A temperature-variable curing low dielectric cyanate ester resin composition, prepreg and preparation method thereof

Abstract

The application discloses a variable-temperature curing low-dielectric cyanate ester resin composition, a prepreg and a preparation method thereof. The variable-temperature curing low-dielectric cyanate ester resin composition comprises the following components in parts by weight: 50-100 parts of cyanate ester resin; 15-30 parts of a multifunctional epoxy resin, wherein the multifunctional epoxy resin is a multifunctional glycidyl amine type epoxy resin, and the molecular structure comprises more than three epoxy groups and an aromatic amine skeleton, and the epoxy equivalent is 95-110 g / Eq; 10-20 parts of a toughening agent comprising one or more of polyphenylene ether, polyether ketone, polyether ether ketone, polyarylether ketone and polyether ether ketone containing terminal hydroxyl groups or terminal amino groups; and 0.05-0.1 parts of an accelerator. In-situ grafting reaction of the terminal hydroxyl groups or the terminal amino groups with the cyanate ester system is utilized, macroscopic phase separation of the thermoplastic resin in the curing process is avoided, excellent film-forming property and excellent dielectric property are ensured.

Description

Technical Field

[0001] This invention relates to the field of resin-based composite materials, and more particularly to a temperature-curing low-dielectric cyanate resin composition, a prepreg, and a method for preparing the same. Background Technology

[0002] Cyanate esters possess superior high-temperature mechanical properties, flexural strength, and tensile strength compared to difunctional epoxy resins. Their glass transition temperatures are typically above 240℃, and their thermal decomposition temperatures are generally above 400℃, surpassing most epoxy resins. They also exhibit low water absorption (<1.5%), minimal molding shrinkage, and good dimensional stability, making them widely used in the aerospace industry. After curing, cyanate ester resins form a triazine ring-containing structure. This symmetry reduces molecular polarity, thereby suppressing dipole polarization and resulting in lower dielectric properties, making them highly suitable for aerospace microwave-transparent materials. Many aerospace components are complex, and prepregs are the most suitable material for their manufacturing processes. Currently, there are relatively few cyanate ester systems used in prepregs, and users often have different curing requirements. Most cyanate ester systems require high-temperature curing (above 180℃), but many customers, due to limited resources or less demanding temperature requirements, require lower-temperature curing (e.g., below 150℃). However, these lower-temperature cured cyanate esters often have poor tack life (less than 10 days at room temperature), which is unfavorable for use in long manufacturing cycles. Summary of the Invention

[0003] The present invention aims to provide a temperature-curing low-dielectric cyanate resin composition, prepreg and its preparation method, which takes into account low-temperature curing, tack life, high-temperature performance and low dielectric constant.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A temperature-curing low-dielectric cyanate resin composition comprising the following materials in parts by weight: 50-100 parts cyanate ester resin, 0.05-0.1 parts accelerator; 15-30 parts of multifunctional epoxy resin, wherein the multifunctional epoxy resin is a multifunctional glycidylamine type epoxy resin, and the molecular structure contains ≥3 epoxy groups and an aromatic amine skeleton, and the epoxy equivalent is 95~110 g / Eq. 10-20 parts of toughening agent include one or more of polyphenylene ether, polyether ketone, polyether ether ketone, polyarylether ketone, and polyether ether ketone containing terminal hydroxyl or terminal amino groups.

[0005] In this invention, temperature-variable curing refers to two curing processes. One curing process involves holding the temperature at 120-140℃ and then curing at 170-190℃. The other curing process involves curing at room temperature and then curing at 120-140℃.

[0006] This invention utilizes an in-situ grafting reaction between terminal hydroxyl or terminal amino groups and a cyanate ester system, avoiding macroscopic phase separation of thermoplastic resins during the curing process, thus ensuring excellent film-forming properties and superior dielectric properties.

