Electron beam curable bio-based conductive compositions, bio-based conductive tapes, their preparation methods and applications

Abstract

This invention provides an electron beam-curable bio-based conductive composition, a bio-based conductive tape, its preparation method, and its applications. Specifically, the bio-based conductive composition comprises: 45-70% by weight of a polymer base; 15-40% by weight of a tackifying resin; 10-20% by weight of conductive particles; and 1-3% by weight of a crosslinking agent. The bio-based conductive composition and the conductive tape prepared therefrom of this invention have a high bio-based content and employ a solvent-free UV prepolymerization + electron beam curing process, significantly improving environmental friendliness and production efficiency. Furthermore, the conductive tape exhibits excellent conductivity and remains stable after high-temperature and high-humidity aging; its passive intermodulation value is far below -55dBm and it demonstrates excellent stability, making it suitable for the high-frequency, low-interference requirements of 5G. Simultaneously, the tape also possesses good adhesion and maintains excellent adhesion performance under high-temperature and high-humidity conditions, meeting the long-term use requirements of electronic device electromagnetic shielding, grounding connections, and other scenarios.

Description

Technical Field

[0001] This invention belongs to the technical fields of bio-based functional polymer materials, conductive voltage-sensitive adhesives and electronic bonding materials. Specifically, it relates to a bio-based conductive composition that can be cured by electron beam, a conductive tape prepared from the bio-based conductive composition and its preparation method, which is mainly used in conductive bonding, electromagnetic shielding, grounding connection and other scenarios in the consumer electronics field. Background Technology

[0002] As the global concept of green and low-carbon development continues to deepen, the demand for renewable and environmentally friendly products in the new materials field continues to rise. Bio-based polymer materials are gradually replacing traditional petroleum-based materials, becoming an important development direction for the industry. At the same time, the consumer electronics and communications industries are developing rapidly, with products such as 5G communication equipment, flexible circuit boards, touch components, and radio frequency components constantly iterating. This has led to a significant increase in market demand for pressure-sensitive tapes with conductive, adhesive, and electromagnetic shielding functions.

[0003] Conductive voltage-sensitive adhesives are special functional adhesives that combine adhesive and conductive properties. They are widely used in scenarios such as grounding of electronic devices, electromagnetic shielding, and conductive connections of components. In addition to requiring reliable adhesive strength and conductivity, 5G high-frequency communication scenarios also place stringent requirements on environmental stability, including passive intermodulation (PIM), resistance to high and low temperatures, and resistance to damp heat aging. Currently, most mainstream conductive voltage-sensitive adhesives and tapes on the market use pure petroleum-based acrylate monomers as their main raw materials. These raw materials rely on non-renewable petrochemical resources, resulting in high carbon emissions and poor sustainability, which does not meet current green production and environmental protection regulations.

[0004] In order to keep up with the trend of sustainable development, some companies in the industry have launched bio-based conductive voltage-sensitive adhesive products. However, existing technologies still have many shortcomings: First, most bio-based conductive adhesives use solvent-based or aqueous polymerization processes, which generate volatile organic compounds or have high energy consumption during production. This not only pollutes the environment but also increases the subsequent desolventizing process, resulting in low production efficiency and significant safety hazards. Second, the proportion of bio-based components in existing products is generally not high, and their green attributes are limited, failing to fully realize the application value of bio-based raw materials.

[0005] From a formulation perspective, traditional bio-based conductive adhesives mostly use conventional polyolefin elastomers as the matrix. Compared to acrylate systems, their adhesion and interfacial wetting capabilities are insufficient, making them difficult to adapt to various electronic substrates. A few competing products using acrylate systems have simple formulations, unreasonable monomer combinations, poor control of the glass transition temperature, and significant shortcomings in flexibility and low-temperature adhesion. Regarding core performance characteristics, the deficiencies of existing products are even more pronounced: firstly, the passive intermodulation values ​​are too high under high-frequency conditions, easily causing signal interference and failing to meet the low-interference standards for 5G communication equipment; secondly, the materials have poor resistance to damp heat, and their conductivity and adhesive strength significantly degrade after long-term placement in high-temperature and high-humidity environments, shortening their service life.

[0006] At the curing process level, traditional conductive voltage-sensitive adhesives mostly use thermal curing, which has high curing energy consumption, poor reaction controllability, and is prone to problems such as over-crosslinking or incomplete curing, directly affecting the cohesive strength and overall performance of the adhesive layer. Existing technologies also lack an integrated process route that combines solvent-free polymerization, UV prepolymerization, and electron beam post-curing, making it difficult to simultaneously achieve a balance between high bio-based content, environmentally friendly production, efficient curing, and excellent performance.

[0007] In summary, existing petroleum-based conductive tapes are not environmentally friendly enough, while commercially available bio-based conductive products suffer from a series of problems, including environmentally unfriendly manufacturing processes, low bio-based content, weak adhesion, poor radio frequency performance, and insufficient resistance to damp heat aging. These issues fail to simultaneously meet the multiple demands of green and low-carbon production, 5G high-frequency communication, and the long-term reliable use of electronic devices. Therefore, developing an acrylate-based conductive composition and conductive tape with high bio-based content, solvent-free preparation, electron beam curing, excellent conductivity, low passive intermodulation, high adhesive strength, and good environmental stability has become a pressing technical challenge in this field. Summary of the Invention

[0008] Based on the aforementioned technical problems, this invention aims to overcome the shortcomings of existing conductive voltage-sensitive adhesives, such as low bio-based content, environmentally unfriendly production, poor passive intermodulation performance, and insufficient resistance to damp heat aging. It provides an electron beam-curable bio-based conductive composition, a conductive tape prepared from the bio-based conductive composition, and a method for preparing the same. This invention employs a solvent-free process, balancing environmental friendliness and production efficiency, resulting in a product with excellent adhesive strength, stable conductivity, low passive intermodulation value, and good resistance to damp heat aging, meeting the application requirements of conductive bonding and electromagnetic shielding in 5G electronic devices.

[0009] Specifically, according to one aspect of the present invention, an electron beam-curable bio-based conductive composition is provided, said bio-based conductive composition comprising, by weight 100%, the following:

[0010] 45-70% by weight of a polymer base, said polymer base comprising a polymer product obtained by polymerization of an acrylate composition and having an intrinsic viscosity in the range of 0.75-1 dL / g;

[0011] 15-40% by weight of tackifying resin;

[0012] 10-20% by weight of conductive particles; and

[0013] 1-3% by weight of crosslinking agent.

[0014] According to certain preferred embodiments of the present invention, the acrylate composition, based on 100% of its total weight, comprises:

[0015] 30-90% by weight, preferably 35-45% by weight, of the first acrylate monomer, wherein the glass transition temperature of the homopolymer of the first acrylate monomer is less than or equal to -70°C.

[0016] 5-65% by weight, preferably 50-60% by weight, of a second acrylate monomer, wherein the glass transition temperature of the homopolymer of the second acrylate monomer is greater than or equal to -50°C;

[0017] 2-5% by weight, preferably 2.5-5% by weight, of functional monomers; and

[0018] Effective amount of free radical polymerization initiator.

[0019] According to certain preferred embodiments of the present invention, the first acrylate monomer is selected from one or more of 2-ethylhexyl acrylate, n-octyl acrylate, n-tetrazyl acrylate, n-hexadecyl acrylate, and n-octadecyl acrylate.

[0020] According to certain preferred embodiments of the present invention, the second acrylate monomer is selected from one or more of 2-octyl methacrylate, ethyl methacrylate, methyl methacrylate and isobornyl methacrylate.

[0021] According to certain preferred embodiments of the present invention, the first acrylate monomer is 2-ethylhexyl acrylate, and the second acrylate monomer is 2-octyl acrylate.

[0022] According to certain preferred embodiments of the present invention, the functional monomer is selected from one or more of (meth)acrylic acid, hydroxyethyl acrylate, hydroxyethyl methyl acrylate, hydroxypropyl (meth)acrylic acid, N-vinylpyrrolidone, and (meth)acrylamide.

[0023] According to certain preferred embodiments of the present invention, the functional monomer is acrylic acid.

[0024] According to certain preferred embodiments of the present invention, the free radical polymerization initiator is selected from one or more of acetylbenzene initiators, α-hydroxyketone initiators, benzoin ether initiators, aryl sulfonyl chloride initiators, and oxime initiators.

[0025] According to certain preferred embodiments of the present invention, the content of the free radical polymerization initiator is 0.01-0.3% by weight.

[0026] According to certain preferred embodiments of the invention, the acrylate composition further comprises a chain transfer agent.

[0027] According to certain preferred embodiments of the invention, the content of the chain transfer agent is 0.01-3% by weight.

[0028] According to certain preferred embodiments of the present invention, the chain transfer agent is selected from one or more of sulfur-containing chain transfer agents and haloalkane chain transfer agents.

[0029] According to certain preferred embodiments of the invention, the acrylate composition further comprises a diluent.

[0030] According to certain preferred embodiments of the present invention, the diluent is 1,6-hexanediol diacrylate.

[0031] According to certain preferred embodiments of the invention, the diluent content is 0.03-0.06% by weight.

[0032] According to certain preferred embodiments of the invention, the acrylate composition further comprises an antioxidant.

[0033] According to certain preferred embodiments of the present invention, the antioxidant is selected from one or more of the following: octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, and dilauryl thiodipropionate.

[0034] According to certain preferred embodiments of the present invention, the content of the antioxidant is 0.1-0.3% by weight.

[0035] According to certain preferred embodiments of the present invention, the viscosity of the acrylate composition at 25°C is less than 50 cP.

[0036] According to certain preferred embodiments of the present invention, the acrylate composition is a solvent-free composition.

[0037] According to certain preferred embodiments of the present invention, the content of the bio-based substance in the acrylate composition is 55% by weight or more.

[0038] According to certain preferred embodiments of the invention, the gel content of the acrylate composition is less than or equal to 23% by weight.

