Fluorine-containing cyanate ester resin and preparation method thereof

Abstract

The invention belongs to the technical field of high-performance resin, and particularly relates to fluorine-containing cyanate resin and a preparation method thereof. The fluorine-containing cyanate ester resin provided by the invention is prepared from the following raw materials: bisphenol A cyanate ester and fluorine-containing tetrafunctional cyanate ester; according to the fluorine-containing tetra-functionality cyanate ester, trifluoromethyl and diphenyl ether structures are introduced into tetra-functionality cyanate ester molecules; the trifluoromethyl enables the fluorine-containing tetra-functionality cyanate ester to have a relatively large free volume, a relatively small dipole moment and relatively low polarizability of a fluorocarbon bond, namely, the fluorine-containing tetra-functionality cyanate ester has an extremely low dielectric constant and dielectric loss. Meanwhile, the strength (116 kJ / mol) of a fluorocarbon bond is higher than that (99.5 kJ / mol) of a carbon-hydrogen bond, so that the fluorine-containing four-functionality cyanate ester has excellent thermal stability. Besides, the fluorine-containing four-functionality cyanate ester has four functionalities, so that the fluorine-containing cyanate ester resin has higher crosslinking density, and the glass-transition temperature of the fluorine-containing cyanate ester resin is favorably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-performance resins, and particularly relates to a fluorinated cyanate ester resin and a preparation method thereof. Background Art

[0002] With the development trend of printed circuit boards towards high integration and fast signal propagation, it is required that its resin matrix has better heat resistance, water resistance and dielectric properties. Cyanate ester resin has excellent high-temperature resistance, good dimensional stability, low water absorption, low dielectric constant and low dielectric loss, so it has become an ideal material for the resin matrix of printed circuit boards. Cyanate ester resin also has good processing performance, excellent mechanical properties, good flame retardancy and high environmental tolerance. Its excellent properties make it widely used in sensing, packaging, aerospace and other fields. However, the glass transition temperature of most cyanate ester resins is between 190 °C and 290 °C, while when welding printed circuit boards, the temperature of the laminate usually rises to 300 °C - 350 °C in a very short time. Therefore, it is necessary to increase the glass transition temperature and heat resistance of cyanate ester resin. In addition, printed circuit boards require the resin matrix to have excellent dielectric properties. Therefore, further reducing the dielectric constant and dielectric loss of cyanate ester resin is of great significance for the application of cyanate ester in printed circuit boards.

[0003] Designing and improving the molecular structure of cyanate ester resin is an important way to improve the performance of cyanate ester resin. The diphenyl ether structure is beneficial to reducing electron interaction and diluting the dipole concentration, so it is beneficial to improving dielectric properties. The prior art modifies bisphenol A cyanate ester by introducing phenolic resin (MPF) containing diphenyl ether structure into it. When 30% by mass of MPF is added, its dielectric constant and dielectric loss at 1 GHz are 3.00 and 0.0062 respectively, which are lower than those of pure bisphenol A cyanate ester. However, phenolic resin with diphenyl ether structure will reduce the thermal stability of cyanate ester resin. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a fluorinated cyanate ester resin and a preparation method thereof. The fluorinated cyanate ester resin provided by the present invention has excellent thermal stability, low dielectric constant and low dielectric loss.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions: The present invention provides a fluorinated cyanate ester resin, and the raw materials for preparation include bisphenol A cyanate ester and fluorinated tetrafunctional cyanate ester. The fluorinated tetrafunctional cyanate ester has the following structure: .

[0006] Preferably, the mass ratio of the bisphenol A cyanate ester to the fluorinated tetrafunctional cyanate ester is 7:3 to 9:1.

[0007] Preferably, the preparation method of the fluorinated tetrafunctional cyanate ester comprises the following steps: Mix 4,4'-(hexafluoroisopropylidene)bisphenol, p-fluorobenzaldehyde, potassium carbonate and a polar solvent, and carry out a first reaction to obtain 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde; Mix the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde, phenol, p-toluenesulfonic acid and zinc chloride, and carry out a second reaction to obtain a fluorinated tetrafunctional phenol; Mix the fluorinated tetrafunctional phenol, triethylamine, cyanogen halide and an organic solvent, and carry out a third reaction to obtain the fluorinated tetrafunctional cyanate ester.

