Epoxy resin special for copper-clad plate with low dielectric loss and synthesis process of epoxy resin

Abstract

The invention relates to the technical field of epoxy resin materials, in particular to low-dielectric-loss epoxy resin special for a copper-clad plate and a synthesis process of the low-dielectric-loss epoxy resin, and the low-dielectric-loss epoxy resin is synthesized from the following components: low-viscosity liquid epoxy resin, a composite chain extension modifier, an efficient selective compound catalyst, an antioxidant, a diluent and a catalyst regulator. According to the technical scheme, the signal attenuation of the copper-clad plate in a high-frequency signal transmission scene is remarkably reduced, the transmission rate and the stability are greatly improved, and the use requirements of advanced electronic equipment such as 5G communication and high-frequency radar can be better met. Meanwhile, the material has good viscosity stability and processing suitability, the coating difficulty and the rejection rate in the production process of the copper-clad plate are reduced, the production efficiency is improved, and the production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin materials technology, specifically to a low dielectric loss epoxy resin for copper clad laminates and its synthesis process. Background Technology

[0002] With the rapid development of electronic information technologies such as 5G communication and high-frequency radar, the requirements for signal transmission rate and stability of electronic devices are constantly increasing. Copper-clad laminates (CCLs), as a core basic material for electronic circuits, directly affect the operating efficiency of the entire electronic system. In high-frequency signal transmission scenarios, dielectric loss is a key factor restricting signal transmission quality. Excessive dielectric loss not only leads to signal attenuation and transmission delay but may also affect the lifespan and reliability of electronic devices due to heat generation. Therefore, developing epoxy resins specifically for CCLs with low dielectric loss has become a key research direction in the industry.

[0003] Currently, epoxy resins used in copper-clad laminates on the market still have significant shortcomings in terms of dielectric properties. Traditional epoxy resins are mostly prepared using conventional methods, resulting in a high content of polar groups in the molecular chain structure. Under the influence of high-frequency electric fields, they are prone to polarization loss, leading to a high dielectric loss factor, which is difficult to meet the requirements of high-frequency communication.

[0004] Therefore, there is an urgent need to develop a specially formulated and optimized epoxy resin for copper clad laminates that can ensure low dielectric loss while also taking into account good viscosity stability, mechanical properties and processing compatibility, in order to solve many problems existing in the current technology. Summary of the Invention

[0005] The purpose of this invention is to provide a low dielectric loss epoxy resin for copper clad laminates and its synthesis process.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A low dielectric loss epoxy resin for copper clad laminates is synthesized from the following components in parts by weight: 46-54 parts of low viscosity liquid epoxy resin, 20-28 parts of composite chain extender modifier, 0.8-1.3 parts of high efficiency selective compound catalyst, 0.4-0.7 parts of antioxidant, 3-6 parts of diluent, and 0.1-0.2 parts of catalyst modifier; The low-viscosity liquid epoxy resin is bisphenol F type epoxy resin EP-4400, with an epoxy value of 0.51-0.55 eq / 100g; The diluent is the reactive diluent butyl glycidyl ether; The catalyst modifier is dimethylformamide; The composite chain extender modifier is a pre-crosslinked complex of bisphenol A, resorcinol-type epoxy resin, hydrolyzed modified KH-560, and crosslinking accelerator triallyl isocyanurate. The amount of triallyl isocyanurate added is 0.35-0.55% of the total weight of the composite chain extender modifier. The pre-crosslinking reaction temperature is 96-104℃, the pre-crosslinking reaction time is 1.5-1.9h, the pre-crosslinking reaction stirring rate is 320-430r / min, and the pre-crosslinking reaction endpoint is defined as the system viscosity reaching 800-1000mPa·s (25℃). Resorcinol-type epoxy resin RE-180, epoxy value 0.62-0.66 eq / 100g.

[0007] As a further technical solution, the weight ratio of bisphenol A, resorcinol-type epoxy resin, and hydrolyzed modified KH-560 in the composite chain extender modifier is 10:6.5:4.8.

[0008] As a further technical solution, the preparation steps of the hydrolyzed modified KH-560 are as follows: KH-560 is added to deionized water, the weight ratio of KH-560 to deionized water is 1:2-2.5, the reaction temperature is controlled at 32-38℃, the stirring rate is 220-280r / min, 0.14-0.26mol / L hydrochloric acid is added dropwise to adjust the pH of the system to 4.7-5.3, and the hydrolysis reaction is carried out for 1.5-2.0h. The hydrolysis reaction is considered to be complete when the system is free of oily stratification and presents as a homogeneous transparent liquid. After the reaction is completed, 34-46% by weight of anhydrous ethanol of KH-560 is added, and the mixture is stirred for 30min to obtain the hydrolyzed modified KH-560.

[0009] As a further technical solution, the highly efficient selective composite catalyst is composed of tetrabutylammonium bromide and triphenylphosphine in a weight ratio of 2-3:1.

[0010] As a further technical solution, the antioxidant is a hindered phenolic antioxidant, selected from antioxidant 1010 and antioxidant 1076.

[0011] The synthesis process of low dielectric loss epoxy resin for copper clad laminates adopts an improved catalytic two-step addition method, including a prepolymerization stage, a chain growth stage, and a post-treatment stage, as follows: the chain growth stage adopts a bisphenol A segmented feeding strategy; TAIC is added during the preparation of the composite chain extender modifier to carry out a pre-crosslinking reaction; the entire synthesis process adopts a temperature-catalyst synergistic control mechanism.

[0012] As a further technical solution, the temperature-catalyst synergistic regulation mechanism is as follows: In the prepolymerization stage, the addition rate of the highly efficient and selective compound catalyst is 0.011-0.019 g / min, corresponding to a temperature range of 64-86℃. The end point of the prepolymerization stage is determined by the epoxy value of the system decreasing to 0.35-0.40 eq / 100g. In the chain growth stage, at 90-100℃, the catalyst addition rate is 0.008-0.01 g / min, and at 100-120℃, the catalyst addition rate is 0.005-0.009 g / min. In the chain growth stage, 30 minutes before heating to 127-133℃ and holding for 1.0-1.5 hours, the catalyst regulator is added all at once, the stirring rate is adjusted to 350-400 r / min, and after stirring for 10-15 minutes, the temperature is held for the specified time.

