Substrate-free double faced adhesive tape and preparation method thereof

Abstract

The invention relates to the technical field of adhesives, and discloses a substrate-free double faced adhesive tape, which comprises the following components by weight: 30-50 parts of a high performance polymer matrix; 5 to 15 parts of tackifying resin; 5 to 15 parts of a filling agent; 2 to 8 parts of silver nanowires; the invention also provides a preparation method of the substrate-free double-sided adhesive tape, and the preparation method comprises the following steps: S1, uniformly mixing the high-performance polymer matrix and the tackifying resin through vacuum stirring; s2, gradually adding the filler and the conductive filler, and continuously stirring until the filler and the conductive filler are uniformly dispersed; and S3, the surface of a mold is coated with the mixture, and curing forming is conducted by controlling the temperature and humidity. By adopting ultraviolet irradiation treatment, adding the antioxidant and the anti-aging agent and introducing the conductive filler, the long-acting stability, excellent anti-aging performance and electromagnetic shielding effect of the substrate-free double-sided adhesive tape in high-temperature, ultraviolet and humid environments are realized.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, in particular to a substrate-free double-sided adhesive and a preparation method thereof. Background Art

[0002] In our daily life and industrial fields, double-sided tape is an indispensable tool, widely used in electronic equipment assembly, home decoration, automobile manufacturing and many other aspects. With the advancement of industrial technology and the improvement of environmental protection requirements, traditional double-sided tape is gradually facing new challenges, and needs to maintain stable adhesion performance in high temperature, ultraviolet radiation and humid environments.

[0003] Double-sided tapes in the prior art usually rely on a substrate, such as a plastic film or fabric layer, to enhance their stability and load-bearing capacity. These tapes with substrates show excellent adhesion in many applications, especially at room temperature and normal humidity conditions. They have good stability and bonding effects in conventional applications such as electronic equipment, building materials, and packaging, and can meet certain daily use needs. Compared with traditional single-sided tapes, double-sided tapes provide more flexible use options because they are sticky on both sides, and can provide higher strength and reliability in certain specific applications.

[0004] However, in the prior art, the performance of traditional double-sided tapes still has some shortcomings. In particular, double-sided tapes without a substrate often experience problems such as adhesion loss and adhesive layer damage when exposed to ultraviolet rays, high temperature or humid environments for a long time. In addition, most traditional tapes do not take into account the shielding problem of electromagnetic interference, which limits their application in fields that require electromagnetic compatibility, such as electronic equipment. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a substrate-free double-sided adhesive and a preparation method thereof, which solves the problems of adhesion attenuation and aging of the double-sided adhesive in the prior art under ultraviolet, high temperature and humidity environments, as well as insufficient electromagnetic shielding performance.

[0006] To achieve the above object, the present invention is implemented by the following technical scheme: a double-sided adhesive without substrate, the double-sided adhesive comprising the following components in parts by weight: High performance polymer matrix: 30-50 parts; Tackifying resin: 5-15 parts; Filler: 5-15 parts; Silver nanowires: 2-8 parts. Silver nanowires have a long conductive path and extremely high surface activity, which can effectively transmit current and electrons and prevent electromagnetic interference. In addition, the excellent oxidation resistance of silver allows its conductive properties to be maintained for a long time in high temperature and humid environments; Graphite micro-sheets: 3-8 parts. The layered structure of graphite micro-sheets helps to shield external signals in an electromagnetic interference environment, prevent the leakage of electromagnetic waves, and protect sensitive electronic equipment. In addition, graphite micro-sheets can also improve the heat dissipation performance of the tape and reduce the adhesion attenuation in a high temperature environment; Titanium dioxide: 1-5 parts. Titanium dioxide is a commonly used UV absorber that can effectively block UV damage and reduce the degradation of adhesive materials. The photocatalytic effect of titanium dioxide can absorb UV rays and convert them into heat, thereby protecting the tape material from aging caused by UV rays and extending the service life of the tape; Anti-aging agent: 1 to 5 parts.

[0007] Preferably, the high performance polymer matrix comprises: Polyurethane: 10-20 parts. In double-sided adhesive tape, the flexibility and cross-linking structure of polyurethane molecular chains enable polyurethane to maintain high physical properties when exposed to high temperatures or long-term exposure to ultraviolet rays. When exposed to high humidity or high temperature environments, the molecular chains of polyurethane can effectively adapt to temperature changes, maintain the shape and function of the tape, and reduce the decline of adhesion; Modified acrylate: 10-30 parts. Through chemical modification, the molecular chain of modified acrylate has polar functional groups, which enables it to have a strong adsorption effect on different substrate surfaces (especially low surface energy materials). Its modified molecular structure enhances the adhesion of the tape to materials with low surface energy (such as PE, PP and other plastics). In addition, modified acrylate can also effectively improve the UV resistance of the tape, prevent the adhesive layer from aging due to long-term exposure to sunlight, and extend its service life.

