A fluorocyanic acid ester resin and its preparation method

Abstract

The present invention belongs to the technical field of high-performance resins, and particularly relates to a fluorinated cyanate ester resin and a preparation method thereof. The raw materials for preparing the fluorinated cyanate ester resin provided by the present invention include bisphenol A cyanate ester and a fluorinated tetrafunctional cyanate ester; the fluorinated tetrafunctional cyanate ester introduces trifluoromethyl and diphenyl ether structures into the tetrafunctional cyanate ester molecule: trifluoromethyl makes the fluorinated tetrafunctional cyanate ester have 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, making the fluorinated cyanate ester resin have a higher crosslinking density, which is beneficial to increasing the glass transition temperature of the fluorinated cyanate ester resin.

Description

Technical Field

[0001] The present invention relates to the technical field of high-performance resins, and particularly relates to a fluorinated cyanate 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 resins have excellent high-temperature resistance, good dimensional stability, low water absorption, low dielectric constant and low dielectric loss, so they have become ideal materials for the resin matrix of printed circuit boards. Cyanate resins also have good processing properties, excellent mechanical properties, good flame retardancy and high environmental tolerance. Their excellent properties make them widely used in fields such as sensing, encapsulation and aerospace. However, the glass transition temperature of most cyanate resins is between 190 and 290 °C, and when welding printed circuit boards, the temperature of the laminate usually rises to 300 - 350 °C in a very short time. Therefore, it is necessary to increase the glass transition temperature and heat resistance of cyanate resins. 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 resins is of great significance for the application of cyanate in printed circuit boards.

[0003] Designing and improving the molecular structure of cyanate resins is an important way to improve the properties of cyanate resins. 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 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. However, phenolic resin with diphenyl ether structure will reduce the thermal stability of cyanate resin. Summary of the Invention

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

[0005] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a fluorinated cyanate resin, and the raw materials for preparation include bisphenol A cyanate and fluorinated tetrafunctional cyanate, and the fluorinated tetrafunctional cyanate has the following structure:

[0007] .

[0008] Preferably, the mass ratio of the bisphenol A cyanate ester to the fluorinated tetrafunctional cyanate ester is 7:3 to 9:1.

[0009] Preferably, the preparation method of the fluorinated tetrafunctional cyanate ester comprises the following steps:

[0010] 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;

[0011] 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;

[0012] 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.

[0013] Preferably, the molar ratio of 4,4'-(hexafluoroisopropylidene)bisphenol to p-fluorobenzaldehyde is 1:2 to 4; the molar ratio of 4,4'-(hexafluoroisopropylidene)bisphenol to potassium carbonate is 1:2 to 4.

[0014] Preferably, the temperature of the first reaction is 135 to 145 °C, and the time is 6 to 10 h.

[0015] Preferably, the molar ratio of 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to phenol is 1:8 to 14; the molar ratio of 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to p-toluenesulfonic acid is 1:0.2 to 0.4; the molar ratio of 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to zinc chloride is 1:0.2 to 0.4.

[0016] Preferably, the temperature of the second reaction is 40 to 50 °C, and the time is 24 to 36 h.

[0017] Preferably, the molar ratio of the fluorinated tetrafunctional phenol to cyanogen halide is 1:6 to 10, and the molar ratio of triethylamine to cyanogen halide is 1:1 to 1.4;

[0018] The temperature of the third reaction is -20 to 0 °C, and the time is 3 to 5 h.

[0019] The present invention also provides a preparation method of the fluorinated cyanate ester resin according to the above technical solution, comprising the following steps:

[0020] 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;

[0021] Cure the fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer to obtain the fluorinated cyanate ester resin.

[0022] Preferably, the temperature for prepolymerization is 100 - 120 °C and the time is 0.5 - 2 h.

[0023] The present invention provides a fluorinated cyanate ester resin.

[0024] The raw materials for preparing 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 gives the fluorinated tetrafunctional cyanate ester a relatively large free volume, a relatively small dipole moment, and a relatively 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, which gives the fluorinated cyanate ester resin a higher cross - linking density, conducive 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 - resistant performance and dielectric performance. Description of the Drawings

[0025] Figure 1 1H NMR spectrum of the fluorinated tetrafunctional cyanate ester obtained in Example 1;

[0026] Figure 2 FT - IR spectrum of the fluorinated tetrafunctional cyanate ester obtained in Example 1. Detailed Embodiments

[0027] 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:

[0028] .