[0008] Preferably, the molar ratio of the 4,4'-(hexafluoroisopropylidene)bisphenol to the p-fluorobenzaldehyde is 1:2 to 4; the molar ratio of the 4,4'-(hexafluoroisopropylidene)bisphenol to the potassium carbonate is 1:2 to 4.

[0009] Preferably, the temperature of the first reaction is 135 to 145 °C, and the time is 6 to 10 h.

[0010] Preferably, the molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to the phenol is 1:8 to 14; the molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to the p-toluenesulfonic acid is 1:0.2 to 0.4; the molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to the zinc chloride is 1:0.2 to 0.4.

[0011] Preferably, the temperature of the second reaction is 40 to 50 °C, and the time is 24 to 36 h.

[0012] Preferably, the molar ratio of the fluorinated tetrafunctional phenol to the cyanogen halide is 1:6 to 10, and the molar ratio of the triethylamine to the cyanogen halide is 1:1 to 1.4; The temperature of the third reaction is -20 to 0 °C, and the time is 3 to 5 h.

[0013] The present invention also provides a preparation method of the fluorinated cyanate ester resin according to the above technical solution, comprising the following steps: Mix the bisphenol A cyanate ester and the fluorinated tetrafunctional cyanate ester, and carry out prepolymerization to obtain a fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer; Carry out curing on the fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer to obtain the fluorinated cyanate ester resin.

[0014] Preferably, the temperature of the prepolymerization is 100 to 120 °C, and the time is 0.5 to 2 h.

[0015] The present invention provides a fluorinated cyanate ester resin.

[0016] The preparation raw materials of the fluorinated cyanate ester resin provided by the present invention include bisphenol A cyanate ester and fluorinated tetrafunctional cyanate ester; the fluorinated tetrafunctional cyanate ester introduces trifluoromethyl and diphenyl ether structures into the tetrafunctional cyanate ester molecule. The trifluoromethyl group endows the fluorinated tetrafunctional cyanate ester with a large free volume, a small dipole moment and a low polarization degree of the carbon-fluorine bond, that is, the fluorinated tetrafunctional cyanate ester has an extremely low dielectric constant and dielectric loss. At the same time, the strength of the carbon-fluorine bond (116 kJ / mol) is higher than that of the carbon-hydrogen bond (99.5 kJ / mol), so the fluorinated tetrafunctional cyanate ester has excellent thermal stability. In addition, the fluorinated tetrafunctional cyanate ester of the present invention has four functional groups, enabling the fluorinated cyanate ester resin to have a higher crosslinking density, which is beneficial to increasing the glass transition temperature of the fluorinated cyanate ester resin. In summary, the fluorinated cyanate ester resin of the present invention has both excellent heat resistance and dielectric properties. Description of the Drawings

[0017] Figure 1 1H NMR spectrum of the fluorinated tetrafunctional cyanate ester obtained in Example 1; Figure 2 1H infrared spectrum of the fluorinated tetrafunctional cyanate ester obtained in Example 1. Detailed Embodiments

[0018] The present invention provides a fluorinated cyanate ester resin, and the preparation raw materials include bisphenol A cyanate ester and fluorinated tetrafunctional cyanate ester. The fluorinated tetrafunctional cyanate ester has the following structure: .

[0019] Unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

[0020] In the present invention, the mass ratio of the bisphenol A cyanate ester to the fluorinated tetrafunctional cyanate ester is preferably 7:3 to 9:1, specifically preferably 7:3, 8:2 or 9:1.

[0021] In the present invention, the preparation method of the fluorinated tetrafunctional cyanate ester preferably includes the following steps: Mix 4,4'-(hexafluoroisopropylidene)bisphenol, p-fluorobenzaldehyde, potassium carbonate and a polar solvent, and carry out a first reaction to obtain 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde; Mix the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde, phenol, p-toluenesulfonic acid and zinc chloride, and carry out a second reaction to obtain a fluorinated tetrafunctional phenol; Mix the fluorinated tetrafunctional phenol, triethylamine, cyanogen halide and organic solvent, and carry out the third reaction to obtain the fluorinated tetrafunctional cyanate ester.

[0022] In the present invention, 4,4'-(hexafluoroisopropylidene)bisphenol, p-fluorobenzaldehyde, potassium carbonate and a polar solvent are mixed and subjected to the first reaction to obtain 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde.