[0007] This invention is based on the above-mentioned multifunctional epoxy resin. In Comparative Example 2, after replacing the epoxy resin with ordinary E51 type bisphenol A, the Tg of the cured system dropped significantly to 197℃ (originally above 240℃), and the dielectric properties deteriorated. Comparative Example 4 removed the multifunctional epoxy resin, directly resulting in an extremely low system viscosity (500cps), which could not meet the coating process requirements of the prepreg.

[0008] The toughening agent must be a polyarylether ketone powder containing terminal hydroxyl or amino groups. Comparative Example 5 used PPO without active end groups, which prevented the toughening agent from chemically bonding with the resin matrix. After standing, phase separation and precipitation occurred, resulting in an uneven coating.

[0009] According to embodiments of the present invention, the present invention can be further optimized, and the optimized technical solution is as follows: The multifunctional epoxy resin includes one or more of Huntsman MY721, MY0510, MY0600, MY742, and MF-4230.

[0010] In one preferred embodiment, the cyanate resin includes one or more of bisphenol A cyanate, bisphenol F cyanate, tetramethylbisphenol F cyanate resin, and bisphenol M cyanate.

[0011] The cyanate esters used in this invention are one or more selected from bisphenol A, bisphenol F, bisphenol M, or tetramethylbisphenol F cyanate esters. In Comparative Example 1, after replacing the cyanate ester with a phenolic cyanate ester, the viscous life at room temperature dropped sharply to 2 days, and the dielectric constant and loss tangent increased significantly.

[0012] In one preferred embodiment, the promoter comprises one or more of acetylacetone transition metal salts or lauric acid transition metal salts, wherein the transition metal salt comprises one or more of chromium, manganese, zinc, iron, cobalt, nickel, and copper.

[0013] This invention requires the use of acetylacetonate or octanoate salts of transition metals (such as manganese, copper, chromium, iron, etc.). In Comparative Example 6, after replacing the metal with a non-transition metal (aluminum acetylacetonate), the catalytic activity was severely insufficient, and the prepolymerization reaction could not achieve the ideal viscosity required for preparing the prepreg.

[0014] In one preferred embodiment, the cyanate resin is present in parts by weight of 50-80 parts.

[0015] The present invention also discloses a method for preparing a temperature-curing low dielectric cyanate resin composition, comprising the following steps: S1. Heating 50-100 parts by weight of cyanate resin in a reaction vessel to 140-180°C, and stirring under nitrogen protection to obtain a prepolymer; S2. Cool the prepolymer from step S1 to 120-140℃, add 15-30 parts by weight of multifunctional epoxy resin and 0.05-0.1 parts by weight of accelerator, and perform prepolymerization under nitrogen protection to obtain the modified component; S3. Cool the modified component from step S2 to 90-110℃, add 10-20 parts by weight of toughening agent, and perform a prepolymerization reaction under nitrogen protection, then discharge the material.

[0016] In the early high-temperature prepolymerization stage (140-180℃), the cyanate ester itself first undergoes partial trimerization (forming a small amount of oxytriazine ring structures). After cooling and adding a multifunctional epoxy resin, the cyanate ester groups further copolymerize with the epoxy groups to form an oxazolinone ring structure. The reasonable ratio of these two heat-resistant and rigid structures is key to maintaining a high Tg and low dielectric constant in the system.

[0017] Commonly used polyethersulfone or polyphenylene ether thermoplastic toughening agents are prone to macroscopic phase separation during resin curing and crosslinking, leading to increased dielectric loss and poor film processability. This invention uses special toughening agents containing terminal hydroxyl or amino groups. These active end groups can covalently bond with cyanate or epoxy groups (i.e., in-situ grafting) during prepolymerization and subsequent curing, forming a stable phase (such as an island structure) at the microscopic level. This not only achieves the toughening effect of the thermoplastic resin but also eliminates precipitation.

[0018] Under nitrogen protection, this invention first performs partial trimerization of the cyanate ester bulk at 140-180℃, then cools down and sequentially adds epoxy resin and active toughening agent to carry out grafting and copolymerization reactions, precisely controlling the molecular weight and system viscosity.

