Modified boron nitride-benzoxazine resin composite material and preparation method and application thereof

Abstract

The present invention relates to the technical field of polymer composite materials, and more particularly to a modified boron nitride-benzoxazine resin composite material, a preparation method thereof, and applications thereof. The preparation method comprises: mixing tyrosol, 1,10-diaminodecane, and paraformaldehyde, and then performing a Mannich condensation reaction to obtain a benzoxazine monomer containing an alcoholic hydroxyl group; and mixing a modified boron nitride containing an epoxy group with the benzoxazine monomer, and then performing a curing treatment to obtain a modified boron nitride-benzoxazine resin composite material. The modified boron nitride-benzoxazine resin composite material obtained by this preparation method realizes chemical grafting of the modified boron nitride and the benzoxazine monomer, overcoming the problems of poor compatibility and uneven dispersion caused by the physical blending method, and thus making the modified boron nitride-benzoxazine resin composite material have excellent thermal conductivity.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer composite materials, and in particular to a modified boron nitride-benzoxazine resin composite material, a preparation method thereof, and an application thereof. Background Art

[0002] In the electronics, information technology, and aerospace sectors, material selection and performance optimization are key factors driving industry progress. Benzoxazine resin, a thermosetting resin with excellent heat resistance, flame retardancy, solvent resistance, low dielectric constant, and dimensional stability, has been widely used in the manufacture of electronic packaging, copper-clad laminates, and aerospace materials.

[0003] As electronic components develop towards miniaturization and integration, heat dissipation issues are becoming increasingly prominent, placing higher demands on the thermal conductivity of materials. Although benzoxazine resins have demonstrated excellent performance in many aspects, their inherent thermal conductivity still cannot meet the urgent needs of current scientific and technological development and needs to be further improved. Boron nitride, as a material with excellent thermal conductivity, is considered a potential choice for improving the thermal conductivity of benzoxazine resins. However, the existing physical blending method for incorporating boron nitride into benzoxazine resins has poor compatibility, resulting in uneven dispersion of boron nitride in the benzoxazine resin and the easy formation of agglomerates, which seriously hinders the effective improvement of the thermal conductivity of benzoxazine resins. Summary of the Invention

[0004] To address the problems of the prior art, the present invention provides a modified boron nitride-benzoxazine resin composite material, its preparation method, and application. For the first time, the present invention uses biomass tyrosol and 1,10-diaminodecane as raw materials, mixes them with paraformaldehyde, and then undergoes a Mannich condensation reaction to synthesize a benzoxazine monomer containing an alcoholic hydroxyl group. This benzoxazine monomer containing an alcoholic hydroxyl group is then reacted with modified boron nitride containing an epoxy group to obtain a modified boron nitride-benzoxazine resin composite material. The modified boron nitride-benzoxazine resin composite material obtained by this preparation method achieves chemical grafting of the modified boron nitride with the benzoxazine monomer, overcoming the poor compatibility and uneven dispersion problems associated with physical blending methods. This results in the modified boron nitride-benzoxazine resin composite material having excellent thermal conductivity.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The first object of the present invention is to provide a method for preparing a modified boron nitride-benzoxazine resin composite material, comprising the following steps:

[0007] Tyrosol, 1,10-diaminodecane and paraformaldehyde are mixed and subjected to a Mannich condensation reaction to obtain a benzoxazine monomer containing an alcoholic hydroxyl group. The molar ratio of tyrosol, 1,10-diaminodecane and paraformaldehyde is 2:1:4 to 4.4. Since paraformaldehyde will partially decompose during the Mannich condensation reaction, the amount of paraformaldehyde used is excessive to ensure that it fully reacts with tyrosol and 1,10-diaminodecane, thereby maximizing the production of benzoxazine containing an alcoholic hydroxyl group.

[0008] Modified boron nitride containing epoxy groups is mixed with a benzoxazine monomer and then cured to obtain a modified boron nitride-benzoxazine resin composite material. During the curing process, the epoxy groups on the modified boron nitride undergo a ring-opening reaction and react with the alcoholic hydroxyl groups on the benzoxazine monomer, as well as with the phenolic hydroxyl groups produced after thermal ring-opening of the benzoxazine monomer to form ether bonds, thereby achieving chemical grafting of the modified boron nitride and the benzoxazine monomer to obtain a modified boron nitride-benzoxazine resin composite material. The mass ratio of the modified boron nitride to the benzoxazine monomer is 5-30:70-95. When the mass of the modified boron nitride is low, the strength of the modified boron nitride-benzoxazine resin composite material is not significantly improved, while when the mass of the modified boron nitride is high, the benzoxazine monomer content is too low, resulting in a decrease in the strength of the modified boron nitride-benzoxazine resin composite material and an increase in brittleness.

[0009] Preferably, the curing treatment conditions are: first curing at 160°C, 170°C, and 180°C for 1 hour respectively, and then curing at 190°C for 2 hours; wherein, compared with curing by gradually increasing the temperature at a heating rate, step-by-step temperature curing can ensure that the modified boron nitride-benzoxazine resin composite material fully reacts at different temperature stages, promotes the formation and cross-linking of the internal structure of the modified boron nitride-benzoxazine resin composite material, and effectively avoids severe thermal stress during the curing process by controlling the temperature and time in stages, thereby helping to reduce defects inside the modified boron nitride-benzoxazine resin composite material and improve the overall performance and stability of the modified boron nitride-benzoxazine resin composite material.

[0010] Preferably, the mixing conditions of the modified boron nitride containing epoxy groups and the benzoxazine monomer are: stirring at 110° C. to 120° C. for 5 to 30 minutes; wherein the benzoxazine monomer is melted and then mixed with the modified boron nitride containing epoxy groups, and the melting point of the benzoxazine monomer is higher than 110° C. Setting the temperature range of 110° C. to 120° C. ensures that the benzoxazine monomer can be effectively melted while avoiding the cross-linking reaction of the benzoxazine monomer caused by excessively high temperature, thereby preventing its viscosity from increasing abnormally.