[0023] In the present invention, the polar solvent is preferably an amide substance, and the amide substance preferably includes one or more of N,N'-dimethylacetamide, N,N'-dimethylformamide and N,N'-dimethylpropionamide. Using an amide substance as the polar solvent in the present invention ensures good solubility of the organic reactants.

[0024] In the present invention, the potassium carbonate is preferably anhydrous potassium carbonate.

[0025] In the present invention, the molar ratio of 4,4'-(hexafluoroisopropylidene)bisphenol to p-fluorobenzaldehyde is preferably 1:2 to 4, specifically preferably 1:2, 1:2.5, 1:3, 1:3.5 or 1:4. In the present invention, the molar ratio of 4,4'-(hexafluoroisopropylidene)bisphenol to potassium carbonate is preferably 1:2 to 4, specifically preferably 1:2, 1:2.5, 1:3, 1:3.5 or 1:4. The present invention does not specifically limit the amount of the polar solvent used, as long as it can dissolve 4,4'-(hexafluoroisopropylidene)bisphenol and p-fluorobenzaldehyde. By controlling the molar ratio of 4,4'-(hexafluoroisopropylidene)bisphenol to p-fluorobenzaldehyde to be 1:2 to 4 and the molar ratio of 4,4'-(hexafluoroisopropylidene)bisphenol to potassium carbonate to be 1:2 to 4 in the present invention, the smooth progress of the reaction is ensured.

[0026] In the present invention, the mixing of 4,4'-(hexafluoroisopropylidene)bisphenol, p-fluorobenzaldehyde, potassium carbonate and a polar solvent preferably includes the following steps: Dissolve 4,4'-(hexafluoroisopropylidene)bisphenol and p-fluorobenzaldehyde in the polar solvent, and then add potassium carbonate.

[0027] In the present invention, the temperature of the first reaction is preferably 135 to 145 °C, specifically preferably 135 °C, 140 °C or 145 °C; the time is preferably 6 to 10 h, specifically preferably 6 h, 7 h, 8 h, 9 h or 10 h. In the present invention, the first reaction is preferably carried out under stirring conditions.

[0028] After the first reaction, the present invention preferably further includes: subjecting the obtained first reaction liquor to water precipitation and dissolution in sequence to obtain a crude product; subjecting the crude product to recrystallization and drying in sequence to obtain the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde. In the present invention, the reagent for dissolution preferably includes one or more of acetone, methanol, ethanol, and tetrahydrofuran. The present invention uses one or more of acetone, methanol, ethanol, and tetrahydrofuran as the reagent for dissolution, ensuring complete dissolution of the crude product and facilitating subsequent separation of impurities. In the present invention, the number of times of water precipitation and dissolution in sequence is preferably 3 to 5 times, specifically preferably 3 times, 4 times, or 5 times. In the present invention, the reagent for recrystallization is preferably an alcohol solvent, and the alcohol solvent preferably includes one or more of isopropanol, n-propanol, ethylene glycol, and propylene glycol; using one or more of isopropanol, n-propanol, ethylene glycol, and propylene glycol as the alcohol solvent for recrystallization ensures the purity of the product. In the present invention, the number of times of recrystallization is preferably 3 to 4 times, specifically preferably 3 times or 4 times.

[0029] In the present invention, the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde has the following structure: .

[0030] After obtaining the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde, the present invention mixes the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde, phenol, p-toluenesulfonic acid, and zinc chloride and conducts a second reaction to obtain a fluorine-containing tetrafunctional phenol.

[0031] In the present invention, the zinc chloride is preferably anhydrous zinc chloride.

[0032] In the present invention, the molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to phenol is preferably 1:8 to 14, specifically preferably 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, or 1:14. In the present invention, the molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to p-toluenesulfonic acid is preferably 1:0.2 to 0.4, specifically preferably 1:0.2, 1:0.25, 1:0.3, 1:0.35, or 1:0.4. In the present invention, the molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to zinc chloride is preferably 1:0.2 to 0.4, specifically preferably 1:0.2, 1:0.25, 1:0.3, 1:0.35, or 1:0.4. The present invention controls the molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to phenol to be 1:8 to 14, the molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to p-toluenesulfonic acid to be 1:0.2 to 0.4, and the molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to zinc chloride to be 1:0.2 to 0.4, which is conducive to the smooth progress of the second reaction.