[0019] Preferably, the heating temperature in step S1 is 140-160°C. This temperature range allows for variable-temperature curing, has lower dielectric properties, and a longer tack life.

[0020] In one preferred embodiment, in step S1, the reaction time under nitrogen protection with stirring is 6-8 hours.

[0021] In one preferred embodiment, in step S2, the prepolymerization reaction under nitrogen protection takes 30-60 minutes.

[0022] In one preferred embodiment, in step S3, the prepolymerization reaction time under nitrogen protection is 60-90 min.

[0023] The present invention also discloses a prepreg comprising the temperature-curing low-dielectric cyanate resin composition described above, or the temperature-curing low-dielectric cyanate resin composition prepared according to the preparation method described above.

[0024] The cyanate ester resin composition is combined with quartz fiber cloth to prepare a fabric prepreg, and the specific method is as follows: (1) The resin premix (the cyanate resin composition prepared in the embodiments of the present invention) is melted into the coating tank. The melted resin premix is ​​evenly coated onto the release paper through the gap between a pair of rollers of the coating machine to form a resin film.

[0025] (2) The upper resin film and the lower quartz fiber cloth are moved forward together in the prepreg machine. The rollers and heating plates are heated and pressurized to melt the resin and penetrate into the fabric fibers. The upper release paper is peeled off and covered with PE film to form quartz cloth prepreg.

[0026] Preferably, the quartz fiber cloth is the plain weave quartz fiber cloth QWB100 from Nanjing Glass Fiber Research Institute.

[0027] Preferably, the resin content of the fabric prepreg is 30-50% by weight.

[0028] Preferably, the melting temperature in step (1) is 70-90℃.

[0029] Preferably, in step (1), the weight of the resin film is controlled to be 60-70g by adjusting the roller speed and roller gap.

[0030] Preferably, the heating temperature in step (2) is 90-110℃.

[0031] In this invention, the selected cyanate ester is a crystalline solid at room temperature, becomes a very dilute liquid at 100°C, and undergoes a triazine reaction gradually under nitrogen protection in the range of 140-180°C. .

[0032] The reaction process is controlled to a certain stage to form a prepolymer, whose crystal structure is destroyed, turning it into a viscous liquid. The prepolymer is then cooled to 120-140℃, where the added epoxy resin reacts with the unreacted cyanate-OCN groups in the cyanate ester prepolymer, and can further react with the generated triazine ring. The products are all oxazolinone ring structures. While this structure has lower heat resistance and lower dielectric properties than cyanate ester, it improves bending performance and toughness. Simultaneously, the modified cyanate ester has a state closer to the viscosity and flowability of epoxy resin, which is beneficial for the processability of prepreg production and use. The added promoter... The accelerator can act as a catalyst to accelerate the reaction. In addition, this type of accelerator is also the basis for temperature-variable curing. The selected toughening agent has good compatibility with epoxy resin and epoxy-modified cyanate, which is conducive to uniform dispersion. At the same time, the active groups contained therein are conducive to grafting reaction with epoxy groups during the curing process, so that the toughening agent can be evenly distributed in the system and ensure the uniformity of the cured product. After screening, the activity of the selected accelerator is extremely weak to the whole system at room temperature, so that the tack life of the quartz cloth prepreg can reach 30 days at room temperature, which is beneficial for the long-term manufacturing of large parts.

[0033] Compared with the prior art, the beneficial effects of the present invention are: This invention breaks down the contradiction between low-temperature curing and long tack life. In existing technologies, lowering the curing temperature (≤150℃) often leads to a sharp reduction in the tack life at room temperature to less than 10 days. This invention, through the combination of a special transition metal catalyst and a stepped prepolymerization process, makes the viscosity of the system extremely stable at room temperature, and the tack life of the prepreg at room temperature is as long as 22-30 days (Examples 1-4), which greatly meets the long-cycle layup and manufacturing requirements of large-size, complex aerospace composite material components.