[0029] Unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

[0030] In the present invention, the mass ratio of the bisphenol A cyanate ester to the fluorinated tetrafunctional cyanate ester is preferably 7:3 - 9:1, specifically preferably 7:3, 8:2, or 9:1.

[0031] In the present invention, the preparation method of the fluorinated tetrafunctional cyanate ester preferably includes the following steps:

[0032] 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;

[0033] 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;

[0034] 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.

[0035] In the present invention, 4,4'-(hexafluoroisopropylidene)bisphenol, p-fluorobenzaldehyde, potassium carbonate and a polar solvent are mixed, and a first reaction is carried out to obtain 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde.

[0036] 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.

[0037] In the present invention, the potassium carbonate is preferably anhydrous potassium carbonate.

[0038] 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.

[0039] 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.

[0040] In the present invention, the temperature of the first reaction is preferably 135 - 145 °C, specifically preferably 135 °C, 140 °C or 145 °C; the time is preferably 6 - 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.

[0041] After the first reaction, the present invention preferably further includes: the obtained first reaction liquor is successively subjected to water precipitation and dissolution to obtain a crude product; the crude product is successively subjected to recrystallization and drying 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. Using one or more of acetone, methanol, ethanol and tetrahydrofuran as the dissolution reagent in the present invention ensures the complete dissolution of the crude product and is conducive to the subsequent separation of impurities. In the present invention, the number of times of successively carrying out water precipitation and dissolution is preferably 3 - 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 - 4 times, specifically preferably 3 times or 4 times.

[0042] In the present invention, the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde has the following structure:

[0043] .

[0044] After obtaining the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde, the present invention mixes the 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde, phenol, p-toluenesulfonic acid and zinc chloride and carries out a second reaction to obtain a fluorinated tetrafunctional phenol.

[0045] In the present invention, the zinc chloride is preferably anhydrous zinc chloride.

[0046] In the present invention, the molar ratio of 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 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 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 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to phenol to be 1:8 to 14, the molar ratio of 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to p-toluenesulfonic acid to be 1:0.2 to 0.4, and the molar ratio of 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde to zinc chloride to be 1:0.2 to 0.4, which is beneficial to the smooth progress of the second reaction.

[0047] In the present invention, the mixing of 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde, phenol, p-toluenesulfonic acid and zinc chloride preferably includes the following steps: dissolving 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde and phenol by heating, and then adding p-toluenesulfonic acid and zinc chloride; the temperature for heating and dissolving is preferably 75 to 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.

[0048] In the present invention, the temperature of the second reaction is preferably 40 to 50°C, specifically preferably 40°C, 45°C or 50°C; the time is preferably 24 to 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.

[0049] After the second reaction, the present invention preferably further comprises: subjecting the obtained second reaction material liquid to alcohol dissolution and water precipitation in sequence to obtain a crude product; subjecting the crude product to rotary evaporation under reduced pressure to obtain the fluorinated tetrafunctional phenol. In the present invention, the alcohol solvent for alcohol dissolution preferably comprises 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 conducive to improving the product purity. In the present invention, the temperature for 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 for rotary evaporation under reduced pressure 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.

[0050] In the present invention, the fluorinated tetrafunctional phenol has the following structure:

[0051] .

[0052] After obtaining the fluorinated tetrafunctional phenol, the present invention mixes the fluorinated tetrafunctional phenol, triethylamine, cyanogen halide and an organic solvent and performs a third reaction to obtain the fluorinated tetrafunctional cyanate.

[0053] 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 conducive to the smooth progress of the cyanation reaction, i.e., the third reaction.

[0054] In the present invention, the organic solvent is preferably a polar solvent, and the polar solvent preferably comprises one or more of ether, dichloromethane, methyl ethyl ketone and toluene. In the present invention, using one or more of ether, dichloromethane, methyl ethyl ketone and toluene as the organic solvent ensures complete dissolution of the reactants.

[0055] In the present invention, the molar ratio of the fluorinated tetrafunctional phenol to the cyanogen halide is preferably 1:6-10, specifically preferably 1:6, 1:7, 1:8, 1:9 or 1:10. In the present invention, the molar ratio of triethylamine to cyanogen halide is preferably 1:1-1.4, 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. The present invention controls the molar ratio of the fluorinated tetrafunctional phenol to the cyanogen halide to be 1:6-10 and the molar ratio of triethylamine to cyanogen halide to be 1:1-1.4, which ensures the full progress of the third reaction and improves the yield.