[0033] In the present invention, the mixing of 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde, phenol, p-toluenesulfonic acid, and zinc chloride preferably includes the following steps: After heating and dissolving 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde and phenol, then adding p-toluenesulfonic acid and zinc chloride; the temperature for heating and dissolving is preferably 75-85°C, specifically preferably 75°C, 80°C, or 85°C; the heating and dissolving is preferably carried out under stirring; the addition temperature of p-toluenesulfonic acid and zinc chloride is preferably the same as the temperature of the second reaction.

[0034] In the present invention, the temperature of the second reaction is preferably 40-50°C, specifically preferably 40°C, 45°C, or 50°C; the time is preferably 24-36 h, specifically preferably 24 h, 26 h, 28 h, 30 h, 32 h, 34 h, or 36 h. In the present invention, the second reaction is preferably carried out under stirring.

[0035] After the second reaction, the present invention preferably further includes: subjecting the obtained second reaction liquor to alcohol dissolution and water precipitation in sequence to obtain a crude product; performing reduced-pressure rotary evaporation on the crude product to obtain the fluorine-containing tetrafunctional phenol. In the present invention, the alcohol solvent for alcohol dissolution preferably includes one or more of ethanol, n-propanol, isopropanol, ethylene glycol, and propylene glycol; using one or more of ethanol, n-propanol, isopropanol, ethylene glycol, and propylene glycol as the alcohol solvent for alcohol dissolution ensures complete dissolution of the crude product and is beneficial to improving the product purity. In the present invention, the temperature of water precipitation is preferably 80-90°C, specifically preferably 80°C, 85°C, or 90°C. In the present invention, the number of times of performing alcohol dissolution and water precipitation in sequence is preferably 3-7 times, specifically preferably 3 times, 4 times, 5 times, 6 times, or 7 times. In the present invention, the temperature of the reduced-pressure rotary evaporation is preferably 135-150°C, specifically preferably 135°C, 140°C, 145°C, or 150°C; the time is preferably 3-5 h, specifically preferably 3 h, 4 h, or 5 h.

[0036] In the present invention, the fluorine-containing tetrafunctional phenol has the following structure: .

[0037] After obtaining the fluorine-containing tetrafunctional phenol, the present invention mixes the fluorine-containing tetrafunctional phenol, triethylamine, cyanogen halide, and an organic solvent to carry out a third reaction to obtain the fluorine-containing tetrafunctional cyanate ester.

[0038] In the present invention, the cyanogen halide is preferably cyanogen bromide or cyanogen chloride. In the present invention, both cyanogen bromide and cyanogen chloride have good reactivity, which is beneficial to the smooth progress of the cyanation reaction, i.e., the third reaction.

[0039] In the present invention, the organic solvent is preferably a polar solvent, and the polar solvent preferably includes one or more of diethyl ether, dichloromethane, methyl ethyl ketone, and toluene. In the present invention, using one or more of diethyl ether, dichloromethane, methyl ethyl ketone, and toluene as the organic solvent ensures the complete dissolution of the reactants.

[0040] In the present invention, the molar ratio of the fluorinated tetrafunctional phenol to the cyanogen halide is preferably 1:6 to 10, specifically preferably 1:6, 1:7, 1:8, 1:9, or 1:10. In the present invention, the molar ratio of triethylamine to the cyanogen halide is preferably 1:1 to 1.4, specifically preferably 1:1, 1:1.1, 1:1.2, 1:1.3, or 1:1.4. The present invention does not specifically limit the amount of the organic solvent used, as long as it can completely dissolve the materials. By controlling the molar ratio of the fluorinated tetrafunctional phenol to the cyanogen halide to be 1:6 to 10 and the molar ratio of triethylamine to the cyanogen halide to be 1:1 to 1.4 in the present invention, the third reaction proceeds fully, improving the yield.

[0041] In the present invention, the mixing of the fluorinated tetrafunctional phenol, triethylamine, cyanogen halide, and organic solvent preferably includes the following steps: mixing the fluorinated tetrafunctional phenol and the organic solvent, and then sequentially adding triethylamine and cyanogen halide. In the present invention, the addition method of triethylamine is preferably dropwise addition; the addition temperature of triethylamine is preferably the same as the temperature of the third reaction, which will not be elaborated here. In the present invention, the addition temperature of the cyanogen halide is preferably the same as the temperature of the third reaction, which will not be elaborated here.

[0042] In the present invention, the mixing of the fluorinated tetrafunctional phenol, triethylamine, cyanogen halide, and organic solvent is preferably carried out under an argon atmosphere.