[0011] Preferably, the conditions for the Mannich condensation reaction are: 65°C to 78°C for 2h to 24h; wherein, when preparing the benzoxazine monomer, the temperature cannot exceed 120°C. Although high temperature can promote the reaction rate, the boiling point of ethanol is 78°C, which is relatively low, so 65°C to 78°C is selected.

[0012] Preferably, the modified boron nitride is prepared according to the following steps: placing boron nitride in a sodium hydroxide solution for hydroxylation to obtain hydroxylated boron nitride; adding a silane coupling agent and an organic solvent to the hydroxylated boron nitride to carry out a substitution reaction to obtain modified boron nitride.

[0013] Preferably, the boron nitride is selected from hexagonal boron nitride; the thermal conductivity of hexagonal boron nitride is 34 W / m·k, which has a thermal conductivity coefficient similar to that of stainless steel; in addition, hexagonal boron nitride does not react with weak acids and strong bases at room temperature, is slightly soluble in hot acid, and has good corrosion resistance to various inorganic acids, bases, salt solutions and organic solvents.

[0014] Preferably, the molar ratio of boron nitride to sodium hydroxide in the sodium hydroxide solution is 1:2-3.

[0015] Preferably, the mass volume ratio of hydroxylated boron nitride, silane coupling agent, and organic solvent is 1 g: 0.5 mL to 2 mL: 5 mL to 10 mL; at this mass volume ratio, the stripping efficiency of boron nitride is the highest.

[0016] Preferably, the conditions for the hydroxylation treatment are: hydroxylation treatment at 80°C to 100°C for 2h to 24h; and the conditions for the substitution reaction are: reaction at 90°C to 95°C for 6h to 12h.

[0017] Preferably, the organic solvent is selected from ethanol, ethyl acetate, N,N'-dimethylformamide or chloroform; more preferably, ethanol, which has good volatility and can be easily removed by distillation or evaporation in subsequent treatments, thereby reducing the generation of hazardous waste; in addition, ethanol as an organic solvent has low toxicity and has little impact on the human body and the environment.

[0018] Preferably, the silane coupling agent is KH560.

[0019] The second object of the present invention is to provide a modified boron nitride-benzoxazine resin composite material prepared by the above preparation method.

[0020] The third object of the present invention is to provide a use of the modified boron nitride-benzoxazine resin composite material in the preparation of a thermal conductive material.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention provides a method for preparing a modified boron nitride-benzoxazine resin composite material. First, tyrosol, 1,10-diaminodecane and paraformaldehyde are mixed and then subjected to a Mannich condensation reaction to synthesize a benzoxazine monomer containing an alcoholic hydroxyl group; wherein the molar ratio of tyrosol, 1,10-diaminodecane and paraformaldehyde is 2:1:4-4.4; then, the benzoxazine monomer is mixed with modified boron nitride containing an epoxy group and cured to obtain a modified boron nitride-benzoxazine resin composite material; wherein the mass ratio of the modified boron nitride to the benzoxazine monomer is 5-30:70-95.

[0023] During the curing process, the epoxy groups on the modified boron nitride undergo a ring-opening reaction, reacting with the alcoholic hydroxyl groups on the benzoxazine monomer and the phenolic hydroxyl groups produced after thermal ring-opening of the benzoxazine monomer to form ether bonds, thereby chemically grafting the modified boron nitride and the benzoxazine monomer to obtain a modified boron nitride-benzoxazine resin composite material with a cross-linked network structure. The modified boron nitride-benzoxazine resin composite material obtained by this preparation method achieves chemical grafting of the modified boron nitride and the benzoxazine monomer, overcoming the poor compatibility and uneven dispersion problems caused by physical blending methods, resulting in the modified boron nitride-benzoxazine resin composite material having excellent thermal conductivity.

[0024] 2. The preparation method of traditional benzoxazine resins is highly dependent on fossil resources, and a large amount of toxic solvents are used in the preparation process, which not only increases the environmental burden but also seriously hinders the sustainable development of benzoxazine resins. In contrast, the present invention uses an environmentally friendly solvent - ethanol - when preparing benzoxazine monomers and modified boron nitride. In particular, in the process of preparing modified boron nitride-benzoxazine resin composite materials, biomass tyrosol and 1,10-diaminodecane are used as raw materials and reacted with paraformaldehyde to undergo a Mannich condensation reaction to synthesize bio-based benzoxazine monomers, reducing dependence on fossil resources. In addition, the present invention also uses the green solvent anhydrous ethanol when synthesizing benzoxazine monomers containing alcoholic hydroxyl groups, successfully avoiding the disadvantages of using toxic solvents in the traditional preparation process of benzoxazine resins, thereby significantly reducing environmental pollution problems.

[0025] 3. The modified boron nitride-benzoxazine resin composite material prepared by the present invention has high thermal conductivity and excellent thermal stability. When the modified boron nitride addition amount is 30wt%, the thermal conductivity of the modified boron nitride-benzoxazine resin composite material can be increased to 0.75W / m·K, which is 139% higher than that of benzoxazine resin. In addition, the temperature of the modified boron nitride-benzoxazine resin composite material at 5wt% mass loss in a nitrogen atmosphere is 293°C, which is 22°C higher than that of benzoxazine resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1This is a synthetic route diagram of the benzoxazine monomers prepared in Examples 1 to 4.

[0027] Figure 2 This is a synthetic route for the modified boron nitride prepared in Examples 1 to 4.

[0028] Figure 3 This is the infrared characterization image of the benzoxazine monomer prepared in Example 1.

[0029] Figure 4 This is the hydrogen nuclear magnetic resonance spectrum of the benzoxazine monomer prepared in Example 1.

[0030] Figure 5 This is the DSC curve of the benzoxazine monomer prepared in Example 1.

[0031] Figure 6 The microscopic morphology of boron nitride and modified boron nitride, among which, Figure 6 Figure (a) is the microscopic morphology of boron nitride. Figure 6 Figure (b) is the microscopic morphology of modified boron nitride.

[0032] Figure 7 This is the infrared characterization of the hydroxylated boron nitride and modified boron nitride prepared in Example 1.

