A cyanate ester composition with high adhesive strength, adhesive film and preparation method and application thereof

Abstract

This invention relates to a high-adhesion-strength cyanate ester composition, an adhesive film, its preparation method, and its applications. The high-adhesion-strength cyanate ester composition comprises the following raw materials in parts by weight: 40-70 parts of cyanate ester resin, 15-30 parts of multifunctional epoxy resin, 20-40 parts of a thermoplastic resin toughening agent containing terminal hydroxyl or terminal amino groups, 10-20 parts of a core-shell rubber toughening agent, and 0.1-0.3 parts of a catalyst. This invention improves the overall flexural properties and toughness of the material, while making the modified cyanate ester resin state closer to the excellent adhesion and flowability of epoxy resin, greatly improving the processability and layability of the cyanate ester adhesive film. Furthermore, selecting a multifunctional epoxy resin can reduce the impact on Tg (glass transition temperature) and increase the rigidity of the cured material.

Description

Technical Field

[0001] This invention relates to the field of resin adhesive film materials, and more particularly to a high-adhesion-strength cyanate ester composition, film, preparation method and application thereof. Background Technology

[0002] Currently, the aerospace industry is increasingly using high-performance cyanate ester composite materials for heat-resistant and microwave-transparent applications. These composites often require high-strength bonding with metal or composite components. Currently, high-temperature resistant epoxy films are commonly used, but the relatively poor temperature resistance and high dielectric constant of epoxy resin systems directly affect their microwave transmission and high-temperature resistance when matched with cyanate ester composite matrixes. Furthermore, since the film material and the composite material are not from the same system, their bonding properties differ. In addition, commercially available cyanate ester film systems are extremely difficult to mass-produce, typically limited to small-batch production, and their high reactivity results in a short tack life, which is highly unfavorable for application in actual industrial production.

[0003] Chinese patent application CN117887376A discloses a high-temperature resistant, low-dielectric cyanate ester structural adhesive film and its preparation method. The structural adhesive film is prepared by hot-melt composite of cyanate ester resin, epoxy resin, toughening agent, and catalyst with a carrier. It comprises the following components: cyanate ester resin, liquid bisphenol A type epoxy resin and multifunctional epoxy resin, toughening agent, and catalyst. The catalyst is 2,6-dimethyl polyphenylene ether with active H-terminated hydroxyl groups, and the molecular weight of the catalyst is 1600–4000. The toughening agent selected in this method exhibits poor dispersion in the cyanate ester system, resulting in limited improvement in roller peeling performance. Summary of the Invention

[0004] The present invention aims to provide a high-adhesion-strength cyanate ester composition, adhesive film, preparation method and application thereof, which improves the overall bending performance and toughness of the material and has excellent adhesion and flowability.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A high-adhesion-strength cyanate ester composition comprising the following raw materials in parts by weight: 40-70 parts of cyanate ester resin, 15-30 parts of multifunctional epoxy resin, 20-40 parts of thermoplastic resin toughening agent containing terminal hydroxyl or terminal amino groups, 10-20 parts of core-shell rubber toughening agent, and 0.1-0.3 parts of catalyst.

[0006] This invention employs a quaternary composite system consisting of a specific ratio of cyanate ester resin, multifunctional epoxy resin, core-shell rubber, and active end-group thermoplastic powder, which interact to enhance bonding strength. An island-like structure is formed within the matrix, inducing plastic deformation through stress concentration, resulting in extremely high roller peel strength (approximately 50 N·m / m).

[0007] Comparative Example 2 used ordinary bisphenol A epoxy, which caused the Tg to drop from above 240°C to below 200°C, demonstrating the key role of multifunctional groups in maintaining crosslinking density.

[0008] Comparative Example 3 demonstrates that powders containing terminal hydroxyl or amino groups must be used to achieve graft compatibility with the matrix. This in-situ grafting avoids macroscopic phase separation, ensuring the uniformity and shear resistance of the film.

[0009] Preferably, a high-adhesion-strength cyanate ester composition comprises the following raw materials in parts by weight: 40-70 parts of cyanate ester resin, 15-30 parts of multifunctional epoxy resin, 20-30 parts of thermoplastic resin toughening agent containing terminal hydroxyl or terminal amino groups, 10-20 parts of core-shell rubber toughening agent, and 0.1-0.3 parts of catalyst.

[0010] According to embodiments of the present invention, the present invention can be further optimized. The optimized technical solution is as follows: the core-shell rubber toughening agent includes one or more of Zhongyuan MX150, MX153, MX154, MX139, and MX257.

[0011] In one preferred embodiment, the thermoplastic resin toughening agent containing terminal hydroxyl or terminal amino groups includes one or more of PPO, PES, PEK, and PEI.