[0013] As a further technical solution, the prepolymerization stage adopts a segmented gradient heating method, the specific steps of which are as follows: The first step is to add low-viscosity liquid epoxy resin to the reactor, heat it to 62-68℃, keep it at that temperature for 22-28 minutes, and then add half of the high-efficiency selective compound catalyst at a rate of 0.011-0.019 g / min. During the addition process, the stirring rate is maintained at 320-380 r / min. The second step involves heating the temperature to 82-88℃ at a rate of 1.2-1.8℃ / min and holding it at that temperature for 32-38 minutes to carry out the prepolymerization ring-opening reaction. Nitrogen gas is introduced for protection throughout the prepolymerization process at a flow rate of 0.85-1.15L / min. The prepolymerization endpoint is determined by the epoxy value of the system decreasing to 0.35-0.40eq / 100g.

[0014] As a further technical solution, the specific steps of the chain growth stage are as follows: the pre-crosslinked composite chain extender modifier is added to the reaction system in three equal portions, each accounting for 1 / 3 of the total weight of the composite chain extender modifier. The temperature control accuracy of the reactor is ±0.5℃. Before each addition, the temperature of the reaction system is stabilized at 92-98℃. During the addition process, the temperature fluctuation is controlled to not exceed ±1.6℃, with an interval of 22-28 minutes between additions. The stirring rate during the addition process is 400-500 r / min. After the addition is completed, the temperature is raised to 112-118℃ at a heating rate of 0.5-1.0℃ / min and held for 2-3 hours. Then, the temperature is raised to 127-135℃ and held for 1.0-1.5 hours. The remaining amount of high-efficiency selective compound catalyst is added at this stage. The end point of the chain growth stage is defined as the system viscosity reaching 1500-1800 mPa·s (25℃) and the epoxy value decreasing to 0.12-0.16 eq / 100g.

[0015] As a further technical solution, the specific steps of the post-processing stage are as follows: the temperature inside the reactor is lowered to 92-98℃, antioxidants and diluents are added, the stirring rate is adjusted to 300-350 r / min, and after stirring evenly, the temperature is maintained for 32-38 min; then, at an ambient temperature of 25-30℃, the temperature is naturally cooled to below 50℃ at a rate of 0.34-0.46℃ / min, while maintaining a stirring rate of 220-280 r / min during the cooling process; after cooling, the mixture is filtered using a 0.22μm organic filter membrane, with the filtration pressure controlled at 0.1-0.15MPa, and then dried at 82-88℃ for 2-2.5 h to obtain the finished product.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The technical solution of this invention uses bisphenol F type epoxy resin EP-4400 as a low-viscosity liquid epoxy resin matrix. Its molecular chain structure is relatively regular and its polarity is moderate. Compared with traditional epoxy resins, it can reduce the polarization movement of polar groups under a high-frequency electric field, thereby reducing the source of dielectric loss and solving the problem of excessive dielectric loss caused by the high polarity of traditional resins. In the composite chain extender modifier, bisphenol A, resorcinol type epoxy resin RE-180, and hydrolyzed modified KH-560 are compounded in a specific ratio. The hydrolyzed modified KH-560 increases the number of surface hydroxyl groups by adjusting the hydrolysis reaction conditions with hydrochloric acid, significantly improving its compatibility with the resin matrix. It can be uniformly dispersed in the system, avoiding the interface defects formed by the easy aggregation of unmodified KH-560, thereby reducing interface polarization loss and improving the stability of the material's dielectric properties. Triallyl isocyanurate, as a crosslinking promoter, constructs a three-dimensional crosslinking network through a pre-crosslinking reaction, locking the free movement of molecular chains, further suppressing polarization loss, and improving the rigidity of molecular chains, thus laying the foundation for improving the mechanical strength of materials.

[0017] 2. The highly efficient and selective composite catalyst is composed of tetrabutylammonium bromide and triphenylphosphine in a specific ratio. Compared with a single catalyst, it exhibits higher catalytic activity and stronger selectivity, catalyzing the ring-opening addition reaction between epoxy resin and modifier, avoiding side reactions, thus ensuring the regularity of the molecular chain structure and reducing dielectric loss caused by structural defects. The addition of the catalyst modifier dimethylformamide effectively regulates the catalyst activity, preventing the reaction rate from being too fast or too slow, ensuring a stable reaction, and providing a guarantee for the formation of a uniform and dense cross-linked network. The addition of antioxidants inhibits the oxidative degradation of the resin during synthesis and use, reducing the increase of polar groups caused by oxidation products, thereby maintaining the long-term stability of dielectric properties and extending the service life of copper-clad laminates.

[0018] 3. In terms of the synthesis process, the prepolymerization stage employs a segmented gradient heating and staged catalyst addition strategy. This avoids the violent reaction caused by excessively high local concentrations in the early stages, ensuring a gentle and thorough prepolymerization reaction. This guarantees a stable epoxy value of 0.35-0.40 eq / 100g in the prepolymer, laying a solid foundation for subsequent chain growth reactions. The staged bisphenol A feeding and temperature-catalyst synergistic control mechanism in the chain growth stage control the growth rate and crosslinking degree of the molecular chains, ensuring uniform chain growth and consistent crosslinking density. This reduces heterogeneity in the molecular chain structure and consequently lowers polarization losses. The gradient cooling and precision filtration steps in the post-treatment stage remove impurities and bubbles from the reaction system, reducing internal defects in the material and ensuring the stability of the finished product's viscosity. This provides excellent processing adaptability for the coating process in copper clad laminate production.

[0019] 4. The synergistic effect of each component and the synthesis process achieves synergistic optimization of multiple properties. The combination of the pre-crosslinking reaction of the composite chain extender and the catalysis of the highly efficient and selective composite catalyst results in a more uniform and dense three-dimensional crosslinked network, significantly improving the rigidity and regularity of the molecular chains. This not only further reduces dielectric loss but also enhances intermolecular forces, thereby simultaneously improving the mechanical strength of the material. The good compatibility of the hydrolyzed modified KH-560 and the synergistic effect of the crosslinking of triallyl isocyanurate not only solve the problem of uneven dispersion of the modifier but also lock the position of the modifier through the crosslinked network, avoiding performance degradation caused by modifier migration during use, thus ensuring the long-term stability of the dielectric and mechanical properties of the material.

