A benzoxazine-based hyperbranched silicone resin and a method for preparing the same

Abstract

The application discloses a kind of benzoxazine-based hyperbranched silicone resin and preparation method thereof, and the preparation method is as follows: amino hyperbranched silicone resin solution, amine compound solution is dropped into aldehyde compound solution, stirring reaction is carried out at 0 DEG C ~ 100 DEG C for 10min ~ 24h, then phenolic compound solution is dropped, stirring reaction is carried out at 0 DEG C ~ 100 DEG C for 10min ~ 24h, heated reflux is carried out at 50 DEG C ~ 150 DEG C for 1h ~ 24h, washed with alkaline washing liquid and deionized water until neutral, separate aqueous phase and organic phase, remove solvent from organic phase, obtain benzoxazine-based hyperbranched silicone resin, and solidify or hot-press at 120 DEG C ~ 250 DEG C.The benzoxazine-based hyperbranched silicone resin prepared by the application has adjustable physical and chemical properties, excellent heat resistance, dielectric property and oxidation resistance, and the preparation process is simple and the production cost is low, so the application can be widely used in electronic, communication, military and other fields, especially in aerospace field.

Description

Technical Field

[0001] This invention pertains to resins and their preparation methods, specifically to a benzoxazine-based hyperbranched organosilicon resin and its preparation method. Background Technology

[0002] Polybenzoxazine is a new type of thermosetting resin developed based on traditional phenolic resin. It not only retains the excellent thermal properties, flame retardancy and electrical insulation of traditional phenolic resin, but also overcomes the shortcomings of traditional phenolic resin in releasing small molecules during the molding and curing process. The products have low porosity and close to zero shrinkage, so it has broad application prospects in the fields of construction, electronics, aerospace and other fields.

[0003] However, traditional benzoxazine resins suffer from poor thermal stability, weak high-temperature oxidation resistance, and high brittleness due to the numerous C-C and CN bonds between molecules. This results in low carbon residue and poor resistance to mechanical erosion and ablation when used as matrix resins for heat-resistant and ablation-resistant materials, limiting their further application in high-temperature and high-heat-flux environments. Furthermore, the presence of numerous benzene ring structures in traditional benzoxazine resin systems often causes them to exist as solid powders at room temperature, significantly restricting their applications and construction scenarios.

[0004] To address the aforementioned issues, Chinese patent CN106633055B simultaneously introduces alkynyl and imide structures into the molecular structure of benzoxazine resin. The alkynyl group can further polymerize and crosslink, increasing the resin's crosslinking density and glass transition temperature, effectively improving its temperature resistance and mechanical properties. However, due to the introduction of the imide ring, the prepared sample is a solid powder, making the subsequent curing process more complex and limiting its application scenarios.

[0005] Chinese patent CN110818932A describes the preparation of a prepreg composition with low viscosity by blending norbornene-terminated benzoxazine resin with epoxy resin, which effectively improves the processability of benzoxazine resin. However, the introduction of a large number of carbon chains lowers the thermal decomposition temperature of benzoxazine resin, resulting in a significant decline in its thermal stability and ablation resistance.

[0006] In summary, improving both the flowability and temperature resistance of benzoxazine resins simultaneously remains a significant challenge. Summary of the Invention

[0007] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a benzoxazine-based hyperbranched organosilicon resin with good high temperature resistance, ablation resistance and flame retardancy; another purpose of this invention is to provide a simple, convenient and low-cost method for preparing benzoxazine-based hyperbranched organosilicon resin.

[0008] Technical Solution: The present invention discloses a benzoxazine-based hyperbranched organosilicon resin, prepared by means of: adding an amino hyperbranched organosilicon resin solution and an amine compound solution dropwise to an aldehyde compound solution, stirring and reacting at 0℃~100℃ for 10min~24h, then adding a phenol compound solution dropwise, stirring and reacting at 0℃~100℃ for 10min~24h, heating and refluxing at 50℃~150℃ for 1h~24h, washing with alkaline washing solution and deionized water until neutral, separating the aqueous phase and the organic phase, removing the solvent from the organic phase to obtain the benzoxazine-based hyperbranched organosilicon resin, and curing or hot pressing at 120℃~250℃.

[0009] Further, the amine compound is one or more of p-phenylenediamine, 4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 2,6'-diaminopyridine, 4,4'-diaminodiphenyl sulfone, m-phenylenediamine, 4,4'-diaminodiphenyl sulfide, 4,4'-bis(3-aminophenoxy)biphenyl, 2,5-bis(4-aminophenyl)pyridine, and 4,4'-diaminobenzophenone.