[0012] In one preferred embodiment, the cyanate resin includes one or more of the following: bisphenol A cyanate resin, bisphenol F cyanate resin, bisphenol M cyanate resin, dicyclopentadiene cyanate resin, tetramethylbisphenol F cyanate resin, bisphenol E cyanate resin, phenolic cyanate resin, and biphenyl cyanate resin.

[0013] In one preferred embodiment, the multifunctional epoxy resin includes one or more of Shanghai Huayi AG80, AFG90, AG601, Huntsman MY0600, and MY742.

[0014] In one preferred embodiment, the catalyst comprises one of manganese acetylacetonate, molybdenum ethoxide, tin octoate, and dibutyltin dilaurate.

[0015] Comparative Examples 4 and 5 demonstrate that the type of catalyst and its single use are crucial. Using a combination of catalysts or replacing them with zinc salt catalysts leads to system runaway (poisoning, failure, or transient gelation).

[0016] The present invention also discloses a method for preparing the high-adhesion cyanate composition, comprising the following steps: S1. Mix 40-70 parts by weight of cyanate ester resin, 15-30 parts by weight of multifunctional epoxy resin, and 10-20 parts by weight of core-shell rubber toughening agent, and heat to 130-150℃; S2. Add 0.1-0.3 parts by weight of catalyst to the mixture obtained in step S1, and fully prepolymerize at 130-150℃ under nitrogen protection; S3. Cool the mixture obtained in step S2 to 110-130℃, add 20-40 parts by weight of thermoplastic resin toughening agent containing terminal hydroxyl or terminal amino groups, stir thoroughly, and control the target viscosity to 40000-60000cps@65℃; S4. Cool to below 70℃ to complete the discharge.

[0017] This invention utilizes a prepolymerization reaction to generate a stable structure containing an oxazolinone ring from cyanate esters and multifunctional epoxy resins (AG80, AFG90, etc.). This structure significantly improves toughness and adhesion and wettability to aluminum alloy surfaces while retaining the heat resistance of cyanate esters.

[0018] This invention introduces a transition metal catalyst during the prepolymerization stage and precisely controls the viscosity to 40,000-60,000 cps to adapt to dry coating processes. Through specific prepolymerization control, the adhesive film achieves a tack life of over 20 days at 25°C, solving the problems of existing cyanate ester films being too active, difficult to store for long periods, and unsuitable for application on large-sized components.

[0019] Comparative Example 6 demonstrates that insufficient prepolymerization at temperatures below 130°C leads to a sharp drop in tensile shear strength (from 35 MPa to 8 MPa).

[0020] The viscosity window (40,000-60,000 cps @ 65℃) is the physical basis for achieving dry coating and ensuring that the adhesive film has a tack life of more than 20 days at room temperature.

[0021] In one preferred embodiment, the prepolymerization reaction time in step S2 is 60-120 min.

[0022] In step S3, the stirring reaction time is 40-80 minutes.

[0023] In step S3, the system viscosity is tested every 20-30 minutes.

[0024] Because this system contains a high proportion of solid powder (toughening agent), conventional rotational viscometers have a large error under high temperature and high viscosity conditions. Using a cone-plate viscometer (such as BROOKFIELD CAP2000+) can more accurately capture the endpoint of the grafting reaction and prevent the system from over-gelling.

[0025] This invention also discloses a method for preparing an adhesive film, comprising the following steps: The high-adhesion-strength cyanate ester composition is melted into the glue tank of a dry coating machine, and uniformly coated onto the release paper through the roller gap to form a resin film. A layer of fiberglass mat is then laminated during the winding stage to prepare the adhesive film.

[0026] It adopts a dry coating process, which does not use solvents (zero VOC emissions), and uses viscosity monitoring to achieve precise substitution from laboratory development to industrial mass production.

[0027] The melting temperature is 60-80℃.

[0028] The resin film has a basis weight of 190-200 gsm, and the fiberglass mat has a basis weight of 20-30 gsm. This specific basis weight combination of the resin film (190-200 gsm) and the fiberglass mat (20-30 gsm) forms a 220 gsm composite adhesive film that combines strength and processability. The 20-30 gsm fiberglass mat not only serves as a carrier for the resin but also acts as a skeleton in the adhesive joint, effectively controlling the consistency of the adhesive layer thickness and preventing insufficient adhesive and debonding caused by excessive adhesive flow during curing and compaction.

[0029] The present invention also discloses the high-adhesion-strength cyanate ester composition and the application of the adhesive film in heat-resistant materials and microwave-transparent materials.

[0030] Regarding Chinese patent application with publication number CN117887376A: 1. Because the triazine rings of cyanate ester resin are rigid and brittle after curing, they have a significant impact on the bonding effect. At the same time, they lack polar groups and have poor affinity with metals and composite materials. Furthermore, most thermoplastic polymer toughening agents have poor compatibility with cyanate ester resin and cannot be directly and uniformly dispersed in cyanate ester resin. Adding toughening agents with end active groups can prepolymerize and graft with cyanate ester resin and epoxy resin, which can be more uniformly dispersed into the system and toughen the cyanate ester resin from the molecular layer, which is beneficial to the overall uniformity and stability of the system.