[0034] The resin system of this invention supports a two-step temperature-varying curing process (holding at 130°C, then curing at 180°C). It can achieve a certain degree of cross-linking and curing at a medium temperature of 130°C while maintaining good shape retention, making it ideal for use as a co-curing system, offering far greater flexibility than conventional pure high-temperature curing systems.

[0035] After introducing epoxy and toughening agents, the dielectric constant at 12.5 GHz is maintained below 3.20, and the loss tangent is as low as about 0.001, due to the strict avoidance of conventional bisphenol A epoxy resin with high polarity. It relies on the formation of highly cross-linked triazine ring and oxazolinone network by multifunctional epoxy and cyanate ester. It is an extremely ideal material for wave transmission and antenna radome.

[0036] After completing the 180℃ post-curing stage, the glass transition temperature (Tg) of the cured system can still reach as high as 244℃-249℃, perfectly preserving the ultra-high temperature mechanical stability of the cyanate ester resin. Attached Figure Description

[0037] Figure 1 The image shown is a photograph of the cyanate resin composition prepared in Example 1.

[0038] Figure 2 Photograph of a quartz fiber cloth prepreg (resin content ≈ 40%) formulated with cyanate ester resin in the same embodiment.

[0039] Figure 3 The DMA curve of the composite material obtained after curing the prepreg in Example 1 at 130℃ for 4 hours is shown.

[0040] Figure 4 The DMA curve of the composite material was obtained by curing the same prepreg at two temperatures: 130℃×2h and 180℃×4h. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. Example 1

[0042] This invention provides a temperature-curable low-dielectric cyanate composition and a method for preparing a prepreg, which consists of the following raw materials by weight: bisphenol A cyanate: 50 parts; MY721: 15 parts; terminal hydroxyl PPO: 10 parts; manganese acetylacetone: 0.05 parts.

[0043] The weighed bisphenol A cyanate was heated to 140°C in a reactor and reacted with stirring under nitrogen protection for 6 hours. The temperature was then lowered to 120°C, and MY721 and manganese acetylacetone were added. The reaction was continued under nitrogen protection for 30 minutes, then lowered to 90°C, and terminal hydroxyl PPO was added. The mixture was then fully prepolymerized under nitrogen protection for 60 minutes before being discharged. The main performance tests of this resin composition are shown in Table 3.

[0044] A cyanate ester resin composition was mixed with plain-weave quartz fiber cloth QWB100 from Nanjing Glass Fiber Research Institute to prepare a fabric prepreg with a resin content of 40%. The specific method is as follows: (1) The resin premix (the cyanate resin composition prepared in the embodiment of the present invention) is melted into the coating tank at a temperature of 80°C. The melted resin premix is ​​evenly coated onto the release paper through the gap between a pair of rollers of the coating machine to form a resin film. The weight of the resin film is controlled to be 67g by adjusting the roller speed and the roller gap.

[0045] (2) The upper resin film and the lower plain weave quartz fiber cloth QWB100 are moved forward together in the prepreg machine. The rollers and heating plates are heated to 100°C for heating and pressurization, so that the resin melts and penetrates into the fabric fibers. The upper release paper is peeled off and covered with PE film to form a quartz cloth prepreg with a resin content of 40%.

[0046] The prepreg prepared by the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min and held for 4 hours) to obtain the laminate properties shown in Table 4.

[0047] The prepreg prepared from the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min, held for 2 hours, and then increased to 180°C at 2°C / min, held for 4 hours). The properties of the resulting laminate are shown in Table 4. Example 2

[0048] This invention provides a temperature-curable low-dielectric cyanate composition and a method for preparing a prepreg, which consists of the following raw materials by weight: bisphenol F cyanate: 100 parts; MY0510: 30 parts; amino-terminated PEK: 20 parts; copper acetylacetonate: 0.1 parts.