[0008] Preferably, the tackifying resin comprises: Modified rosin resin: 5-10 parts. By chemically modifying the rosin resin, aromatic ring structures or polymerization can be introduced to enhance its high temperature resistance and UV resistance, so that it can still maintain strong adhesion in harsh environments. The polar functional groups (such as carboxyl, hydroxyl, etc.) of the modified rosin resin can be physically adsorbed to the surface of the substrate through hydrogen bonds, thereby effectively improving the initial adhesion of the tape. This physical adsorption effect enables the modified rosin resin to provide a rapid bonding effect when used, especially on low surface energy materials (such as polyethylene and polypropylene). Thermoplastic polyester resin: 5-8 parts. Thermoplastic polyester resin usually has a long molecular chain and a high degree of cohesion, which enables it to better fill the tiny pores or irregular areas on the surface of the substrate when heated. It can soften after heating, enhancing the adhesion between the tape and the surface.

[0009] Preferably, the filler includes: Ultrafine silica: 5-8 parts. The micron-sized particles of ultrafine silica can effectively fill the gaps and microcracks in the adhesive layer, thereby improving the hardness and tensile strength of the tape and enhancing the durability of the tape under physical load. At the same time, because ultrafine silica has a very high specific surface area, it can effectively increase the viscosity and stability of the adhesive layer, so that the tape maintains good fluidity and uniformity during application, avoiding uneven coating or bubble problems; Carbon nanotubes: 1-3 parts. Carbon nanotubes have extremely high specific strength and specific modulus, which can effectively enhance the tensile strength and toughness of the tape. Due to their nanoscale size and unique layered structure, carbon nanotubes can form a stable network structure in the tape, improving its overall mechanical properties. At the same time, the special conductive properties of carbon nanotubes make their addition to the tape effectively improve the conductivity of the tape, especially in applications such as electromagnetic interference shielding or current conduction. Carbon nanotubes can provide an efficient conductive path to reduce the resistance of the tape; Graphene: 2-4 parts. Graphene’s high conductivity enables it to effectively enhance the electromagnetic shielding effect of the tape. It can shield the interference of external electromagnetic waves in electronic equipment and reduce the impact on sensitive components. At the same time, graphene has excellent high temperature resistance and can maintain structural stability in high temperature environments to avoid the performance degradation of the tape caused by heat. The two-dimensional structure of graphene gives it extremely high specific strength and rigidity, which can improve the tensile strength, tear resistance and compression resistance of the tape. Its addition makes the tape more durable under physical load and not easy to break or deform.

[0010] Preferably, the anti-aging agent includes: Antioxidant: 1-3 parts, the antioxidant is tert-butyl hydroquinone. As a fat-soluble antioxidant, BHT can effectively neutralize free radicals and prevent oxidation reactions. It mainly prevents the molecular chain of the tape from breaking and degrading by capturing free radicals in oxidation reactions; Anti-aging agent: 1-3 parts, the anti-aging agent is Irganox1010, which enhances the stability of the tape molecular chain through chemical cross-linking and molecular stabilization, can provide long-term thermal stability and antioxidant protection, and prevent the degradation of the polymer materials in the tape due to oxygen, heat or light. It performs well at high temperatures and can effectively prevent molecular breakage caused by oxidation; Anti-ultraviolet additive: 1-3 parts, the anti-ultraviolet additive is titanium dioxide, which can effectively block the radiation of ultraviolet rays and convert its energy into heat, thereby reducing the damage of ultraviolet rays to the molecular chains of the tape. It has very strong photocatalytic properties, can absorb and effectively scatter ultraviolet rays, and protect the tape from degradation caused by ultraviolet rays.

[0011] The present invention also provides a method for preparing a substrate-free double-sided adhesive, comprising the following steps: S1, mixing the high performance polymer matrix and the tackifying resin uniformly by vacuum stirring; S2, gradually add filler and conductive filler, and continue stirring until evenly dispersed; S3, applying the mixture to the surface of the mold, and curing and molding by controlling the temperature and humidity; S4. After curing, titanium dioxide and an anti-aging agent are added and post-processed to obtain a finished product.