[0031] 2. Although thermoplastic polymer toughening agents can improve the toughness of cyanate ester resins and enhance adhesion, these thermoplastic polymers, due to the increased chain length, do not significantly reduce rigidity. They can improve instantaneous adhesion, i.e., enhance shear toughness, but lack flexibility, thus failing to improve adhesion during slow peeling. Therefore, this invention also enhances flexibility by adding core-shell rubber particles. The selected core-shell rubber particles all have a high-temperature resistant shell, with a flexible rubber interior, having minimal impact on Tg. The toughening effect of the core-shell rubber particles in the system is phase migration toughening, which forms an island effect after curing, i.e., uniformly disperses flexible elastic particles in the material structure. When the material is subjected to impact or torsion, it absorbs a large amount of energy, improving both instantaneous shear toughness and roller peel toughness.

[0032] 3. The amount of excessive metal salts or complex catalysts used is extremely small, and they have almost no effect on the dielectric properties of the material.

[0033] In summary, the toughening agent selected in the Chinese patent application with publication number CN117887376A cannot be dispersed very evenly in the cyanate ester system. It only uses thermoplastic polymer toughening agents to have an effect on tensile shearing, lacks flexible toughening agents, and has a limited effect on improving the torsional force of roller peeling.

[0034] Compared with currently commercially available or traditional high-temperature resistant adhesive films, the present invention has the following significant advantages: It has a tensile shear strength of ≥35 MPa at room temperature, and even in extreme environments of 200℃, the strength can still be maintained above 27 MPa (with a retention rate of about 80%), far exceeding the upper limit of temperature resistance of traditional epoxy films.

[0035] The peel strength of the aluminum honeycomb roller is consistently around 50 N·m / m. The dual toughening effect of core-shell rubber and grafted thermoplastic resin solves the common problem of brittleness in cyanate ester systems.

[0036] Compared with the prior art, the beneficial effects of the present invention are: This invention employs a prepolymerization process using cyanate ester resin and a multifunctional epoxy resin (including the epoxy resin portion of a core-shell rubber). The resulting products all contain an oxazolinone ring (under the action of a transition metal catalyst, the cyanate ester group (-OCN) undergoes exothermic crosslinking with the epoxy group, forming a five-membered ring structure, which is the chemical basis for the system's high Tg and high adhesion). This structure not only improves the overall flexural properties and toughness of the material but also makes the modified cyanate ester state closer to the excellent adhesion and flowability of epoxy resin, greatly improving the processability of the cyanate ester film. Furthermore, selecting a multifunctional epoxy resin reduces the impact on Tg (glass transition temperature) and increases the rigidity of the cured material.

[0037] The selected core-shell rubber toughening agent can achieve phase migration toughening, forming a unique island structure in the matrix. When subjected to impact, the core-shell particles become stress concentration centers, and micro-voidification occurs inside the rubber core or at its interface, releasing energy. Voidification changes the stress state around the particles, inducing extensive plastic deformation (shear yielding). At the same time, the particles can induce and bridge a large number of micro-crazing, preventing the propagation of the main crack and uniformly distributing the impact energy within the material, thereby avoiding overall material fracture and having minimal impact on the system's Tg.

[0038] This invention selects a bulk thermoplastic toughening agent containing active groups such as terminal hydroxyl or amino groups to enable it to undergo a grafting reaction with the resin, achieving a superior dispersion state within the matrix and thus uniformly improving the overall shear resistance. Simultaneously, the grafting process is rigorously monitored through viscosity testing to achieve the optimal coating process viscosity. At this specific viscosity, the adhesive film exhibits a process tack life exceeding 20 days at room temperature (around 25°C), which is extremely beneficial for practical production.

[0039] Adding an appropriate amount of catalyst ensures a stable prepolymerization reaction even at lower temperatures; nitrogen protection prevents oxidation by oxygen during the reaction process, thus avoiding the generation of byproducts. Combined with a dry resin coating machine, continuous production can be achieved at certain temperatures, significantly improving production efficiency and reducing costs. The addition of fiberglass mat during the winding stage further enhances the product's shear resistance and significantly improves the adhesive film's bonding effect. Attached Figure Description

[0040] Figure 1 The image shows a physical representation of a cyanate ester resin film with an overall basis weight of 220 gsm prepared according to an embodiment of the present invention. Detailed Implementation

[0041] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0042] Example 1

[0043] The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate ester: Bisphenol A cyanate ester: 40 parts; Multifunctional epoxy resin: AG80: 15 parts; Thermoplastic toughening agent containing terminal hydroxyl or terminal amino groups: PPO: 20 parts; Core-shell toughening agent: MX150: 10 parts; Catalyst: Manganese acetylacetone: 0.1 parts.

