A low-temperature-curable high-heat cyanate ester resin system and a preparation method thereof

Abstract

The present application relates to a kind of low-temperature curable high heat cyanate ester resin system and preparation method, it relates to high polymer material technical field, the low-temperature curable high heat cyanate ester resin system includes cyanate ester resin, temperature-resistant modified resin, crosslinking catalyst, accelerator, toughening agent.The present application is by using the crosslinking catalyst containing poly-b amine and cyano group low-temperature curing cyanate ester resin and occurs crosslinking reaction with cyanate ester resin, solves the existing cyanate ester resin system high curing temperature, stress after curing, metal ion residue and other technical problems.The low-temperature curable high heat cyanate ester resin body realizes low-temperature curing, with high glass transition temperature, low heat loss and excellent dielectric performance, and the resin after curing has good comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a low-temperature curable high heat-resistant cyanate ester resin system and its preparation method. Background Technology

[0002] Cyanate ester resins, due to their highly aromatic triazine crosslinking structure, combine the processability of epoxy resins with the heat resistance of polyimides, occupying an irreplaceable position in aerospace structural composites, high-frequency printed circuit boards, and high-reliability electronic packaging. The curing mechanism of cyanate esters involves the cyclization of cyanate ester groups (–OCN) into triazine rings under heat or catalysis; this reaction is exothermic, with a theoretical heat release of approximately 105 kJ / mol. However, the curing reaction of industrial-grade bisphenol C (CE) typically requires post-curing at 180–220°C, or even 250°C. The resulting high energy consumption, large temperature difference residual stress, and expensive mold costs have become common bottlenecks in the manufacturing process of large composite components.

[0003] Existing low-temperature curing strategies can be broadly classified into three categories: (1) metal catalyst systems; (2) active hydrogen synergistic systems; and (3) latent ionic liquid or microcapsule systems. The first category uses acetylacetone metal salts (such as...) The first type, represented by phenolic hydroxyl groups, can initiate cyanate ester cyclization at 120–140°C. However, residual metal ions migrate under high temperature and humidity, leading to a sharp increase in dielectric loss, a decrease in tracking resistance, and a potential threat to the insulation reliability of RF substrates. Furthermore, metal salts are prone to hydrolysis, and their shelf life is typically less than one month. The second type uses phenolic hydroxyl groups, carboxyl groups, or primary amines as cooperating proton donors to reduce the cyclization activation energy through a six-membered ring transition state. The phenol-cyanate ester system has been studied most extensively. However, an equal amount of phenol is required to significantly reduce the curing temperature, resulting in a decrease in crosslinking density and a significant reduction in Tg and damp heat strength. Moreover, phenolic hydroxyl groups are easily oxidized to quinone structures at high temperatures, causing a darker substrate color and an increased dielectric constant. Furthermore, the active hydrogen cooperating system (phenolic hydroxyl groups, carboxyl groups, primary / secondary amines) generally suffers from a significant decrease in heat resistance while reducing the curing temperature of cyanate esters, becoming another bottleneck limiting its high-end applications. The third type involves microencapsulating ionic liquids, quaternary ammonium salts, or amine catalysts. Although these catalysts have a latent effect at room temperature, the thermal decomposition temperature of the microcapsule wall material (<200°C) overlaps with the curing temperature of the cyanate ester. The amine salts released after the capsule wall ruptures also cause degradation of εr and tanδ. Furthermore, the preparation process is complex and costly.

[0004] In recent years, although some studies have attempted to introduce primary amines or phenolic hydroxyl groups into aromatic rings and synergistically cure cyanate esters, their catalytic activity is still insufficient to initiate full triazineization at temperatures below 100°C, and excessive active hydrogen leads to increased network polarity and decreased heat resistance. Therefore, how to integrate a "low-temperature high-activity catalytic center" and a "high-temperature self-crosslinking site" within a single molecule, and precisely control the room-temperature pot life and final crosslinking density through a designable stoichiometric ratio, has become a key scientific problem in overcoming the bottleneck of low-temperature curing technology for cyanate ester resins. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a low-temperature curable high heat-resistant cyanate ester resin system and its preparation method, in order to solve the problems of high curing temperature, high stress after curing, and metal ion residue in existing cyanate ester resin compositions.