[0056] In the present invention, the mixing of the fluorinated tetrafunctional phenol, triethylamine, cyanogen halide and organic solvent preferably comprises the following steps: mixing the fluorinated tetrafunctional phenol and the organic solvent, and then successively adding triethylamine and cyanogen halide. In the present invention, the addition manner of the triethylamine is preferably dropwise addition; the addition temperature of the triethylamine is preferably the same as the temperature of the third reaction, which will not be elaborated herein. 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 herein.

[0057] 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.

[0058] 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 counted 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.

[0059] After the third reaction, the present invention preferably further comprises: 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, precipitating with alcohol 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 to 14%, specifically preferably 8 to 13%, specifically preferably 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13% or 14%. In the present invention, the organic extractant preferably comprises 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 to 1.1 mol / L, specifically preferably 0.95 to 1.05%, specifically preferably 0.9%, 0.95%, 1%, 1.05% or 1.1%. In the present invention, the dissolving reagent preferably comprises dichloromethane. In the present invention, the alcohol solvent for precipitation with alcohol preferably comprises methanol.

[0060] In the present invention, the preparation formula of the fluorinated tetrafunctional cyanate ester is as follows:

[0061] .

[0062] The present invention also provides a preparation method of the fluorinated cyanate ester resin described in the above technical solution, including the following steps:

[0063] Mix bisphenol A cyanate ester and fluorinated tetrafunctional cyanate ester, and carry out prepolymerization to obtain a fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer;

[0064] Cure the fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer to obtain the fluorinated cyanate ester resin.

[0065] The present invention mixes bisphenol A cyanate ester and fluorinated tetrafunctional cyanate ester, and carries out prepolymerization to obtain a fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer.

[0066] In the present invention, the mixing of bisphenol A cyanate ester and fluorinated tetrafunctional cyanate ester preferably includes the following steps: melt the bisphenol A cyanate ester monomer, and then add 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.

[0067] In the present invention, the prepolymerization temperature 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.

[0068] After obtaining the fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer, the present invention cures the fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer to obtain the fluorinated cyanate ester resin.

[0069] Before the curing, the present invention preferably further includes defoaming, and the defoaming is preferably carried out in a vacuum oven.

[0070] 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.

[0071] The following is a detailed description of the fluorinated cyanate ester resin provided by the present invention and its preparation method in combination with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0072] Example 1

[0073] A preparation method of a fluorinated tetrafunctional cyanate ester is as follows:

[0074] 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 were added to a three-necked flask. After 4,4'-(hexafluoroisopropylidene)bisphenol was completely dissolved, 221.2 g of anhydrous potassium carbonate was added. The reaction system was heated to 140 °C and stirred for 10 h. After the reaction was completed, water was added to the system to precipitate the crude product. The crude product was dissolved in acetone and then dropped into water to precipitate the crude product. After repeating the operation of acetone dissolution - water precipitation 4 times according to this method, the crude product was recrystallized with isopropanol 3 times. After drying, 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde was obtained.

[0075] In the second step, 744.6 g of phenol and 430.6 g of the product of the first step, 4,4'-(hexafluoroisopropylidene)diphenoxybenzaldehyde, were added to a three-necked flask. The system was heated to 80 °C and stirred to dissolve. Then the temperature of the system was lowered to 40 °C, 37.6 g of p-toluenesulfonic acid and 27.0 g of anhydrous zinc chloride were added, and the reaction was stirred at this temperature for 30 h. After the reaction was completed, the crude product was dissolved in ethanol and then dropped into hot water at 80 °C to precipitate the crude product. The operation of alcohol dissolution - water precipitation was repeated 6 times. Then the crude product was rotary evaporated under reduced pressure at 140 °C for 5 h to obtain a fluorinated tetrafunctional phenol.