[0043] In the present invention, the temperature of the third reaction is preferably -20 to 0 °C, specifically preferably -20 °C, -15 °C, -10 °C, -5 °C, or 0 °C; the time is preferably 3 to 5 h, specifically preferably 3 h, 4 h, or 5 h. In the present invention, the time of the third reaction is preferably timed from the completion of the addition of the cyanogen halide. In the present invention, the third reaction is preferably carried out under stirring conditions. In the present invention, the third reaction is preferably carried out under an argon atmosphere.

[0044] After the third reaction, the present invention preferably further includes: quenching the third reaction with a quenching agent, then spinning dry the third reaction solution to obtain a viscous substance; extracting the viscous substance with an organic extractant and water, and combining the organic phases; washing, drying, and spinning dry the organic phase in sequence to obtain a crude product; dissolving, alcohol precipitating, and filtering the crude product in sequence to obtain the fluorinated tetrafunctional cyanate ester. In the present invention, the quenching agent is preferably an aqueous sodium hypochlorite solution, and the concentration of the aqueous sodium hypochlorite solution is preferably 6-14%, specifically preferably 8-13%, specifically preferably 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13% or 14%. In the present invention, the organic extractant preferably includes one or more of dichloromethane, ethyl acetate, and n-butanol; using one or more of dichloromethane, ethyl acetate, and n-butanol as the organic extractant ensures the separation of impurities. In the present invention, the number of extractions is preferably 2 times. In the present invention, the washing reagent is preferably a hydrochloric acid solution, and the concentration of the hydrochloric acid solution is preferably 0.9-1.1 mol / L, specifically preferably 0.95-1.05%, specifically preferably 0.9%, 0.95%, 1%, 1.05% or 1.1%. In the present invention, the dissolving reagent preferably includes dichloromethane. In the present invention, the alcohol solvent for alcohol precipitation preferably includes methanol.

[0045] In the present invention, the preparation formula of the fluorinated tetrafunctional cyanate ester is as follows: 。

[0046] The present invention also provides a preparation method of the fluorinated cyanate ester resin described in the above technical solution, including the following steps: Mix bisphenol A cyanate ester and fluorinated tetrafunctional cyanate ester, and perform prepolymerization to obtain a fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer; Cure the fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer to obtain the fluorinated cyanate ester resin.

[0047] The present invention mixes bisphenol A cyanate ester and fluorinated tetrafunctional cyanate ester, and performs prepolymerization to obtain a fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer.

[0048] In the present invention, the mixing of bisphenol A cyanate ester and fluorinated tetrafunctional cyanate ester preferably includes the following steps: melting the bisphenol A cyanate ester monomer, and then adding the fluorinated tetrafunctional cyanate ester. In the present invention, the melting temperature is preferably 90-100 °C, specifically preferably 90 °C, 95 °C or 100 °C; the present invention does not specifically limit the melting time, as long as the bisphenol A cyanate ester monomer can be completely melted.

[0049] In the present invention, the temperature of the prepolymerization is preferably 100~120°C, specifically preferably 100°C, 105°C, 110°C, 115°C or 120°C; the time is preferably 0.5~2 h, specifically preferably 0.5 h, 1 h, 1.5 h or 2 h.

[0050] After obtaining the fluorinated tetrafunctional cyanate modified bisphenol A cyanate prepolymer, the present invention cures the fluorinated tetrafunctional cyanate modified bisphenol A cyanate prepolymer to obtain the fluorinated cyanate resin.

[0051] Before the curing, the present invention preferably further includes defoaming, and the defoaming is preferably carried out in a vacuum oven.

[0052] In the present invention, the curing preferably includes first curing, second curing, third curing, fourth curing, fifth curing and sixth curing in sequence; the temperature of the first curing is preferably 110°C, and the heat preservation time is preferably 2 h; the temperature of the second curing is preferably 130°C, and the heat preservation time is preferably 2 h; the temperature of the third curing is preferably 160°C, and the heat preservation time is preferably 2 h; the temperature of the fourth curing is preferably 190°C, and the heat preservation time is preferably 2 h; the temperature of the fifth curing is preferably 220°C, and the heat preservation time is preferably 2 h; the temperature of the sixth curing is preferably 250°C, and the heat preservation time is preferably 2 h. In the present invention, the curing is preferably carried out in a forced air oven.