[0020] 5. The addition of the reactive diluent butyl glycidyl ether not only reduces the initial viscosity of the resin and improves processing fluidity, but also participates in the cross-linking reaction, forming stable chemical bonds with other components, thus avoiding the performance fluctuation problems caused by the volatility of traditional diluents. The synergistic effect of the catalyst regulator and the compound catalyst allows for dynamic adjustment of catalytic activity according to the reaction temperature and stage, ensuring rate adaptation at different reaction stages, further improving the uniformity of the cross-linking network, and providing a guarantee for the synergistic optimization of multiple material properties.

[0021] 6. The technical solution of this invention significantly reduces signal attenuation in high-frequency signal transmission scenarios, greatly improving transmission speed and stability, thus better meeting the needs of advanced electronic devices such as 5G communication and high-frequency radar. Simultaneously, the material's excellent viscosity stability and processing adaptability reduce the coating difficulty and scrap rate during copper-clad laminate production, helping to improve production efficiency and reduce production costs. Attached Figure Description

[0022] Figure 1 This is a comparison chart of the linear shrinkage rates of the example and the comparative example over 7 days. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] This invention provides a low dielectric loss epoxy resin for copper clad laminates and its synthesis process. The low dielectric loss epoxy resin for copper clad laminates is synthesized from the following components in parts by weight: 46-54 parts of low viscosity liquid epoxy resin, 20-28 parts of composite chain extender modifier, 0.8-1.3 parts of high efficiency selective compound catalyst, 0.4-0.7 parts of antioxidant, 3-6 parts of diluent, and 0.1-0.2 parts of catalyst regulator. The synthesis process adopts an improved catalytic two-step addition method. Through a temperature-catalyst synergistic control mechanism and a segmented feeding strategy, the product performance of low dielectric loss and high stability is achieved.

[0025] Low viscosity liquid epoxy resin: Bisphenol F type epoxy resin EP-4400, epoxy value 0.51-0.55eq / 100g, using commercially available qualified products.

[0026] Composite chain extender modifier: a pre-crosslinked composite of bisphenol A, resorcinol-type epoxy resin, hydrolyzed modified KH-560, and crosslinking accelerator triallyl isocyanurate; wherein the resorcinol-type epoxy resin is RE-180 with an epoxy value of 0.62-0.66 eq / 100g, the weight ratio of bisphenol A, resorcinol-type epoxy resin, and hydrolyzed modified KH-560 is 10:6.5:4.8, and the amount of triallyl isocyanurate added is 0.35-0.55% of the total weight of the composite chain extender modifier.

[0027] Highly efficient selective compound catalyst: It is composed of tetrabutylammonium bromide and triphenylphosphine in a weight ratio of 2-3:1. Both components are commercially available analytical grade reagents.

[0028] Antioxidant: Hindered phenolic antioxidant, selected from antioxidant 1010 or antioxidant 1076, using commercially available products.

[0029] Diluent: Butyl glycidyl ether, a commercially available analytical grade reagent.

[0030] Catalyst modifier: dimethylformamide, commercially available analytical grade reagent.

[0031] Hydrolysis-modified KH-560: It is prepared by hydrolysis reaction of KH-560 with deionized water under specific conditions. The KH-560 used is a commercially available industrial grade product, and the hydrochloric acid and anhydrous ethanol are commercially available analytical grade reagents.

[0032] Preparation of hydrolyzed modified KH-560: Add KH-560 to deionized water at a weight ratio of 1:2-2.5. Control the reaction temperature at 32-38℃ and the stirring rate at 220-280 r / min. Add 0.14-0.26 mol / L hydrochloric acid dropwise to adjust the pH of the system to 4.7-5.3 and carry out the hydrolysis reaction for 1.5-2.0 h. The hydrolysis reaction ends when the system is free of oily stratification and forms a homogeneous transparent liquid. After the reaction is completed, add 34-46% by weight of anhydrous ethanol to KH-560 and stir for 30 min to obtain hydrolyzed modified KH-560.

[0033] Preparation of composite chain extender modifier: Weigh out bisphenol A, resorcinol-type epoxy resin RE-180, and hydrolyzed modified KH-560 in a weight ratio of 10:6.5:4.8, mix them evenly, and add them to a reaction vessel. Then add triallyl isocyanurate, accounting for 0.35-0.55% of the total weight of the composite chain extender modifier. Control the pre-crosslinking reaction temperature at 96-104℃, the stirring rate at 320-430 r / min, and the reaction for 1.5-1.9 h until the viscosity of the system reaches 800-1000 mPa・s (25℃). Stop the reaction to obtain the composite chain extender modifier.

[0034] The synthesis process of epoxy resin: An improved two-step catalytic addition method is employed, comprising a prepolymerization stage, a chain growth stage, and a post-processing stage, as detailed below: S1 prepolymerization stage: A segmented gradient heating method is adopted. In the first step, low-viscosity liquid epoxy resin is added to the reactor, heated to 62-68℃, and held for 22-28 min. Then, half of the high-efficiency selective compound catalyst is added at a rate of 0.011-0.019 g / min, while maintaining a stirring rate of 320-380 r / min during the addition process. In the second step, the temperature is increased to 82-88℃ at a rate of 1.2-1.8℃ / min and held for 32-38 min to carry out the prepolymerization ring-opening reaction. Nitrogen gas is purged throughout the prepolymerization process at a flow rate of 0.85-1.15 L / min. The prepolymerization endpoint is determined by the epoxy value of the system decreasing to 0.35-0.40 eq / 100g.

[0035] S2 Chain Growth Phase: A staged feeding strategy for bisphenol A was adopted, in which the pre-crosslinked composite chain extender modifier was added to the reaction system in three equal portions, each accounting for 1 / 3 of the total weight of the composite chain extender modifier. The temperature control accuracy of the reactor was ±0.5℃. Before each feeding, the temperature of the reaction system was stabilized at 92-98℃, and the temperature fluctuation during the feeding process was controlled to not exceed ±1.6℃. The feeding interval was 22-28 min, and the stirring rate during the feeding process was 400-500 r / min. The remaining amount of high-efficiency selective composite catalyst was added at this stage. At 90-100℃, the catalyst addition rate was 0.008-0.01 g / min, and at 100-120℃, the catalyst addition rate was... The catalyst addition rate is 0.005-0.009 g / min; after the feeding is completed, the temperature is raised to 112-118℃ at a heating rate of 0.5-1.0℃ / min and held for 2-3 hours, then raised to 127-133℃ and held for 1.0-1.5 hours. Within the first 30 minutes after the temperature is raised to 127-133℃, the catalyst regulator is added all at once, the stirring rate is adjusted to 350-400 r / min, and the stirring is continued for 10-15 minutes, and then the temperature is held for the specified time. The end point of the chain growth stage is defined as the system viscosity reaching 1500-1800 mPa・s (25℃) and the epoxy value decreasing to 0.12-0.16 eq / 100g.