[0039] According to certain preferred embodiments of the invention, the residual monomer content of the acrylate composition is less than or equal to 0.5% by weight.

[0040] According to certain preferred embodiments of the present invention, the polymer base is prepared by the following steps:

[0041] The acrylate composition is sealed in a plastic bag;

[0042] The acrylate composition in the plastic packaging bag is subjected to ultraviolet radiation to induce polymerization; and

[0043] The acrylate composition exposed to ultraviolet radiation and the plastic packaging bag are melt-extruded together to obtain the polymer base material.

[0044] According to certain preferred embodiments of the present invention, the intensity of the ultraviolet radiation is between 0.01 and 20 mW / cm². 2 Within the range.

[0045] According to certain preferred embodiments of the invention, the polymer base material further comprises a viscosity modifier.

[0046] According to certain preferred embodiments of the present invention, the viscosity modifier is an ethylene-vinyl acrylate copolymer or an ethylene-acrylic acid copolymer.

[0047] According to certain preferred embodiments of the present invention, the tackifying resin is a hydrogenated rosin resin.

[0048] According to certain preferred embodiments of the present invention, the softening point of the hydrogenated rosin resin is 70-100°C.

[0049] According to certain preferred embodiments of the present invention, the conductive particles are selected from one or more of graphite particles, conductive carbon black particles, carbon nanotube particles, graphene particles, silver particles, and gold particles.

[0050] According to certain preferred embodiments of the present invention, the conductive particles are nickel-coated graphite particles.

[0051] According to certain preferred embodiments of the present invention, the nickel coating amount of the nickel-coated graphite particles is 60-85% by weight.

[0052] According to certain preferred embodiments of the present invention, the crosslinking agent is a polyfunctional acrylate crosslinking agent.

[0053] According to certain preferred embodiments of the present invention, the crosslinking agent is one or more of a multifunctional aliphatic acrylate oligomer or trimethylolpropane triacrylate.

[0054] According to another aspect of the present invention, an electron beam-curable bio-based conductive tape is provided, the electron beam-curable bio-based conductive tape comprising:

[0055] The adhesive layer formed from the electron beam-curable bio-based conductive composition described above; and

[0056] Release substrate bonded to the adhesive layer.

[0057] According to certain preferred embodiments of the present invention, the method includes:

[0058] (1) The polymer base, the tackifying resin, the conductive particles and the crosslinking agent are mixed to obtain a conductive adhesive mixture;

[0059] (2) The conductive adhesive mixture is applied to at least one surface of the release substrate to form a voltage-sensitive adhesive layer; and

[0060] (3) Apply electron beam radiation to the voltage-sensitive adhesive layer to cause the voltage-sensitive adhesive layer to crosslink and cure.

[0061] According to certain preferred embodiments of the invention, the electron beam radiation dose is 20-150 kGy and the accelerating voltage is 80-300 kV.

[0062] According to certain preferred embodiments of the invention, the mixing in step (1) is a melt mix, a knead mix, or an extrusion mix.

[0063] According to certain preferred embodiments of the present invention, the coating in step (2) is hot melt coating, extrusion coating or doctor blade coating.

[0064] According to another aspect of the present invention, the use of the electron beam curable bio-based conductive composition or the electron beam curable bio-based conductive tape described above is provided in electronic device assembly, electromagnetic shielding, grounding connection or conductive bonding.

[0065] This invention offers several significant advantages over existing technologies. First, it boasts superior environmental friendliness. The overall bio-based content of the product can reach over 45%, utilizing a large amount of 2-octyl acrylate (2OA) derived from renewable raw materials, reducing reliance on petrochemical feedstocks. The entire process employs a solvent-free system, combined with UV prepolymerization and electron beam curing, resulting in zero VOC emissions. Compared to traditional solvent-based products, it is more environmentally friendly and low-carbon, and the production process is more streamlined and efficient. Second, it exhibits excellent overall performance. The product has low DC resistance, which remains stable or even lower after aging at 85℃ and 85% high humidity. Its passive intermodulation value is far below industry limits and remains stable after aging, meeting the low-interference requirements of 5G high-frequency communication equipment. Simultaneously, it demonstrates excellent adhesion, achieving high peel strength with a short dwell time, and exhibits strong adhesion reliability. Third, the formulation and process of this invention are highly adaptable. By rationally combining monomers, chain transfer agents, and crosslinking agents, the polymer molecular weight and crosslinking degree are precisely controlled, avoiding problems such as over-crosslinking and coating difficulties. The electron beam curing dosage can be flexibly adjusted to adapt to different application scenarios. Fourth, it has excellent environmental tolerance. Under harsh conditions of high temperature and high humidity, its bonding, conductivity, and radio frequency performance do not show significant attenuation, resulting in a longer service life. It can be stably applied to scenarios such as conductive connection of electronic devices, electromagnetic shielding, and grounding. Its overall competitiveness is superior to similar bio-based conductive adhesive products on the market. Detailed Implementation

[0066] The present invention will now be described in further detail with reference to specific embodiments. It will be understood that other embodiments may be implemented without departing from the scope or spirit of the invention. Therefore, the following detailed description is non-limiting.

[0067] Unless otherwise specified, all figures used in this specification to represent characteristic dimensions, quantities, and physical properties should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters listed in the foregoing specification are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired properties using the teachings disclosed herein.

[0068] As mentioned above, existing conductive voltage-sensitive adhesives are mostly made from petroleum-based raw materials, resulting in poor sustainability. Some bio-based competing products have a low proportion of bio-based components and generally use solvent-based production methods, leading to VOC emissions and insufficient environmental friendliness. Furthermore, traditional curing methods are outdated and inefficient. In addition, existing products generally suffer from high passive intermodulation values ​​and are prone to signal interference at high frequencies, making them unsuitable for 5G applications. Moreover, the materials are susceptible to conductivity and adhesion degradation under high temperature and humidity conditions, exhibiting insufficient environmental stability. This invention aims to solve one or more of the above problems.

[0069] According to one aspect of the present invention, an electron beam-curable bio-based conductive composition is provided, said bio-based conductive composition comprising, by weight 100%, the following:

[0070] 45-70% by weight of a polymer base, said polymer base comprising a polymer product obtained by polymerization of an acrylate composition and having an intrinsic viscosity in the range of 0.75-1 dL / g;

[0071] 15-40% by weight of tackifying resin;

[0072] 10-20% by weight of conductive particles; and

[0073] 1-3% by weight of crosslinking agent.

[0074] Specifically, this invention employs a specific ratio range of four components: polymer base material, tackifying resin, conductive particles, and crosslinking agent. This ratio system is optimized by considering the characteristics of bio-based raw materials, solvent-free processing technology, electron beam crosslinking mechanism, and the comprehensive application requirements of 5G electronic devices. The polymer base material, serving as the main framework of the composition, accounts for 45-70% by weight. This range ensures that the composition exhibits excellent film-forming properties, flexibility, and basic adhesion after molding, while also supporting the uniform dispersion of conductive particles to construct a continuous and stable conductive network. When the polymer base content is less than 45% by weight, the proportion of functional components such as tackifying resin and conductive particles in the system is relatively too high, which will lead to a significant decrease in the overall cohesion of the adhesive layer. During use, the tape is prone to problems such as adhesive layer breakage, residual adhesive, and edge lifting. At the same time, the polymer matrix cannot fully encapsulate the conductive particles, and the particles are prone to agglomeration and sedimentation. This will not only increase the DC resistance and destroy the continuity of conductivity, but also aggravate the nonlinear effect of the interface, resulting in an increase in the passive intermodulation (PIM) value, which cannot meet the low interference requirements of 5G high-frequency communication. If the polymer base content is higher than 70% by weight and the content of functional components is insufficient, on the one hand, the lack of tackifying resin will cause the initial tack of the composition to be poor, and the peel strength at short residence time will be low, making it difficult to quickly bond to various substrates of electronic devices. On the other hand, the insufficient content of conductive particles cannot form a dense conductive path, resulting in a decrease in conductivity. The relatively reduced proportion of crosslinking agent will also lead to insufficient crosslinking density after electron beam irradiation, resulting in a deterioration of the adhesive layer's resistance to damp heat aging and high temperature resistance, and a decrease in long-term service reliability.

[0075] Tackifying resins, as components that enhance the pressure-sensitive adhesive properties of the composition, account for 15-40% by weight. The adhesive effect of pressure-sensitive adhesives depends on the surface wetting ability of the adhesive layer on the substrate and the interfacial bonding force. Although pure acrylic polymer bases have certain adhesive properties, their wetting effect on different substrates commonly used in the electronics field, such as stainless steel, copper foil, PET, and flexible circuit boards, is limited. Introducing tackifying resins can effectively reduce the surface tension of the adhesive layer and improve the initial adhesion and interfacial adhesion. When the amount of tackifying resin added is less than 15% by weight, the wetting modification effect is weak, the initial tack of the tape is insufficient, and local debonding is likely to occur after bonding to the substrate. In particular, the risk of bonding failure increases significantly under dynamic vibration conditions. When the proportion of tackifying resin exceeds 40% by weight, a large number of small resin molecules will be interspersed between polymer molecular chains, destroying the molecular chain entanglement structure and significantly reducing the cohesive force of the adhesive layer. At the same time, excessive tackifying resin will dilute the distribution density of conductive particles, block the conductive path, and cause a decrease in conductivity. In addition, excessive small molecule resin is prone to migration and precipitation in high temperature and high humidity environments, further deteriorating the aging resistance and radio frequency stability.