[0053] The following describes in detail the fluorinated cyanate resin and its preparation method provided by the present invention in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0054] Example 1 A preparation method of a fluorinated tetrafunctional cyanate is as follows: In the first step, 269.0 g of 4,4'-(hexafluoroisopropylidene) bisphenol, 198.6 g of p-fluorobenzaldehyde and 700 mL of N,N'-dimethylacetamide are added to a three-necked flask. After the 4,4'-(hexafluoroisopropylidene) bisphenol is completely dissolved, 221.2 g of anhydrous potassium carbonate is added. The reaction system is heated to 140°C and stirred for reaction for 10 h. After the reaction is completed, water is added to the system to precipitate the crude product. The crude product is dissolved in acetone and then dropped into water to precipitate the crude product. After repeating the acetone dissolution-water precipitation operation 4 times in this way, the crude product is recrystallized 3 times with isopropanol. After drying, 4,4'-(hexafluoroisopropylidene) diphenoxybenzaldehyde is obtained.

[0055] Step 2: Add 744.6 g of phenol and 430.6 g of the product from the first step, 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde, into a three-necked flask. Heat the system to 80 °C and stir to dissolve. Then cool the system temperature to 40 °C, add 37.6 g of p-toluenesulfonic acid and 27.0 g of anhydrous zinc chloride, and stir the reaction at this temperature for 30 h. After the reaction is completed, dissolve the crude product in ethanol, and then dropwise add it to hot water at 80 °C to precipitate the crude product. Repeat the ethanol dissolution - water precipitation operation 6 times. Then rotary evaporate the crude product under reduced pressure at 140 °C for 5 h to obtain the fluorinated tetra-functional phenol.

[0056] Step 3: Under an argon atmosphere, add 75.0 g of the fluorinated tetra-functional phenol, the product from the second step, and ether into a three-necked flask and stir to dissolve. Then dropwise add 60.0 g of triethylamine and cool the reaction system temperature to 0 °C. Add 72.0 g of cyanogen bromide and stir the reaction for 3 h. Quench the reaction with an aqueous sodium hypochlorite solution (concentration 10%). Then rotary evaporate the reaction solution to dryness, extract with dichloromethane and water, extract the aqueous phase one more time, combine the organic phases and wash with a hydrochloric acid solution (concentration 1 mol / L). After drying the organic phase, rotary evaporate it to dryness. Then dissolve the crude product in dichloromethane, add the obtained solution to a large amount of methanol to precipitate the solid product. After filtration, obtain the fluorinated tetra-functional cyanate ester.

[0057] Figure 1 is the 1H NMR spectrum of the obtained fluorinated tetra-functional cyanate ester. From Figure 1 it can be seen that: the aromatic proton signals are in the range of 6.91 - 7.45 ppm, and the chemical shifts of the hydrogens connected to the tertiary carbon (the carbon connecting three benzene rings) are 5.76 and 5.85 ppm. The reason for the appearance of two different chemical shifts here is that the cyanate ester group may be in the para or ortho position of the tertiary carbon. From the integration of the chemical shift peaks, it can be known that most of the cyanate ester groups are in the para position of the tertiary carbon. The peak of deuterated DMSO appears at about 2.50 ppm, and the peak of water appears at about 3.33 ppm.

[0058] Figure 2 is the infrared spectrum of the obtained fluorinated tetra-functional cyanate ester. From Figure 2 it can be seen that: at about 2237 and 2266 cm -1 are the two characteristic stretching vibration peaks of the cyanate ester group, at about 1244 cm -1 is the absorption peak of the aromatic ether bond, and at about 1135 cm -1 is the absorption peak of the trifluoromethyl group.

[0059] Solubility: At room temperature, dissolve 1.1 g of the fluorinated tetra-functional cyanate ester in 10 g of dichloromethane, acetone, and dimethyl sulfoxide respectively. All three solvents can dissolve it, indicating that this fluorinated tetra-functional cyanate ester is soluble in dichloromethane, acetone, and dimethyl sulfoxide.

[0060] Weigh a certain mass of bisphenol A cyanate ester monomer and the fluorinated tetrafunctional cyanate ester monomer prepared in the above steps respectively. The specific mass ratio is shown in Table 1.

[0061] Table 1 Material ratio of fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester

[0062] Heat the bisphenol A cyanate ester monomer to 95 °C until it melts, then add the fluorinated tetrafunctional cyanate ester monomer, and pre-polymerize at 110 °C for 1 h to obtain a fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer.