[0010] Furthermore, the aldehyde compound is one or more of formaldehyde, 1-naphthaldehyde, paraformaldehyde, vanillin, furfural, benzaldehyde, p-hydroxybenzaldehyde, and 4-ethynylbenzaldehyde.

[0011] Furthermore, the phenolic compound is one or more of alkyl-substituted phenols, alkoxy-substituted phenols, isopropenyl-substituted phenols, aryl-substituted phenols, and polyhydroxy-substituted phenols.

[0012] The present invention discloses a method for preparing a benzoxazine-based hyperbranched organosilicon resin, comprising the following steps:

[0013] Step 1: Dissolve the amino hyperbranched organosilicon resin in an organic solvent by stirring to obtain a hyperbranched organosilicon solution; dissolve the amine compound in an organic solvent by stirring to obtain an amine compound solution; disperse the aldehyde compound in an organic solvent by stirring to obtain an aldehyde compound solution; and dissolve the phenolic compound in an organic solvent by stirring to obtain a phenolic compound solution.

[0014] Step 2: Slowly add the hyperbranched organosilicon solution and amine compound solution to the aldehyde compound solution, and stir the reaction at 0℃~100℃ for 10min~24h.

[0015] Step 3: Slowly add the phenolic compound solution dropwise to the product obtained in step 5, and stir the reaction at 0℃~100℃ for 10min~24h.

[0016] Step 4: Heat the product obtained in Step 6 under reflux at 50℃~150℃ for 1h~24h to obtain a pale yellow benzoxazine-based hyperbranched organosilicon solution.

[0017] Step 5: Wash the benzoxazine-based hyperbranched organosilicon solution with alkaline washing solution and deionized water until neutral, separate the aqueous phase and organic phase, and remove the solvent by rotary evaporation of the organic phase to obtain benzoxazine-based hyperbranched organosilicon resin.

[0018] Step six: cure or hot press at 120℃~250℃ to obtain a low-viscosity light yellow liquid or light yellow powder, namely polybenzoxazine-based hyperbranched organosilicon resin.

[0019] Furthermore, the molar ratio of amine compounds, aldehyde compounds, phenolic compounds, and organic solvents is 1:0.1~4:0.1~4:0.1~4:0.1~10.

[0020] Furthermore, the organic solvent is one or more of acetone, butanone, ethanol, tetrahydrofuran, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, ethyl acetate, dichloromethane, chloroform, and toluene.

[0021] Further, the amine compound is one or more of p-phenylenediamine, 4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 2,6'-diaminopyridine, 4,4'-diaminodiphenyl sulfone, m-phenylenediamine, 4,4'-diaminodiphenyl sulfide, 4,4'-bis(3-aminophenoxy)biphenyl, 2,5-bis(4-aminophenyl)pyridine, and 4,4'-diaminobenzophenone.

[0022] Furthermore, the aldehyde compound is one or more of formaldehyde, 1-naphthaldehyde, paraformaldehyde, vanillin, furfural, benzaldehyde, p-hydroxybenzaldehyde, and 4-ethynylbenzaldehyde.

[0023] Furthermore, the phenolic compound is one or more of alkyl-substituted phenols, alkoxy-substituted phenols, isopropenyl-substituted phenols, aryl-substituted phenols, and polyhydroxy-substituted phenols.

[0024] Further, in step six, the curing process involves placing the mold in an oven and curing it sequentially at 120℃ to 250℃ for 8 to 10 hours; or placing it in a mold and pressing it under a flat vulcanizing machine at 160℃ for 1 hour under a certain pressure.

[0025] Furthermore, the structural formula of the amino hyperbranched organosilicon resin (HPSi-NH2) is as follows:

[0026]

[0027] Furthermore, the structural formula of the benzoxazine-based hyperbranched organosilicon resin is as follows:

[0028]

[0029] Preparation Principle: To improve the mobile phase of traditional benzoxazine materials while maintaining their thermal stability, this invention introduces highly reactive HPSi-NH2 as an amine source into the benzoxazine material. The phase composition, temperature resistance, and ablation resistance of the benzoxazine material are adjusted by adding different amounts of amino-hyperbranched siloxanes. Simultaneously, the Si-O-Si core in the organosilicon structure provides advantages in electrical and thermal properties. Furthermore, the unique molecular structure of hyperbranched organosilicon polymers endows them with abundant functional units, larger intramolecular free volume, lower viscosity, and good solubility. Introducing hyperbranched organosilicon polymers into the synthesis of benzoxazine resins improves viscosity controllability, multifunctionality, ablation resistance, and oxidation resistance. The highly reactive, large intramolecular free volume, and low viscosity amino-hyperbranched organosilicon resin (HPSi-NH2) provides excellent flowability while offering reactive silaneoxy groups (Si-OR). At high temperatures, the silaneoxy groups undergo condensation reactions and self-polymerize to form a highly crosslinked Si-O-Si core. Compared to the CO2 gas emitted during the combustion of conventional carbon-based polymers, the Si-O-Si bonds have higher bond energies and only break chemically at higher temperatures. Furthermore, when burning in air, a dense SiO2 layer is formed, further contributing to flame retardancy and ablation resistance.