[0033] Figure 8 These are infrared spectra of the modified boron nitride-benzoxazine resin composite materials prepared in Examples 1 to 4 and the benzoxazine resin prepared in Comparative Example 1.

[0034] Figure 9 The fracture morphology of the modified boron nitride-benzoxazine resin composite materials prepared in Examples 1 to 4 and the benzoxazine resin prepared in Comparative Example 1 is shown, wherein: Figure 9 Figure (a) is the fracture morphology of the benzoxazine resin prepared in Comparative Example 1. Figure 9 Figure (b) is a fracture morphology of the modified boron nitride-benzoxazine resin composite material prepared in Example 1. Figure 9 Figure (c) is a fracture morphology of the modified boron nitride-benzoxazine resin composite material prepared in Example 2. Figure 9 Figure (d) is a fracture morphology of the modified boron nitride-benzoxazine resin composite material prepared in Example 3. Figure 9 Figure (e) is a fracture morphology of the modified boron nitride-benzoxazine resin composite material prepared in Example 4.

[0035] Figure 10 This is a curing mechanism diagram of the modified boron nitride-benzoxazine resin composite material prepared in Examples 1 to 4 and the benzoxazine resin prepared in Comparative Example 1, wherein: Figure 10Figure (a) is a curing mechanism diagram of the benzoxazine resin prepared in Comparative Example 1. Figure 10 Figure (b) is a curing mechanism diagram of the modified boron nitride-benzoxazine resin composite materials prepared in Examples 1 to 4.

[0036] Figure 11 The infrared thermal imaging results of the modified boron nitride-benzoxazine resin composite materials prepared in Examples 1 to 4 and the benzoxazine resin prepared in Comparative Example 1 are shown, wherein: Figure 11 Figure (a) is an infrared thermal image of the modified boron nitride-benzoxazine resin composite material prepared in Examples 1 to 4 and the benzoxazine resin prepared in Comparative Example 1. Figure 11 Figure (b) is an infrared thermal image temperature-time curve of the modified boron nitride-benzoxazine resin composite materials prepared in Examples 1 to 4 and the benzoxazine resin prepared in Comparative Example 1.

[0037] Figure 12 Graph showing the thermal conductivity test results of the modified boron nitride-benzoxazine resin composite materials prepared in Examples 1 to 4 and the benzoxazine resin prepared in Comparative Example 1.

[0038] Figure 13 These are TGA curves of the modified boron nitride-benzoxazine resin composite materials prepared in Examples 1 to 4 and the benzoxazine resin prepared in Comparative Example 1. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solution of the present invention in conjunction with the data in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] Considering the ever-increasing demands for thermal conductivity in materials as technology advances, conventional benzoxazine resins have limited thermal conductivity and are unable to meet current demands. While attempts have been made to improve the thermal conductivity of benzoxazine resins using boron nitride through physical blending, the poor compatibility of boron nitride with benzoxazine resins results in uneven dispersion of boron nitride within the resin, hindering its effective thermal conductivity.

[0041] In response to the problems existing in the prior art, the present invention provides a method for preparing a modified boron nitride-benzoxazine resin composite material, comprising the following steps: mixing tyrosol, 1,10-diaminodecane and paraformaldehyde, and performing a Mannich condensation reaction to obtain a benzoxazine monomer containing an alcoholic hydroxyl group; wherein the molar ratio of tyrosol, 1,10-diaminodecane and paraformaldehyde is 2:1:4-4.4; mixing a modified boron nitride containing an epoxy group and the benzoxazine monomer, and performing a curing treatment; during the curing process, the epoxy groups on the modified boron nitride undergo a ring-opening reaction, react with the alcoholic hydroxyl groups on the benzoxazine monomer, and react with the phenolic hydroxyl groups generated after thermal ring opening of the benzoxazine monomer to form an ether bond, thereby achieving chemical grafting of the modified boron nitride and the benzoxazine monomer to obtain the modified boron nitride-benzoxazine resin composite material; wherein the mass ratio of the modified boron nitride to the benzoxazine monomer is 5-30:70-95.

[0042] The modified boron nitride-benzoxazine resin composite material obtained by this preparation method realizes the chemical grafting of modified boron nitride and benzoxazine monomer, overcoming the problems of poor compatibility and uneven dispersion caused by the physical blending method, so that the modified boron nitride-benzoxazine resin composite material has excellent thermal conductivity.

[0043] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0044] Example 1

[0045] The preparation method of the modified boron nitride-benzoxazine resin composite material comprises the following steps:

[0046] S1. Synthesize benzoxazine monomers. The synthesis technology route is as follows: Figure 1 As shown:

[0047] 20g of tyrosol, 12.464g of 1,10-diaminodecane, 8.68g of paraformaldehyde, and 200mL of anhydrous ethanol were added to a flask equipped with a magnetic stirrer. The mixture was thoroughly mixed using a heat-collecting constant-temperature magnetic stirrer. The temperature was raised to 78°C and the reaction was maintained at this temperature for 12 hours. After the reaction, the mixture was poured into a beaker and allowed to stand. After cooling and crystallization, the mixture was transferred to a vacuum drying oven at 50°C for 12 hours to obtain a benzoxazine monomer containing an alcoholic hydroxyl group, designated T-fa.

[0048] S2. Preparation of modified boron nitride, its synthesis technology route is as follows Figure 2 As shown:

[0049] Weigh 15.0g of hexagonal boron nitride and 60g of sodium hydroxide, add sodium hydroxide and deionized water to a beaker and mix evenly to prepare a 5mol / L sodium hydroxide aqueous solution. Then add the weighed hexagonal boron nitride and sodium hydroxide aqueous solution to a flask equipped with a magnet, use a heat-collecting constant temperature heating magnetic stirrer to mix them thoroughly, and stir at a constant temperature and high speed for 12h at 95°C. After the reaction is completed, wait for it to cool to room temperature, filter it repeatedly with a suction flask, and rinse it with deionized water 5 times. Subsequently, place the solid in a vacuum drying oven and dry it at 60°C for 24h to obtain hydroxylated hexagonal boron nitride, recorded as BN-OH.