[0076] According to the technical solution of the present invention, conductive particles are functional fillers that impart conductivity, electromagnetic shielding, and grounding functions to the composition, and their content is 10-20% by weight. When the content of conductive particles is less than 10% by weight, the particle spacing is too large, making it difficult to form a continuous conductive network with overlapping particles. The DC resistance of the composition is too high, and the conductivity, grounding, and electromagnetic shielding effects cannot meet the standards. As the amount of conductive particles gradually increases to 10-20% by weight, the particles are uniformly dispersed in the polymer matrix and come into contact with each other, constructing a three-dimensional continuous conductive network, and the conductivity meets the requirements for use. If the proportion of conductive particles is higher than 20% by weight, on the one hand, the probability of particle agglomeration increases, and micro-voids and contact defects are easily generated inside the agglomerates, increasing the interface nonlinearity and pushing up the passive intermodulation value. On the other hand, a large number of hard conductive particles will destroy the flexibility and continuity of the acrylate polymer matrix, causing the adhesive layer to become hard and brittle, reducing its flexibility. During the coating process, appearance defects such as pinholes and scratches are likely to occur. At the same time, it will significantly reduce the peel strength and bending resistance of the adhesive layer, making it unsuitable for the application scenarios of flexible electronic devices.

[0077] According to the technical solution of the present invention, the crosslinking agent accounts for 1-3% by weight. Its main function is to induce crosslinking reactions in polymer molecular chains under electron beam irradiation, constructing a dense three-dimensional crosslinked network, thereby improving the cohesiveness, temperature resistance, resistance to humid heat aging, and structural stability of the adhesive layer. When the crosslinking agent content is less than 1% by weight, there are insufficient crosslinking active sites, the crosslinking reaction is incomplete after electron beam irradiation, the crosslinked network is sparse, the cohesiveness of the adhesive layer is weak, and the molecular chains are prone to slippage under high temperature and high humidity conditions, resulting in a continuous decline in adhesive strength and conductivity stability. When the crosslinking agent content is higher than 3% by weight, the crosslinking activity of the system is too high, and over-crosslinking is prone to occur after electron beam irradiation. The movement of polymer molecular chains is severely restricted, the hardness of the adhesive layer increases significantly, flexibility is lost, and it becomes stiff and easy to crack. Not only does the adhesion deteriorate, but a large amount of crosslinking internal stress is also generated, accelerating the aging of the adhesive layer. At the same time, over-crosslinking will change the contact state of conductive particles, destroy the original conductive network, and cause fluctuations in conductivity.

[0078] According to certain preferred embodiments of the present invention, the acrylate composition, by weight of 100%, comprises: 30-90% by weight, preferably 35-45% by weight, of a first acrylate monomer, wherein the glass transition temperature of the homopolymer of the first acrylate monomer is less than or equal to -70°C; 5-65% by weight, preferably 50-60% by weight, of a second acrylate monomer, wherein the glass transition temperature of the homopolymer of the second acrylate monomer is greater than or equal to -50°C; 2-5% by weight, preferably 2.5-5% by weight, of a functional monomer; and an effective amount of a free radical polymerization initiator.

[0079] This invention employs an acrylate copolymer system modified with a combination of soft and hard monomers and functional monomers, by precisely matching different glass transition temperatures (T). g The first acrylate monomer is used to regulate the flexibility, low-temperature performance, cohesive strength, and adhesive properties of the copolymer. The Tg of the homopolymer of the first acrylate monomer is below or equal to -70°C. After polymerization, it imparts excellent low-temperature flexibility, surface wettability, and initial tack to the polymer base material, ensuring that the conductive tape can still tightly adhere to various irregular and flexible electronic substrates in low-temperature environments, avoiding delamination and cracking problems caused by low-temperature hardening. Preferably, the content of the first acrylate monomer is 35-45% by weight. Within this range, the first acrylate monomer can fully exert its toughening and wetting-enhancing effects.

[0080] T of the homopolymer of the second acrylate monomer g At temperatures above or equal to -50°C, it is mainly used to improve the cohesiveness, heat resistance, structural strength, and tackiness of polymer base materials, compensating for the deficiencies of insufficient cohesiveness and poor heat resistance caused by the polymerization of the first acrylate monomer alone. The preferred content of the second acrylate monomer is 50-60% by weight, forming a complementary ratio with the preferred content of the first acrylate monomer, so that the copolymer has both high flexibility and high cohesiveness.

[0081] According to certain preferred embodiments of the present invention, the content of the functional monomer is 2.5-5% by weight. This type of monomer has polar functional groups, which can introduce polar groups into the molecular chain of the acrylate copolymer. On the one hand, it can improve the interfacial bonding force between the polymer matrix and conductive particles and tackifying resin, improve the compatibility of each component, avoid filler agglomeration and delamination, and ensure the long-term stability of the conductive network. On the other hand, the polar groups can enhance the interfacial adhesion between the adhesive layer and electronic substrates such as metals and polymers, and further improve the peel strength.

[0082] Free radical polymerization initiators provide active free radicals for UV prepolymerization, enabling solvent-free UV prepolymerization of acrylate compositions. The amount added should be sufficient to fully initiate monomer polymerization while keeping the residual monomer content within the standard range.

[0083] According to certain preferred embodiments of the present invention, the first acrylate monomer is selected from one or more of 2-ethylhexyl acrylate, n-octyl acrylate, n-tetrazyl acrylate, n-hexadecyl acrylate, and n-octadecyl acrylate. The above-mentioned long-chain alkyl acrylate monomers all possess low homopolymer glass transition temperatures and excellent molecular chain flexibility. The long alkyl chain structure can increase the interchain spacing, reduce internal frictional resistance of the polymer, and endow the polymer with excellent extensibility and surface wetting ability. Simultaneously, the hydrophobic properties of the long carbon chains can improve the water resistance of the polymer matrix and help enhance the resistance of the adhesive layer to humid heat aging. The use of multiple monomers in combination can further regulate the polymer molecular chain arrangement and optimize film formation and mechanical properties.

[0084] According to certain preferred embodiments of the present invention, the second acrylate monomer is selected from one or more of 2-octyl methacrylate, ethyl methacrylate, methyl methacrylate, and isobornyl methacrylate. These monomers have relatively rigid molecular chains, and after polymerization, they can effectively improve the hardness, cohesiveness, heat resistance, and tack of the copolymer. Among them, 2-octyl methacrylate is a high-bio-based monomer, prepared from renewable raw materials, and is the core raw material for achieving high bio-based content in this invention, balancing performance and environmental friendliness; copolymerization of methyl methacrylate and ethyl methacrylate can improve the structural strength and weather resistance of the polymer; isobornyl methacrylate possesses excellent heat resistance and rigidity, which can further enhance the polymer's high-temperature resistance. The combination of multiple monomers allows for flexible control of the overall polymer performance according to actual needs.

[0085] According to certain preferred embodiments of the present invention, the first acrylate monomer is 2-ethylhexyl acrylate, and the second acrylate monomer is 2-octyl acrylate. This combination is the optimal monomer pairing of the present invention.

[0086] 2-Ethylhexyl acrylate has a structure represented by the following formula (I):

[0087]

[0088] Formula (I)

[0089] 2-Octyl acrylate has a structure represented by the following formula (II):

[0090]

[0091] Equation (II)

[0092] 2-Ethylhexyl acrylate, as a classic soft monomer, exhibits balanced flexibility and wettability in its polymerized product, resulting in excellent processing performance. 2-Octyl acrylate, a bio-based transition monomer, boasts a bio-based carbon content of up to 73%, significantly enhancing the overall bio-based content. Simultaneously, its polymerized product combines a certain degree of rigidity and flexibility, exhibiting excellent compatibility with 2-ethylhexyl acrylate. The copolymerization of the two forms a copolymer with uniformly distributed molecular chains, retaining excellent low-temperature adhesion and initial tack while possessing good cohesiveness, heat resistance, and holding power. Furthermore, the polymerization system exhibits moderate viscosity, making it suitable for solvent-free UV prepolymerization and subsequent hot-melt coating processes, avoiding issues such as poor material flowability and coating defects.

[0093] According to certain preferred embodiments of the present invention, the functional monomer is selected from one or more of (meth)acrylic acid, hydroxyethyl acrylate, hydroxyethyl methyl acrylate, hydroxypropyl methacrylate, N-vinylpyrrolidone, and (meth)acrylamide. These monomers each possess strongly polar functional groups such as carboxyl, hydroxyl, amide, and pyrrolyl groups. Carboxyl and hydroxyl groups can form hydrogen bonds with the surface of conductive particles and metal substrates, enhancing interfacial adhesion; amide and pyrrolyl groups can enhance intermolecular forces in polymers, improving the cohesive strength and aging resistance of the adhesive layer. Various functional monomers can be used alone or in combination to meet the bonding and aging resistance requirements of different application scenarios.

[0094] According to certain preferred embodiments of the present invention, the functional monomer is acrylic acid. Acrylic acid has highly reactive carboxyl groups, strong polarity, and high copolymerization activity. It exhibits excellent copolymerization effect with acrylate main monomers, and a small amount can significantly improve the polarity of the system, enhance the compatibility of each component, and improve the adhesion of the adhesive layer to the metal substrate.

[0095] According to certain preferred embodiments of the present invention, the free radical polymerization initiator is selected from one or more of acetylbenzene initiators, α-hydroxyketone initiators, benzoin ether initiators, aryl sulfonyl chloride initiators, and oxime initiators. All of the above are photoinitiators suitable for ultraviolet light-induced polymerization, possessing high absorption efficiency in the 300-400 nm ultraviolet band. They can rapidly decompose at room temperature in a solvent-free system to generate free radicals, initiating the polymerization reaction of acrylate monomers. These initiators have high initiation efficiency, few byproducts, and can effectively control the polymerization reaction rate, avoiding excessively vigorous local reactions that could lead to excessive gelation. Furthermore, the residual initiator content after the reaction is low, and it does not affect the aging resistance and electrical properties of the adhesive layer.

[0096] According to certain preferred embodiments of the present invention, the content of the free radical polymerization initiator is 0.01-0.3% by weight.

[0097] According to certain preferred embodiments of the present invention, the acrylate composition further comprises a chain transfer agent. The role of the chain transfer agent is to regulate the molecular weight and molecular weight distribution of the acrylate copolymer. During free radical polymerization, the chain transfer agent can actively capture growing molecular chain free radicals, terminate molecular chain growth, avoid excessively large polymer molecular weight and excessive molecular chain entanglement, and prevent excessive gelation; at the same time, it can narrow the molecular weight distribution, making the polymer properties uniform and stable, with small batch-to-batch performance differences, suitable for large-scale industrial production.