[0030] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0031] 1. The prepared benzoxazine-based hyperbranched organosilicon resin has adjustable physicochemical properties and excellent heat resistance, dielectric properties, antioxidant properties, insulation and flame retardancy. The product has low porosity, high carbon residue, low viscosity, and modifiable end groups. At the same time, the preparation process is simple and the production cost is low. It can be widely used in electronics, communications, military and other fields, especially in the aerospace field.

[0032] 2. The phase composition, temperature resistance, and ablation resistance of benzoxazine materials can be adjusted by adding different amounts of amino hyperbranched siloxanes;

[0033] 3. The prepared benzoxazine-based hyperbranched organosilicon resin is soluble and fusible, and has good processability, so as to facilitate impregnation of carbon fiber or carbon cloth reinforcement;

[0034] 4. The cured product has a high carbon and silicon atomic content, and features good insulation and low linear ablation rate over a wide temperature range;

[0035] 5. It has a high char yield after pyrolysis, forming strong char with excellent flame retardant and ablation resistance properties;

[0036] 6. The high silicon content gives the material excellent resistance to thermal oxidation, which can meet the application requirements of special scenarios. Attached Figure Description

[0037] Figure 1 These are the infrared spectra of the benzoxazine-based hyperbranched organosilicon resin before and after the reaction of the present invention;

[0038] Figure 2 This is a physical image of the benzoxazine-based hyperbranched organosilicon resin of the present invention;

[0039] Figure 3 This is a diagram of the benzoxazine-based hyperbranched organosilicon resin polymer of the present invention;

[0040] Figure 4 This is a nitrogen atmosphere thermal stability diagram of the product obtained in Example 1 of the present invention;

[0041] Figure 5 This is an air atmosphere thermal stability diagram of the product obtained in Example 1 of the present invention;

[0042] Figure 6 These are test images of the micro cone calorimeter obtained in Embodiment 1 of the present invention, wherein (a) is the HRR test image and (b) is the THR test image;

[0043] Figure 7 This is a nitrogen atmosphere thermal stability diagram of the product obtained in Example 2 of the present invention;

[0044] Figure 8 This is an air atmosphere thermal stability diagram of the product obtained in Example 2 of the present invention;

[0045] Figure 9 This is a schematic diagram of the flame retardant material obtained in Embodiment 2 of the present invention;

[0046] Figure 10 This is a nitrogen atmosphere thermal stability diagram of the product obtained in Example 7 of the present invention;

[0047] Figure 11 This is a thermal stability diagram of the substance obtained in Example 7 of the present invention under oxygen atmosphere. Detailed Implementation

[0048] In the following embodiments, the preparation method of the amino hyperbranched organosilicon resin (HPSi-NH2) is as follows: 0.1 mol of phenyltrimethoxysiloxane, 1 mol of aminotrimethoxysiloxane, and 30 wt% anhydrous methanol are added to a 500 mL three-necked flask equipped with a mechanical stirrer and a condenser, and the mixture is stirred at 0°C for 4 h to mix evenly; 0.55 mol of water is slowly added dropwise to the reaction system to carry out the reaction at 0°C for 24 h; the solvent is removed by vacuum distillation at 40°C and a pressure of -0.1 MPa for 3 h to obtain HPSi-NH2.

[0049] Example 1

[0050] A method for preparing a benzoxazine-based hyperbranched organosilicon resin includes the following steps:

[0051] (1) Add 80ml of tetrahydrofuran, 20ml of ethanol solution and 15g of paraformaldehyde to a 500ml three-necked flask equipped with a condenser and a mechanical stirrer. Stir at 30℃ for 20min to obtain a paraformaldehyde dispersion.

[0052] (2) Dissolve 60g HPSi-NH2 and 0.05mol m-phenylenediamine in 80ml tetrahydrofuran and 20ml ethanol solution to obtain an amine compound solution.

[0053] (3) Dissolve 23.5g of phenol in 80ml of tetrahydrofuran and 20ml of ethanol solution to obtain a phenolic compound solution.