[0076] In the third step, under an argon atmosphere, 75.0 g of the product of the second step, fluorinated tetrafunctional phenol, and ether were added to a three-necked flask and stirred to dissolve. Then 60.0 g of triethylamine was added dropwise and the temperature of the reaction system was lowered to 0 °C. 72.0 g of cyanogen bromide was added and the reaction was stirred for 3 h. The reaction was quenched with an aqueous sodium hypochlorite solution (concentration 10%). Then the reaction solution was rotary evaporated to dryness, extracted with dichloromethane and water, and the aqueous phase was extracted again. The organic phases were combined and washed with a hydrochloric acid solution (concentration 1 mol / L). The organic phase was dried and rotary evaporated to dryness. Then the crude product was dissolved in dichloromethane, and the obtained solution was added to a large amount of methanol to precipitate the solid product. After filtration, a fluorinated tetrafunctional cyanate ester was obtained.

[0077] Figure 1 is the nuclear magnetic resonance hydrogen spectrum of the obtained fluorinated tetrafunctional cyanate ester. From Figure 1It 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 groups may be in the para or ortho positions 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.

[0078] Figure 2 Figure 4 is the infrared spectrum of the obtained fluorinated tetrafunctional cyanate ester. From Figure 2 It can be seen that: there are two characteristic stretching vibration peaks of the cyanate ester groups at about 2237 and 2266 cm -1 -1, the absorption peak of the aromatic ether bond is at about 1244 cm -1 -1, and the absorption peak of the trifluoromethyl group is at about 1135 cm -1 -1.

[0079] Solubility: At room temperature, 1.1 g of the fluorinated tetrafunctional cyanate ester was respectively dissolved in 10 g of dichloromethane, acetone, and dimethyl sulfoxide. All three solvents can dissolve it, indicating that this fluorinated tetrafunctional cyanate ester is soluble in dichloromethane, acetone, and dimethyl sulfoxide.

[0080] Weigh a certain mass of bisphenol A cyanate ester monomer and the fluorinated tetrafunctional cyanate ester monomer prepared in the above steps. The specific mass ratio is shown in Table 1.

[0081] Table 1 Material ratio of fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester

[0082]

[0083] Heat the bisphenol A cyanate ester monomer to 95 °C to melt it, 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.

[0084] Heat the fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer and the purchased pure bisphenol A cyanate ester prepolymer to 90 °C, pour them into the molds coated with mold release agent respectively, remove the bubbles under reduced pressure in a vacuum oven, and then put them into 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.

[0085] The heat resistance of the cured cyanate ester resin was tested by thermogravimetric analysis (TGA) and dynamic thermomechanical analysis (DMA), its dielectric properties were tested using a broadband dielectric impedance resistance measuring instrument, and its dimensional stability was tested by thermal expansion analysis. The test results are shown in Table 2.

[0086] Table 2 Performance test results of fluorinated tetrafunctional cyanate ester modified bisphenol A cyanate ester

[0087]

[0088] 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 coefficient of thermal expansion. Therefore, adding fluorinated tetrafunctional cyanate ester is beneficial to enhancing the heat resistance, dielectric properties and dimensional stability of cyanate ester resin.

[0089] 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 fluorine-containing cyanate resin, characterized in that The preparation raw materials include bisphenol A cyanate and fluorine-containing tetrafunctional cyanate, and the fluorine-containing tetrafunctional cyanate has the following structure: 。 2. The fluorine-containing cyanate resin according to claim 1, characterized in that The mass ratio of the bisphenol A cyanate ester to the fluorine-containing tetrafunctional cyanate ester is 7:3 to 9:

1.

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

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

5. The fluorine-containing cyanate resin according to claim 3, characterized in that The temperature of the first reaction is 135-145° C., and the time is 6-10 hours.

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

4.

7. The fluorine-containing cyanate resin according to claim 3, characterized in that The temperature of the second reaction is 40-50° C., and the time is 24-36 hours.

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

9. The method for preparing the fluorine-containing cyanate resin according to any one of claims 1 to 8, wherein: The following steps are involved: Mixing bisphenol A cyanate ester and fluorine-containing tetrafunctional cyanate ester, and prepolymerizing to obtain fluorine-containing tetrafunctional cyanate ester modified bisphenol A cyanate ester prepolymer; The fluorine-containing tetrafunctional cyanate-modified bisphenol A cyanate prepolymer is cured to obtain the fluorine-containing cyanate resin.

10. The preparation method according to claim 9, characterized in that The prepolymerization temperature is 100-120° C., and the prepolymerization time is 0.5-2 h.

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