[0050] 8.0 g of BN-OH, 8 mL of KH-560, and 80 mL of anhydrous ethanol were added to a flask containing a magnet, and the mixture was thoroughly mixed using a heat-collecting constant-temperature heating magnetic stirrer. The mixture was heated to 90°C and stirred at this constant temperature for 12 hours to obtain a mixed solution. After the stirring, the mixed solution was placed in a centrifuge tube and centrifuged at 3000 rad / min for 5 minutes, and then at 5000 rad / min for 10 minutes to retain a white precipitate. The white precipitate was placed in a vacuum drying oven and dried at 50°C for 12 hours to obtain modified boron nitride containing epoxy groups, i.e., modified boron nitride, which was recorded as KH-560-modified BN-OH.

[0051] S3. Preparation of modified boron nitride-benzoxazine resin composite material:

[0052] First, T-fa and modified boron nitride were weighed according to a mass ratio of T-fa to modified boron nitride of 95:5, added to a flask, and the mixture was fully mixed using a heat-collecting constant-temperature heating magnetic stirrer. The temperature was precisely controlled at 110°C and stirred continuously and evenly for 10 minutes to obtain a molten mixture.

[0053] The molten mixture was then placed in a vacuum drying oven and evenly added to a mold at 110°C. After evacuation until no bubbles were present, the mixture was transferred to a mold after the temperature in an electric constant-temperature blower dryer reached 160°C. The mixture was then cured at 160°C, 170°C, and 180°C for 1 hour each, followed by 190°C for 2 hours. The mixture was then naturally cooled to obtain a modified boron nitride-benzoxazine resin composite material, which was recorded as 5 wt%.

[0054] Example 2

[0055] The preparation method of the modified boron nitride-benzoxazine resin composite material comprises the following steps:

[0056] S1. Synthesize benzoxazine monomers. The synthesis technology route is as follows: Figure 1 As shown:

[0057] 20g of tyrosol, 12.464g of 1,10-diaminodecane, 8.68g of paraformaldehyde, and 200mL of anhydrous ethanol were added to a flask equipped with a magnetic stirrer. The mixture was thoroughly mixed using a heat-collecting constant-temperature magnetic stirrer. The temperature was raised to 78°C and the reaction was maintained at this temperature for 12 hours. After the reaction, the mixture was poured into a beaker and allowed to stand. After cooling and crystallization, the mixture was transferred to a vacuum drying oven at 50°C for 12 hours to obtain a benzoxazine monomer containing an alcoholic hydroxyl group, designated T-fa.

[0058] S2. Preparation of modified boron nitride, its synthesis technology route is as follows Figure 2 As shown:

[0059] Weigh 15.0g of hexagonal boron nitride and 60g of sodium hydroxide, add sodium hydroxide and deionized water to a beaker and mix evenly to prepare a 5mol / L sodium hydroxide aqueous solution. Then add the weighed hexagonal boron nitride and sodium hydroxide aqueous solution to a flask equipped with a magnet, use a heat-collecting constant temperature heating magnetic stirrer to mix them thoroughly, and stir at a constant temperature and high speed for 12h at 95°C. After the reaction is completed, wait for it to cool to room temperature, filter it repeatedly with a suction flask, and rinse it with deionized water 5 times. Subsequently, place the solid in a vacuum drying oven and dry it at 60°C for 24h to obtain hydroxylated hexagonal boron nitride, recorded as BN-OH.

[0060] 8.0 g of BN-OH, 8 mL of KH-560, and 80 mL of anhydrous ethanol were added to a flask containing a magnet, and the mixture was thoroughly mixed using a heat-collecting constant-temperature heating magnetic stirrer. The mixture was heated to 90°C and stirred at this constant temperature for 12 hours to obtain a mixed solution. After the stirring, the mixed solution was placed in a centrifuge tube and centrifuged at 3000 rad / min for 5 minutes, and then at 5000 rad / min for 10 minutes to retain a white precipitate. The white precipitate was placed in a vacuum drying oven and dried at 50°C for 12 hours to obtain modified boron nitride containing epoxy groups, i.e., modified boron nitride, which was recorded as KH-560-modified BN-OH.

[0061] S3. Preparation of modified boron nitride-benzoxazine resin composite material:

[0062] First, T-fa and modified boron nitride were weighed in a mass ratio of 90:10 and added to a flask. The mixture was fully mixed using a heat-collecting constant-temperature heating magnetic stirrer. The temperature was precisely controlled at 110°C and stirred continuously and evenly for 10 minutes to obtain a molten mixture.

[0063] The molten mixture was then placed in a vacuum drying oven and evenly added to a mold at 110°C. After evacuation until no bubbles were present, the mixture was transferred to a mold after the temperature in an electric constant-temperature blower dryer reached 160°C. The mixture was then cured at 160°C, 170°C, and 180°C for 1 hour each, followed by 190°C for 2 hours. The mixture was then naturally cooled to obtain a modified boron nitride-benzoxazine resin composite material, which was recorded as 10 wt%.

[0064] Example 3

[0065] The preparation method of the modified boron nitride-benzoxazine resin composite material comprises the following steps:

[0066] S1. Synthesize benzoxazine monomers. The synthesis technology route is as follows: Figure 1 As shown:

[0067] 20g of tyrosol, 12.464g of 1,10-diaminodecane, 8.68g of paraformaldehyde, and 200mL of anhydrous ethanol were added to a flask equipped with a magnetic stirrer. The mixture was thoroughly mixed using a heat-collecting constant-temperature magnetic stirrer. The temperature was raised to 78°C and the reaction was maintained at this temperature for 12 hours. After the reaction, the mixture was poured into a beaker and allowed to stand. After cooling and crystallization, the mixture was transferred to a vacuum drying oven at 50°C for 12 hours to obtain a benzoxazine monomer containing an alcoholic hydroxyl group, designated T-fa.