[0044] Weigh each raw material according to the above proportions. Add bisphenol A cyanate, AG80, and MX150 to the reactor. Raise the temperature to 130°C, add manganese acetylacetone, and maintain the prepolymerization reaction at 130°C for 60 minutes under nitrogen protection. Reduce the temperature to 110°C, add PPO, and perform a grafting reaction for 60 minutes. Test the viscosity every 20-30 minutes until the viscosity is between 40,000 and 60,000 cps at 65°C. Cool the temperature to below 70°C and discharge the material.

[0045] The main performance tests of this resin system are shown in Table 2.

[0046] The test conditions / reference methods for viscosity (65℃) are ASTM D4287, for gel time (160℃) are ASTM D2471, for tensile shear strength (25℃) are GB / T 7124, for tensile shear strength (200℃) are GB / T 7124, and for aluminum honeycomb roller peeling (25℃) are GJB 130.7.

[0047] After the resin composition was made into a 220gsm resin film, a single-lap joint test specimen was made using aluminum alloy sheet 2A12 (meeting the requirements of GJB 2053A standard) to test the tensile shear strength. A double-layer resin film, i.e., 420gsm, was used to bond the aluminum alloy sheet 2A12 and the aluminum alloy honeycomb component 2A12 (meeting the requirements of GJB 2053A standard), and then the specimens were cured in an oven (2 hours at 150℃ + 3 hours at 200℃). The performance of the cured specimens is shown in Table 2.

[0048] Example 2

[0049] The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate ester: Bisphenol F cyanate ester: 70 parts; Multifunctional epoxy resin: AFG90: 30 parts; Thermoplastic toughening agent containing terminal hydroxyl or terminal amino groups: PES: 20 parts; Core-shell toughening agent: MX154: 20 parts; Catalyst: Molybdenum ethanol: 0.3 parts.

[0050] Weigh each raw material according to the above proportions. Add bisphenol F cyanate, AFG90, and MX154 to the reactor. Raise the temperature to 150°C, add molybdenum ethanol, and maintain the prepolymerization reaction at 150°C for 120 minutes under nitrogen protection. Reduce the temperature to 130°C, add PES, and perform a grafting reaction for 60 minutes. Test the viscosity every 20-30 minutes until the viscosity is between 40,000 and 60,000 cps at 65°C. Cool the temperature to below 70°C and discharge the material.

[0051] The main performance tests of this resin system are shown in Table 2.

[0052] After the resin composition was made into a 220gsm resin film, a single-lap joint test specimen was made using aluminum alloy sheet 2A12 (meeting the requirements of GJB 2053A standard) to test the tensile shear strength. A double-layer resin film, i.e., 420gsm, was used to bond the aluminum alloy sheet 2A12 and the aluminum alloy honeycomb component 2A12 (meeting the requirements of GJB 2053A standard), and then the specimens were cured in an oven (2 hours at 150℃ + 3 hours at 200℃). The performance of the cured specimens is shown in Table 2.

[0053] Example 3

[0054] The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate esters: Bisphenol M cyanate ester: 25 parts; Dicyclopentadiene cyanate ester: 30 parts; Multifunctional epoxy resins: AG601: 11 parts; MY742: 11 parts; Thermoplastic toughening agents containing terminal hydroxyl or terminal amino groups: PEK: 15 parts; PEI: 15 parts; Core-shell toughening agents: MX153: 7 parts; MX257: 7 parts; Catalyst: Tin octoate: 0.2 parts.

[0055] Weigh each raw material according to the above proportions. Add bisphenol M cyanate, dicyclopentadiene cyanate, AG601, MY742, MX153, and MX257 to the reactor. Raise the temperature to 140°C, add tin octoate, and maintain the temperature at 140°C for 90 minutes under nitrogen protection to fully prepolymerize. Reduce the temperature to 120°C, add PEK and PEI, and perform a grafting reaction for 60 minutes. Test the viscosity every 20-30 minutes until the viscosity is between 40,000 and 60,000 cps at 65°C. Cool the temperature to below 70°C and discharge the material.

[0056] The main performance tests of this resin system are shown in Table 2.

[0057] After the resin composition was made into a 220gsm resin film, a single-lap joint test specimen was made using aluminum alloy sheet 2A12 (meeting the requirements of GJB 2053A standard) to test the tensile shear strength. A double-layer resin film, i.e., 420gsm, was used to bond the aluminum alloy sheet 2A12 and the aluminum alloy honeycomb component 2A12 (meeting the requirements of GJB 2053A standard), and then the specimens were cured in an oven (2 hours at 150℃ + 3 hours at 200℃). The performance of the cured specimens is shown in Table 2.