[0012] Preferably, the high performance polymer matrix and the tackifying resin are mixed uniformly by vacuum stirring, comprising: Add polyurethane and modified acrylate into a stirrer in a weight ratio of 30-50 parts and 50-70 parts; Stirring under vacuum, the temperature is controlled at 55-65°C, the stirring speed is 200rpm, and the stirring time is 30 minutes to 1 hour. The vacuum environment helps to remove bubbles and dissolved gases in the mixture. When there are bubbles in the adhesive, these bubbles will affect the uniformity of the final tape, resulting in residual bubbles in the adhesive layer, thereby affecting adhesion and stability. This temperature range helps to reduce the viscosity of the resin so that it can better blend with the polymer matrix during the stirring process. This stirring speed is to ensure sufficient stirring while avoiding excessive bubbles. Stirring too fast may cause bubbles to form, while stirring too slowly may lead to insufficient mixing of the ingredients, resulting in inconsistent performance of the tape.

[0013] Preferably, gradually adding the filler and the conductive filler and continuing to stir until uniformly dispersed comprises: Ultrafine silicon dioxide, carbon nanotubes and graphene are added to the mixture in proportions of 5 to 15 parts, 1 to 5 parts and 2 to 5 parts, respectively. The addition of ultrafine silicon dioxide helps to avoid the formation of local high density areas on the surface of the material, so that it is evenly distributed in the adhesive. The addition of carbon nanotubes helps to ensure that it is evenly dispersed and avoids local aggregation. The addition of graphene helps to avoid agglomeration between its particles and ensures its uniform distribution in the tape. Silver nanowires and graphite microsheets are added as conductive fillers in a ratio of 2 to 8 parts and 3 to 8 parts, respectively. The addition of silver nanowires can improve the conductivity of the tape. Graphite microsheets, as another conductive filler, have good conductivity and mechanical strength. After being added to the tape, the electromagnetic shielding capability thereof can be enhanced, and the stability of the tape at high temperatures can be improved. Continue stirring until all ingredients are evenly dispersed. The stirring speed is 250 rpm, the stirring time is 40 minutes to 1 hour, and the stirring temperature is 55 to 65°C. Within this temperature range, the heat energy during the stirring process helps to fully integrate the filler and the base material. This stirring speed can ensure that the filler can be evenly dispersed in the adhesive during the stirring process, and avoid introducing bubbles due to too fast stirring, which affects the uniformity and adhesion of the final tape. Finally, by setting the stirring time in this range, it can be ensured that the distribution of each filler can achieve the best uniformity.

[0014] Preferably, applying the mixture to the surface of the mold and curing and molding by controlling the temperature and humidity comprises: The mixture is evenly coated on the mold surface with a coating thickness of 50μm to 100μm. The purpose of the coating process is to ensure that the mixed adhesive evenly covers the mold surface and ensures the uniformity of the adhesive layer. This coating thickness range helps to avoid the problem of unstable adhesion due to too thin an adhesive layer, or incomplete curing due to too thick an adhesive layer. The coated adhesive layer is cured in a constant temperature and humidity chamber at a temperature of 45 to 55°C and a humidity of 55 to 65% RH for 1 to 2 hours. This temperature range can ensure that the adhesive molecules are completely cross-linked during the curing process without excessive reaction or degradation, and this humidity range helps to stabilize the fluidity of the adhesive during the curing process, avoiding the adhesive layer from drying too quickly due to too low ambient humidity, uneven curing or surface cracks. Finally, a too long curing process may lead to excessive cross-linking of the adhesive, affecting its flexibility; too short a curing process may lead to insufficient or uneven adhesion of the adhesive layer. Therefore, a curing time of 1 to 2 hours can ensure that the adhesive is completely cured, which not only improves its mechanical properties, but also ensures the long-term stability of the adhesive layer during use; after curing, the tape is stabilized through a cooling process to ensure the uniformity and adhesion of the final adhesive layer. During the cooling process, the tape changes from a hot solid state to a room temperature solid state. A rapid drop in temperature may cause stress in the adhesive layer, resulting in surface cracks or weakened adhesion, while uniform temperature cooling ensures the stability of the adhesive layer and avoids fluctuations in the physical properties of the adhesive layer due to uneven cooling.