[0098] According to certain preferred embodiments of the invention, the content of the chain transfer agent is 0.01-3% by weight.

[0099] According to certain preferred embodiments of the present invention, the chain transfer agent is selected from one or more of sulfur-containing chain transfer agents and haloalkane chain transfer agents. Sulfur-containing chain transfer agents (such as thiols) have high chain transfer constants, precise molecular weight control, are suitable for UV polymerization systems of acrylates, have low odor and little residue, and do not affect the performance of the product. Haloalkane chain transfer agents have excellent chemical stability, few side reactions during polymerization, and can stably control the molecular weight of the polymer. Both can be used alone or in combination to achieve precise control of intrinsic viscosity.

[0100] According to certain preferred embodiments of the present invention, the acrylate composition further comprises a diluent. The acrylate composition of the present invention is a solvent-free system, and the diluent is not a traditional organic solvent, but a reactive diluent that can participate in copolymerization. Its function is to slightly reduce the overall viscosity of the monomer composition, ensuring that the system viscosity is below 50 cP at 25°C, improving material flowability, ensuring uniform heating and light exposure of the material during UV prepolymerization, resulting in uniform polymer product properties, and simultaneously assisting in fine-tuning the polymer crosslinking density and optimizing the overall performance of the adhesive layer.

[0101] According to certain preferred embodiments of the present invention, the diluent is 1,6-hexanediol diacrylate. This substance is a bifunctional acrylate, belonging to reactive diluents. It can reduce the viscosity of the system, improve processing fluidity, and participate in crosslinking reactions during the UV prepolymerization and electron beam curing stages, integrating into the polymer molecular chain. It does not generate volatile small molecules, meeting the environmental protection requirements of solvent-free and low VOC. At the same time, its molecular chain length is moderate, which does not damage the flexibility of the polymer after copolymerization, and can also slightly improve the cohesiveness of the adhesive layer.

[0102] According to certain preferred embodiments of the present invention, the content of the diluent is 0.03-0.06% by weight. This amount can achieve fine-tuning of viscosity without changing the bulk properties of the polymer.

[0103] According to certain preferred embodiments of the present invention, the acrylate composition further comprises an antioxidant. Acrylate polymer molecular chains are prone to oxidative degradation under light, high temperature, and high humidity conditions, leading to problems such as molecular chain breakage and performance degradation. Antioxidants can capture active free radicals generated during the oxidation reaction, inhibit polymer oxidative degradation, significantly improve the aging resistance and storage stability of the polymer base material and the final tape, and simultaneously prevent interfacial nonlinearity caused by oxidation products, ensuring long-term stable PIM performance.

[0104] According to certain preferred embodiments of the present invention, the antioxidant is selected from one or more of the following: octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, and dilauryl thiodipropionate. These substances are all commonly used high-efficiency antioxidants in polymer materials, classified as primary and secondary antioxidants. When used in combination, they can form a synergistic antioxidant system, blocking different oxidation reaction pathways. They exhibit high antioxidant efficiency, good thermal stability, and are suitable for hot-melt processing, electron beam irradiation, and other operating conditions. They are not easily decomposed or degraded at high temperatures and have excellent compatibility with acrylate matrices, preventing precipitation and migration.

[0105] According to certain preferred embodiments of the present invention, the content of the antioxidant is 0.1-0.3% by weight.

[0106] According to certain preferred embodiments of the present invention, the viscosity of the acrylate composition at 25°C is less than 50 cP. This viscosity range is an important indicator for solvent-free UV prepolymerization processes. When the viscosity is below 50 cP, the liquid monomer composition has good fluidity and can be evenly spread inside a sealed plastic bag. UV light can penetrate the material, achieving uniform polymerization and avoiding problems such as uneven local polymerization and large performance differences. If the viscosity is above 50 cP, the material is viscous and has poor fluidity. Dead corners are prone to accumulation in the packaging bag. During UV irradiation, polymerization in the dead corner areas is incomplete, the residual monomer content increases, and the molecular weight distribution of the polymer product is uneven, which affects subsequent coating and performance.

[0107] According to certain preferred embodiments of the present invention, the acrylate composition is a solvent-free composition. The completely solvent-free system is the core embodiment of the environmental friendliness of this invention. Compared with traditional solvent-based conductive acrylate adhesives, this solution completely eliminates the use of organic solvents such as ethyl acetate and toluene, resulting in no VOC emissions during production. This eliminates environmental pollution and flammable / explosive safety hazards caused by solvent volatilization. Furthermore, it eliminates the need for a high-temperature desolventizing process after coating, simplifying the production process, reducing energy consumption, and improving production efficiency, aligning with the green and low-carbon industry development trend and environmental regulations.

[0108] According to certain preferred embodiments of the present invention, the content of bio-based substances in the acrylate composition is 55% by weight or more. The present invention mainly relies on monomers such as 2-octyl acrylate derived from renewable biomass feedstocks to achieve a high bio-based content. A bio-based content ≥55% by weight can significantly reduce the use of petroleum-based fossil fuels, thereby reducing carbon emissions and resource consumption. The acrylate composition with high bio-based content not only exhibits outstanding green properties, but its polymerized product has a more regular molecular structure, better compatibility with conductive particles and tackifying resins, and further enhances the overall stability of the adhesive layer.

[0109] According to certain preferred embodiments of the present invention, the gel content of the acrylate composition is less than or equal to 23% by weight. Gel content represents the content of highly cross-linked components in the polymer that are insoluble in organic solvents. A gel content ≤ 23% by weight is an important indicator for ensuring the processing and performance of the material. Excessive gel content means that there are too many highly cross-linked macromolecular groups in the polymer, resulting in a sharp decrease in the hot melt flowability of the material. This can easily lead to material blockage, uneven coating thickness, surface particles, pinholes, and other appearance defects during hot melt coating and extrusion coating. Simultaneously, high gel content results in poor toughness, reducing the overall flexibility and adhesion of the adhesive layer. When the gel content is controlled within 23% by weight, the polymer is dominated by linear, slightly branched molecular chains, exhibiting excellent flowability and adaptability to various coating processes. At the same time, the molecular chains retain sufficient mobility, combining flexibility and cohesion.

[0110] According to certain preferred embodiments of the present invention, the residual monomer content of the acrylate composition is less than or equal to 0.5% by weight. The residual monomer is acrylate monomer that has not been completely converted in the polymerization reaction. A residual monomer content ≤ 0.5% by weight ensures the overall performance and safety of the product. When the residual monomer content exceeds the standard, on the one hand, the product will have an irritating odor, and the monomer will continue to volatilize during storage, affecting the usage environment; on the other hand, free monomers are small molecules that will migrate and accumulate within the adhesive layer, disrupting the polymer molecular chain entanglement structure, reducing cohesion, and simultaneously forming an isolation layer at the conductive particle interface, increasing contact resistance and interfacial nonlinearity, causing deterioration of conductivity and PIM performance. This defect will be further amplified under high temperature and high humidity aging conditions.

[0111] According to certain preferred embodiments of the present invention, the polymer base material is prepared by the following steps: sealing the above-described acrylate composition in a plastic packaging bag; subjecting the acrylate composition in the plastic packaging bag to ultraviolet radiation to induce polymerization; and melting and extruding the ultraviolet-radiated acrylate composition and the plastic packaging bag together to obtain the polymer base material. This bag-sealed ultraviolet prepolymerization process is a solvent-free polymerization process, which has multiple advantages over traditional bulk polymerization and emulsion polymerization: the sealed packaging bag isolates air, preventing oxygen from quenching the free radicals generated by ultraviolet polymerization, ensuring the polymerization reaction proceeds fully, and reducing residual monomer content; the polymerization process is completely enclosed, with no material leakage or small molecule volatilization, further enhancing the solvent-free and environmentally friendly characteristics; after polymerization, there is no need to unpack the bag; it can be directly melt-extruded along with the packaging bag. The packaging bag material has good compatibility with the acrylate matrix and, after melting, can be uniformly dispersed in the base material as a viscosity modifier, simplifying the process, improving production continuity, and making it suitable for industrial continuous production.

[0112] According to certain preferred embodiments of the present invention, the intensity of the ultraviolet radiation is between 0.01 and 20 mW / cm². 2 Within the range.

[0113] According to certain preferred embodiments of the present invention, the polymer base material further comprises a viscosity modifier. The viscosity modifier can assist in fine-tuning the melt viscosity of the polymer base material, matching different coating equipment and coating conditions, broadening the process adaptability range, and further improving the compatibility between polymer molecular chains, enhancing the flexibility and low-temperature resistance of the adhesive layer. According to certain preferred embodiments of the present invention, the viscosity modifier is an ethylene-vinyl acrylate copolymer or an ethylene-acrylic acid copolymer. These two types of polymers have excellent compatibility with the acrylate copolymer matrix, can be uniformly dispersed in the molten state, can slightly adjust the melt viscosity of the system, improve the flowability of hot melt coating, and enhance the low-temperature resistance, impact resistance, and flexibility of the adhesive layer. Furthermore, they possess good thermal stability and will not decompose or fail under electron beam irradiation, high temperature and high humidity environments, and will not affect conductivity and radio frequency performance.

[0114] According to certain preferred embodiments of the present invention, the tackifying resin is hydrogenated rosin resin. Hydrogenated rosin resin is a fully bio-based tackifying resin, derived from natural rosin and prepared through hydrogenation modification. Compared to petroleum-based tackifying resins, hydrogenated rosin resin exhibits better compatibility with acrylate polymer matrices, can be uniformly dispersed, and effectively improves the initial tack and interfacial wettability of the adhesive layer. Simultaneously, the hydrogenated rosin resin shows significantly improved thermal stability and aging resistance, is less prone to oxidation and precipitation, maintains stable performance under high temperature and high humidity conditions, and does not cause degradation in conductivity or PIM performance.