[0058] Example 4

[0059] The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate esters: Tetramethylbisphenol F cyanate ester: 15 parts; Bisphenol E cyanate ester: 15 parts; Phenolic cyanate ester: 15 parts; Biphenyl cyanate ester: 15 parts; Multifunctional epoxy resins: AG601: 8 parts; AFG90: 8 parts; MY0600: 8 parts; Thermoplastic toughening agents containing terminal hydroxyl or terminal amino groups: PPO: 10 parts; PES: 10 parts; PEI: 10 parts; Core-shell toughening agents: MX153: 5 parts; MX139: 5 parts; MX257: 5 parts; Catalyst: Dibutyltin dilaurate: 0.2 parts.

[0060] Weigh each raw material according to the above proportions. Add tetramethylbisphenol F cyanate, bisphenol E cyanate, phenolic cyanate, biphenyl cyanate, AG601, AFG90, MY0600, MX153, MX139, and MX257 to the reactor. Raise the temperature to 130°C, add dibutyltin dilaurate, and maintain the temperature at 130°C for a full prepolymerization reaction for 60 minutes under nitrogen protection. Maintain the temperature, add PPO, PES, and PEI, and perform a grafting reaction for 60 minutes. Test the viscosity every 20-30 minutes until the viscosity is between 40,000 and 60,000 cps at 65°C. Cool the temperature to below 70°C and discharge the material.

[0061] The main performance tests of this resin system are shown in Table 2.

[0062] After the resin composition was made into a 220gsm resin film, a single-lap joint test specimen was made using aluminum alloy sheet 2A12 (meeting the requirements of GJB 2053A standard) to test the tensile shear strength. A double-layer resin film, i.e., 420gsm, was used to bond the aluminum alloy sheet 2A12 and the aluminum alloy honeycomb component 2A12 (meeting the requirements of GJB 2053A standard), and then the specimens were cured in an oven (2 hours at 150℃ + 3 hours at 200℃). The performance of the cured specimens is shown in Table 2.

[0063] Comparative Example 1 (replacing the cyanate ester with a naphthol-type cyanate ester) The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate ester: Naphthol type cyanate ester: 40 parts; Multifunctional epoxy resin: AG80: 15 parts; Thermoplastic toughening agent containing terminal hydroxyl or terminal amino groups: PPO: 20 parts; Core-shell toughening agent: MX150: 10 parts; Catalyst: Manganese acetylacetone: 0.1 parts.

[0064] Weigh each raw material according to the above proportions. Add naphthol-type cyanate, AG80, and MX150 to the reactor. Raise the temperature to 130°C, add manganese acetylacetone, and maintain the prepolymerization reaction at 130°C for 60 minutes under nitrogen protection. Reduce the temperature to 110°C, add PPO, and perform a grafting reaction for 60 minutes. Test the viscosity every 20-30 minutes until the viscosity is between 40,000 and 60,000 cps at 65°C. Cool the temperature to below 70°C and discharge the material.

[0065] The main performance tests of this resin system are shown in Table 2.

[0066] After the resin composition was made into a 220gsm resin film, a single-lap joint test specimen was made using aluminum alloy sheet 2A12 (meeting the requirements of GJB 2053A standard) to test the tensile shear strength. A double-layer resin film, i.e., 420gsm, was used to bond aluminum alloy sheet 2A12 and aluminum alloy honeycomb component 2A12 (meeting the requirements of GJB 2053A standard), and then oven cured (2 hours at 150℃ + 3 hours at 200℃). The performance is shown in Table 2.

[0067] Comparative Example 2 (Epoxy resin replaced with ordinary bisphenol A epoxy resin) The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate ester: Bisphenol A cyanate ester: 40 parts; Bisphenol A epoxy resin: Nan Ya NPEL-128: 15 parts; Thermoplastic toughening agent containing terminal hydroxyl or terminal amino groups: PPO: 20 parts; Core-shell toughening agent: MX150: 10 parts; Catalyst: Manganese acetylacetone: 0.1 parts.

[0068] Weigh each raw material according to the above proportions. Add bisphenol A cyanate, Nan Ya NPEL-128, and MX150 to the reactor. Raise the temperature to 130°C, add manganese acetylacetone, and maintain the temperature at 130°C under nitrogen protection for a full prepolymerization reaction of 60 minutes. Reduce the temperature to 110°C, add PPO, and perform a grafting reaction for 60 minutes. Test the viscosity every 20-30 minutes until the viscosity is between 40,000 and 60,000 cps at 65°C. Cool the temperature to below 70°C and discharge the material.

[0069] The main performance tests of this resin system are shown in Table 2.