[0049] The weighed bisphenol F cyanate was heated to 160°C in a reactor and reacted with stirring under nitrogen protection for 8 hours. The temperature was then lowered to 140°C, and MY0510 and manganese acetylacetone were added. The reaction was continued under nitrogen protection for 60 minutes, then lowered to 110°C, and terminal amino group PEK was added. The mixture was then fully prepolymerized under nitrogen protection for 90 minutes before being discharged. The main performance tests of this resin composition are shown in Table 3.

[0050] The prepreg prepared from the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min, and held for 4 hours). The properties of the resulting laminate are shown in Table 4.

[0051] The prepreg prepared by the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min and held for 2 hours, then increased to 180°C at 2°C / min and held for 4 hours) to obtain the laminate properties shown in Table 4. Example 3

[0052] This invention provides a temperature-curing low-dielectric cyanate composition and a method for preparing a prepreg, comprising the following raw materials by weight: tetramethylbisphenol F cyanate: 35 parts; bisphenol M cyanate: 35 parts; MY0600: 10 parts; MY742: 10 parts; terminal hydroxyl PEEK: 7.5 parts; terminal amino PEKK: 7.5 parts; ferric laurate: 0.03 parts; chromium acetylacetone: 0.03 parts.

[0053] The weighed tetramethylbisphenol F cyanate and bisphenol M cyanate were heated to 150°C in a reactor and reacted under nitrogen protection with stirring for 7 hours. The temperature was then lowered to 130°C, and MY0600, MY742, ferric laurate, and manganese acetylacetone were added. The reaction was maintained under nitrogen protection for 45 minutes, then lowered to 100°C, and terminal hydroxyl PEEK and terminal amino PEKK were added. The mixture was then fully prepolymerized under nitrogen protection for 75 minutes before being discharged. The main performance tests of this resin composition are shown in Table 3.

[0054] The prepreg prepared by the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min and held for 4 hours) to obtain the laminate properties shown in Table 4.

[0055] The prepreg prepared from the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min, held for 2 hours, and then increased to 180°C at 2°C / min, held for 4 hours). The properties of the resulting laminate are shown in Table 4. Example 4

[0056] This invention provides a temperature-curing low-dielectric cyanate composition and a method for preparing a prepreg, which consists of the following raw materials by weight: bisphenol A cyanate: 50 parts; Hubei Zhenzhengfeng MF-4230: 15 parts; hydroxyl-terminated PPO: 10 parts; zinc laurate: 0.05 parts.

[0057] The weighed bisphenol A cyanate was heated to 140°C in a reactor and reacted with stirring under nitrogen protection for 6 hours. The temperature was then lowered to 120°C, and MF-4230 and zinc laurate were added. The reaction was continued under nitrogen protection for 30 minutes, then lowered to 90°C, and terminal hydroxyl PPO was added. The mixture was then fully prepolymerized under nitrogen protection for 60 minutes before being discharged. The main performance tests of this resin composition are shown in Table 3.

[0058] The prepreg prepared from the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min, and held for 4 hours). The properties of the resulting laminate are shown in Table 4.

[0059] The prepreg prepared from the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min, held for 2 hours, and then increased to 180°C at 2°C / min, held for 4 hours). The properties of the resulting laminate are shown in Table 4. Example 5

[0060] This invention provides a temperature-curable low-dielectric cyanate composition and a method for preparing a prepreg, which consists of the following raw materials by weight: bisphenol A cyanate: 50 parts; MY721: 15 parts; terminal hydroxyl PPO: 10 parts; manganese acetylacetone: 0.05 parts.

[0061] The weighed bisphenol A cyanate was heated to 180°C in a reactor (to increase the prepolymerization temperature), and stirred under nitrogen protection for 6 hours. The temperature was then lowered to 120°C, MY721 and manganese acetylacetone were added, and the reaction was continued under nitrogen protection for 30 minutes. The temperature was then lowered to 90°C, terminal hydroxyl PPO was added, and the mixture was fully prepolymerized under nitrogen protection for 60 minutes before being discharged. The main performance tests of this resin composition are shown in Table 3.