[0115] According to certain preferred embodiments of the present invention, the softening point of the hydrogenated rosin resin is 70-100°C. The softening point is a core indicator of tackifying resins; hydrogenated rosin resin with a softening point of 70-100°C can achieve a balance between adhesive properties and heat resistance.

[0116] According to certain preferred embodiments of the present invention, the conductive particles are selected from one or more of graphite particles, conductive carbon black particles, carbon nanotube particles, graphene particles, silver particles, and gold particles. These are all commonly used conductive fillers in electronic conductive materials, capable of constructing highly conductive pathways. Different types of conductive particles can be used individually or in combination, flexibly selected based on conductivity indicators, cost, and application scenarios. According to certain preferred embodiments of the present invention, the conductive particles are nickel-coated graphite particles. This filler is the optimal conductive particle of the present invention, combining the dual advantages of graphite and metallic nickel: the graphite core possesses excellent chemical stability, flexibility, and dispersibility, with low density and low agglomeration; the surface metallic nickel exhibits excellent conductivity, while the nickel layer can reduce interparticle contact resistance, weaken interfacial nonlinearity, and significantly improve passive intermodulation performance. Compared to pure carbon-based fillers, nickel-coated graphite has stronger conductivity; compared to pure silver, gold, and other precious metal fillers, it has lower cost and stronger anti-migration ability, offering the best overall cost-effectiveness and performance, and is suitable for the application requirements of 5G high-frequency, low-interference applications.

[0117] According to certain preferred embodiments of the present invention, the nickel coating amount of the nickel-coated graphite particles is 60-85% by weight.

[0118] According to certain preferred embodiments of the present invention, the crosslinking agent is a multifunctional acrylate crosslinking agent. Multifunctional acrylate crosslinking agents have similar chemical structures to acrylate polymer base materials, exhibiting good compatibility. Under high-energy electron beam radiation, multiple acrylate functional groups in the molecule can simultaneously react with the polymer molecular chains, forming multi-point crosslinks and constructing a stable three-dimensional crosslinked network. This type of crosslinking agent has high crosslinking efficiency and uniform reaction, significantly improving the cohesion, temperature resistance, and resistance to damp heat aging of the crosslinked adhesive layer, while not introducing impurities, ensuring stable radio frequency performance.

[0119] According to certain preferred embodiments of the present invention, the crosslinking agent is one or more of a multifunctional aliphatic acrylate oligomer or trimethylolpropane triacrylate. Both are highly active multifunctional crosslinking agents: trimethylolpropane triacrylate is a trifunctional monomer with a high crosslinking point density, which can rapidly improve the cohesion and heat resistance of the adhesive layer; the multifunctional aliphatic acrylate oligomer has a longer molecular chain, resulting in better network flexibility after crosslinking, which can prevent the adhesive layer from becoming hard and brittle after crosslinking. The two crosslinking agents can be used alone or in combination, and the crosslinking density and adhesive layer flexibility can be adjusted according to actual needs to adapt to the usage requirements of different electronic devices.

[0120] According to another aspect of the present invention, an electron beam curable bio-based conductive tape is provided, the electron beam curable bio-based conductive tape comprising: an adhesive layer formed of the electron beam curable bio-based conductive composition described above; and a release substrate bonded to the adhesive layer.

[0121] The bio-based conductive tape prepared in this invention is an integrated functional material composed of the aforementioned bio-based conductive composition as the functional adhesive layer and a release substrate. The release substrate primarily protects the voltage-sensitive conductive adhesive layer during storage, transportation, and processing, preventing dust contamination, adhesion, and surface damage. It is easy to use; simply peel it off. Commonly used release substrates such as PET and PE release films can be selected, with different surface release forces chosen based on the tape's application and peel strength requirements. The adhesive layer and release substrate adhere tightly, without bubbles or delamination, exhibiting excellent winding and cutting properties, making it suitable for die-cutting into tapes and gaskets of various specifications, and compatible with automated assembly lines for electronic devices. This conductive tape inherits all the advantages of the conductive composition: high bio-based content, environmentally friendly and VOC-free, with excellent balanced conductivity, low passive intermodulation, adhesion, and resistance to damp heat aging. It is an ideal material for electromagnetic shielding, grounding connections, and conductive bonding in 5G communication equipment and consumer electronics.

[0122] According to certain preferred embodiments of the present invention, the method includes: (1) mixing the polymer base material, the tackifying resin, the conductive particles and the crosslinking agent to obtain a conductive adhesive mixture; (2) applying the conductive adhesive mixture to at least one surface of the release substrate to form a voltage-sensitive adhesive layer; and (3) applying electron beam radiation to the voltage-sensitive adhesive layer to cause the voltage-sensitive adhesive layer to crosslink and cure.

[0123] This invention employs a fully continuous solvent-free preparation process consisting of melt mixing, coating, and electron beam radiation crosslinking. The process is simple, highly automated, and efficient, with no organic solvents involved throughout, eliminating VOC emissions. Step (1) The melt mixing process completes the uniform mixing of each component under high-temperature molten conditions. The polymer base and tackifying resin have good fluidity after melting, and conductive particles and crosslinking agents can be uniformly dispersed in the matrix, effectively preventing filler agglomeration. Step (2) The mixed molten adhesive is directly coated onto the release substrate, forming a conductive voltage-sensitive adhesive layer in one step. No drying process is required, shortening the production cycle. Step (3) Electron beam radiation crosslinking is a room-temperature rapid curing process. The high-energy electron beam can penetrate the entire adhesive layer, achieving uniform crosslinking. Compared with traditional thermosetting, the crosslinking reaction is more controllable, avoiding problems such as excessive surface crosslinking and incomplete internal curing. At the same time, the curing speed is fast, making it suitable for high-speed continuous production.

[0124] According to certain preferred embodiments of the invention, the electron beam radiation dose is 20-150 kGy and the accelerating voltage is 80-300 kV.

[0125] According to certain preferred embodiments of the present invention, the mixing in step (1) is melt mixing, kneading mixing, or extrusion mixing. All three mixing methods are suitable for high-temperature solvent-free systems. The three methods can be flexibly selected according to production scale and equipment conditions, and all can achieve uniform mixing of components, ensuring the uniformity of the conductive adhesive mixture's properties.

[0126] According to certain preferred embodiments of the present invention, the coating in step (2) is hot melt coating, extrusion coating, or doctor blade coating. Hot melt coating and extrusion coating are suitable for molten conductive adhesive mixtures, with fast coating speed and uniform coating thickness, making them suitable for high-speed production lines; doctor blade coating can precisely control the adhesive layer thickness, making it suitable for preparing thin, high-precision conductive tapes to meet the needs of precision electronic devices.

[0127] According to another aspect of the present invention, the use of the electron beam curable bio-based conductive composition or the electron beam curable bio-based conductive tape described above is provided in electronic device assembly, electromagnetic shielding, grounding connection or conductive bonding.

[0128] The bio-based conductive composition and conductive tape of this invention, with their high bio-based content, solvent-free and environmentally friendly properties, excellent conductivity, low passive intermodulation value, strong adhesion, and good high-temperature and high-humidity aging stability, can be widely used in various electronic device fields. In 5G communication base stations and radio frequency components, they can be used for electromagnetic shielding and grounding connections; the low PIM value effectively avoids high-frequency signal interference, ensuring stable operation of communication equipment. In flexible circuit boards, touch components, and the assembly of internal components in consumer electronics, they can serve as conductive adhesive materials, combining adhesion, conductivity, and shielding functions, simplifying device structure. Simultaneously, their excellent resistance to damp heat aging ensures long-term stable operation of electronic devices in complex temperature and humidity environments, extending their service life. Furthermore, the products are manufactured entirely using green production processes, meeting the requirements of a green supply chain in the electronics industry, and also possess broad application prospects in fields with stringent environmental and reliability requirements, such as new energy electronics and automotive electronics.

[0129] The present invention will now be described in more detail with reference to embodiments. It should be noted that these descriptions and embodiments are intended to facilitate understanding of the present invention and are not intended to limit the invention.

[0130] Example

[0131] In this invention, unless otherwise specified, all reagents used are commercially available products and are used directly without further purification. Furthermore, "%" refers to "weight %" and "parts" refers to "parts by weight".

[0132] Table 1 below lists specific information about the raw materials used in the embodiments and comparative examples of the present invention.

[0133]

[0134] Test and Calculation Methods

[0135] Intrinsic viscosity measurement

[0136] The intrinsic viscosity (in dL / g) of the polymer base materials 1-5 and the comparative polymer base materials 1-3 prepared in the following preparation examples 1-5 (PE1-PE5) and comparative preparation examples 1-3 (CPE1-CPE3) was measured according to the method described in detail below.

[0137] The intrinsic viscosity (IV) was determined according to the method described in GB / T 1632.1-2024 "Determination of Viscosity of Polymer Dilute Solutions Using Capillary Viscometers – Part 1: General Rules". Specifically, the intrinsic viscosity (IV) was determined using the dilute solution viscosity method, which was performed using a single-bath polymer viscometer at a temperature of 25°C. Polymer base materials 1-5 and comparative polymer base materials 1-3 prepared in Preparation Examples 1-5 (PE1-PE5) and Comparative Preparation Examples 1-3 (CPE1-CPE3) were dissolved in ethyl acetate to prepare polymer solutions with a concentration of 0.25 g / dL. 9 g of the solution was added to the viscometer, and the flow time was measured at 25°C. The intrinsic viscosity of the polymer was determined based on the measured flow time.

[0138] According to the application requirements of the technical solution of the present invention for use as a substrate raw material in bio-based conductive compositions, the intrinsic viscosity of the polymer base needs to be in the range of 0.75-1 dL / g. An intrinsic viscosity value below 0.75 indicates that the polymer molecular weight is too small, resulting in insufficient crosslinking effect and cohesive force of the adhesive layer in subsequent preparation; an intrinsic viscosity value above 1 results in excessive gel content in the polymer base, poor material flowability, and appearance defects in the coating.