[0006] The crosslinking catalyst with a specific structure in the low-temperature curable high heat-resistant cyanate ester resin composition of the present invention can synergistically undergo cycloaddition of –OCN in the cyanate ester resin to form a triazine ring, realizing the integration of "catalysis-copolymerization". Without the need for external crosslinking agent, a cyanate ester resin that can be cured at a minimum temperature below 80°C (e.g., 72°C) can be prepared under metal-free and low-polarity conditions.

[0007] To achieve the above objectives, a first aspect of the present invention provides a low-temperature curable, high-heat-resistant cyanate ester resin composition, the composition comprising: 60-90 parts by weight of cyanate ester resin, 1-30 parts by weight of heat-resistant thermosetting resin, 1-8 parts by weight of crosslinking catalyst, 0.2-4 parts by weight of accelerator, and 0-10 parts by weight of toughening agent; wherein the crosslinking catalyst has the structure shown in Formula I: Formula I Where Ar is aryl; m=1~3, n=2~3, m+n=3~6.

[0008] Furthermore, in the crosslinking catalyst, the aryl group is selected from at least one of benzene, biphenyl, naphthalene, anthracene, pyridine, pyrimidine, furan, or thiophene.

[0009] Furthermore, in the crosslinking catalyst, the cyano group and the primary amine group are located at the para, ortho, meta, or biphenyl bridge position of the aryl group.

[0010] Furthermore, the cyanate resin is selected from monomers or prepolymers of at least one compound selected from bisphenol A cyanate, bisphenol E cyanate, bisphenol M cyanate, phenolic cyanate, dicyclopentadiene cyanate, and bisphenol F cyanate.

[0011] Furthermore, the temperature-resistant thermosetting resin is selected from at least one thermosetting resin selected from bismaleimide resin, benzoxazine resin and polyimide resin.

[0012] Furthermore, the accelerator is selected from at least one of boron trifluoride complex, 4-dimethylaminopyridine, aromatic diazonium salt, imidazole, benzimidazole, pyridine, 2,2′-(1,3-phenylene)-dioxazoline, phosphononitrile base, phosphononitrile salt, polysilazane, and tertiary amine.

[0013] Furthermore, the toughening agent is selected from at least one of polyetherimide, phenolphthalein polyethersulfone, polyethersulfone, carboxyl-terminated butadiene-acrylonitrile rubber, epoxy-terminated butadiene-acrylonitrile rubber, amino-terminated butadiene-acrylonitrile rubber, amino-terminated polyether, and silicone rubber.

[0014] The second aspect of the present invention provides a method for preparing a low-temperature curable high heat-resistant cyanate ester resin composition, wherein the composition described in the first aspect is mixed to obtain a low-temperature curable high heat-resistant cyanate ester resin.

[0015] Furthermore, the method includes: S1. In the first reaction vessel, under the first stirring, the cyanate ester resin, toughening agent and accelerator are mixed evenly at the first temperature; S2: In the second reactor, under the second stirring, the temperature-resistant thermosetting resin and the crosslinking catalyst are mixed and homogenized at the second temperature; S3: Mix the products from the first and second reaction vessels and perform a third stirring to obtain a low-temperature curable high-heat-resistant cyanate ester resin.

[0016] Furthermore, the conditions for the first, second, and third stirring are independent: stirring speed of 50~300 rpm and stirring time of 20~100 min.

[0017] Furthermore, the first temperature is 50~120℃, the second temperature is 50~100℃, and the third temperature is 20~30℃.

[0018] The third aspect of the present invention provides a low-temperature curable, high-heat-resistant cyanate ester resin prepared by the preparation method described in the first aspect.

[0019] The fourth aspect of this invention provides the application of a low-temperature curable, high-heat-resistant cyanate ester resin in aerospace structural composite materials, high-frequency printed circuit boards, and high-reliability electronic packaging.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. The crosslinking catalyst with the structure shown in Formula I introduced in this invention simultaneously carries nucleophilic primary amine groups within the same molecular framework. With the high-temperature self-crosslinking site of the cyano group (–C≡N), a single-molecule bifunctional integration is achieved. The primary amine group catalyzes the curing of cyanate ester at ≤100℃, significantly reducing the reaction activation energy. The cyano group copolymerizes with the cyanate ester to form a triazine-trionitrile crosslinking network, eliminating the need for additional metal catalysts. The resulting low-temperature curable, high-heat-resistant cyanate ester resin exhibits excellent dielectric properties, with a metal ion content of <20ppm in the cured product and a volume resistivity reaching [missing value]. The above methods can effectively avoid the risk of electromigration in high-frequency and high-speed packaging, while significantly simplifying the design of the formulation system and the control of the production process.