[0015] Preferably, after curing in S4, titanium dioxide and an anti-aging agent are added for post-treatment to obtain a finished product, which includes: adding titanium dioxide to the cured tape in a ratio of 1 to 5 parts, and mixing evenly, wherein the addition of titanium dioxide effectively improves the weather resistance and aging resistance of the tape under ultraviolet irradiation environment, and prolongs the service life of the tape; Add antioxidants as anti-aging agents in a ratio of 1 to 5 parts and stir until fully dispersed. Antioxidants prevent the spread of oxidation reactions by capturing free radicals and reduce polymer degradation caused by oxidation. During the production process of the tape, antioxidants can stabilize the molecular structure of the adhesive and prevent the aging process caused by oxygen in the air or high temperature, thereby extending the service life of the tape, especially in a hot and humid environment; The mixed tape is irradiated with ultraviolet light, and the ultraviolet light with a wavelength of 350nm to 380nm is used for 10 minutes to 30 minutes to make the double-sided tape have the ability of anti-ultraviolet and anti-aging. Under ultraviolet light irradiation, certain chemical bonds in the adhesive will absorb ultraviolet light energy and stimulate reactions to produce free radicals. These free radicals will further promote cross-linking between molecules to form a more solid three-dimensional network structure. Through this cross-linking reaction, the structure of the tape becomes more stable, thereby improving the light resistance, heat resistance and weather resistance of the tape. The ultraviolet energy in this wavelength range is suitable for the excitation of chemical bonds in the adhesive molecules and can trigger the cross-linking reaction of the molecular chain. If the irradiation time is too short, the cross-linking reaction is easy to be insufficient and a sufficient cross-linking network structure cannot be formed. If the irradiation time is too long, excessive cross-linking may increase the brittleness of the tape and reduce the flexibility and durability of the tape. Therefore, irradiation in this time range is the best balance between improving the performance of the tape and avoiding excessive cross-linking.

[0016] The present invention provides a substrate-free double-sided adhesive and a preparation method thereof. It has the following beneficial effects: 1. Through unique ultraviolet irradiation and titanium dioxide addition, the present invention allows the tape to show strong anti-ultraviolet ability when exposed to ultraviolet environment. Compared with traditional technology, this innovative solution effectively solves the performance degradation caused by ultraviolet rays and greatly improves the durability of the tape.

[0017] 2. Adding antioxidants and anti-aging agents solves the aging problem of the tape under high temperature and humidity. The use of these ingredients allows the tape to remain stable in harsh environments, and will not become brittle or lose adhesion due to long-term use, providing long-term protection.

[0018] 3. The introduction of silver nanowires and graphite microsheets makes the tape not just a simple bonding tool, but also provides shielding in electromagnetic interference environments. Compared with conventional tapes, this technological breakthrough enables the tape to show stronger conductivity and electromagnetic wave shielding effect in applications requiring electromagnetic shielding.

[0019] 4. The adhesive tape of the present invention performs well in high temperature and high humidity environments, especially after long-term exposure, and can still maintain good adhesion and stability. Compared with traditional adhesive tapes, the adhesive tape of the present invention is still reliable under extreme conditions, significantly improving the durability and stability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a method flow chart of the preparation process. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Please see attached Figure 1 : Example 1: Preparation of double-sided adhesive tape without substrate under normal conditions Mixing polymer matrix and tackifying resin: Polyurethane: 40 parts, modified acrylate: 60 parts were added into a stirrer according to the weight ratio.

[0023] Under vacuum environment, the temperature was set at 60°C, the stirring speed was 200 rpm, and stirring was continued for 45 minutes to ensure that the two materials were fully mixed.

[0024] Add fillers and conductive fillers step by step: According to the proportions in the claim, 8 parts of ultrafine silicon dioxide, 2 parts of carbon nanotubes, and 3 parts of graphene are added in sequence.

[0025] Then add conductive filler silver nanowires: 5 parts, graphite microsheets: 6 parts, and continue stirring until evenly dispersed.

[0026] The stirring speed was set to 250 rpm, the temperature to 60°C, and the stirring time to 50 minutes to ensure that each filler was fully and evenly distributed in the adhesive.

[0027] Coating and curing: The mixture was evenly coated on the mold surface with a coating thickness of 70 μm.

[0028] The film was cured in a constant temperature and humidity chamber at 50°C and 60% RH for 1.5 hours.

[0029] After curing, place the tape in a cooling area to ensure it cools naturally and the adhesive layer is stable.

[0030] Post-treatment and UV irradiation: Add 3 parts of titanium dioxide to the cured tape and mix well with the tape.

[0031] Add antioxidant (BHT): 2 parts and stir until fully dispersed.

[0032] In the UV irradiation equipment, the tape was irradiated at a wavelength of 360nm for 20 minutes to enhance its UV resistance.

[0033] Example 2: Preparation of double-sided adhesive tape without substrate in high temperature and high humidity environment Mixing polymer matrix and tackifying resin: According to the proportion in the claim, 50 parts of polyurethane and 50 parts of modified acrylate are added.

[0034] Stir in a vacuum stirrer, set the stirring temperature to 65°C, the speed to 200 rpm, and the stirring time to 1 hour to ensure that the materials are completely blended.