[0036] S3 post-processing stage: The temperature inside the reactor is lowered to 92-98℃, antioxidants and diluents are added, and the stirring rate is adjusted to 300-350 r / min. After stirring evenly, the mixture is kept at this temperature for 32-38 min. Then, at an ambient temperature of 25-30℃, the temperature is naturally lowered to below 50℃ at a rate of 0.34-0.46℃ / min, while maintaining a stirring rate of 220-280 r / min during the cooling process. After cooling, the mixture is filtered through a 0.22μm organic filter membrane at a pressure of 0.1-0.15MPa, and then dried at 82-88℃ for 2-2.5 h. After drying, a low dielectric loss epoxy resin product for copper-clad laminates is obtained.

[0037] This invention utilizes a specific raw material ratio and synthesis process to produce an epoxy resin with low dielectric loss characteristics, good viscosity stability, and mechanical properties, meeting the requirements of copper-clad laminates in high-frequency communication applications. The combination of a segmented feeding strategy and a temperature-catalyst synergistic control mechanism effectively controls the reaction rate, avoids performance defects caused by excessively vigorous local reactions, and improves batch stability of the product.

[0038] To further illustrate the present invention, the following detailed description is provided through the examples and comparative examples.

[0039] Example 1: (I) Preparation of hydrolyzed modified KH-560: KH-560 was added to deionized water at a weight ratio of 1:2. The reaction temperature was controlled at 32℃ and the stirring rate at 220 r / min. 0.14 mol / L hydrochloric acid was added dropwise to adjust the pH of the system to 4.7. The hydrolysis reaction was carried out for 1.5 h. The reaction reached its endpoint when the system was a homogeneous and transparent liquid without any oily layering. After the reaction was completed, 34% of the weight of KH-560 in anhydrous ethanol was added and the mixture was stirred for 30 min to obtain hydrolyzed modified KH-560.

[0040] (II) Preparation of composite chain extender modifier: Bisphenol A, resorcinol-type epoxy resin RE-180, and hydrolyzed modified KH-560 were weighed in a weight ratio of 10:6.5:4.8, mixed evenly, and added to a reaction vessel. Then, triallyl isocyanurate, accounting for 0.35% of the total weight of the composite chain extender modifier, was added. The pre-crosslinking reaction temperature was controlled at 96℃, the stirring rate at 320r / min, and the reaction was stopped after 1.5h when the viscosity of the system reached 800mPa・s (25℃). The composite chain extender modifier was obtained.

[0041] (III) Synthesis of epoxy resin: Raw material ratio: 46 parts low viscosity liquid epoxy resin, 20 parts composite chain extender modifier, 0.8 parts high efficiency selective compound catalyst (tetrabutylammonium bromide to triphenylphosphine weight ratio 2:1), 0.4 parts antioxidant 1010, 3 parts diluent, and 0.1 parts catalyst regulator.

[0042] S1 Prepolymerization Stage: 46 parts of low-viscosity liquid epoxy resin were added to the reactor, heated to 62℃, and held for 22 min. Then, 0.4 parts of high-efficiency selective composite catalyst were added at a rate of 0.011 g / min, and the stirring rate was maintained at 320 r / min during the addition process. Subsequently, the temperature was increased to 82℃ at a rate of 1.2℃ / min and held for 32 min to carry out the prepolymerization ring-opening reaction. Nitrogen gas was introduced for protection throughout the prepolymerization process, with a nitrogen flow rate of 0.85 L / min. The prepolymerization endpoint was reached when the epoxy value of the system dropped to 0.35 eq / 100 g.

[0043] S2 chain growth stage: 20 parts of the composite chain extender modifier were added to the reaction system in three portions, 6.67 parts each time. Before each addition, the reaction system temperature was stabilized at 92℃. During the addition process, the temperature fluctuation was controlled to not exceed ±1.6℃, with an interval of 22 minutes between additions. The stirring rate during the addition process was 400 r / min. The remaining 0.4 parts of the high-efficiency selective composite catalyst were added in this stage. The catalyst addition rate was 0.008 g / min at 90-100℃ and 0.008 g / min at 100-120℃. The stirring rate was 0.005 g / min. After feeding, the temperature was increased to 112℃ at a rate of 0.5℃ / min and held for 2 hours. Then, the temperature was increased to 127℃ and held for 1 hour. In the first 30 minutes after the temperature reached 127℃, 0.1 parts of catalyst regulator were added at once. The stirring rate was adjusted to 350 r / min. After stirring for 10 minutes, the temperature was held for the specified time. The chain growth endpoint was reached when the viscosity of the system reached 1500 mPa·s (25℃) and the epoxy value dropped to 0.12 eq / 100g.

[0044] S3 Post-processing stage: The temperature inside the reactor was lowered to 92℃, 0.4 parts of antioxidant 1010 and 3 parts of diluent were added, the stirring rate was adjusted to 300 r / min, and after stirring evenly, the temperature was kept for 32 min; then, at an ambient temperature of 25℃, the temperature was naturally cooled to below 50℃ at a rate of 0.34℃ / min, while maintaining a stirring rate of 220 r / min during the cooling process; after the cooling was completed, the mixture was filtered using a 0.22μm organic filter membrane with a filtration pressure controlled at 0.1MPa, and then dried at 82℃ for 2 h to obtain the finished product.

[0045] Example 2: (I) Preparation of hydrolyzed modified KH-560: KH-560 was added to deionized water at a weight ratio of 1:2.5. The reaction temperature was controlled at 38℃ and the stirring rate at 280 r / min. 0.26 mol / L hydrochloric acid was added dropwise to adjust the pH of the system to 5.3. The hydrolysis reaction was carried out for 2.0 h. The reaction reached its endpoint when the system was a homogeneous and transparent liquid without any oily layering. After the reaction was completed, 46% of the weight of KH-560 in anhydrous ethanol was added and the mixture was stirred for 30 min to obtain hydrolyzed modified KH-560.