[0054] (4) The amine compound solution was slowly added dropwise to the paraformaldehyde dispersion at 30°C and the mixture was stirred for 1 hour.

[0055] (5) The phenolic compound solution was slowly added dropwise to the product obtained in step (4) at 30°C, and the mixture was stirred for 1 hour.

[0056] (6) The product obtained in step (5) is heated to 70°C and refluxed for 24 hours to obtain a pale yellow benzoxazine hyperbranched organosilicon solution.

[0057] (7) Pour the benzoxazine hyperbranched organosilicon solution obtained in step (6) into an alkaline washing solution and then wash it with deionized water until neutral. Separate the aqueous phase and the organic phase using a separatory funnel. Remove the solvent from the organic phase using a rotary evaporator to obtain a low-viscosity light yellow liquid, which is the benzoxazine hyperbranched organosilicon resin.

[0058] (8) The benzoxazine-based hyperbranched organosilicon resin obtained in step (7) is loaded into a mold and kept at 120°C for 3 hours, 150°C for 2 hours, 180°C for 2 hours, and 210°C for 1 hour in sequence to obtain polybenzoxazine-based hyperbranched organosilicon resin.

[0059] The polybenzoxazine-based hyperbranched silicone resin prepared in this embodiment was subjected to room temperature viscosity testing. The viscosity was measured using a rotational viscometer according to the viscosity measurement method in GB-T 10247-2008, and the shear viscosity was 1490 mPa·s.

[0060] Figure 1 Infrared images of benzoxazine-based hyperbranched organosilicon resin before and after synthesis, from... Figure 1 As can be seen, the characteristic peak of the amino group disappears and the characteristic peak of the oxazine ring appears as the reaction proceeds, indicating the successful preparation of amino hyperbranched siloxanes.

[0061] Figures 2-3 Images of benzoxazine-based hyperbranched silicone resin before and after curing are shown. As can be seen from the images, after heat curing, the benzoxazine-based hyperbranched silicone resin changes from a pale yellow liquid to a reddish-brown solid and exhibits good film-forming properties.

[0062] Figures 4-5 The thermal stability of polybenzoxazine-based hyperbranched silicone resin was demonstrated, showing that its T0.05 under a nitrogen atmosphere is [not specified]. 5％ At 385℃, the residual weight at 1000℃ is 73.5%. In an oxygen atmosphere, its T... 5％ The residual weight is 68.4% at 366℃ and 700℃, and 34% at 1000℃.

[0063] like Figure 6 The maximum heat release rate (peak HRR) of the polybenzoxazine-based hyperbranched silicone resin obtained in this embodiment is only 39.88 W / g, and the total heat release (THR) is 9.2 KJ / g. The heat release measured by a micro cone calorimeter is 46 J / g·K, and the flame retardancy rating is V0. The material is not easily ignited and is typically rated V0.

[0064] Example 2

[0065] The synthesis of a flame-retardant, highly thermally stable benzoxazine-based hyperbranched organosilicon resin includes the following steps:

[0066] (1) Add 50 ml of ethyl acetate, 50 ml of toluene solution and 15 g of formaldehyde to a 500 ml three-necked flask equipped with a condenser and a mechanical stirrer, and stir at 0 °C for 20 min to obtain an aldehyde dispersion.

[0067] (2) Dissolve 60g HPSi-NH2, 0.05mol 4,4'-diaminodiphenyl sulfide and 0.05mol p-phenylenediamine in 50ml ethyl acetate and 50ml toluene solution to obtain an amine compound solution.

[0068] (3) Dissolve 23.5g of p-hydroxybenzonitrile in 50ml of ethyl acetate and 50ml of toluene solution to obtain a phenolic compound solution.

[0069] (4) The amine compound solution was slowly added dropwise to the paraformaldehyde dispersion at 0°C and the mixture was stirred for 10 hours.

[0070] (5) The phenolic compound solution was slowly added dropwise to the product obtained in step (4) at 0°C, and the mixture was stirred for 10 h.

[0071] (6) The product obtained in step (5) is heated to 50°C and refluxed for 10 hours to obtain a brownish-yellow benzoxazine-based hyperbranched organosilicon solution.

[0072] (7) Pour the benzoxazine hyperbranched organosilicon solution obtained in step (6) into an alkaline washing solution and wash it with deionized water until neutral. Separate the aqueous phase and the organic phase with a separatory funnel. Remove the solvent from the organic phase with a rotary evaporator to obtain a low-viscosity light yellow liquid, which is the benzoxazine hyperbranched organosilicon resin.