[0068] S2. Preparation of modified boron nitride, its synthesis technology route is as follows Figure 2 As shown:

[0069] Weigh 15.0g of hexagonal boron nitride and 60g of sodium hydroxide, add sodium hydroxide and deionized water to a beaker and mix evenly to prepare a 5mol / L sodium hydroxide aqueous solution. Then add the weighed hexagonal boron nitride and sodium hydroxide aqueous solution to a flask equipped with a magnet, use a heat-collecting constant temperature heating magnetic stirrer to mix them thoroughly, and stir at a constant temperature and high speed for 12h at 95°C. After the reaction is completed, wait for it to cool to room temperature, filter it repeatedly with a suction flask, and rinse it with deionized water 5 times. Subsequently, place the solid in a vacuum drying oven and dry it at 60°C for 24h to obtain hydroxylated hexagonal boron nitride, recorded as BN-OH.

[0070] 8.0 g of BN-OH, 8 mL of KH-560, and 80 mL of anhydrous ethanol were added to a flask containing a magnet, and the mixture was thoroughly mixed using a heat-collecting constant-temperature heating magnetic stirrer. The mixture was heated to 90°C and stirred at this constant temperature for 12 hours to obtain a mixed solution. After the stirring, the mixed solution was placed in a centrifuge tube and centrifuged at 3000 rad / min for 5 minutes, and then at 5000 rad / min for 10 minutes to retain a white precipitate. The white precipitate was placed in a vacuum drying oven and dried at 50°C for 12 hours to obtain modified boron nitride containing epoxy groups, i.e., modified boron nitride, which was recorded as KH-560-modified BN-OH.

[0071] S3. Preparation of modified boron nitride-benzoxazine resin composite material:

[0072] First, T-fa and modified boron nitride were weighed in a mass ratio of 80:20 and added to a flask. The mixture was fully mixed using a heat-collecting constant-temperature heating magnetic stirrer. The temperature was precisely controlled at 110°C and stirred continuously and evenly for 10 minutes to obtain a molten mixture.

[0073] The molten mixture was then placed in a vacuum drying oven and evenly added to a mold at 110°C. After evacuation until no bubbles were present, the mixture was transferred to a mold after the temperature in an electric constant-temperature blower dryer reached 160°C. The mixture was then cured at 160°C, 170°C, and 180°C for 1 hour each, followed by 190°C for 2 hours. The mixture was then naturally cooled to obtain a modified boron nitride-benzoxazine resin composite material, which was recorded as 20 wt%.

[0074] Example 4

[0075] The preparation method of the modified boron nitride-benzoxazine resin composite material comprises the following steps:

[0076] S1. Synthesize benzoxazine monomers. The synthesis technology route is as follows: Figure 1 As shown:

[0077] 20g of tyrosol, 12.464g of 1,10-diaminodecane, 8.68g of paraformaldehyde, and 200mL of anhydrous ethanol were added to a flask equipped with a magnetic stirrer. The mixture was thoroughly mixed using a heat-collecting constant-temperature magnetic stirrer. The temperature was raised to 78°C and the reaction was maintained at this temperature for 12 hours. After the reaction, the mixture was poured into a beaker and allowed to stand. After cooling and crystallization, the mixture was transferred to a vacuum drying oven at 50°C for 12 hours to obtain a benzoxazine monomer containing an alcoholic hydroxyl group, designated T-fa.

[0078] S2. Preparation of modified boron nitride, its synthesis technology route is as follows Figure 2 As shown:

[0079] Weigh 15.0g of hexagonal boron nitride and 60g of sodium hydroxide, add sodium hydroxide and deionized water to a beaker and mix evenly to prepare a 5mol / L sodium hydroxide aqueous solution. Then add the weighed hexagonal boron nitride and sodium hydroxide aqueous solution to a flask equipped with a magnet, use a heat-collecting constant temperature heating magnetic stirrer to mix them thoroughly, and stir at a constant temperature and high speed for 12h at 95°C. After the reaction is completed, wait for it to cool to room temperature, filter it repeatedly with a suction flask, and rinse it with deionized water 5 times. Subsequently, place the solid in a vacuum drying oven and dry it at 60°C for 24h to obtain hydroxylated hexagonal boron nitride, recorded as BN-OH.

[0080] 8.0 g of BN-OH, 8 mL of KH-560, and 80 mL of anhydrous ethanol were added to a flask containing a magnet, and the mixture was thoroughly mixed using a heat-collecting constant-temperature heating magnetic stirrer. The mixture was heated to 90°C and stirred at this constant temperature for 12 hours to obtain a mixed solution. After the stirring, the mixed solution was placed in a centrifuge tube and centrifuged at 3000 rad / min for 5 minutes, and then at 5000 rad / min for 10 minutes to retain a white precipitate. The white precipitate was placed in a vacuum drying oven and dried at 50°C for 12 hours to obtain modified boron nitride containing epoxy groups, i.e., modified boron nitride, which was recorded as KH-560-modified BN-OH.

[0081] S3. Preparation of modified boron nitride-benzoxazine resin composite material:

[0082] First, T-fa and modified boron nitride were weighed in a mass ratio of 70:30 and added to a flask. The mixture was fully mixed using a heat-collecting constant-temperature heating magnetic stirrer. The temperature was precisely controlled at 110°C and stirred continuously and evenly for 10 minutes to obtain a molten mixture.

[0083] The molten mixture was then placed in a vacuum drying oven and evenly added to a mold at 110°C. After evacuation until no bubbles were present, the mixture was transferred to a mold after the temperature in an electric constant-temperature blower dryer reached 160°C. The mixture was then cured at 160°C, 170°C, and 180°C for 1 hour each, followed by 190°C for 2 hours. The mixture was then naturally cooled to obtain a modified boron nitride-benzoxazine resin composite material, which was recorded as 30 wt%.

[0084] Example 5

[0085] The preparation method of the modified boron nitride-benzoxazine resin composite material comprises the following steps:

[0086] S1. Synthesis of benzoxazine monomer:

[0087] 20g of tyrosol, 12.464g of 1,10-diaminodecane, 8.68g of paraformaldehyde, and 200mL of anhydrous ethanol were added to a flask equipped with a magnetic stirrer. The mixture was thoroughly mixed using a heat-collecting constant-temperature magnetic stirrer. The temperature was raised to 65°C and the reaction was maintained at this temperature for 24 hours. After the reaction, the mixture was poured into a beaker and allowed to stand. After cooling and crystallization, the mixture was transferred to a vacuum drying oven at 50°C for 12 hours to obtain a benzoxazine monomer containing an alcoholic hydroxyl group, designated T-fa.