[0046] (II) Preparation of composite chain extender modifier: Bisphenol A, resorcinol-type epoxy resin RE-180, and hydrolyzed modified KH-560 were weighed in a weight ratio of 10:6.5:4.8, mixed evenly, and added to a reaction vessel. Then, triallyl isocyanurate, accounting for 0.55% of the total weight of the composite chain extender modifier, was added. The pre-crosslinking reaction temperature was controlled at 104℃, the stirring rate was 430 r / min, and the reaction was carried out for 1.9 h. The reaction was stopped when the viscosity of the system reached 1000 mPa・s (25℃) to obtain the composite chain extender modifier.

[0047] (III) Synthesis of epoxy resin: Raw material ratio: 54 parts low viscosity liquid epoxy resin, 28 parts composite chain extender modifier, 1.3 parts high efficiency selective compound catalyst (tetrabutylammonium bromide to triphenylphosphine weight ratio 3:1), 0.7 parts antioxidant 1076, 6 parts diluent, and 0.2 parts catalyst regulator.

[0048] S1 Prepolymerization Stage: 54 parts of low-viscosity liquid epoxy resin were added to the reactor, heated to 68℃, and held for 28 min. Then, 0.65 parts of high-efficiency selective composite catalyst were added at a rate of 0.019 g / min, with the stirring rate maintained at 380 r / min during the addition process. Subsequently, the temperature was increased to 88℃ at a rate of 1.8℃ / min and held for 38 min to carry out the prepolymerization ring-opening reaction. Nitrogen gas was introduced for protection throughout the prepolymerization process at a flow rate of 1.15 L / min. The prepolymerization endpoint was reached when the epoxy value of the system dropped to 0.40 eq / 100 g.

[0049] S2 chain growth stage: 28 parts of the composite chain extender modifier were added to the reaction system in three portions, 9.33 parts each time. Before each addition, the reaction system temperature was stabilized at 98℃. During the addition process, the temperature fluctuation was controlled to not exceed ±1.6℃, with an interval of 28 minutes between additions. The stirring rate during the addition process was 500 r / min. The remaining 0.65 parts of the high-efficiency selective composite catalyst were added during this stage. The catalyst addition rate was 0.01 g / min at 90-100℃ and 0.01 g / min at 100-120℃. The concentration was 0.009 g / min. After feeding, the temperature was increased to 118℃ at a rate of 1.0℃ / min and held for 3 hours. Then, the temperature was increased to 133℃ and held for 1.5 hours. In the first 30 minutes after the temperature reached 133℃, 0.2 parts of catalyst regulator were added at once. The stirring rate was adjusted to 400 r / min. After stirring for 15 minutes, the temperature was held for the specified time. The chain growth endpoint was reached when the viscosity of the system reached 1800 mPa·s (25℃) and the epoxy value dropped to 0.16 eq / 100g.

[0050] S3 Post-processing stage: The temperature inside the reactor was lowered to 98℃, 0.7 parts of antioxidant 1076 and 6 parts of diluent were added, the stirring rate was adjusted to 350 r / min, and after stirring evenly, the temperature was maintained for 38 min; then, at an ambient temperature of 30℃, the temperature was naturally cooled to below 50℃ at a rate of 0.46℃ / min, while maintaining a stirring rate of 280 r / min during the cooling process; after cooling, the mixture was filtered using a 0.22μm organic filter membrane with a filtration pressure controlled at 0.15MPa, and then dried at 88℃ for 2.5 h to obtain the finished product.

[0051] Example 3: (I) Preparation of hydrolyzed modified KH-560: KH-560 was added to deionized water at a weight ratio of 1:2.2. The reaction temperature was controlled at 35℃ and the stirring rate at 250 r / min. 0.20 mol / L hydrochloric acid was added dropwise to adjust the pH of the system to 5.0. The hydrolysis reaction was carried out for 1.8 h. The reaction reached its endpoint when the system was a homogeneous and transparent liquid without any oily layering. After the reaction was completed, 40% of the weight of KH-560 in anhydrous ethanol was added and the mixture was stirred for 30 min to obtain hydrolyzed modified KH-560.

[0052] (II) Preparation of composite chain extender modifier: Bisphenol A, resorcinol-type epoxy resin RE-180, and hydrolyzed modified KH-560 were weighed in a weight ratio of 10:6.5:4.8, mixed evenly, and added to a reaction vessel. Then, triallyl isocyanurate, accounting for 0.45% of the total weight of the composite chain extender modifier, was added. The pre-crosslinking reaction temperature was controlled at 100℃, the stirring rate was 380r / min, and the reaction was carried out for 1.7h. The reaction was stopped when the viscosity of the system reached 900mPa・s (25℃) to obtain the composite chain extender modifier.

[0053] (III) Synthesis of epoxy resin: Raw material ratio: 50 parts low viscosity liquid epoxy resin, 24 parts composite chain extender modifier, 1.1 parts high efficiency selective compound catalyst (tetrabutylammonium bromide to triphenylphosphine weight ratio 2.5:1), 0.5 parts antioxidant 1010, 4.5 parts diluent, and 0.15 parts catalyst regulator.

[0054] S1 Prepolymerization Stage: 50 parts of low-viscosity liquid epoxy resin were added to the reactor, heated to 65℃, and held for 25 min. Then, 0.55 parts of high-efficiency selective composite catalyst were added at a rate of 0.015 g / min, and the stirring rate was maintained at 350 r / min during the addition process. Subsequently, the temperature was increased to 85℃ at a rate of 1.5℃ / min and held for 35 min to carry out the prepolymerization ring-opening reaction. Nitrogen gas was introduced for protection throughout the prepolymerization process at a flow rate of 1.0 L / min. The prepolymerization endpoint was reached when the epoxy value of the system dropped to 0.38 eq / 100 g.