[0139] Measurement of gel volume

[0140] The gel content (in weight %) of polymer base materials 1-5 and comparative polymer base materials 1-3 prepared in the following preparation examples 1-5 (PE1-PE5) and comparative preparation examples 1-3 (CPE1-CPE3) was measured according to the method described in detail below.

[0141] Specifically, the gel content of polymer base materials 1-5 and comparative polymer base materials 1-3 was determined using solvent extraction. The testing apparatus was a 304 stainless steel wire mesh with a 150-mesh plain weave square hole structure, a wire diameter of 66 µm, and a hole diameter of 104 µm. The wire mesh was weighed separately and the value was recorded. Approximately 26 g of the polymer base material sample was weighed and placed in the center of the wire mesh. The edges of the wire mesh were folded inwards to completely wrap the sample, preventing sample spillage during extraction. The entire wire mesh covering the sample was then weighed. Next, a container of suitable volume was prepared, and approximately 240 mL of ethyl acetate was added as the extraction solvent. The wire mesh covering the sample was completely immersed in the solvent. The container was placed on a mechanical rolling device and continuously rolled for extraction for 24 hours to fully dissolve the soluble components in the sample. After extraction, the wire mesh and sample were removed, the surface solvent was drained, and the samples were dried in a 120℃ oven for 30 minutes to completely remove residual ethyl acetate. After the samples cooled to room temperature, the total weight was weighed again.

[0142] Gel content is calculated as a percentage by weight, using the following formula:

[0143] Gel content % = [(total weight after extraction - weight of screen) ÷ (total weight before extraction - weight of screen)] × 100%.

[0144] Gel content directly reflects the degree of polymer crosslinking. According to the application requirements of the technical solution of this invention for use as a substrate raw material in bio-based conductive compositions, the gel content of the polymer base needs to be less than or equal to 23% by weight. If the gel content exceeds 23% by weight, the material flowability decreases, hot-melt coating becomes more difficult, and the product is prone to appearance defects; a low gel content indicates insufficient polymer crosslinking, weak cohesion in the adhesive layer, affecting the bonding strength, heat resistance, and long-term stability of the conductive tape.

[0145] Measurement of residual monomer content

[0146] The residual monomer content (in weight %) of polymer base materials 1-5 and comparative polymer base materials 1-3 prepared in the following preparation examples 1-5 (PE1-PE5) and comparative preparation examples 1-3 (CPE1-CPE3) was measured according to the method described in detail below.

[0147] Specifically, the residual monomer content in the polymer was determined using chromatographic detection. First, 0.5 g of the polymer sample to be tested was accurately weighed and placed in a sealed sample vial, and 10 mL of ethyl acetate was added for extraction and dissolution. The sample solution was then subjected to shaking, standing, sonication, or heating treatment sequentially to ensure complete dissolution of the residual monomer, completing the sample pretreatment. A gas chromatograph was used for detection. A series of monomer standard solutions of different concentrations were prepared, analyzed on the instrument, and a standard curve was plotted based on peak area or peak height to establish the correlation between concentration and response signal. Subsequently, the prepared sample solution to be tested was injected into the instrument for detection, and the peak area or peak height corresponding to the target monomer was recorded. The mass of residual monomer in the test solution was calculated using the standard curve, and the residual monomer content was then calculated according to the following formula:

[0148] Residual monomer content (weight %) = (residual monomer mass ÷ total mass of sample to be tested) × 100%.

[0149] According to the application requirements of the technical solution of the present invention for use as a substrate raw material in bio-based conductive compositions, the residual monomer content in the polymer base needs to be less than or equal to 0.5% by weight. Excessive residual monomer content not only leads to a stronger product odor and decreased storage stability, but also affects the crosslinking reaction of the adhesive layer, reducing adhesion, aging resistance, and electrical stability.

[0150] Measurement of biomass content

[0151] The bio-based content (in weight %) of polymer base materials 1-5 and comparative polymer base materials 1-3 prepared in Preparation Examples 1-5 (PE1-PE5) and Comparative Preparation Examples 1-3 (CPE1-CPE3) and bio-based conductive tapes 1-5 and comparative bio-based conductive tapes 1-6 prepared in Examples 1-5 (E1-E5) and Comparative Examples (CE1-CE6) was measured according to the method described in detail below.

[0152] The bio-based content in this invention is expressed as a mass percentage and is calculated by weighting the proportion of bio-based components in each component. The specific calculation formula is as follows:

[0153] Bio-based content (%) = [∑(mass of a single component × bio-based percentage of that component) ÷ total mass of all components] × 100%.

[0154] The calculation first clarifies the mass and inherent bio-based content of each raw material in the formulation. 2-Octyl acrylate (2OA) is a bio-based monomer with a bio-based carbon content of approximately 73%, making it the primary source of bio-based components. 2-Ethylhexyl acrylate (2EHA) is a fossil-based raw material with a bio-based content of 0%. The hydrogenated rosin ester tackifying resin is a fully bio-based material, and the bio-based proportions of other additives, conductive particles, crosslinking agents, etc., are determined based on their material composition. The mass of each raw material is multiplied by its corresponding bio-based content, summed, and then divided by the total mass of all components in the formulation to obtain the overall bio-based content. The bio-based content of the acrylate polymer base material in this invention can reach over 56%, and the overall bio-based content of the final conductive composition reaches over 46%.

[0155] Measurement of DC resistance

[0156] The DC resistance (in ohms) of the bio-based conductive tapes 1-5 and the comparative bio-based conductive tapes 1-6 prepared in Examples 1-5 (E1-E5) and Comparative Examples (CE1-CE6) were measured according to the method described in detail below.

[0157] This invention uses an ETM-12 testing device to determine the DC resistance of the conductive composition adhesive layer, measuring the resistance values ​​in the initial state and after aging at 85°C and 85% relative humidity for 3 days. The specific testing procedure is as follows: Before testing, sample preparation is performed by cutting the conductive tape into 10 mm × 10 mm samples and removing the surface release film. Two samples are taken and sequentially attached to the center of the electrodes on the 3M ETM-12 testing plate, completing manual pre-attachment. Then, a 3M ETM-12-SS316L stainless steel pressure plate is placed on top of the sample, and a 2 kg rubber roller is used to roll the pressure plate at a uniform speed to ensure close contact between the sample, electrodes, and pressure plate, eliminating interference from gaps in the contact surface on the test results. After standing at room temperature for 20 minutes, the sample is ready for testing. A micro-ohmmeter is connected to the electrodes of the testing plate to read and record the initial DC resistance value, which is the DC resistance of the prepared sample.

[0158] During the damp heat aging test, the sample to be tested was placed entirely in a constant temperature and humidity test chamber, and the environmental parameters were set to a temperature of 85℃ and a relative humidity of 85%, for continuous aging for 72 hours (3 days). After aging, the sample was removed. The same sample assembly, rolling, and standing steps were repeated, and the DC resistance was measured again using a micro-ohmmeter to obtain the DC resistance data after aging.

[0159] DC resistance is an indicator of a material's conductivity. According to the technical solution of this invention, for conductive bonding, electromagnetic shielding, and grounding connections in 5G electronic devices, the DC resistance of the prepared sample needs to be less than or equal to 0.45 ohms, and the DC resistance after aging at 85°C and 85% relative humidity for 3 days needs to be less than or equal to 0.2 ohms. This test method simulates the harsh operating environment of the product and can effectively evaluate the stability of the conductive network. If the resistance is too high or increases significantly after aging, it indicates uneven dispersion of the conductive filler and poor interfacial bonding, which will affect the grounding and electromagnetic shielding performance of the electronic device.

[0160] Measurement of PIM performance

[0161] The PIM performance (in dBm) of the bio-based conductive tapes 1-5 and comparative bio-based conductive tapes 1-6 prepared in Examples 1-5 (E1-E5) and Comparative Examples (CE1-CE6) were measured according to the methods described in detail below.

[0162] The testing fixture consists of a 50-ohm microstrip test board and a coaxial cable. The test board substrate is an FR-4 dielectric board, measuring 50mm × 80mm, with a thickness of 60 mil. The surface is made of 1 ounce copper and chemically plated with nickel and then gold. The microstrip line on the board is 3mm wide, with a 10mm break in the middle of the line. First, two 3mm × 15mm samples of the conductive tape to be tested are cut. After removing the release layer, they are pasted onto the microstrip lines on both sides of the break.

[0163] Take a 316L stainless steel connecting bridge with dimensions of 40mm × 3mm × 1mm, align it with the circuit break and place it on the sample, apply a pressure of 0.103 MPa to tighten it, connect the circuit, and let it stand at room temperature for at least 20 minutes to ensure full interface adhesion. Connect the Rosenberger benchtop PIM analyzer to the test fixture coaxial cable, select the LTE700L frequency band, input two frequency signals of 729-758 MHz with a single-channel power of 30dBm, collect and record the maximum value of the third-order intermodulation, which is the initial PIM value (in dBm) after sample preparation.

[0164] During the damp heat aging stage, the entire test assembly containing the sample was placed in a constant temperature and humidity chamber, set at 85℃ and 85% relative humidity, for 72 hours. After aging, the assembly was removed and allowed to return to room temperature. The same wiring and test parameters were then used to retest, obtaining the PIM data (in dBm) after aging.

[0165] According to the technical solution of this invention, the PIM values ​​of the samples used for conductive bonding, electromagnetic shielding, and grounding connections in 5G electronic devices are all below or equal to -60 dBm and exhibit minimal fluctuations after aging, thus meeting the low-interference requirements of 5G high-frequency communication. Higher PIM values ​​indicate more severe radio frequency signal interference. This test effectively verifies the radio frequency stability of the product under harsh environments and assesses its reliability in electromagnetic shielding and radio frequency device applications.