[0088] S2. Preparation of modified boron nitride:

[0089] Weigh 15.0g of hexagonal boron nitride and 48.34g of sodium hydroxide, add sodium hydroxide and deionized water to a beaker and mix evenly to prepare a 5mol / L sodium hydroxide aqueous solution. Then add the weighed hexagonal boron nitride and sodium hydroxide aqueous solution to a flask equipped with a magnet, use a heat-collecting constant temperature heating magnetic stirrer to mix them thoroughly, and stir at a constant temperature and high speed for 24h at 80°C. After the reaction is completed, wait for it to cool to room temperature, filter it repeatedly with a suction flask, and rinse it with deionized water 5 times. Subsequently, place the solid in a vacuum drying oven and dry it at 60°C for 24h to obtain hydroxylated hexagonal boron nitride, recorded as BN-OH.

[0090] 8.0 g of BN-OH, 4 mL of KH-560, and 40 mL of anhydrous ethanol were added to a flask containing a magnet, and the mixture was thoroughly mixed using a heat-collecting constant-temperature heating magnetic stirrer. The mixture was heated to 95° C. and stirred at this constant temperature for 6 h to obtain a mixed solution. After the stirring, the mixed solution was placed in a centrifuge tube and centrifuged at 3000 rad / min for 5 min, and then at 5000 rad / min for 10 min to retain a white precipitate. The white precipitate was placed in a vacuum drying oven and dried at 50° C. for 12 h to obtain modified boron nitride containing epoxy groups, i.e., modified boron nitride, which was recorded as KH-560-modified BN-OH.

[0091] S3. Preparation of modified boron nitride-benzoxazine resin composite material:

[0092] First, T-fa and modified boron nitride were weighed according to a mass ratio of T-fa to modified boron nitride of 90:10 and added to a flask. The mixture was fully mixed using a heat-collecting constant-temperature heating magnetic stirrer, the temperature was precisely controlled at 110°C, and the mixture was continuously and evenly stirred for 10 minutes to obtain a molten mixture.

[0093] Then, the molten mixture was placed in a vacuum drying oven, and then evenly added into the mold at 110°C, and evacuated until there were no bubbles. After the temperature of the electric constant temperature blower dryer rose to 160°C, it was moved into the mold and first cured at 160°C, 170°C, and 180°C for 1 hour respectively, and then cured at 190°C for 2 hours. After cooling naturally, a modified boron nitride-benzoxazine resin composite material was obtained.

[0094] Example 6

[0095] The preparation method of the modified boron nitride-benzoxazine resin composite material is the same as the preparation steps of Example 1, except that it includes the following steps:

[0096] S1. Synthesis of benzoxazine monomer:

[0097] 20g of tyrosol, 12.464g of 1,10-diaminodecane, 9.55g of paraformaldehyde, and 200mL of anhydrous ethanol were added to a flask equipped with a magnetic stirrer. The mixture was thoroughly mixed using a heat-collecting constant-temperature magnetic stirrer. The temperature was raised to 65°C and the mixture was kept constant for 2 hours. After the reaction, the mixture was poured into a beaker and allowed to stand. After cooling and crystallization, the mixture was transferred to a vacuum drying oven at 50°C for 12 hours to obtain a benzoxazine monomer containing an alcoholic hydroxyl group, designated T-fa.

[0098] S2. Preparation of modified boron nitride:

[0099] Weigh 15.0g of hexagonal boron nitride and 72.5g of sodium hydroxide, add the sodium hydroxide and deionized water to a beaker and mix evenly to prepare a 5mol / L sodium hydroxide aqueous solution. Then add the weighed hexagonal boron nitride and sodium hydroxide aqueous solution to a flask equipped with a magnet, use a heat-collecting constant temperature heating magnetic stirrer to mix them thoroughly, and stir at a constant temperature of 100°C for 2h. After the reaction is completed, wait for it to cool to room temperature, filter it repeatedly with a suction flask, and rinse it with deionized water 5 times. Subsequently, place the solid in a vacuum drying oven and dry it at 60°C for 24h to obtain hydroxylated hexagonal boron nitride, recorded as BN-OH.

[0100] 8.0 g of BN-OH, 16 mL of KH-560 and 80 mL of anhydrous ethanol were added to a flask containing a magnet, and the mixture was thoroughly mixed using a heat-collecting constant-temperature heating magnetic stirrer. The mixture was heated to 95°C and stirred at this constant temperature for 2 hours to obtain a mixed solution. After stirring, the mixed solution was placed in a centrifuge tube and centrifuged at 3000 rad / min for 5 minutes, and then at 5000 rad / min for 10 minutes to retain a white precipitate. The white precipitate was placed in a vacuum drying oven and dried at 50°C for 12 hours to obtain modified boron nitride, which was recorded as KH-560-modified BN-OH.

[0101] S3. Preparation of modified boron nitride-benzoxazine resin composite material:

[0102] First, T-fa and modified boron nitride were weighed according to a mass ratio of T-fa to modified boron nitride of 80:20 and added to a flask. The mixture was fully mixed using a heat-collecting constant-temperature heating magnetic stirrer, the temperature was precisely controlled at 110°C, and the mixture was continuously and evenly stirred for 10 minutes to obtain a molten mixture.

[0103] Then, the molten mixture was placed in a vacuum drying oven, and then evenly added into the mold at 110°C, and evacuated until there were no bubbles. After the temperature of the electric constant temperature blower dryer rose to 160°C, it was moved into the mold and first cured at 160°C, 170°C, and 180°C for 1 hour respectively, and then cured at 190°C for 2 hours. After cooling naturally, a modified boron nitride-benzoxazine resin composite material was obtained.