[0070] After the resin composition was made into a 220gsm resin film, a single-lap joint test specimen was made using aluminum alloy sheet 2A12 (meeting the requirements of GJB 2053A standard) to test the tensile shear strength. A double-layer resin film, i.e., 420gsm, was used to bond aluminum alloy sheet 2A12 and aluminum alloy honeycomb component 2A12 (meeting the requirements of GJB 2053A standard), and then oven cured (2 hours at 150℃ + 3 hours at 200℃). The performance is shown in Table 2.

[0071] Comparative Example 3 (using a thermoplastic toughening agent without terminal active groups) The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate ester: Bisphenol A cyanate ester: 40 parts; Multifunctional epoxy resin: AG80: 15 parts; Thermoplastic toughening agent without end-active groups: PPO (without end-active groups): 20 parts; Core-shell toughening agent: MX150: 10 parts; Catalyst: Manganese acetylacetone: 0.1 parts.

[0072] Weigh each raw material according to the above proportions. Add bisphenol A cyanate, AG80 and MX150 to the reactor. Raise the temperature to 130°C, add manganese acetylacetone, and maintain the temperature at 130°C under nitrogen protection for a full prepolymerization reaction for 60 minutes. Reduce the temperature to 110°C, add PPO (without terminal active groups), and mix and react for 180 minutes. However, PPO is still incompatible and the phase separates in the liquid. The formulation mixing has failed.

[0073] Comparative Example 4 (using two catalysts in combination) The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate ester: Bisphenol A cyanate ester: 40 parts; Multifunctional epoxy resin: AG80: 15 parts; Thermoplastic toughening agent containing terminal hydroxyl or terminal amino groups: PPO: 20 parts; Core-shell toughening agent: MX150: 10 parts; Catalysts: Manganese acetylacetone: 0.1 parts; Molybdenum ethoxide: 0.1 parts.

[0074] Weigh each raw material according to the above proportions. Add bisphenol A cyanate, AG80, and MX150 to the reactor. Raise the temperature to 130°C, add manganese acetylacetone and molybdenum ethoxide, and maintain the temperature at 130°C for a full prepolymerization reaction for 60 minutes under nitrogen protection. Reduce the temperature to 110°C, add PPO, and perform a grafting reaction for 60 minutes. Test the viscosity every 20-30 minutes until the viscosity is between 40,000 and 60,000 cps at 65°C. Cool the temperature to below 70°C and discharge the material.

[0075] The main performance tests of this resin system are shown in Table 2.

[0076] After the resin composition was made into a 220gsm resin film, a single-lap joint test specimen was made using aluminum alloy sheet 2A12 (meeting the requirements of GJB 2053A standard) to test the tensile shear strength. A double-layer resin film, i.e., 420gsm, was used to bond aluminum alloy sheet 2A12 and aluminum alloy honeycomb component 2A12 (meeting the requirements of GJB 2053A standard), and then oven cured (2 hours at 150℃ + 3 hours at 200℃). The performance is shown in Table 2.

[0077] Comparative Example 5 (catalyst replaced with zinc acetylacetonate) The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate ester: Bisphenol A cyanate ester: 40 parts; Multifunctional epoxy resin: AG80: 15 parts; Thermoplastic toughening agent containing terminal hydroxyl or terminal amino groups: PPO: 20 parts; Core-shell toughening agent: MX150: 10 parts; Catalyst: Zinc acetylacetonate: 0.1 parts.

[0078] Weigh each raw material according to the above proportions, add bisphenol A cyanate, AG80 and MX150 to the reactor, raise the temperature to 130°C, add zinc acetylacetonate, and maintain the temperature at 130°C for 60 minutes under nitrogen protection to fully prepolymerize. The resin is close to gel and difficult to stir.

[0079] Comparative Example 6 (Prepolymerization temperature too low) The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate ester: Bisphenol A cyanate ester: 40 parts; Multifunctional epoxy resin: AG80: 15 parts; Thermoplastic toughening agent containing terminal hydroxyl or terminal amino groups: PPO: 20 parts; Core-shell toughening agent: MX150: 10 parts; Catalyst: Manganese acetylacetone: 0.1 parts.

[0080] Weigh each raw material according to the above proportions. Add bisphenol A cyanate, AG80, and MX150 to the reactor. Raise the temperature to 120℃ (lower the prepolymerization temperature), add manganese acetylacetone, and maintain the prepolymerization reaction at 120℃ for 60 minutes under nitrogen protection. Lower the temperature to 110℃, add PPO, and perform a grafting reaction for 60 minutes. Test the viscosity every 20-30 minutes until the viscosity is between 40,000-60,000 cps@65℃. Cool the temperature to below 70℃ and discharge the material.

[0081] The main performance tests of this resin system are shown in Table 2.