[0166] Measurement of peeling performance

[0167] The peel performance (in N / mm) of the bio-based conductive tapes 1-5 and comparative bio-based conductive tapes 1-6 prepared in Examples 1-5 (E1-E5) and Comparative Examples (CE1-CE6) were measured according to the methods described in detail below.

[0168] Peel performance tests were conducted according to ASTM D3330 / D3330M standards. The 180° peel strength of the samples after 20 minutes and 72 hours of exposure at room temperature was measured, with the unit being N / mm. The specific operating procedure is as follows.

[0169] First, sample preparation was performed. Conductive tape was cut to an appropriate size, the release liner was removed, and the adhesive layer was bonded to a 50μm thick PET film. The entire film was then adhered to the clean stainless steel test substrate. After bonding, the samples were divided into two groups. The first group was left to stand at room temperature for 20 minutes, while the second group was left to stand under the same conditions for 72 hours, thus differentiating between different residence times. A universal testing machine (Instron 3400 series universal testing system) was used, with the peel angle set to 180° and the peel speed to 12 inches / minute. The stainless steel substrate was fixed to the machine base, the clamping end of the tape sample was secured to the free end, and the machine was started to peel at a uniform speed, recording the peel force values ​​throughout the process. Each group of samples underwent three parallel tests, and the average value was taken as the final peel strength result.

[0170] Peel strength is an indicator of the reliability of pressure-sensitive adhesive bonding. Short-term peel strength reflects the initial tack performance of the product, while long-term peel strength reflects the adhesion holding power and interfacial bonding stability of the adhesive layer. According to the technical solution of this invention, for conductive bonding, electromagnetic shielding, and grounding connections in 5G electronic devices, the conductive tape must have a 20-minute 180° peel strength greater than or equal to 0.4 N / mm, and a 72-hour 180° peel strength greater than or equal to 0.6 N / mm.

[0171] Preparation Example 1 (PE1: Preparation of Polymer Base Material 1)

[0172] Preparation Example 1 uses a sealed bag UV polymerization process to prepare polymer base material 1, which is a solvent-free production process. The specific operation steps are as follows.

[0173] The first step is to weigh and mix the raw materials. According to the formulation ratios shown in Table 2 below, weigh out 39 wt% of 2-ethylhexyl acrylate (2EHA), 55.49 wt% of 2-octyl acrylate (2OA), 5 wt% of acrylic acid (AA), 0.1 wt% of isooctyl thioglycolate (IOTG, chain transfer agent), 0.06 wt% of 1,6-hexanediol diacrylate (HDDA, diluent), 0.2 wt% of Irganox 1076 (antioxidant), and 0.15 wt% of Irgacure 651 (photoinitiator). Add all raw materials to a mixing device and mix thoroughly at room temperature until a homogeneous, non-stratified, and non-agglomerated acrylate composition 1 is formed. The viscosity of this composition at 25°C is less than 10 cP.

[0174] Then, the sealing packaging bags were prepared and the materials were filled. On a plastic sealing machine, two heat-sealable ethylene-vinyl acrylate copolymer films (VA24) (0.0635 mm thick, containing 6% by weight of vinyl acrylate), purchased from Consolidated Thermoplastics Co., Ltd., USA, were heat-sealed to form rectangular bags. The acrylate composition prepared above was then filled into the rectangular bags. The filling opening of the filled rectangular bags was then heat-sealed to form a sealed bag with dimensions of 13.6 cm × 4.6 cm, containing 25 ± 1 g of the acrylate composition.

[0175] Then, water bath temperature control and ultraviolet radiation polymerization are performed. The sealed material bag is placed entirely in a constant temperature water bath, and the water bath temperature is controlled to be stable within the range of 21-32℃ to keep the material temperature inside the bag uniform. The ultraviolet light source is then turned on to irradiate the sealed bag, and the ultraviolet radiation intensity is set to 2 mW / cm². 2 The irradiation time was 8.33 minutes; the ultraviolet lamp used emitted wavelengths concentrated in the 300-400 nm range, with a peak wavelength of 351 nm, which could stably initiate the free radical polymerization of acrylate monomers. After polymerization, the ultraviolet-irradiated acrylate composition and the plastic packaging bag were melt-extruded together in a melt extruder to obtain polymer base material 1.

[0176] Polymer base material 1 was tested according to the methods described above for measuring the intrinsic viscosity, gel content, residual monomer content, and biomass content of the polymer base material, and the results are shown in Table 2 below.

[0177] Preparation Examples 2-5 (PE2-PE5) and Comparative Preparation Examples 1-3 (CPE1-CPE3)

[0178] Acrylate compositions 2-5 and comparative acrylate compositions 1-3 were prepared in a manner similar to that of Preparation Example 1. Furthermore, polymer base materials 2-5 and comparative polymer base materials 1-3 were prepared in a manner similar to that of Preparation Example 1, except that the types and contents of the raw materials were changed according to Table 2 shown below. In addition, polymer base materials 2-5 and comparative polymer base materials 1-3 were tested according to the methods described in detail above for measuring the intrinsic viscosity, gel content, residual monomer content, and biomass content of the polymer base materials, and the results are shown in Table 2 below.

[0179] Table 2. Raw material composition and test results of the products obtained in Preparation Examples 1-5 (PE1-PE5) and Comparative Preparation Examples 1-3 (CPE1-CPE3)

[0180]

[0181] Example 1 (E1)

[0182] In this embodiment, the polymer base material PE1 obtained in Preparation Example 1 is used as raw material, and combined with tackifying resin, conductive particles and crosslinking agent, and a bio-based conductive tape is prepared by melt mixing, hot melt coating and electron beam curing process.

[0183] Specifically, the raw materials are weighed according to the following weight ratio: 50% by weight of polymer base PE1, 35% by weight of hydrogenated rosin ester tackifying resin Foral 85, 14% by weight of conductive particles E2806, and 1% by weight of trimethylolpropane triacrylate (TMPTA) crosslinking agent.

[0184] The first step is the material mixing process. The weighed polymer base and tackifying resin are added together to a melt mixing device, and the temperature is raised to 150℃ to melt the materials. Once the system is in a uniform molten state, conductive particles and crosslinking agents are added sequentially. The entire process involves continuous stirring using a melt mixing method to ensure that the conductive particles are uniformly dispersed in the adhesive, avoiding agglomeration and stratification, until a homogeneous conductive adhesive mixture is formed.

[0185] Then, the coating and molding process is carried out. A hot melt coating process is selected, and the surface of the PET release substrate is used as the bearing surface. The uniformly mixed conductive adhesive mixture is evenly coated on the surface of the PET release substrate to form a conductive voltage-sensitive adhesive layer with a thickness of 25µm.

[0186] Finally, electron beam crosslinking and curing treatment was performed. The coated adhesive tape semi-finished product was irradiated with an electron beam irradiation device, specifically a CB-300 electron beam processing system manufactured by Energy Sciences, Inc. (ESI), USA. The electron beam accelerating voltage was set to 200 kV, and the irradiation dose to 50 kGy. The high-energy electron beam radiation induced a crosslinking reaction within the adhesive layer, enhancing its cohesiveness, adhesive strength, and structural stability. After irradiation, the tape was allowed to cool naturally to room temperature, yielding the bio-based conductive tape 1.

[0187] The bio-based conductive tape 1 prepared in Example 1 was tested for conductivity, PIM performance, and peel performance according to the methods described in detail above. The initial DC resistance of the sample was 0.38 ohms, which decreased to 0.17 ohms after aging at 85°C and 85% humidity for 72 hours; the initial passive intermodulation value was -61.9 dBm, which decreased to -72 dBm after aging at 85°C and 85% humidity for 72 hours. The peel strength of the tape after 20 minutes at room temperature was 0.65 N / mm, and the peel strength after 72 hours of standing was 0.64 N / mm. The conductivity, radio frequency, and adhesive properties were stable, and all indicators met the requirements for conductive bonding, electromagnetic shielding, and grounding connection of 5G electronic devices.

[0188] Examples 2-5 (E2-E5) and Comparative Examples 1-6 (CE1-CE6)

[0189] Examples 2-5 (E2-E5) and Comparative Examples 1-6 (CE1-CE6) were prepared in a manner similar to that of Example 1 to prepare bio-based conductive tapes 2-5 and comparative bio-based conductive tapes 1-6, the only difference being that the component types and ratios were changed as shown in Table 3 below.

[0190] The conductivity, PIM performance, and peel performance of bio-based conductive tapes 2-5 and comparative bio-based conductive tapes 1-6 were tested according to the methods described in detail above, and the test results are shown in Table 3 below.

[0191] Table 3 shows the raw material composition and performance measurement results of the resulting adhesive tapes in Examples 1-5 (E1-E5) and Comparative Examples (CE1-CE6).

[0192]

[0193] As can be seen from the results in Table 3 above, the bio-based conductive tapes prepared in Examples 1-5 of the present invention exhibit balanced and excellent performance in terms of conductivity, passive intermodulation, adhesion, and bio-based content, verifying the rationality of the formulation ratio, raw material selection, and preparation process of the present invention.

[0194] Regarding conductivity, the initial DC resistance of all samples in the examples was controlled within 0.45 ohms. After aging at 85°C and 85% humidity for 72 hours, the DC resistance further decreased to 0.11-0.17 ohms. The conductive network exhibited strong stability under high temperature and high humidity conditions, and its conductivity increased rather than decreased after aging. In contrast, the comparative examples showed that CE2 had insufficient conductive particle addition, resulting in an initial resistance as high as 0.94 ohms, indicating severely substandard conductivity. CE5 and CE6 used polymer base materials with intrinsic viscosity deviating from the standard range, and their resistances increased to 0.32 ohms and 0.77 ohms respectively after aging, indicating a significant decrease in conductivity stability. CE3 and CE4 had an imbalance in the ratio of tackifying resin to conductive particles, leading to a significant increase in resistance after aging, which failed to meet the requirements for long-term use.