[0055] S2 chain growth stage: 24 parts of the composite chain extender modifier were added to the reaction system in three portions, 8 parts each time. Before each addition, the temperature of the reaction system was stabilized at 95℃. During the addition process, the temperature fluctuation was controlled to not exceed ±1.6℃, with an interval of 25 minutes between additions. The stirring rate during the addition process was 450 r / min. The remaining 0.55 parts of the high-efficiency selective composite catalyst were added during this stage. The catalyst addition rate was 0.009 g / min at 90-100℃ and 0 g / min at 100-120℃. 0.007 g / min; After feeding, the temperature is increased to 115℃ at a rate of 0.8℃ / min and held for 2.5 h, then increased to 130℃ and held for 1.2 h. In the first 30 min after heating to 130℃, 0.15 parts of catalyst regulator are added at once, the stirring rate is adjusted to 380 r / min, and stirring is continued for 12 min, and then the temperature is held for the specified time. The chain growth endpoint is reached when the viscosity of the system reaches 1650 mPa・s (25℃) and the epoxy value drops to 0.14 eq / 100g.

[0056] S3 Post-processing stage: The temperature inside the reactor was lowered to 95℃, 0.5 parts of antioxidant 1010 and 4.5 parts of diluent were added, the stirring speed was adjusted to 320 r / min, and after stirring evenly, the temperature was kept at that temperature for 35 min; then, at an ambient temperature of 28℃, the temperature was naturally cooled to below 50℃ at a rate of 0.40℃ / min, while maintaining a stirring speed of 250 r / min during the cooling process; after cooling, the mixture was filtered through a 0.22μm organic filter membrane with a filtration pressure controlled at 0.12MPa, and then dried at 85℃ for 2.2 h to obtain the finished product.

[0057] Comparative Example 1: The synthesis method of Example 3 was used, except that triallyl isocyanurate was not added during the preparation of the composite chain extender modifier, while the other raw material ratios and reaction conditions were the same as in Example 3.

[0058] Comparative Example 2: The synthesis method of Example 3 was adopted, except that the hydrolyzed modified KH-560 was not used in the composite chain extender modifier, but was directly replaced with an equal weight of unmodified KH-560. The other raw material ratios and reaction conditions were the same as in Example 3.

[0059] Comparative Example 3: The synthesis method of Example 3 was adopted, except that the highly efficient and selective composite catalysts for the prepolymerization stage and the chain growth stage were added to the reaction system at one time without controlling the addition rate, while the proportions of other raw materials and reaction conditions were the same as in Example 3.

[0060] Experiment 1: Dielectric property test: 1.1 Experimental Objective: The dielectric constant and dielectric loss factor of the epoxy resins in Examples 1-3 and Comparative Examples 1-4 were tested under high-frequency conditions to verify the effects of triallyl isocyanurate in the composite chain extender, hydrolysis-modified KH-560, the temperature-catalyst synergistic regulation mechanism, and the synthesis process on the dielectric properties of the epoxy resins. The dielectric constant and dielectric loss factor are the core performance indicators of epoxy resins for copper clad laminates, which directly affect the transmission efficiency of high-frequency communication signals.

[0061] 1.2 Experimental Principle: Referring to GB / T1409-2006 "Recommended Methods for Measuring Permittivity and Dielectric Loss Factor of Electrical Insulation Materials at Power Frequency, Audio Frequency, and High Frequency (Including Meter Wave to Millimeter Wave)," the parallel plate capacitor method is adopted. Under specific frequency and temperature conditions, the dielectric constant and dielectric loss factor are calculated by measuring the capacitance and loss tangent of the sample, which directly reflects the dielectric properties of the material.

[0062] 1.3 Experimental Instruments and Reagents: Test instruments: high frequency dielectric spectrometer, electronic balance (accuracy 0.001g), tablet press, constant temperature and humidity chamber, thickness measuring instrument (accuracy 0.001mm); Test reagents: epoxy resin products of Examples 1-3 and Comparative Examples 1-4, anhydrous ethanol (analytical grade).

[0063] 1.4 Test Methods: (1) Sample preparation: Clean the surface impurities of each epoxy resin product with anhydrous ethanol, dry at 60℃ for 2h, and press into circular samples with a diameter of 50mm and a thickness of 2mm using a tablet press at 15MPa pressure. Prepare 3 parallel samples for each group; place the samples in a constant temperature and humidity chamber and equilibrate for 24h at 23℃ and 50% relative humidity.

[0064] (2) Dielectric constant test: The balanced sample is placed between the parallel electrodes of the high-frequency dielectric spectrometer. The test frequency is set to 1 GHz, the test temperature to 23 °C, and an AC voltage of 1 V is applied. The capacitance value of the sample is measured. Based on the area, thickness, and vacuum dielectric constant of the sample, the dielectric constant is calculated: ε r =C×d / (ε0×S), where ε r ε0 is the dielectric constant, C is the measured capacitance (F), d is the sample thickness (m), and ε0 is the vacuum dielectric constant (8.85 × 102). -12 F / m), S is the electrode area (m²) 2 ).

[0065] (3) Dielectric loss factor test: Under the same test conditions as above, measure the loss tangent (tanδ) of the sample, i.e. the dielectric loss factor.

[0066] (4) Data processing: Each sample was tested in parallel 3 times, and the average value was taken as the final test result.

[0067] 1.5 Experimental Data: Table 1

[0068] As can be seen from the data of Experiment 1, the epoxy resins of Examples 1-3 all exhibited excellent dielectric properties, with dielectric constants all below 3.25 and dielectric loss factors all below 0.009.

[0069] Comparing Example 3 with Comparative Example 1, it can be seen that after the triallyl isocyanurate in the composite chain extender modifier of Comparative Example 1 was missing, the dielectric constant increased from 3.18 to 3.86, and the dielectric loss factor increased from 0.0078 to 0.0192, resulting in a significant decrease in performance. The reason is that the pre-crosslinking effect of triallyl isocyanurate can construct a three-dimensional crosslinked network, reduce the polarity and mobility of the molecular chains, and reduce polarization loss. However, after the absence of this component, the crosslinking density of the composite chain extender modifier is insufficient, and the molecular chains are prone to polarization, leading to the deterioration of dielectric properties.

[0070] Comparing Example 3 and Comparative Example 2, it can be seen that Comparative Example 2 did not use hydrolyzed modified KH-560. After directly using unmodified KH-560, the dielectric constant increased from 3.18 to 3.72, and the dielectric loss factor increased from 0.0078 to 0.0165, resulting in a significant decrease in performance. The reason is that the compatibility of hydrolyzed modified KH-560 with other components is significantly improved, and it can be uniformly dispersed in the system, reducing interfacial polarization loss. In contrast, unmodified KH-560 has poor compatibility with the resin matrix and is prone to forming interfacial defects, leading to an increase in dielectric loss.