[0062] The prepreg prepared by the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min and held for 4 hours) to obtain the laminate properties shown in Table 4.

[0063] The prepreg prepared by the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min and held for 2 hours, then increased to 180°C at 2°C / min and held for 4 hours) to obtain the laminate properties shown in Table 4.

[0064] Comparative Example 1 This invention provides a temperature-curing low-dielectric cyanate composition and a method for preparing a prepreg, which consists of the following raw materials by weight: phenolic cyanate: 50 parts (the type of cyanate may be changed); MY721: 15 parts; terminal hydroxyl PPO: 10 parts; manganese acetylacetone: 0.05 parts.

[0065] The weighed phenolic cyanate was heated to 120°C in a reactor (phenolic cyanate is a viscous liquid and does not require prepolymerization). MY721 and manganese acetylacetone were added, and the reaction was maintained at this temperature for 30 minutes under nitrogen protection. The temperature was then lowered to 90°C, and terminal hydroxyl PPO was added. The mixture was then fully prepolymerized for 60 minutes under nitrogen protection before being discharged. The main performance tests of this resin composition are shown in Table 3.

[0066] The prepreg prepared by the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min and held for 4 hours) to obtain the laminate properties shown in Table 4.

[0067] The prepreg prepared from the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min, held for 2 hours, and then increased to 180°C at 2°C / min, held for 4 hours). The properties of the resulting laminate are shown in Table 4.

[0068] Comparative Example 2 This invention provides a temperature-curing low-dielectric cyanate composition and a method for preparing a prepreg, which consists of the following raw materials by weight: phenolic cyanate: 50 parts; Nanya NPEL-128: 15 parts (replaced with E51 type bifunctional epoxy); terminal hydroxyl PPO: 10 parts; manganese acetylacetone: 0.05 parts.

[0069] The weighed bisphenol A cyanate was heated to 140°C in a reactor and reacted with stirring under nitrogen protection for 6 hours. The temperature was then lowered to 120°C, and NPEL-128 and manganese acetylacetone were added. The reaction was continued under nitrogen protection for 30 minutes, then lowered to 90°C, and terminal hydroxyl PPO was added. The mixture was then fully prepolymerized under nitrogen protection for 60 minutes before being discharged. The main performance tests of this resin composition are shown in Table 3.

[0070] The prepreg prepared by the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min and held for 4 hours) to obtain the laminate properties shown in Table 4.

[0071] The prepreg prepared by the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min and held for 2 hours, then increased to 180°C at 2°C / min and held for 4 hours) to obtain the laminate properties shown in Table 4.

[0072] Comparative Example 3 This invention provides a temperature-curable low-dielectric cyanate composition and a method for preparing a prepreg, which consists of the following raw materials by weight: bisphenol A cyanate: 50 parts; MY721: 15 parts; terminal hydroxyl PPO: 10 parts; manganese acetylacetone: 0.05 parts.

[0073] The weighed bisphenol A cyanate was heated to 140°C in a reaction vessel and stirred for 6 hours (without nitrogen gas). The composition was very dark black in color and had a high viscosity, making it impossible to stir with the stirrer.

[0074] Comparative Example 4 (Removal of Epoxy Resin) This invention provides a temperature-curable low-dielectric cyanate composition and a method for preparing a prepreg, which consists of the following raw materials by weight: bisphenol A cyanate: 50 parts; terminal hydroxyl PPO: 10 parts; manganese acetylacetone: 0.05 parts.

[0075] The weighed bisphenol A cyanate was heated to 140°C in a reactor and stirred under nitrogen protection for 6 hours. The temperature was then lowered to 120°C, manganese acetylacetone was added, and the reaction was carried out under nitrogen protection for 30 minutes. The temperature was then lowered to 90°C, terminal hydroxyl PPO was added, and the mixture was fully prepolymerized under nitrogen protection for 60 minutes before being discharged.

[0076] The resin composition has a very low viscosity, only 500 cps at 80°C (tested using a rotational viscometer), making it unsuitable for preparing prepregs.