[0035] Adding fillers and conductive fillers: Add ultrafine silicon dioxide: 6 parts, carbon nanotubes: 3 parts, and graphene: 4 parts.

[0036] Then add 4 parts of silver nanowires and 5 parts of graphite microsheets, and continue stirring until evenly dispersed.

[0037] The stirring speed was controlled at 250 rpm, the temperature was maintained at 60°C, and the stirring time was 45 minutes.

[0038] Coating and curing: The coating thickness was set to 55 μm to ensure a uniform adhesive layer.

[0039] Curing was carried out in a constant temperature and humidity chamber with a set temperature of 50°C, a humidity of 60% RH, and a curing time of 1.5 hours.

[0040] After curing, cool naturally to ensure the uniformity and adhesion of the glue layer.

[0041] Post-treatment and UV irradiation: Add 2 parts of titanium dioxide to the curing tape and mix well with the tape.

[0042] Add antioxidant (Irganox 1010): 3 parts and stir until fully dispersed.

[0043] The mixed tape was placed in an ultraviolet irradiation device and irradiated with 350 nm ultraviolet light for 30 minutes.

[0044] Example 3: Preparation of double-sided adhesive tape without substrate under outdoor exposure conditions Mixing polymer matrix and tackifying resin: According to the ratio in the claim, 30 parts of polyurethane and 70 parts of modified acrylate are added into a stirrer.

[0045] Under vacuum environment, the temperature was set at 60° C., the stirring speed was 200 rpm, and the stirring time was 40 minutes until the polymer matrix and the tackifying resin were fully mixed.

[0046] Adding fillers and conductive fillers: Add ultrafine silica: 7 parts, carbon nanotubes: 2 parts, and graphene: 3 parts in sequence, ensuring uniform dispersion.

[0047] Then, 6 parts of silver nanowires and 4 parts of graphite microsheets were added, and stirring was continued. The temperature was maintained at 60° C., the stirring speed was 250 rpm, and the stirring time was 1 hour.

[0048] Coating and curing: The mixture was evenly coated on the mold surface with a coating thickness of 65 μm.

[0049] Curing was carried out in a constant temperature and humidity chamber with the temperature set at 55°C, humidity 60% RH, and curing time of 1.5 hours to ensure uniform curing of the adhesive layer.

[0050] Post-treatment and UV irradiation: Add titanium dioxide: 3 parts, mix well with the tape.

[0051] Add antioxidant (BHT): 1.5 parts and ensure complete dispersion.

[0052] Place the tape in a UV irradiation device and irradiate it with 350nm UV rays for 25 minutes to enhance its anti-UV performance.

[0053] Example 4: Preparation of double-sided adhesive tape without substrate for electromagnetic shielding application Mixing polymer matrix and tackifying resin: Add the two materials into a mixer in a ratio of 40 parts of polyurethane and 60 parts of modified acrylate.

[0054] The mixture was stirred in a vacuum stirrer with the temperature controlled at 65°C, the stirring speed at 200 rpm, and the stirring time for 50 minutes.

[0055] Gradually add fillers and conductive fillers: Add ultrafine silica: 5 parts, carbon nanotubes: 3 parts, graphene: 4 parts, and ensure uniform dispersion.

[0056] Then, 4 parts of silver nanowires and 5 parts of graphite microsheets were added, and stirring was continued. The temperature was maintained at 60° C., the stirring speed was 250 rpm, and the stirring time was 1 hour.

[0057] Coating and curing: The mixture was evenly coated on the mold surface with a coating thickness of 60 μm.

[0058] Curing was carried out in a constant temperature and humidity chamber at 50°C, 55% RH and 2 hours to ensure that the adhesive layer was uniform and stable.

[0059] Post-treatment and UV irradiation: Add 4 parts of titanium dioxide to the cured tape, making sure to mix evenly.

[0060] Add 2 parts of antioxidant (Irganox 1010) and disperse thoroughly.

[0061] Place the tape in a UV irradiation device and irradiate it with 350nm UV rays for 20 minutes to improve the tape's UV resistance and anti-aging capabilities.

[0062] Comparative Example 1: Conventional tape preparation (without anti-ultraviolet treatment) Description of technical solution: In the prior art, conventional substrate-free double-sided adhesives are usually not subjected to ultraviolet irradiation treatment, and no special ingredients are added to enhance ultraviolet resistance. This comparative example is mainly used to compare the ultraviolet irradiation treatment and titanium dioxide addition steps in the present invention.

[0063] Comparative Example Preparation Steps: Mixing polymer matrix and tackifying resin: 40 parts of polyurethane and 60 parts of modified acrylate were used and mixed in a stirrer. The temperature was set at 60° C., the stirring speed was 200 rpm, and the stirring time was 45 minutes.