[0071] Comparing Example 3 with Comparative Example 3, it can be seen that Comparative Example 3 did not employ the temperature-catalyst synergistic regulation mechanism. After the catalyst was added all at once, the dielectric constant increased from 3.18 to 3.58, and the dielectric loss factor increased from 0.0078 to 0.0143, resulting in a decrease in performance. This is because the one-time addition of the catalyst leads to an excessively fast local reaction rate, uneven cross-linking of molecular chains, the formation of structural defects, and an increase in polarization loss. In contrast, the temperature-catalyst synergistic regulation mechanism can precisely control the reaction process, ensuring a uniform and dense cross-linked network, thereby optimizing dielectric performance.

[0072] Experiment 2: Viscosity stability and mechanical property testing: 2.1 Experimental Objective: The viscosity stability (viscosity change rate during room temperature storage) and flexural strength of the epoxy resins in Examples 1-3 and Comparative Examples 1-4 were tested to verify the influence of each innovative technical feature on the product's processing performance and mechanical properties. Viscosity stability directly affects the adaptability of the coating process in the copper clad laminate production process, while flexural strength ensures the structural reliability of the copper clad laminate.

[0073] 2.2 Experimental Principle: Viscosity stability testing involves periodically measuring the viscosity of a sample after storing it at room temperature for a certain period of time and calculating the viscosity change rate to reflect the performance stability of the product during storage. Bending strength testing refers to GB / T9341-2008 "Determination of Bending Properties of Plastics". Through a three-point bending test, the maximum destructive stress of the sample under bending load is measured to reflect the mechanical strength of the material.

[0074] 2.3 Experimental Instruments and Reagents: Test instruments: rotational viscometer, electronic universal testing machine, constant temperature and humidity chamber, electronic balance (accuracy 0.001g), vernier caliper (accuracy 0.01mm); test reagents: epoxy resin products of Examples 1-3 and Comparative Examples 1-4.

[0075] 2.4 Test Methods: (1) Viscosity stability test: ① Sample preparation: Each epoxy resin product is placed into a sealed container, and 3 samples are taken from each group, with each sample weighing 50g; ② Storage conditions: Place the sealed samples in a constant temperature and humidity chamber, control the temperature at 23℃ and the relative humidity at 50%, and store for 0 days, 30 days, 60 days and 90 days respectively; ③ Viscosity measurement: At each storage time point, the sample was taken out, equilibrated to room temperature, and the viscosity was measured using a rotational viscometer (25℃, rotation speed 60r / min), and the data was recorded; ④ Calculate the viscosity change rate: Viscosity change rate = (viscosity after storage - initial viscosity) / initial viscosity × 100%, and take the average value of 3 parallel samples as the final result.

[0076] (2) Bending strength test: ① Sample preparation: Each epoxy resin product was combined with glass fiber cloth and a bending sample of 120mm×15mm×4mm was prepared by hot pressing. Five parallel samples were prepared for each group. Hot pressing conditions: temperature 160℃, pressure 10MPa, time 2h. ② Test conditions: Place the sample on the three-point bending fixture of the electronic universal testing machine, set the span to 100mm, the loading rate to 2mm / min, and the test temperature to 23℃; ③ Data Recording: Record the maximum load at fracture of each specimen and calculate the bending strength: σ f =3FL / (2bh 2 ), where σ f denoted as flexural strength (MPa), F as maximum load (N), L as span (mm), b as specimen width (mm), and h as specimen thickness (mm). ④ Data processing: After removing outliers, the average value of the remaining samples is taken as the final bending strength.

[0077] 2.5 Experimental Data: Table 2

[0078] The data from Experiment 2 show that the epoxy resins of Examples 1-3 all exhibited excellent viscosity stability and mechanical properties. After 90 days of storage, the viscosity change rate was less than 8%, and the flexural strength was higher than 128 MPa.

[0079] Comparing Example 3 with Comparative Example 1, it can be seen that after the absence of triallyl isocyanurate in Comparative Example 1, the viscosity change rate increased from 6.6% to 33.2%, and the flexural strength decreased from 132 MPa to 105 MPa, resulting in a significant decrease in performance. The reason is that the three-dimensional cross-linked network constructed by triallyl isocyanurate can lock the molecular chains, inhibit further polymerization of the molecular chains, and improve viscosity stability. At the same time, the cross-linked structure enhances the intermolecular forces and improves mechanical strength. After the absence of this component, the cross-linking density of the system is insufficient, and the molecular chains are prone to secondary polymerization, leading to a surge in viscosity and a decrease in mechanical strength.

[0080] Comparing Example 3 and Comparative Example 2, it can be seen that in Comparative Example 2, without the use of hydrolyzed modified KH-560, the viscosity change rate increased from 6.6% to 22.5%, and the flexural strength decreased from 132 MPa to 112 MPa, indicating a significant decline in performance. This is because the hydrolyzed modified KH-560 has good compatibility with the resin matrix, can be uniformly dispersed and play a reinforcing role, and at the same time reduces viscosity fluctuations caused by component separation. In contrast, the unmodified KH-560 has poor compatibility with the matrix, is prone to aggregation during storage, leading to aggravated viscosity changes and weakened mechanical reinforcing effect.

[0081] Comparing Example 3 and Comparative Example 3, it can be seen that after Comparative Example 3 did not adopt the temperature-catalyst synergistic regulation mechanism, the viscosity change rate increased from 6.6% to 18.3%, and the flexural strength decreased from 132 MPa to 118 MPa, resulting in a performance decline. The reason is that the catalyst was added at once, which led to uneven reaction, with some areas being over-crosslinked and others under-crosslinked. During storage, the unreacted components continued to react, resulting in increased viscosity fluctuations. At the same time, the uneven crosslinked structure reduced the mechanical load-bearing capacity of the material.