[0021] 2. This invention utilizes the strong electron-withdrawing effect of the cyano group to reduce the electron cloud density of the aromatic ring, significantly weakening the nucleophilicity of the primary amine. By adjusting the number of m and n in the crosslinked catalyst with the structure shown in Formula I, it can be adapted to the operating window requirements of different processes, making the solution of this invention more flexible and with a wider range of applications.

[0022] 3. This invention significantly optimizes the thermal stability of low-temperature curable, high-heat-resistant cyanate ester resin by crosslinking the formonitrile groups of the catalyst and the cyanate ester self-polymerization network through a triazine-trionitrile heterocyclic structure and a secondary self-polymerization reaction. Thermal stability test results show that the mass loss during the curing process is greatly reduced, with the mass loss at 300℃ reduced to below 1.22%.

[0023] 4. This invention does not introduce catalysts such as transition metal chelates that do not participate in the reaction. Characterization by inductively coupled plasma spectroscopy / mass spectrometry (ICP-OES / MS) confirmed that the residual metal ions are <10ppm and the dielectric properties are excellent: the dielectric constant (εr) at 10MHz is reduced to 2.88-2.95 and the dielectric loss tangent (tanδ) is ≤0.003, which meets the material requirements for high-power chip and antenna integrated packaging.

[0024] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0025] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0026] Figure 1 This is a schematic diagram of the cyanate reaction catalyzed by the crosslinking catalyst of the present invention. Detailed Implementation

[0027] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0028] Currently, existing cyanate ester resin compositions suffer from problems such as high curing temperature, high stress after curing, and residual metal ions, which seriously affect the application of cyanate ester resins. Based on this, in order to solve the above problems, the first aspect of the present invention provides a low-temperature curable high heat-resistant cyanate ester resin composition, characterized in that the composition comprises: 60-90 parts by weight of cyanate ester resin, 1-30 parts by weight of heat-resistant thermosetting resin, 1-8 parts by weight of crosslinking catalyst, 0.2-4 parts by weight of accelerator, and 0-10 parts by weight of toughening agent; The crosslinking catalyst has the structure shown in Formula I: Formula I Where Ar is aryl; m=1~3, n=2~3, m+n=3~6.

[0029] In this invention, by simultaneously introducing primary amine and cyano groups into the crosslinking catalyst, synergistic effects with other components in the composition can be achieved. Specifically, the primary amine groups in the crosslinking catalyst can cure the cyanate resin in the composition at low temperatures, significantly reducing the activation energy of the reaction. At the same time, the cyano groups in the crosslinking catalyst undergo a self-crosslinking reaction with the -OCN in the cyanate resin in the composition to form a stable triazine structure, reducing additional gas production and other defects caused by non-crosslinking catalysts, eliminating the need for additional metal catalysts. Furthermore, the accelerator further optimizes the curing process, and the introduction of the toughening agent effectively releases internal stress. Without significantly sacrificing heat resistance and mechanical properties, the resulting low-temperature curable high-heat-resistant cyanate resin is ensured to have excellent comprehensive performance, including an ultra-high glass transition temperature (Tg>240℃) and extremely low dielectric loss (tanδ<0.006).

[0030] Furthermore, the cyano group in the crosslinking catalyst undergoes a "cyano-cyanate" copolymerization reaction with the -OCN group of the cyanate ester resin during the heating process. It not only participates in the construction of a dense triazine-trionitrile hybrid crosslinking network, but also forms an interpenetrating or co-crosslinking structure with the heat-resistant thermosetting resin. This greatly improves the thermal stability of the cured product while avoiding the use of metal catalysts and eliminating ion residues.

[0031] According to some embodiments of the present invention, in the crosslinking catalyst, the aryl group is selected from at least one of benzene, biphenyl, naphthalene, anthracene, pyridine, pyrimidine, furan or thiophene, preferably benzene, biphenyl or naphthalene.

[0032] In this invention, the aryl group serves as the core skeleton, and its conjugated structure regulates the electronic effects of the primary amine and cyano groups. Benzene, biphenyl, or naphthalene are preferred, which, while ensuring high activity, endows the system with excellent storage and thermal stability. Benzene is even more preferred.