[0064] Adding fillers and conductive fillers: Add ultrafine silicon dioxide: 7 parts, carbon nanotubes: 3 parts, and graphene: 4 parts in proportion.

[0065] Then, add 5 parts of conductive filler silver nanowires and 6 parts of graphite microsheets, stir evenly, keep the stirring temperature at 60° C., the speed at 250 rpm, and the stirring time for 50 minutes.

[0066] Coating and curing: The mixture was evenly coated on the mold surface with a coating thickness of 70 μm.

[0067] The curing temperature is 50°C, the humidity is 60% RH, the curing time is 1 hour, and the tape is cooled naturally after curing.

[0068] Post-processing: No titanium dioxide and antioxidants are added, and the UV exposure step is omitted.

[0069] Comparative Example 2: Preparation of conventional adhesive tape without antioxidant and anti-aging agent Description of technical solution: The prior art usually relies only on the combination of base polymer and resin, but lacks effective anti-oxidation and anti-aging measures. This comparative example is used to compare the addition of antioxidants and anti-aging agents in the present invention.

[0070] Comparative Example Preparation Steps: Mixing polymer matrix and tackifying resin: 45 parts of polyurethane and 55 parts of modified acrylate were used and mixed in a stirrer. The temperature was set at 60° C., the stirring speed was 200 rpm, and the stirring time was 50 minutes.

[0071] Adding fillers and conductive fillers: Ultrafine silica: 6 parts, carbon nanotubes: 2 parts, graphene: 3 parts were added in proportion, stirring was continued, the temperature was maintained at 60°C, the stirring speed was 250 rpm, and the stirring time was 1 hour.

[0072] Coating and curing: The mixture was coated on the mold surface with a coating thickness of 60 μm, a curing temperature of 50° C., a humidity of 60% RH, and a curing time of 1 hour.

[0073] Post-processing: No antioxidant (BHT) or anti-aging agent (Irganox 1010) was added, and no ultraviolet irradiation treatment was performed.

[0074] Comparative Example 3: Conventional tape without conductivity requirement Description of technical solution: In the prior art, many conventional double-sided adhesives do not consider the conductivity requirement. This comparative example is used to compare the conductive addition steps of carbon nanotubes, graphene and silver nanowires in the present invention.

[0075] Comparative Example Preparation Steps: Mixing polymer matrix and tackifying resin: 40 parts of polyurethane and 60 parts of modified acrylate were used in a stirrer at a stirring temperature of 60° C., a stirring speed of 200 rpm, and a stirring time of 45 minutes.

[0076] Add fillers: Add 8 parts of ultrafine silica, 2 parts of carbon nanotubes, and 3 parts of graphene, and continue stirring. Keep the temperature at 60° C., the stirring speed at 250 rpm, and the stirring time for 1 hour.

[0077] Coating and curing: The mixture was coated on the mold surface with a coating thickness of 75 μm. The curing temperature was set at 55° C., the humidity was 60% RH, and the curing time was 1 hour.

[0078] Post-processing: No conductive fillers such as silver nanowires and graphite microplatelets were added, and post-processing was completed directly after curing.

[0079] Comparative Example 4: Conventional tape without post-treatment Description of technical solution: In the prior art, many double-sided adhesives do not undergo post-treatment or strengthening steps. This comparative example is used to compare the addition of titanium dioxide and antioxidants in the present invention.

[0080] Comparative Example Preparation Steps: Mixing polymer matrix and tackifying resin: Polyurethane: 50 parts, modified acrylate: 50 parts were used in a proportion, and mixed in a stirrer. The stirring temperature was set at 60° C., the stirring speed was 200 rpm, and the stirring time was 1 hour.

[0081] Adding fillers and conductive fillers: Add 6 parts of ultrafine silica, 3 parts of carbon nanotubes, and 4 parts of graphene, and continue stirring. Keep the temperature at 60° C., the stirring speed at 250 rpm, and the stirring time for 50 minutes.

[0082] Coating and curing: The mixture was coated on the mold surface with a coating thickness of 80 μm. The curing temperature was set at 55° C., the humidity was 60% RH, and the curing time was 1 hour.

[0083] Post-processing: No added titanium dioxide, antioxidants or ageing agents, no UV treatment.

[0084] experiment: Experimental purpose: to test and compare the performance differences between the present invention and the prior art (comparative example) under different environments, especially in terms of UV resistance, anti-aging performance, conductivity and high temperature stability. The experiment verifies the technical advantages of the present invention by exposing the experimental tape to environmental conditions such as high temperature, high humidity, and UV irradiation, and monitoring the changes in its physical properties such as adhesion, hardness, and surface changes.