[0082] After the resin composition was made into a 220gsm resin film, a single-lap joint test specimen was made using aluminum alloy sheet 2A12 (meeting the requirements of GJB 2053A standard) to test the tensile shear strength. A double-layer resin film, i.e., 420gsm, was used to bond aluminum alloy sheet 2A12 and aluminum alloy honeycomb component 2A12 (meeting the requirements of GJB 2053A standard), and then oven cured (2 hours at 150℃ + 3 hours at 200℃). The performance is shown in Table 2.

[0083] When the resin film is bonded to the aluminum sheet, the wetting is poor, which may be due to the epoxy resin and cyanate ester not being prepolymerized properly, or the prepolymerization temperature being too low.

[0084] Comparative Example 7 (with core-shell rubber toughening agent removed) The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate ester: Bisphenol A cyanate ester: 40 parts; Multifunctional epoxy resin: AG80: 15 parts; Thermoplastic toughening agent containing terminal hydroxyl or terminal amino groups: PPO: 20 parts; Catalyst: Manganese acetylacetone: 0.1 parts.

[0085] Weigh each raw material according to the above proportions. Add bisphenol A cyanate and AG80 to the reactor. Raise the temperature to 130°C, add manganese acetylacetone, and maintain the temperature at 130°C under nitrogen protection for a full prepolymerization reaction for 60 minutes. Reduce the temperature to 110°C, add PPO, and perform a grafting reaction for 60 minutes. Test the viscosity every 20-30 minutes until the viscosity is between 40,000-60,000 cps@65°C. Cool the temperature to below 70°C and discharge the material.

[0086] The main performance tests of this resin system are shown in Table 2.

[0087] After the resin composition was made into a 220gsm resin film, a single-lap joint test specimen was made using aluminum alloy sheet 2A12 (meeting the requirements of GJB 2053A standard) to test the tensile shear strength. A double-layer resin film, i.e., 420gsm, was used to bond aluminum alloy sheet 2A12 and aluminum alloy honeycomb component 2A12 (meeting the requirements of GJB 2053A standard), and then oven cured (2 hours at 150℃ + 3 hours at 200℃). The performance is shown in Table 2.

[0088] Comparative Example 8 (The core-shell rubber toughening agent was replaced with a liquid nitrile rubber toughening agent) The cyanate composition of the present invention comprises the following raw materials by weight: Cyanate ester: Bisphenol A cyanate ester: 40 parts; Multifunctional epoxy resin: AG80: 15 parts; Thermoplastic toughening agent containing terminal hydroxyl or terminal amino groups: PPO: 20 parts; Carboxyl-terminated liquid nitrile butadiene rubber: CTBN: 10 parts; Catalyst: Manganese acetylacetone: 0.1 parts.

[0089] Weigh each raw material according to the above proportions. Add bisphenol A cyanate, AG80, and CTBN to the reactor. Raise the temperature to 130°C, add manganese acetylacetone, and maintain the prepolymerization reaction at 130°C for 60 minutes under nitrogen protection. Reduce the temperature to 110°C, add PPO, and perform a grafting reaction for 60 minutes. Test the viscosity every 20-30 minutes until the viscosity is between 40,000-60,000 cps at 65°C. Cool the temperature to below 70°C and discharge the material.

[0090] The main performance tests of this resin system are shown in Table 2.

[0091] After the resin composition was made into a 220gsm resin film, a single-lap joint test specimen was made using aluminum alloy sheet 2A12 (meeting the requirements of GJB 2053A standard) to test the tensile shear strength. A double-layer resin film, i.e., 420gsm, was used to bond aluminum alloy sheet 2A12 and aluminum alloy honeycomb component 2A12 (meeting the requirements of GJB 2053A standard), and then oven cured (2 hours at 150℃ + 3 hours at 200℃). The performance is shown in Table 2.