[0033] According to some embodiments of the present invention, in the crosslinking catalyst, the cyano group and the primary amine group are located at the para, ortho, meta, or biphenyl bridging position of the aryl group. The position of the functional groups regulates the intensity of the electronic effect through spatial arrangement such as para and meta positions, achieving a precise balance between curing rate and storage stability, and providing flexibility for process design.

[0034] According to some preferred embodiments of the present invention, the crosslinking catalyst is, by way of example, at least one selected from 1,4-diamino-2,5-dicyanophenylene, 2,5-diaminobenzonitrile, 4,4'-diamino-[1,1'-biphenyl]-3,3'-dicarboxynitrile and 4,4'-diamino-[1,1'-biphenyl]-3-carboxynitrile.

[0035] According to some embodiments of the present invention, the cyanate resin is selected from monomers or prepolymers of at least one compound selected from bisphenol A cyanate, bisphenol E cyanate, bisphenol M cyanate, phenolic cyanate, dicyclopentadiene cyanate, and bisphenol F cyanate.

[0036] In this invention, when the cyanate ester is selected from the above-mentioned types, it can precisely synergize with the crosslinking catalyst to ensure efficient catalytic curing by the primary amine at low temperature. At the same time, its own -OCN functional group can copolymerize with the cyano group of the crosslinking catalyst to jointly construct a dense and thermally stable triazine network, which is the basis for achieving a balance between low-temperature process and ultimate heat resistance. Preferably, it is 1,1-bis(4-cyanoxyphenyl)ethane.

[0037] According to some embodiments of the present invention, the temperature-resistant thermosetting resin is selected from at least one thermosetting resin selected from bismaleimide resin, benzoxazine resin and polyimide resin.

[0038] In this invention, the thermosetting resin with high temperature resistance is used as a key copolymer component. Its high rigidity skeleton and active groups (such as maleimide double bonds and oxazine rings) can undergo co-crosslinking reactions with cyanate ester and cyano groups in the catalyst to synergistically construct a denser and more stable interpenetrating network. This improves the glass transition temperature of the prepared cyanate ester resin without sacrificing the advantages of low-temperature curing.

[0039] According to some preferred embodiments of the present invention, the temperature-resistant thermosetting resin is selected from at least one of 4,4'-diphenylmethane bismaleimide, bisphenol A diphenyl ether bismaleimide, N,N'-ethylidene bismaleimide, N,N'-hexamethylene bismaleimide, polyphenylmethane polymaleimide, bismaleimide-triazine resin, bisphenol A type benzoxazine, bisphenol F type benzoxazine, MDA type benzoxazine, DCPD type benzoxazine, phenol type benzoxazine, phenolphthalein type benzoxazine, and polyimide.

[0040] According to some embodiments of the present invention, the accelerator is selected from at least one of boron trifluoride complex, 4-dimethylaminopyridine, aromatic diazonium salt, imidazole, benzimidazole, pyridine, 2,2'-(1,3-phenylene)-dioxazoline, triphenylphosphine, phosphononitrile base, phosphononitrile salt, polysilazane, and tertiary amine.

[0041] In this invention, the aforementioned types of accelerators and primary amines in the crosslinking catalyst synergistically enhance each other, precisely controlling the trimerization process of cyanate esters, significantly reducing the curing temperature and accelerating the reaction rate, while ensuring that the obtained cyanate ester resin has excellent processability at room temperature.

[0042] According to some embodiments of the present invention, the toughening agent is selected from at least one of polyetherimide, phenolphthalein polyethersulfone, polyethersulfone, carboxyl-terminated butadiene-acrylonitrile rubber, epoxy-terminated butadiene-acrylonitrile rubber, amino-terminated butadiene-acrylonitrile rubber, amino-terminated polyether, and silicone rubber.

[0043] In this invention, the inventors discovered that the toughening agent selected from the above-mentioned types can significantly improve the impact resistance and fracture toughness of the cured product and inhibit internal stress cracking without significantly sacrificing the heat resistance and mechanical properties of the system.

[0044] According to some preferred embodiments of the present invention, the composition comprises, by weight, 70-90 parts of cyanate ester resin, 5-10 parts of heat-resistant thermosetting resin, 2-6 parts of crosslinking catalyst, 0.5-2 parts of accelerator, and 5-8 parts of toughening agent.