[0063] Heat the fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer and the purchased pure bisphenol A cyanate ester prepolymer to 90 °C, and pour them into molds coated with a release agent respectively. Remove the bubbles under reduced pressure in a vacuum oven, and then place them in a forced-air oven for curing. The curing process is: 110 °C / 2 h → 130 °C / 2 h → 160 °C / 2 h → 190 °C / 2 h → 220 °C / 2 h → 250 °C / 2 h.

[0064] Use thermogravimetric analysis (TGA) and dynamic thermomechanical analysis (DMA) to test the heat resistance of the cured cyanate ester resin, use a broadband dielectric impedance resistance measuring instrument to test its dielectric properties, and use thermal expansion analysis to test its dimensional stability. The test results are shown in Table 2.

[0065] Table 2 Performance test results of fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester

[0066] It can be seen from Table 2 that compared with the cured product of pure bisphenol A cyanate ester, after copolymerization and curing of fluorinated tetrafunctional cyanate ester and bisphenol A cyanate ester, the fluorinated cyanate ester resin has a higher 5% weight loss temperature and glass transition temperature, and also has a lower dielectric constant and thermal expansion coefficient. Therefore, adding fluorinated tetrafunctional cyanate ester is beneficial to enhancing the heat resistance, dielectric properties and dimensional stability of cyanate ester resin.

[0067] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A fluorocyanic acid ester resin, characterized in that, The preparation raw materials include bisphenol A cyanate ester and fluorine-containing tetrafunctional cyanate ester, and the fluorine-containing tetrafunctional cyanate ester has the following structure: 。 2. The fluorocyanic acid ester resin according to claim 1, wherein, The mass ratio of the bisphenol A cyanate ester to the fluorine-containing tetrafunctional cyanate ester is 7:3 to 9:

1.

3. The fluorocyanic acid ester resin according to claim 1 or 2, characterized in that, The preparation method of the fluorine-containing tetrafunctional cyanate ester includes the following steps: Mix 4,4'-(hexafluoroisopropylidene)bisphenol, p-fluorobenzaldehyde, potassium carbonate and a polar solvent, and carry out a first reaction to obtain 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde; Mix the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde, phenol, p-toluenesulfonic acid and zinc chloride, and carry out a second reaction to obtain a fluorine-containing tetrafunctional phenol; Mix the fluorine-containing tetrafunctional phenol, triethylamine, cyanogen halide and an organic solvent, and carry out a third reaction to obtain the fluorine-containing tetrafunctional cyanate ester.

4. The fluorocyanic acid ester resin according to claim 3, characterized in that, The molar ratio of the 4,4'-(hexafluoroisopropylidene)bisphenol to the p-fluorobenzaldehyde is 1:2 to 4; the molar ratio of the 4,4'-(hexafluoroisopropylidene)bisphenol to the potassium carbonate is 1:2 to 4.

5. The fluorocyanic acid ester resin according to claim 3, characterized in that, The temperature of the first reaction is 135 to 145 °C, and the time is 6 to 10 h.

6. The fluorocyanic acid ester resin according to claim 3, characterized in that, The molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to the phenol is 1:8 to 14; the molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to the p-toluenesulfonic acid is 1:0.2 to 0.4; the molar ratio of the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to the zinc chloride is 1:0.2 to 0.

4.

7. The fluorocyanic acid ester resin according to claim 3, characterized in that, The temperature of the second reaction is 40 to 50 °C, and the time is 24 to 36 h.

8. The fluorinated cyanate ester resin according to claim 3, wherein, The molar ratio of the fluorine-containing tetrafunctional phenol to the cyanogen halide is 1:6 to 10, and the molar ratio of the triethylamine to the cyanogen halide is 1:1 to 1.4; The temperature of the third reaction is -20 to 0 °C, and the time is 3 to 5 h.

9. The preparation method of the fluorocyanic acid ester resin according to any one of claims 1 to 8, characterized in that, It includes the following steps: Mix the bisphenol A cyanate ester and the fluorine-containing tetrafunctional cyanate ester, and carry out prepolymerization to obtain a fluorine-containing tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer; Carry out curing on the fluorine-containing tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer to obtain the fluorine-containing cyanate ester resin.

10. The preparation method according to claim 9, wherein The temperature of the prepolymerization is 100 to 120 °C, and the time is 0.5 to 2 h.

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