at 80 to 100°C for 20 to 40 minutes to complete the curing.

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