[0104] Comparative Example 1

[0105] The preparation method of benzoxazine resin comprises the following steps:

[0106] S1. Synthesis of benzoxazine monomer:

[0107] 20g of tyrosol, 12.464g of 1,10-diaminodecane, 8.68g of paraformaldehyde, and 200mL of anhydrous ethanol were added to a flask equipped with a magnetic stirrer. The mixture was thoroughly mixed using a heat-collecting constant-temperature magnetic stirrer. The temperature was raised to 78°C and the reaction was maintained at this temperature for 12 hours. After the reaction, the mixture was poured into a beaker and allowed to stand. After cooling and crystallization, the mixture was transferred to a vacuum drying oven at 50°C for 12 hours to obtain a benzoxazine monomer containing an alcoholic hydroxyl group, designated T-fa.

[0108] S2. Preparation of benzoxazine resin:

[0109] First, T-fa was weighed and added to a flask, and placed in a vacuum drying oven. It was then evenly added to a mold at 110°C and evacuated until there were no bubbles. After the temperature of the electric constant temperature blower dryer rose to 160°C, it was moved into the mold and cured at 160°C, 170°C, and 180°C for 1 hour, respectively, and then cured at 190°C for 2 hours. The mixture was then naturally cooled to obtain a benzoxazine resin, which was recorded as 0 wt%.

[0110] observe Figure 3 It was found that the asymmetric characteristic peak of COC on the benzoxazine ring was located at 1229 cm -1 The symmetrical characteristic peak of COC is located at 1045 cm -1 In addition, the characteristic absorption peak of the benzoxazine ring is located at 928 cm -1 , which preliminarily proved that T-fa was successfully synthesized.

[0111] observe Figure 4 It was concluded that δ=1.30ppm was the methylene absorption peak of C-(CH2)6-, δ=1.56ppm was the methylene absorption peak of N-CH2-CH2-, δ=2.73ppm was the methylene absorption peak of N-CH2-, δ=2.78ppm was the methylene absorption peak of -CH2-OH, δ=3.82ppm was the methylene absorption peak on -CH2-CH2-OH, δ=3.98ppm was the methylene absorption peak on -CH2-N, δ=4.84ppm was the methylene absorption peak on O-CH2-N, and δ=6.74ppm~6.99ppm was the proton absorption peak on the benzene ring. The successful synthesis of T-fa was further verified by the hydrogen nuclear magnetic resonance spectrum.

[0112] observe Figure 5 The results show that 90.3°C is the absorption peak temperature of T-fa, which is also the melting temperature. During the curing process, there is only one exothermic peak at 224.5°C, which is the peak curing temperature. The curing process starts at 146°C, peaks at 224.5°C, and ends at 247°C.

[0113] observe Figure 6 The results show that hexagonal boron nitride is in the shape of petals and lamellar stacking, which is large and cannot be used directly. However, the modified hexagonal boron nitride has a lamellar structure with increased lamellar spacing, making it easy to disperse.

[0114] observe Figure 7 It was found that the infrared curves of BN-OH and modified boron nitride both showed a significant peak at 1372 cm -1 The stretching absorption peak and 817cm -1 The bending vibration absorption peaks are all characteristic absorption peaks of hexagonal boron nitride; on the infrared curve of BN-OH, 3431cm -1 The peak is hydroxyl, which proves that hydroxylated hexagonal boron nitride is successfully obtained. Further comparison shows that the infrared curve of modified boron nitride has an additional 2939 cm -1 and 2836cm -1 Two significant characteristic peaks correspond to the vibration absorption peaks of methyl and methylene, respectively, indicating that the modified boron nitride containing epoxy groups was successfully prepared.

[0115] observe Figure 8 It was found that the benzoxazine ring was located at 1229 cm -1 The COC asymmetric characteristic peak is located at 1045cm -1 The COC symmetrical characteristic peak and the peak at 928 cm -1The characteristic absorption peaks on the benzoxazine ring disappeared, proving that as the curing temperature increased, the oxazine ring in the benzoxazine monomer underwent a ring-opening reaction. It was preliminarily determined that the modified boron nitride-benzoxazine resin composite material was successfully prepared.

[0116] observe Figure 9 As shown in Figure (a), the fracture surface of the benzoxazine resin prepared in Comparative Example 1 is smooth and exhibits obvious brittle fracture. Figure 9 Figure (b) and observation Figure 9 Figure (c) shows that as the content of modified boron nitride increases, the distribution and amount of modified boron nitride in the benzoxazine monomer also increase; Figure 9 Figure (e) shows that as the amount of modified boron nitride added increases, the lamellar structure of the modified boron nitride-benzoxazine resin composite material becomes increasingly apparent. Notably, no significant agglomeration was observed in the modified boron nitride-benzoxazine resin composite materials prepared in Examples 1 to 4, indicating that the modified boron nitride has good dispersibility. This is due to the epoxy groups in the modified boron nitride undergoing a ring-opening reaction, reacting with the alcoholic hydroxyl groups on the benzoxazine monomer, and reacting with the phenolic hydroxyl groups produced after thermal ring-opening of the benzoxazine monomer to form ether bonds. Compared to simple physical mixing or hydrogen bonding, the formation of ether bonds can effectively increase the interfacial compatibility between the modified boron nitride and the benzoxazine monomer.

[0117] observe Figure 10 It was concluded that the curing process of the benzoxazine monomer is that the oxazine ring of the benzoxazine monomer undergoes a ring-opening reaction to produce phenolic hydroxyl groups, forming a cross-linked network structure; the curing process of the modified boron nitride-benzoxazine resin composite materials prepared in Examples 1 to 4 is that the epoxy groups on the modified boron nitride undergo a ring-opening reaction, react with the alcoholic hydroxyl groups on the benzoxazine monomer, and react with the phenolic hydroxyl groups produced after thermal ring opening of the benzoxazine monomer to form ether bonds, so that the modified boron nitride is evenly dispersed in the benzoxazine monomer without agglomeration.