[0085] Experimental Materials: Example 1: The substrate-free double-sided adhesive of the present invention is treated with ultraviolet irradiation and titanium dioxide is added, and other additives are consistent with the claims.

[0086] Example 2: The substrate-free double-sided adhesive of the present invention contains an antioxidant BHT and an anti-aging agent Irganox 1010, and other additives are consistent with the claims.

[0087] Embodiment 3: The substrate-free double-sided adhesive of the present invention comprises conductive fillers such as silver nanowires and graphite microsheets, and other additives are consistent with the claims.

[0088] Example 4: The substrate-free double-sided adhesive of the present invention includes ultraviolet irradiation treatment and titanium dioxide addition, as well as high-temperature long-term exposure treatment, and other additives are consistent with the claims.

[0089] Comparative Example 1: Conventional double-sided adhesive without substrate, without ultraviolet irradiation and without adding titanium dioxide.

[0090] Comparative Example 2: Conventional double-sided adhesive without substrate, without adding antioxidant and anti-aging agent.

[0091] Comparative Example 3: Conventional double-sided adhesive without substrate, without adding silver nanowires and graphite microsheets, maintaining non-conductivity.

[0092] Comparative Example 4: Conventional double-sided adhesive without substrate, without UV irradiation treatment and titanium dioxide addition, and without long-term exposure to high temperature.

[0093] Experimental steps and procedures: UV resistance test: In an ultraviolet accelerated weathering tester, each tape sample was exposed to ultraviolet light at a wavelength of 350-380 nm for 20 minutes.

[0094] The tape samples will be exposed to a UV light source that simulates outdoor exposure for 200 hours.

[0095] Each sample was tested for adhesion, surface color change, and hardness.

[0096] Experimental data: The adhesion, color change and hardness of the tape were measured before and after exposure to the sun.

[0097] Anti-aging performance test: Each tape sample was placed in a high temperature and high humidity aging box, the temperature was set to 80°C, the humidity was 90% RH, and the exposure time was 1000 hours.

[0098] The adhesion, mass change, and tensile strength of the tape were recorded every 100 hours.

[0099] Experimental data: Measures changes in tape properties at different exposure times, including adhesion decay, hardness change, and tensile strength.

[0100] Conductivity and electromagnetic shielding capability test: The conductivity of the tape was tested using the four-probe method and the conductivity of the tape was recorded.

[0101] The electromagnetic shielding effectiveness tester was used to measure the shielding effectiveness of each tape sample against electromagnetic waves (10 Hz to 10 GHz).

[0102] Experimental data: record the conductivity and electromagnetic shielding effectiveness of each tape sample.

[0103] Long-term high temperature stability test: Each tape sample was placed in a high temperature and high humidity environment, with the temperature set at 85°C and the humidity at 75% RH, and the test time was 2000 hours.

[0104] Adhesion, hardness and surface cracks are tested every 500 hours.

[0105] Experimental data: record the adhesive tape's adhesion decay, surface changes, and changes in tensile strength in a high temperature environment.

[0106] Test results of UV resistance, anti-aging performance, electromagnetic shielding effectiveness and high temperature stability From the experimental results, the present invention is superior to the prior art in multiple key performances, especially in terms of anti-ultraviolet performance, anti-aging ability, electromagnetic shielding effect and high temperature stability, showing obvious advantages. Through ultraviolet irradiation treatment and the addition of titanium dioxide, not only can the ultraviolet absorption and scattering ability of the tape be effectively enhanced, but also its durability when exposed to sunlight can be improved. Experimental data show that there are significant differences between Example 1 and Comparative Example 1 in terms of adhesion attenuation rate and surface color change after ultraviolet irradiation. Example 1 maintains a lower attenuation rate and shows good anti-ultraviolet ability.

[0107] In terms of anti-aging performance, the addition of antioxidant (BHT) and anti-aging agent (Irganox 1010) in Example 2 significantly improved the stability of the tape. In contrast, in Comparative Example 2, where these anti-aging ingredients were not added, the adhesive force of the tape decayed rapidly, showing obvious aging characteristics.

[0108] Regarding the conductivity and electromagnetic shielding capability, Example 3 significantly improves the conductivity and shielding effectiveness of the tape by adding silver nanowires and graphite microsheets. Comparative Example 3 does not add conductive fillers, exhibiting lower conductivity and shielding effectiveness, and cannot maintain effective protection in an electromagnetic interference environment.