[0045] The second aspect of the present invention provides a method for preparing a low-temperature curable high heat-resistant cyanate ester resin composition, wherein the composition described in the first aspect is mixed to obtain a low-temperature curable high heat-resistant cyanate ester resin.

[0046] According to a specific embodiment of the present invention, the method includes: S1. In the first reaction vessel, under the first stirring, the cyanate ester resin, toughening agent and accelerator are mixed evenly at the first temperature; S2: In the second reactor, under the second stirring, the temperature-resistant thermosetting resin and the crosslinking catalyst are mixed and homogenized at the second temperature; S3: Mix the products from the first and second reaction vessels and perform a third stirring to obtain a low-temperature curable high-heat-resistant cyanate ester resin.

[0047] In this invention, a separate mixing process is employed to prevent prepolymerization by isolating the highly active primary amine groups from the -CNO groups in the cyanate ester resin, thus ensuring storage stability. Simultaneously, the solubility of each component is optimized through independent temperature control, ultimately achieving homogeneous blending and ensuring the system's excellent low-temperature curing properties and high heat resistance.

[0048] In this invention, Figure 1 As can be seen, the primary amine group in the crosslinking catalyst molecule acts as a highly efficient nucleophilic catalyst, attacking the cyanate groups of the cyanate ester resin at relatively low temperatures (≤120℃), significantly reducing the activation energy of its cyclization trimerization, and catalyzing the formation of a highly crosslinked network with a triazine ring as the core. Simultaneously, the cyano group of the catalyst itself, as a polymerizable functional group, can undergo copolymerization with the remaining -OCN groups in the system, further integrating and strengthening the triazine network, avoiding the residue of small molecule catalysts. Furthermore, the temperature-resistant thermosetting resin possesses highly active reaction sites. During the curing process, these active sites can react chemically with the intermediates or triazine rings of the cyanate ester resin; on the other hand, they can also undergo addition or cyclization copolymerization reactions with the cyano groups that have participated in or have not participated in the reaction in the crosslinking catalyst. This results in a dense interpenetrating or co-crosslinked network structure formed by covalent bonds between the triazine network formed by the cyanate ester and the rigid network of the temperature-resistant resin.

[0049] According to a specific embodiment of the present invention, the conditions for the first stirring, the second stirring and the third stirring are each independently: stirring rate of 50~300 rpm and stirring time of 20~100 min.

[0050] In this invention, when the conditions of the first stirring, the second stirring, and the third stirring each independently meet the above-mentioned range, the materials can be fully and uniformly mixed through appropriate shear force, while avoiding air entrainment or premature resin reaction due to excessive shearing, thus ensuring the uniformity and stability of the system.

[0051] According to a specific embodiment of the present invention, the first temperature is 50~120℃, the second temperature is 50~100℃, and the third temperature is 20~30℃.

[0052] In this invention, the first temperature (50~120℃) ensures that the cyanate ester resin and the additives are fully melted and mixed; the second temperature (50~100℃) ensures that the heat-resistant resin melts and the catalyst is dispersed; and the third temperature (20~30℃) maintains the stability of the final mixed system and prevents premature curing, thus ensuring the feasibility of the process and the performance of the product.

[0053] The third aspect of the present invention provides a low-temperature curable, high-heat-resistant cyanate ester resin prepared by the preparation method described in the second aspect.

[0054] The fourth aspect of this invention provides an application of the low-temperature curable, high-heat-resistant cyanate ester resin described in the third aspect in aerospace structural composite materials, high-frequency printed circuit boards, and high-reliability electronic packaging.

[0055] To more clearly describe the present invention, the following embodiments and comparative examples are provided for further illustration.

[0056] In the following examples and comparative examples, the thermal stability of the low-temperature curable high heat-resistant cyanate ester resin was characterized by mass loss at 300°C, which was measured by TGA (thermogravimetric analysis) at 300°C in air atmosphere. Curing temperature: The curing exothermic peak temperature was measured by DSC (differential scanning calorimetry).

[0057] Glass transition temperature (Tg): Measured by DSC.

[0058] Dielectric properties: The dielectric loss tangent at 10MHz was measured using an impedance analyzer.

[0059] Volume resistivity: Measured by a high-resistivity meter.

[0060] Metal ion content: analyzed by inductively coupled plasma spectroscopy / mass spectrometry.