[0118] observe Figure 11It was found that when the content of modified boron nitride added increased, the surface temperature rise rate of the modified boron nitride-benzoxazine resin composite material slowed down, and within the same heating time, the maximum temperature reached was quite different. After heating for 60 seconds, the temperature of the benzoxazine resin prepared in Comparative Example 1 had reached 90.2°C. However, the surface temperatures of the modified boron nitride-benzoxazine resin composite material containing 20wt% modified boron nitride and the modified boron nitride-benzoxazine resin composite material containing 30wt% modified boron nitride were only 60.2°C and 53.8°C, respectively; when the heating time reached 120 seconds, the surface temperatures of the modified boron nitride-benzoxazine resin composite material containing 20wt% modified boron nitride and the modified boron nitride-benzoxazine resin composite material containing 30wt% modified boron nitride were only 65.4°C and 59.1°C, respectively. This effectively proves that the modified boron nitride-benzoxazine resin composite material has a stronger thermal conductivity than the benzoxazine resin prepared in Comparative Example 1.

[0119] observe Figure 12 It was concluded that the thermal conductivity of the modified boron nitride-benzoxazine resin composite material with a modified boron nitride content of 5wt% was only 0.329W / m·K, which is not much different from the thermal conductivity of the benzoxazine resin obtained in Comparative Example 1 of 0.3118W / m·K. When the modified boron nitride content was 30wt%, the thermal conductivity of the modified boron nitride-benzoxazine resin composite material reached as high as 0.7454W / m·K. When the content of modified boron nitride is relatively low, it will be widely dispersed in the benzoxazine monomer and it is difficult to form an effective cross-linking structure with the benzoxazine monomer, so the change in thermal conductivity is not significant. However, as the content of modified boron nitride gradually increases, the modified boron nitride and the benzoxazine monomer begin to build a continuous heat conduction channel. This change significantly improves the thermal conductivity of the modified boron nitride-benzoxazine resin composite material.

[0120] Table 1 TGA parameters of modified boron nitride-benzoxazine resin composite materials prepared in Examples 1 to 4 and benzoxazine resin prepared in Comparative Example 1

[0121] Sample name <![CDATA[T di , unit ℃]]> <![CDATA[Y c ,Unit %]]> Comparative Example 1 271 9.8 Example 1 275 / Example 2 281 / Example 3 286 / Example 4 293 /

[0122] Note: T di is the temperature at which the resin material loses 5 wt% of its mass in a nitrogen atmosphere, Y c is the carbon residue rate of the resin material at 800°C in a nitrogen atmosphere, and / indicates that the carbon residue rate of the resin material at 800°C in a nitrogen atmosphere is 0.

[0123] observe Figure 13It is concluded that the thermal decomposition curve of the modified boron nitride-benzoxazine resin composite material is similar to the thermal decomposition curve of the benzoxazine resin prepared in Comparative Example 1, indicating that the introduction of modified boron nitride does not change the thermal decomposition mechanism of the benzoxazine monomer and maintains its inherent thermal degradation characteristics. Figure 13 The analysis shows that the carbon residue rate of the benzoxazine resin prepared in Comparative Example 1 is 9.8% at 800°C, indicating that it has a thermal stability foundation. As the content of modified boron nitride increases, the thermal stability of the modified boron nitride-benzoxazine resin composite material is significantly improved. Specifically, the temperature of the modified boron nitride-benzoxazine resin composite material at 5wt% mass loss shows a gradually increasing trend. When the content of modified boron nitride in the modified boron nitride-benzoxazine resin composite material reaches 30wt%, T di is 293℃, compared with the benzoxazine resin prepared in Comparative Example 1, T di The improvement is as high as 22°C, indicating that the addition of modified boron nitride improves the thermal stability of modified boron nitride-benzoxazine resin composites.

[0124] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A method for preparing a modified boron nitride-benzoxazine resin composite material, characterized in that: The following steps are involved: Tyrosol, 1,10-diaminodecane and paraformaldehyde are mixed and subjected to a Mannich condensation reaction to obtain a benzoxazine monomer containing an alcoholic hydroxyl group; wherein the molar ratio of tyrosol, 1,10-diaminodecane and paraformaldehyde is 2:1:4-4.4; After mixing modified boron nitride containing epoxy groups with a benzoxazine monomer, a curing treatment is performed. During the curing process, the epoxy groups on the modified boron nitride undergo a ring-opening reaction and react with the alcoholic hydroxyl groups on the benzoxazine monomer, and react with the phenolic hydroxyl groups generated after the benzoxazine monomer is thermally ring-opened to form ether bonds, thereby achieving chemical grafting of the modified boron nitride and the benzoxazine monomer to obtain a modified boron nitride-benzoxazine resin composite material. The mass ratio of the modified boron nitride to the benzoxazine monomer is 5-30:70-95. Modified boron nitride is prepared according to the following steps: placing boron nitride in a sodium hydroxide solution for hydroxylation to obtain hydroxylated boron nitride; adding a silane coupling agent and an organic solvent to the hydroxylated boron nitride to carry out a substitution reaction to obtain modified boron nitride; The silane coupling agent is selected from KH-560.

2. The method for preparing the modified boron nitride-benzoxazine resin composite material according to claim 1, wherein: The curing conditions are as follows: first, curing at 160°C, 170°C, and 180°C for 1 hour respectively, and then curing at 190°C for 2 hours.

3. The method for preparing the modified boron nitride-benzoxazine resin composite material according to claim 1, wherein: The conditions for the Mannich condensation reaction are: reaction at 65°C~78°C for 2h~24h.

4. The method for preparing the modified boron nitride-benzoxazine resin composite material according to claim 1, characterized in that: The boron nitride is selected from hexagonal boron nitride.

5. The method for preparing the modified boron nitride-benzoxazine resin composite material according to claim 1, wherein: The molar ratio of boron nitride to sodium hydroxide in the sodium hydroxide solution is 1:2~3.

6. The method for preparing the modified boron nitride-benzoxazine resin composite material according to claim 1, wherein: The mass volume ratio of hydroxylated boron nitride, silane coupling agent and organic solvent is 1g:0.5mL~2mL:5mL~10mL.

7. A modified boron nitride-benzoxazine resin composite material prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the modified boron nitride-benzoxazine resin composite material according to claim 7 in preparing a thermal conductive material.

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