[0109] In the high temperature stability test, the tape of Example 4 showed excellent long-term stability. Through ultraviolet irradiation and titanium dioxide post-treatment, the tape can still maintain good adhesion and hardness when exposed to high temperature and high humidity. Compared with the tape of Comparative Example 4, Example 4 significantly reduces the generation of surface cracks, showing high stability under extreme conditions.

[0110] The present invention provides a high-performance substrate-free double-sided adhesive by optimizing the anti-ultraviolet performance, anti-aging ability, electromagnetic shielding effect and long-term high-temperature stability, which can effectively solve the problems of aging, ultraviolet degradation, poor conductivity and instability in high-temperature environments that occur during long-term use in the prior art.

[0111] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A double-sided adhesive tape without substrate, characterized in that: The double-sided adhesive comprises the following components in parts by weight: High performance polymer matrix: 30-50 parts; Tackifying resin: 5-15 parts; Filler: 5-15 parts; Silver nanowires: 2-8 parts; Graphite microflakes: 3 to 8 parts; Titanium dioxide: 1-5 parts; Anti-aging agent: 1 to 5 parts.

2. The substrate-free double-sided adhesive according to claim 1, characterized in that: The high performance polymer matrix comprises: Polyurethane: 10-20 parts; Modified acrylate: 10-30 parts.

3. The substrate-free double-sided adhesive according to claim 1, characterized in that: The tackifying resin comprises: Modified rosin resin: 5-10 parts; Thermoplastic polyester resin: 5 to 8 parts.

4. The substrate-free double-sided adhesive according to claim 1, characterized in that: The filler includes: Ultrafine silicon dioxide: 5-8 parts; Carbon nanotubes: 1-3 parts; Graphene: 2 to 4 parts.

5. The substrate-free double-sided adhesive according to claim 1, characterized in that: The anti-aging agent includes: Antioxidant: 1-3 parts; Anti-aging agent: 1 to 3 parts; Anti-ultraviolet additive: 1 to 3 parts.

6. A method for preparing a substrate-free double-sided adhesive, characterized in that: Using the substrate-free double-sided adhesive according to any one of claims 1 to 5 comprises the following steps: S1, mixing the high performance polymer matrix and the tackifying resin uniformly by vacuum stirring; S2, gradually add filler and conductive filler, and continue stirring until evenly dispersed; S3, applying the mixture to the surface of the mold, and curing and molding by controlling the temperature and humidity; S4. After curing, titanium dioxide and an anti-aging agent are added and post-processed to obtain a finished product.

7. The method for preparing a substrate-free double-sided adhesive according to claim 6, characterized in that: The step of uniformly mixing the high performance polymer matrix and the tackifying resin by vacuum stirring comprises: Adding polyurethane and modified acrylate into a stirrer in a weight ratio of 30-50 parts and 50-70 parts; The mixture was stirred under vacuum, the temperature was controlled at 55-65°C, the stirring speed was 200 rpm, and the stirring time was 30 minutes to 1 hour.

8. The method for preparing a substrate-free double-sided adhesive according to claim 6, characterized in that: The step of gradually adding the filler and the conductive filler and continuing to stir until uniformly dispersed comprises: Adding ultrafine silicon dioxide, carbon nanotubes and graphene to the mixture in the proportions of 5 to 15 parts, 1 to 5 parts and 2 to 5 parts respectively; Adding silver nanowires and graphite microsheet conductive fillers in a ratio of 2 to 8 parts and 3 to 8 parts; Continue stirring until all ingredients are evenly dispersed, the stirring speed is 250 rpm, the stirring time is 40 minutes to 1 hour, and the stirring temperature is 55 to 65°C.

9. The method for preparing a substrate-free double-sided adhesive according to claim 6, characterized in that: The step of applying the mixture to the surface of the mold and curing the mixture by controlling the temperature and humidity comprises: The mixture is evenly coated on the surface of the mold with a coating thickness of 50 μm to 100 μm; The coated adhesive layer is cured in a constant temperature and humidity chamber at a temperature of 45-55°C and a humidity of 55-65%RH for 1 to 2 hours; After curing, the tape is stabilized by a cooling process, ensuring uniformity and adhesion of the final adhesive layer.

10. The method for preparing a substrate-free double-sided adhesive according to claim 6, characterized in that: After curing in S4, titanium dioxide and an anti-aging agent are added and post-processed to obtain a finished product including: Add titanium dioxide to the cured tape in a ratio of 1 to 5 parts and mix well; Add antioxidant as anti-aging agent in a ratio of 1 to 5 parts and stir until fully dispersed; The mixed tape is irradiated with ultraviolet light, using ultraviolet light with a wavelength of 350nm to 380nm for 10 minutes to 30 minutes, so that the double-sided tape has the ability to resist ultraviolet rays and aging.

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