[0061] Example 1 S1. In the first reaction vessel, 90g of 1,1-bis(4-cyanooxyphenyl)ethane, 8g of terminal epoxy butadiene-acrylonitrile rubber (ETBN-20) and 1g of 2,2′-(1,3-phenylene)-dioxazoline are mixed and the temperature is slowly increased to 50°C at a rate of 5°C / min. The mixture is stirred at a stirring rate of 150 rpm until homogeneous. S2: In the second reactor, 5g of N,N'-hexamethylene bismaleimide and 5g of 2,4-diaminobenzonitrile are mixed and the temperature is slowly increased to 80°C at a rate of 4°C / min to dissolve the crosslinking catalyst and mix evenly at a stirring rate of 200 rpm. S3: Mix the products from the first and second reaction vessels and stir at a stirring rate of 100 rpm for 35 minutes to obtain a low-temperature curable high heat-resistant cyanate ester resin.

[0062] Example 2 The method is the same as in Example 1, except that in step S2, 2,4-diaminobenzonitrile is replaced with 4g of 4,4'-diamino-[1,1'-biphenyl]-3-carboxynitrile.

[0063] Example 3 The method is the same as in Example 1, except that in step S2, 2,4-diaminobenzonitrile is replaced with 4g of 1,4-diamino-2,5-dicyanobenzene.

[0064] Example 4 The method is the same as in Example 1, except that in step S2, 2,4-diaminobenzonitrile is replaced with 4g of 2,5-diaminobenzonitrile.

[0065] Example 5 The method is the same as in Example 1, except that the amount of 2,4-diaminobenzonitrile used is 8g.

[0066] Example 6 The method is the same as in Example 1, except that in step S1, the first reaction vessel contains 70g of 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 10g of carboxyl-terminated butadiene-acrylonitrile rubber CTBN-8, and 0.2g of triphenylphosphine; the second reaction vessel contains 10g of 4,4'-diaminodiphenyl sulfone benzoxazine and 5.2g of 1,4-diamino-2,5-dicyanobenzene.

[0067] The other steps are the same as in Example 1.

[0068] Example 7 S1. In the first reaction vessel, 85g of 1,1-bis(4-cyanooxyphenyl)ethane, 5g of terminal epoxy butadiene-acrylonitrile rubber (ETBN-20) and 1g of 2,2′-(1,3-phenylene)-dioxazoline are mixed and the temperature is slowly increased to 50°C at a rate of 5°C / min. The mixture is stirred at a stirring rate of 150 rpm until homogeneous. S2: In the second reactor, 10g of N,N'-hexamethylene bismaleimide and 5g of 2,4-diaminobenzonitrile are mixed and the mixture is slowly heated to 80°C at a rate of 5°C / min to dissolve the crosslinking catalyst and mix evenly at a stirring rate of 150 rpm. S3: Mix the products from the first and second reaction vessels and stir at a stirring rate of 100 rpm for 35 minutes to obtain a low-temperature curable high heat-resistant cyanate ester resin.

[0069] Example 8 S1. In the first reaction vessel, 70g of 2,2-bis(4-cyanoxyphenyl)propane, 10g of polyethersulfone E-2020 and 0.4g of 2-ethyl-4-methylimidazolium are mixed and the temperature is slowly increased to 95℃ at a rate of 10℃ / min. The mixture is stirred at a stirring rate of 200rpm until homogeneous. S2: In the second reactor, 15g of 6,6'-(propane-2,2-diyl)bis(3-phenyl-3,4-dihydro-2H-benzo[e][1,3]oxazine) and 1g of 2,4-diaminobenzonitrile are mixed, and the temperature is slowly increased to 80℃ at a rate of 10℃ / min to dissolve the crosslinking catalyst and mix evenly at a stirring rate of 300rpm. S3: Mix the products from the first and second reaction vessels and stir at a stirring rate of 120 rpm for 35 minutes to obtain a low-temperature curable high heat-resistant cyanate ester resin.

[0070] Example 9 The method is the same as in Example 1, except that in step S1, the temperature is slowly increased to 90°C at a rate of 5°C / min. In step S2, the temperature is slowly increased to 60°C at a rate of 5°C / min.

[0071] Comparative Example 1 The method is the same as in Example 1, except that it does not contain 2,4-diaminobenzonitrile, and the amount of N,N'-hexamethylene bismaleimide used is 7g.