[0077] Comparative Example 5 This invention provides a temperature-curable low-dielectric cyanate composition and a method for preparing a prepreg, which consists of the following raw materials by weight: bisphenol A cyanate: 50 parts; MY721: 15 parts; PPO (without terminal hydroxyl or amino groups): 10 parts; manganese acetylacetone: 0.05 parts.

[0078] The weighed bisphenol A cyanate was heated to 140°C in a reactor and stirred under nitrogen protection for 6 hours. The temperature was then lowered to 120°C, MY721 and manganese acetylacetone were added, and the reaction was carried out under nitrogen protection for 30 minutes. The temperature was then lowered to 90°C, terminal hydroxyl PPO was added, and the mixture was fully prepolymerized under nitrogen protection for 60 minutes before being discharged.

[0079] After being left for a few days, PPO precipitates out from the composition, making it impossible to prepare a prepreg by uniform coating.

[0080] Comparative Example 6 This invention provides a temperature-curable low-dielectric cyanate composition and a method for preparing a prepreg, which consists of the following raw materials by weight: bisphenol A cyanate: 50 parts; MY721: 15 parts; hydroxyl-terminated PPO: 10 parts; aluminum acetylacetonate (without transition metal complexes): 0.05 parts.

[0081] The weighed bisphenol A cyanate was heated to 140°C in a reactor and stirred under nitrogen protection for 6 hours. The temperature was then lowered to 120°C, MY721 and manganese acetylacetone were added, and the reaction was carried out under nitrogen protection for 30 minutes. The temperature was then lowered to 90°C, terminal hydroxyl PPO was added, and the mixture was fully prepolymerized under nitrogen protection for 60 minutes before being discharged.

[0082] The resin composition has a very low viscosity, only 900 cps at 80°C (tested using a rotational viscometer), making it unsuitable for preparing prepregs.

[0083] Comparative Example 7 This comparative example provides a temperature-curing low-dielectric cyanate composition and a method for preparing a prepreg, which consists of the following raw materials by weight: bisphenol A cyanate: 50 parts; MY721: 15 parts; hydroxyl-terminated PPO: 10 parts; manganese acetylacetone: 0.05 parts.

[0084] The weighed bisphenol A cyanate was heated to 120°C in a reactor (reducing the reaction temperature), and stirred under nitrogen protection for 8 hours. MY721 and manganese acetylacetone were added, and the reaction was maintained under nitrogen protection for 30 minutes. The temperature was then lowered to 90°C, and terminal hydroxyl PPO was added. The mixture was prepolymerized under nitrogen protection for 60 minutes before being discharged. The main performance tests of the resin composition are shown in Table 3.

[0085] The cyanate composition had such low viscosity that the coating temperature was reduced to 70°C and the impregnation temperature to 90°C, thus enabling the preparation of prepreg.

[0086] The prepreg prepared from the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min and held for 4 hours). It was not fully cured and the prepreg still had fluidity.

[0087] The prepreg prepared by the above cyanate ester resin composition was cured in an autoclave (from room temperature at 6 bar pressure, the temperature was increased to 130°C at 2°C / min and held for 2 hours, then increased to 180°C at 2°C / min and held for 4 hours) to obtain the laminate properties shown in Table 4.