[0195] Passive intermodulation (PIM) performance is a core indicator for adapting to 5G high-frequency scenarios. The initial and post-aging PIM values ​​of Examples 1-5 are all below or equal to -60 dBm, with the lowest reaching -73.3 dBm, indicating low signal interference and small fluctuations after aging. In contrast, the comparative samples have significant defects. CE2 has an initial PIM as high as -46.2 dBm, and it still reaches the limit of -46.2 dBm after aging, indicating severe radio frequency interference. CE6 uses a polymer base material with excessive gel content and unbalanced molecular weight, resulting in unstable interfacial contact and a PIM value as high as -34 dBm, making it unsuitable for 5G radio frequency devices. The PIM values ​​of the other comparative examples all showed varying degrees of recovery after aging, indicating insufficient radio frequency stability.

[0196] Regarding adhesive performance, the samples in Examples 1-5 all exhibited a short-term peel strength of ≥0.4 N / mm at 20 minutes and a long-term peel strength of ≥0.6 N / mm at 72 hours, demonstrating excellent initial tack and holding power. Excessive crosslinking agent in CE2 and an excessively high proportion of conductive particles in CE4 both resulted in decreased cohesion of the adhesive layer, with a short-term peel strength of less than 0.4 N / mm. The polymer base of CE6 had a high intrinsic viscosity, resulting in weak cohesion of the adhesive layer and a 72-hour peel strength of only 0.28 N / mm, indicating poor adhesive reliability. CE1, lacking a crosslinking agent, had a relatively high initial adhesive strength, but the adhesive layer lacked effective crosslinking, making it prone to delamination during long-term use.

[0197] In terms of bio-based content, the bio-based content of the samples in Examples 1-5 ranged from 46% to 63%, demonstrating outstanding green and environmentally friendly properties. Although the bio-based content of CE5 and CE6 was similar to that of the examples, their core performance was compromised. Some comparative examples simply increased the proportion of bio-based raw materials without considering the synergistic effect of the formulation, resulting in a significant deterioration in overall performance.

[0198] In summary, this invention achieves a balance between high bio-based content, excellent conductivity, low passive intermodulation value, and strong adhesion stability by precisely controlling the intrinsic viscosity of the polymer base material and the distribution ratio of each component, combined with electron beam curing technology. It effectively solves the industry pain points of existing bio-based conductive tape processes, such as being environmentally unfriendly and having significant performance shortcomings. It has significant application advantages in fields such as electromagnetic shielding and grounding connections for 5G electronic devices.

[0199] Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from the spirit and scope of this disclosure. Therefore, if such modifications and variations fall within the scope of this invention, this disclosure is also intended to include such modifications and variations.

Claims

1. An electron beam-curable bio-based conductive composition, said bio-based conductive composition comprising, by weight 100%,: 45-70% by weight of a polymer base, said polymer base comprising a polymer product obtained by polymerization of an acrylate composition and having an intrinsic viscosity in the range of 0.75-1 dL / g; 15-40% by weight of tackifying resin; 10-20% by weight of conductive particles; and 1-3% by weight of crosslinking agent.

2. The electron beam-curable bio-based conductive composition according to claim 1, wherein the acrylate composition, by weight of 100%, comprises: 30-90% by weight of a first acrylate monomer, wherein the glass transition temperature of the homopolymer of the first acrylate monomer is less than or equal to -70°C; 5-65% by weight of a second acrylate monomer, wherein the glass transition temperature of the homopolymer of the second acrylate monomer is greater than or equal to -50°C; 2-5% by weight of functional monomers; and Effective amount of free radical polymerization initiator.

3. The electron beam curable bio-based conductive composition according to claim 2, wherein the first acrylate monomer is selected from one or more of 2-ethylhexyl acrylate, n-octyl acrylate, n-tetrazyl acrylate, n-hexadecyl acrylate, and n-octadecyl acrylate.

4. The electron beam curable bio-based conductive composition according to claim 2, wherein the second acrylate monomer is selected from one or more of 2-octyl methacrylate, ethyl methacrylate, methyl methacrylate, and isobornyl methacrylate.

5. The electron beam curable bio-based conductive composition according to claim 2, wherein the first acrylate monomer is 2-ethylhexyl acrylate and the second acrylate monomer is 2-octyl acrylate.

6. The electron beam curable bio-based conductive composition according to claim 2, wherein the functional monomer is selected from one or more of (meth)acrylic acid, hydroxyethyl acrylate, hydroxyethyl methyl acrylate, hydroxypropyl (meth)acrylic acid, N-vinylpyrrolidone, and (meth)acrylamide.

7. The electron beam curable bio-based conductive composition according to claim 2, wherein the functional monomer is acrylic acid.

8. The electron beam curable bio-based conductive composition according to claim 2, wherein the free radical polymerization initiator is selected from one or more of acetylbenzene initiators, α-hydroxyketone initiators, benzoin ether initiators, aryl sulfonyl chloride initiators, and oxime initiators.

9. The electron beam curable bio-based conductive composition according to claim 2, wherein the content of the free radical polymerization initiator is 0.01-0.3% by weight.

10. The electron beam curable bio-based conductive composition according to claim 2, wherein the acrylate composition further comprises a chain transfer agent.

11. The electron beam curable bio-based conductive composition according to claim 10, wherein the chain transfer agent is present in an amount of 0.01-3 by weight.

12. The electron beam curable bio-based conductive composition according to claim 10, wherein the chain transfer agent is selected from one or more of sulfur-containing chain transfer agents and haloalkane chain transfer agents.

13. The electron beam curable bio-based conductive composition according to claim 2, wherein the acrylate composition further comprises a diluent.

14. The electron beam curable bio-based conductive composition according to claim 13, wherein the diluent is 1,6-hexanediol diacrylate.

15. The electron beam curable bio-based conductive composition according to claim 13, wherein the diluent is present in an amount of 0.03-0.06 by weight.

16. The electron beam curable bio-based conductive composition according to claim 2, wherein the acrylate composition further comprises an antioxidant.

17. The electron beam curable bio-based conductive composition according to claim 16, wherein the antioxidant is selected from one or more of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl)phosphite, and dilauryl thiodipropionate.

18. The electron beam curable bio-based conductive composition according to claim 16, wherein the antioxidant content is 0.1-0.3% by weight.

19. The electron beam curable bio-based conductive composition according to claim 2, wherein the acrylate composition has a viscosity of less than 50 cP at 25°C.

20. The electron beam curable bio-based conductive composition according to claim 2, wherein the acrylate composition is a solvent-free composition.

21. The electron beam curable bio-based conductive composition according to claim 1, wherein the content of the bio-based substance in the acrylate composition is 55% by weight or more.

22. The electron beam curable bio-based conductive composition according to claim 1, wherein the gel amount of the acrylate composition is less than or equal to 23% by weight.

23. The electron beam curable bio-based conductive composition according to claim 1, wherein the residual monomer content of the acrylate composition is less than or equal to 0.5% by weight.

24. The electron beam-curable bio-based conductive composition according to claim 2, wherein the polymer base is prepared by the following steps: The acrylate composition is sealed in a plastic bag; The acrylic composition in the plastic packaging bag is subjected to ultraviolet radiation to induce polymerization. and The acrylate composition exposed to ultraviolet radiation and the plastic packaging bag are melt-extruded together to obtain the polymer base material.

25. The electron beam-curable bio-based conductive composition according to claim 24, wherein the intensity of the ultraviolet radiation is in the range of 0.01-20 mW / cm². 2 Within the range.

26. The electron beam curable bio-based conductive composition of claim 24, wherein the polymer base further comprises a viscosity modifier.

27. The electron beam curable bio-based conductive composition according to claim 26, wherein the viscosity modifier is an ethylene-vinyl acrylate copolymer or an ethylene-acrylic acid copolymer.

28. The electron beam curable bio-based conductive composition according to claim 1, wherein the tackifying resin is a hydrogenated rosin resin.

29. The electron beam curable bio-based conductive composition according to claim 28, wherein the hydrogenated rosin resin has a softening point of 70-100°C.

30. The electron beam curable bio-based conductive composition according to claim 1, wherein the conductive particles are selected from one or more of graphite particles, conductive carbon black particles, carbon nanotube particles, graphene particles, silver particles, and gold particles.

31. The electron beam curable bio-based conductive composition according to claim 1, wherein the conductive particles are nickel-coated graphite particles.

32. The electron beam curable bio-based conductive composition according to claim 31, wherein the nickel coating amount of the nickel-coated graphite particles is 60-85% by weight.

33. The electron beam curable bio-based conductive composition according to claim 1, wherein the crosslinking agent is a polyfunctional acrylate crosslinking agent.

34. The electron beam curable bio-based conductive composition according to claim 1, wherein the crosslinking agent is one or more of a multifunctional aliphatic acrylate oligomer or trimethylolpropane triacrylate.

35. An electron beam-curable bio-based conductive tape, said electron beam-curable bio-based conductive tape comprising: Adhesive layer formed from the electron beam curable bio-based conductive composition according to any one of claims 1 to 34; and Release substrate bonded to the adhesive layer.

36. A method for preparing an electron beam-curable bio-based conductive tape according to claim 35, the method comprising: (1) The polymer base, the tackifying resin, the conductive particles and the crosslinking agent are mixed to obtain a conductive adhesive mixture; (2) The conductive adhesive mixture is applied to at least one surface of the release substrate to form a voltage-sensitive adhesive layer; and (3) Apply electron beam radiation to the voltage-sensitive adhesive layer to cause the voltage-sensitive adhesive layer to crosslink and cure.

37. The preparation method according to claim 36, wherein the electron beam radiation dose is 20-150 kGy and the accelerating voltage is 80-300 kV.

38. The preparation method according to claim 36, wherein the mixing in step (1) is melt mixing, kneading mixing or extrusion mixing.

39. The preparation method according to claim 36, wherein the coating in step (2) is hot melt coating, extrusion coating or blade coating.

40. Use of the electron beam curable bio-based conductive composition of any one of claims 1-34 or the electron beam curable bio-based conductive tape of claim 35 in electronic device assembly, electromagnetic shielding, grounding connection or conductive bonding.

Images