[0072] Comparative Example 2 The method is the same as in Example 1, except that 2,4-diaminobenzonitrile is replaced with 4g of benzonitrile.

[0073] Comparative Example 3 The method is the same as in Example 1, except that 2,4-diaminobenzonitrile is replaced with 4g of isophorone diisocyanate.

[0074] Comparative Example 4 The method is the same as in Example 1, except that 2,4-diaminobenzonitrile is replaced with 4g of 2,4-diaminobenzane.

[0075] Comparative Example 5 The method is the same as in Example 1, except that 2,4-diaminobenzonitrile is replaced with 4g of 4-(dimethylamino)benzonitrile.

[0076] Comparative Example 6 The method is the same as in Example 1, except that the amount of 2,4-diaminobenzonitrile used is 10g.

[0077] Comparative Example 7 The method is the same as in Example 1, except that in step S1, the first reaction vessel contains: 95g of 1,1-bis(4-cyanooxyphenyl)ethane, 1g of terminal epoxy butadiene nitrile rubber (ETBN-20), and 0.1g of 2,2'-(1,3-phenylene)-dioxazoline. In step S2, the second reaction vessel contains: 35g of N,N'-hexamethylene bismaleimide and 0.5g of 2,4-diaminobenzonitrile.

[0078] Comparative Example 8 The method is the same as in Example 1, except that 2,4-diaminobenzonitrile is replaced with 4g of copper acetylacetonate.

[0079] Comparative Example 9 The method is the same as in Example 1, except that 2,4-diaminobenzonitrile is replaced with an equal amount of p-aminobenzonitrile.

[0080] Test case The low-temperature curable high heat-resistant cyanate ester resins prepared in the examples and comparative examples were cured as follows: 10 mg of the low-temperature curable high heat-resistant cyanate ester resin was placed in a sealed aluminum crucible, and under nitrogen atmosphere at a rate of 10 °C / min, the temperature was scanned from room temperature to 250 °C. The DSC curve was recorded, and the initial curing temperature was characterized by the exothermic peak onset temperature. The results are shown in Table 1.

[0081] The low-temperature curable high-heat-resistant cyanate ester resins prepared in the examples and comparative examples were subjected to thermal stability tests. Specifically, 10 mg of the low-temperature curable high-heat-resistant cyanate ester resin was placed in a ceramic crucible, and the temperature was increased from 30°C to 400°C at a rate of 10°C / min under air at a rate of 25 mL / min. The initial mass and the remaining mass at 300°C were recorded, and the percentage of mass loss at 300°C was calculated. The results are shown in Table 1.

[0082] Glass transition temperature: The low-temperature curable, high-heat-resistant cyanate ester resin was placed in an oven and heated at 80℃ for 2 hours, followed by heating at 300℃ for 1 hour to achieve complete curing. 10 mg of the cured resin was taken and heated from 30℃ to 400℃ at a rate of 10℃ / min under nitrogen atmosphere (50 mL / min). The DSC curve was recorded, and the glass transition temperature was represented by the characteristic peak. The results are shown in Table 1.

[0083] Dielectric loss tangent: Low-temperature curable, high-heat-resistant cyanate ester resin was placed in an oven and heated at 80℃ for 2 hours, followed by heating at 300℃ for 1 hour to achieve complete curing. The cured resin was cut into cylindrical sheets with a diameter of 20 mm and a thickness of 2 mm. The dielectric loss tangent tanδ of the resin at 10 MHz was measured and recorded using a dielectric testing instrument. The results are shown in Table 1.

[0084] Volume resistivity: The low-temperature curable, high-heat-resistant cyanate ester resin was placed in an oven and heated at 80°C for 2 hours, followed by heating at 300°C for 1 hour to achieve complete curing. The cured resin was then cut into cylindrical sheets with a diameter of 12.7 mm and a thickness of 1 mm. The volume resistivity of the resin samples was measured and recorded using a high-resistivity meter. The results are shown in Table 2.

[0085] Ion content: Take 10 mL of low-temperature curable high heat-resistant cyanate ester resin, digest all organic matter with nitric acid, and test and calculate the metal ion content of the resin by inductively coupled plasma mass spectrometry. The results are shown in Table 2.