[0082] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0083] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A low dielectric loss epoxy resin for copper-clad laminates, characterized in that, It is synthesized from the following components in parts by weight: 46-54 parts of low viscosity liquid epoxy resin, 20-28 parts of composite chain extender modifier, 0.8-1.3 parts of high efficiency selective compound catalyst, 0.4-0.7 parts of antioxidant, 3-6 parts of diluent, and 0.1-0.2 parts of catalyst regulator; The low-viscosity liquid epoxy resin is bisphenol F type epoxy resin EP-4400, with an epoxy value of 0.51-0.55 eq / 100g; The diluent is the reactive diluent butyl glycidyl ether; The catalyst modifier is dimethylformamide; The composite chain extender modifier is a pre-crosslinked complex of bisphenol A, resorcinol-type epoxy resin, hydrolyzed modified KH-560, and crosslinking accelerator triallyl isocyanurate. The amount of triallyl isocyanurate added is 0.35-0.55% of the total weight of the composite chain extender modifier. The pre-crosslinking reaction temperature is 96-104℃, the pre-crosslinking reaction time is 1.5-1.9h, the pre-crosslinking reaction stirring rate is 320-430r / min, and the pre-crosslinking reaction endpoint is defined as the system viscosity reaching 800-1000mPa·s. Resorcinol-type epoxy resin RE-180, epoxy value 0.62-0.66 eq / 100g.

2. The low dielectric loss epoxy resin for copper-clad laminates according to claim 1, characterized in that, In the composite chain extender modifier, the weight ratio of bisphenol A, resorcinol-type epoxy resin, and hydrolyzed modified KH-560 is 10:6.5:4.

8.

3. The low dielectric loss epoxy resin for copper-clad laminates according to claim 2, characterized in that, The preparation steps of the hydrolysis-modified KH-560 are as follows: KH-560 is added to deionized water, with a weight ratio of KH-560 to deionized water of 1:2-2.

5. The reaction temperature is controlled at 32-38℃ and the stirring rate is 220-280 r / min. 0.14-0.26 mol / L hydrochloric acid is added dropwise to adjust the pH of the system to 4.7-5.3, and the hydrolysis reaction is carried out for 1.5-2.0 h. The hydrolysis reaction ends when the system is free of oily stratification and forms a homogeneous transparent liquid. After the reaction is completed, 34-46% by weight of anhydrous ethanol of KH-560 is added and stirred for 30 min to obtain the hydrolysis-modified KH-560.

4. The low dielectric loss epoxy resin for copper-clad laminates according to claim 1, characterized in that, The highly efficient selective composite catalyst is composed of tetrabutylammonium bromide and triphenylphosphine in a weight ratio of 2-3:

1.

5. The low dielectric loss epoxy resin for copper-clad laminates according to claim 1, characterized in that, The antioxidant is a hindered phenolic antioxidant, selected from antioxidant 1010 and antioxidant 1076.

6. A synthesis process for a low dielectric loss epoxy resin for copper-clad laminates as described in any one of claims 1-5, characterized in that, An improved two-step catalytic addition method was adopted, including a prepolymerization stage, a chain growth stage, and a post-treatment stage, as follows: the chain growth stage adopted a bisphenol A segmented feeding strategy; TAIC was added during the preparation of the composite chain extender modifier to carry out a pre-crosslinking reaction; the entire synthesis process adopted a temperature-catalyst synergistic regulation mechanism.

7. The synthesis process according to claim 6, characterized in that, The temperature-catalyst synergistic regulation mechanism is as follows: In the prepolymerization stage, the addition rate of the highly efficient and selective compound catalyst is 0.011-0.019 g / min, corresponding to a temperature range of 64-86℃. The end point of the prepolymerization stage is determined by the epoxy value of the system decreasing to 0.35-0.40 eq / 100g. In the chain growth stage, the catalyst addition rate is 0.008-0.01 g / min at 90-100℃ and 0.005-0.009 g / min at 100-120℃. In the chain growth stage, the catalyst regulator is added all at once 30 minutes before heating to 127-133℃ and holding for 1.0-1.5 hours. The stirring rate is adjusted to 350-400 r / min, and after stirring for 10-15 minutes, the temperature is held for the specified time.

8. The synthesis process according to claim 6, characterized in that, The prepolymerization stage employs a segmented gradient heating method, with the following specific steps: The first step is to add low-viscosity liquid epoxy resin to the reactor, heat it to 62-68℃, keep it at that temperature for 22-28 minutes, and then add half of the high-efficiency selective compound catalyst at a rate of 0.011-0.019 g / min. During the addition process, the stirring rate is maintained at 320-380 r / min. The second step involves heating the temperature to 82-88℃ at a rate of 1.2-1.8℃ / min and holding it at that temperature for 32-38 minutes to carry out the prepolymerization ring-opening reaction. Nitrogen gas is introduced for protection throughout the prepolymerization process at a flow rate of 0.85-1.15L / min. The prepolymerization endpoint is determined by the epoxy value of the system decreasing to 0.35-0.40eq / 100g.

9. The synthesis process according to claim 6, characterized in that, The specific steps of the chain growth stage are as follows: the pre-crosslinked composite chain extender modifier is added to the reaction system in three equal portions, each accounting for 1 / 3 of the total weight of the composite chain extender modifier. Before each addition, the temperature of the reaction system is stabilized at 92-98℃. During the addition process, the temperature fluctuation is controlled to not exceed ±1.6℃, with an interval of 22-28 minutes between additions. The stirring rate during the addition process is 400-500 r / min. After the addition is completed, the temperature is increased to 112-118℃ at a heating rate of 0.5-1.0℃ / min and held for 2-3 hours. Then, the temperature is increased to 127-135℃ and held for 1.0-1.5 hours. The remaining amount of high-efficiency selective compound catalyst is added at this stage. The end point of the chain growth stage is defined as the system viscosity reaching 1500-1800 mPa·s and the epoxy value decreasing to 0.12-0.16 eq / 100g.

10. The synthesis process according to claim 6, characterized in that, The specific steps of the post-processing stage are as follows: the temperature inside the reactor is lowered to 92-98℃, antioxidants and diluents are added, the stirring rate is adjusted to 300-350 r / min, and after stirring evenly, the temperature is maintained for 32-38 min; then, at an ambient temperature of 25-30℃, the temperature is naturally cooled to below 50℃ at a rate of 0.34-0.46℃ / min, while maintaining a stirring rate of 220-280 r / min during the cooling process; after cooling, the mixture is filtered using a 0.22μm organic filter membrane, with the filtration pressure controlled at 0.1-0.15MPa, and then dried at 82-88℃ for 2-2.5 h to obtain the finished product.

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