[0092] Table 1. Raw material composition of the examples and comparative examples Table 2 Performance Comparison of Examples and Comparative Examples As can be seen from Examples 1-4 above, the formulation and preparation method system of the present invention possesses extremely high stability, with stable viscosity and gel time under different combinations. The tensile shear strength of the adhesive film at room temperature (25℃) remains stable at around 33-37 MPa, and even under severe high temperatures of 200℃, its tensile shear strength decreases very little, exhibiting excellent heat resistance retention; simultaneously, the roller peel strength is as high as approximately 50 N·m / m, ensuring extremely high structural bonding toughness. Comparative Example 1, by replacing the cyanate ester with a naphthol-type cyanate ester, showed that the gel time was significantly extended to 32 min; the tensile shear strength decreased significantly at both room temperature and high temperature, the roller peel performance decreased, and the overall bonding performance decreased; Comparative Example 2, by replacing the multifunctional epoxy resin AG80 with Nanya NPEL-128 (ordinary bisphenol A epoxy resin), extended the gel time to 38 min. The tensile shear strength and roller peel performance decreased significantly. In Comparative Example 3, the PPO was replaced with a version without terminal active groups. The results showed that even after cooling to 110℃ and reacting for 180 min, the PPO was still incompatible and phase separation occurred in the liquid, resulting in uneven dispersion and formulation failure. In Comparative Example 4, 0.1 parts of manganese acetylacetone and 0.1 parts of molybdenum ethanol were added simultaneously. The surface resin film adhered poorly to the aluminum sheet, the tensile shear strength at room temperature dropped sharply, and it detached directly at high temperature. In the aluminum honeycomb roller peel test, it detached easily by hand and could not be tested. The reason is speculated to be that the use of two catalysts together caused catalyst failure or poisoning, and the epoxy resin and cyanate ester failed to prepolymerize successfully. In Comparative Example 5, the catalyst was replaced with acetylacetone. With 0.1 parts zinc, the results showed that after a full prepolymerization reaction at 130℃ for 60 min, the resin state was close to gel. Due to the strong effect of the accelerator, stirring was difficult, and prepolymerization failed. In Comparative Example 6, the prepolymerization temperature was too low, and the epoxy resin and cyanate ester failed to prepolymerize as expected, resulting in insufficient wettability with the aluminum sheet and poor adhesion. In Comparative Example 7, the viscosity increased after removing the core-shell rubber toughening agent, and the tensile shear strength at both room temperature and high temperature decreased. The roller peel performance decreased significantly, and the overall adhesion performance decreased. In Comparative Example 8, after replacing the core-shell rubber toughening agent with liquid nitrile rubber toughening agent, the results showed that the tensile shear strength at room temperature decreased, and the tensile shear strength at high temperature decreased significantly. The roller peel performance also decreased, and the overall adhesion performance decreased.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high bond strength cyanate ester composition characterized in that The raw materials include the following parts by weight: 40-70 parts of cyanate ester resin, 15-30 parts of multifunctional epoxy resin, 20-40 parts of thermoplastic resin toughening agent containing terminal hydroxyl or terminal amino groups, 10-20 parts of core-shell rubber toughening agent, and 0.1-0.3 parts of catalyst.

2. The high bond strength cyanate ester composition of claim 1, wherein, The core-shell rubber toughening agent includes one or more of Zhongyuan MX150, MX153, MX154, MX139, and MX257.

3. The high bond strength cyanate ester composition of claim 1, wherein, The thermoplastic resin toughening agent containing terminal hydroxyl or terminal amino groups includes one or more of PPO, PES, PEK, and PEI.

4. The high bond strength cyanate ester composition of claim 1, wherein, The cyanate resin includes one or more of the following: bisphenol A cyanate resin, bisphenol F cyanate resin, bisphenol M cyanate resin, dicyclopentadiene cyanate resin, tetramethylbisphenol F cyanate resin, bisphenol E cyanate resin, phenolic cyanate resin, and biphenyl cyanate resin.

5. The high bond strength cyanate ester composition of claim 1, wherein, The multifunctional epoxy resin includes one or more of Shanghai Huayi AG80, AFG90, AG601, Huntsman MY0600, and MY742.

6. The high bond strength cyanate ester composition of claim 1, wherein, The catalyst includes one of manganese acetylacetonate, molybdenum ethoxylate, tin octoate, and dibutyltin dilaurate.

7. A method for preparing a high-adhesion-strength cyanate ester composition according to any one of claims 1-6, characterized in that... Includes the following steps: S1. Mix 40-70 parts by weight of cyanate ester resin, 15-30 parts by weight of multifunctional epoxy resin, and 10-20 parts by weight of core-shell rubber toughening agent, and heat to 130-150℃; S2. Add 0.1-0.3 parts by weight of catalyst to the mixture obtained in step S1, and fully prepolymerize at 130-150℃ under nitrogen protection; S3. Cool the mixture obtained in step S2 to 110-130℃, add 20-40 parts by weight of thermoplastic resin toughening agent containing terminal hydroxyl or terminal amino groups, stir thoroughly, and control the target viscosity to 40000-60000cps@65℃; S4. Cool to below 70℃ to complete the discharge.

8. The high-adhesion-strength cyanate composition according to claim 7, characterized in that, In step S2, the prepolymerization reaction takes 60-120 minutes.

9. A method for preparing an adhesive film, characterized in that... Includes the following steps: The high-adhesion-strength cyanate ester composition according to any one of claims 1-6 is melted into the glue tank of a dry coating machine, and uniformly coated onto the release paper through the roller gap to form a resin film. A layer of fiberglass felt is then laminated during the winding stage to prepare an adhesive film.

10. The use of a high-adhesion-strength cyanate ester composition according to any one of claims 1-6, or the adhesive film according to claim 9, in heat-resistant materials and microwave-transparent materials.

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