[0086]

[0087]

[0088] The results above show that the simultaneous presence of at least two primary amine groups (-NH2) and cyano groups (–C≡N) in the crosslinking catalyst is key to achieving low-temperature curing and high thermal stability. In Examples 1-4 and 7-9, catalysts conforming to Formula I exhibited initial curing temperatures below 120°C and thermal weight loss below 1.22% at 300°C, indicating that the primary amine groups effectively catalyze the low-temperature triazinization of cyanate esters, while the cyano groups participate in copolymerization to construct a stable network, significantly improving thermal stability. In contrast, Comparative Example 2 (containing only cyano groups), Comparative Example 4 (containing only primary amines), and Comparative Example 5 (containing both tertiary amines and cyano groups) all showed increased curing temperatures or significantly increased thermal weight loss, confirming the synergistic effect of the primary amine-cyano bifunctional interaction.

[0089] In summary, this invention, by employing a crosslinking catalyst with a specific bifunctional structure, combined with a rationally proportioned cyanate ester resin, heat-resistant resin, and additives, achieves low-temperature (≤120℃) curing of cyanate ester resin without the need for a metal catalyst. Simultaneously, it achieves superior overall performance with high glass transition temperature (>240℃), low thermal weight loss (weight loss <1.22% at 300℃), low dielectric loss (tanδ <0.003), and high volume resistivity. This makes it particularly suitable for high-end applications such as high-frequency, high-speed electronic packaging and aerospace composite materials.

[0090] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-temperature curable, high-heat-resistant cyanate ester resin composition, characterized in that, The composition comprises, by weight, 60-90 parts of cyanate ester resin, 1-30 parts of heat-resistant thermosetting resin, 1-8 parts of crosslinking catalyst, 0.2-4 parts of accelerator, and 0-10 parts of toughening agent, wherein the crosslinking catalyst is at least one selected from 2,4-diaminobenzonitrile, 4,4'-diamino-[1,1'-biphenyl]-3-carboxynitrile, 1,4-diamino-2,5-dicyanophenylene, and 2,5-diaminobenzonitrile.

2. The composition according to claim 1, characterized in that, The cyanate resin is selected from monomers or prepolymers of at least one of the following compounds: bisphenol A cyanate, bisphenol E cyanate, bisphenol M cyanate, phenolic cyanate, dicyclopentadiene cyanate, and bisphenol F cyanate.

3. The composition according to claim 1, characterized in that, The temperature-resistant thermosetting resin is selected from at least one thermosetting resin among bismaleimide resin, benzoxazine resin and polyimide resin.

4. The composition according to any one of claims 1-3, characterized in that, The accelerator is selected from at least one of boron trifluoride complex, 4-dimethylaminopyridine, aromatic diazonium salt, imidazole, benzimidazole, pyridine, 2,2′-(1,3-phenylene)-dioxazoline, phosphononitrile base, phosphononitrile salt, polysilazane, and tertiary amine. And / or, the toughening agent is selected from at least one of polyetherimide, phenolphthalein polyethersulfone, polyethersulfone, carboxyl-terminated butadiene-acrylonitrile rubber, epoxy-terminated butadiene-acrylonitrile rubber, amino-terminated butadiene-acrylonitrile rubber, amino-terminated polyether, and silicone rubber.

5. A method for preparing a low-temperature curable, high-heat-resistant cyanate ester resin composition, characterized in that, Mixing the composition according to any one of claims 1-4 yields a low-temperature curable high heat-resistant cyanate ester resin.

6. The preparation method according to claim 5, characterized in that, The method includes: S1. In the first reaction vessel, under the first stirring, the cyanate ester resin, toughening agent and accelerator are mixed evenly at the first temperature; S2: In the second reactor, under the second stirring, the temperature-resistant thermosetting resin and the crosslinking catalyst are mixed and homogenized at the second temperature; S3: Mix the products from the first and second reaction vessels and perform a third stirring to obtain a low-temperature curable high-heat-resistant cyanate ester resin.

7. The preparation method according to claim 5 or 6, characterized in that, The conditions for the first, second, and third stirring are independent: stirring speed of 50~300 rpm and stirring time of 20~100 min.

8. A low-temperature curable, high-heat-resistant cyanate ester resin prepared by the preparation method according to any one of claims 5-7.

9. The application of the low-temperature curable, high-heat-resistant cyanate ester resin as described in claim 8 in aerospace structural composite materials, high-frequency printed circuit boards, and high-reliability electronic packaging.

Images