[0088] Examples 1-4 show little difference in performance, all exhibiting variable-temperature curing, low dielectric properties, and long tack life. In Example 5, although the viscosity of the cyanate composition increased after raising the prepolymer temperature, prepreg could still be prepared, and the dielectric properties remained largely unchanged. However, the tack life at room temperature was significantly reduced, making long-term storage at room temperature unsuitable. In Comparative Example 7, although the viscosity of the cyanate decreased after lowering the prepolymer temperature and the process could be adjusted to produce prepreg, it could not simultaneously meet the variable-temperature curing conditions of 130°C and 180°C, requiring only high-temperature curing. In Comparative Example 1, changing to a phenolic cyanate ester resulted in a drastically reduced tack life at room temperature, making room-temperature storage virtually impossible. Although the Tg increased, its dielectric constant and loss tangent increased significantly. After Comparative Example 2 was replaced with a difunctional ordinary bisphenol A epoxy resin, the Tg decreased significantly, and the dielectric constant and loss tangent also increased. After Comparative Example 3 was not prepolymerized with nitrogen, the entire prepolymerization process was uncontrollable and it basically gelled, making it unusable as a prepreg resin. After Comparative Example 4 removed the epoxy resin, the viscosity was too low to meet the requirements for making prepreg resin. After Comparative Example 5 used a toughening agent without terminal active hydroxyl and amino groups, the toughening agent could not be dispersed evenly. After Comparative Example 6 was replaced with a non-transition metal acetylacetone complex, the activity was too low, and the prepolymerization reaction could not reach the state for preparing prepreg.

Claims

1. A temperature-curing, low-dielectric cyanate ester resin composition, characterized in that, The materials include the following parts by weight: 50-100 parts cyanate ester resin, 0.05-0.1 parts accelerator; 15-30 parts of multifunctional epoxy resin, wherein the multifunctional epoxy resin is a multifunctional glycidylamine type epoxy resin, and the molecular structure contains ≥3 epoxy groups and an aromatic amine skeleton, and the epoxy equivalent is 95~110 g / Eq. 10-20 parts of toughening agent include one or more of polyphenylene ether, polyether ketone, polyether ether ketone, polyarylether ketone, and polyether ether ketone containing terminal hydroxyl or terminal amino groups.

2. The temperature-curing low-dielectric cyanate ester resin composition according to claim 1, characterized in that, The multifunctional epoxy resin includes one or more of Huntsman MY721, MY0510, MY0600, MY742, and MF-4230.

3. The temperature-curing low-dielectric cyanate ester resin composition according to claim 1, characterized in that, The cyanate resin includes one or more of bisphenol A cyanate, bisphenol F cyanate, tetramethylbisphenol F cyanate resin, and bisphenol M cyanate.

4. The temperature-curing low-dielectric cyanate resin composition according to claim 1, characterized in that, The accelerator includes one or more of acetylacetone transition metal salts or lauric acid transition metal salts, wherein the transition metal salts include one or more of chromium, manganese, zinc, iron, cobalt, nickel, and copper.

5. The temperature-curing low-dielectric cyanate ester resin composition according to claim 1, characterized in that, The cyanate ester resin is present in parts by weight of 50-80 parts.

6. A method for preparing a temperature-curing low-dielectric cyanate ester resin composition, characterized in that, Includes the following steps: S1. Heat 50-100 parts by weight of cyanate ester resin in a reactor to 140-180℃, and stir under nitrogen protection to obtain a prepolymer; S2. Cool the prepolymer from step S1 to 120-140℃, add 15-30 parts by weight of multifunctional epoxy resin and 0.05-0.1 parts by weight of accelerator, and perform prepolymerization under nitrogen protection to obtain the modified component; S3. Cool the modified component from step S2 to 90-110℃, add 10-20 parts by weight of toughening agent, and perform a prepolymerization reaction under nitrogen protection, then discharge the material.

7. The method for preparing the temperature-curing low-dielectric cyanate ester resin composition according to claim 6, characterized in that, In step S1, the reaction is carried out under nitrogen protection with stirring for 6-8 hours.

8. The method for preparing the temperature-curing low-dielectric cyanate resin composition according to claim 6, characterized in that, In step S2, the prepolymerization reaction under nitrogen protection takes 30-60 minutes.

9. The method for preparing the temperature-curing low-dielectric cyanate ester resin composition according to claim 6, characterized in that, In step S3, the prepolymerization reaction under nitrogen protection takes 60-90 minutes.

10. A prepreg, characterized in that, Includes the temperature-curing low-dielectric cyanate resin composition according to any one of claims 1-5, or the temperature-curing low-dielectric cyanate resin composition prepared by the preparation method according to any one of claims 6-9.

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