[0073] (8) The benzoxazine-based hyperbranched organosilicon resin described in step (7) is loaded into a mold and kept at 120°C for 3 hours, 150°C for 2 hours, 180°C for 2 hours, 200°C for 2 hours, and 250°C for 1 hour in sequence to obtain polybenzoxazine-based hyperbranched organosilicon resin.

[0074] Figures 7-8 The thermal stability of polybenzoxazine-based hyperbranched silicone resin was demonstrated, showing that its T0.05 under a nitrogen atmosphere is [not specified]. 5％ Its temperature is 348℃, its peak thermal decomposition temperature is 500℃, and its residual weight at 1000℃ is 60%. Under an oxygen atmosphere, its T... 5％ The maximum decomposition temperature is 345℃, and the maximum decomposition temperatures are 467℃ and 621℃, respectively. The residual weight at 1000℃ is 22.5%.

[0075] Figure 9 The image shows a polybenzoxazine-based hyperbranched silicone resin after being burned in a flame. As can be seen from the image, the foam material does not burn after being ignited by a flame, exhibiting excellent flame retardant properties.

[0076] Example 3

[0077] The synthesis of a high-carbon-residue benzoxazine-based hyperbranched organosilicon resin includes the following steps:

[0078] (1) Add 80ml of butanone, 20ml of N,N-dimethylformamide solution and 53g of benzaldehyde to a 500ml three-necked flask equipped with a condenser and a mechanical stirrer. Stir at 100℃ for 20min to obtain an aldehyde dispersion.

[0079] (2) Dissolve 50g HPSi-NH2 and 0.1mol 3,3'-dichloro-4,4'-diaminodiphenylmethane in 80ml butanone and 20ml N,N-dimethylformamide solution to obtain an amine compound solution.

[0080] (3) Dissolve 36g of naphthol in 80ml of butanone and 20ml of N,N-dimethylformamide solution to obtain a phenolic compound solution.

[0081] (4) The amine compound solution was slowly added dropwise to the paraformaldehyde dispersion at 100°C and the mixture was stirred for 24 hours.

[0082] (5) The phenolic compound solution was slowly added dropwise to the product obtained in step (4) at 100°C, and the mixture was stirred for 24 hours.

[0083] (6) The product obtained in step (5) is heated to 120°C and refluxed for 1 hour to obtain a yellowish-brown benzoxazine hyperbranched organosilicon solution.

[0084] (7) Pour the benzoxazine hyperbranched organosilicon solution obtained in step (6) into an alkaline washing solution and wash it with deionized water until neutral. Separate the aqueous phase and the organic phase with a separatory funnel. Remove the solvent from the organic phase with a rotary evaporator to obtain a high-viscosity light yellow liquid, which is the benzoxazine hyperbranched organosilicon resin.

[0085] (8) The benzoxazine-based hyperbranched organosilicon resin obtained in step (7) is loaded into a mold and kept at 120°C for 3 hours, 150°C for 2 hours, 180°C for 2 hours, 200°C for 2 hours, and 250°C for 1 hour in sequence to obtain polybenzoxazine-based hyperbranched organosilicon resin.

[0086] Example 4

[0087] The synthesis of a high-strength benzoxazine-based hyperbranched organosilicon resin includes the following steps:

[0088] (1) Add 80ml of acetone, 20ml of dichloromethane solution and 65g of 4-ethynylbenzaldehyde to a 500ml three-necked flask equipped with a condenser and a mechanical stirrer, and stir at 50℃ for 12h to obtain a formaldehyde dispersion.

[0089] (2) Dissolve 20g HPSi-NH2, 0.1mol 4,4'-diaminodiphenylmethane and 0.1mol 4,4'-diaminodiphenyl sulfide in 80ml acetone and 20ml dichloromethane solution to obtain an amine compound solution.

[0090] (3) Dissolve 61g of p-hydroxybenzaldehyde in 80ml of acetone and 20ml of dichloromethane solution to obtain a phenolic compound solution.

[0091] (4) The amine compound solution was slowly added dropwise to the paraformaldehyde dispersion at 50°C and the mixture was stirred for 12 hours.

[0092] (5) The phenolic compound solution was slowly added dropwise to the product obtained in step (4) at 50°C, and the mixture was stirred for 12 hours.

[0093] (6) The product obtained in step (5) is heated to 100°C and refluxed for 24 hours to obtain a pale yellow benzoxazine hyperbranched organosilicon solution.

[0094] (7) Pour the benzoxazine hyperbranched organosilicon solution obtained in step (6) into an alkaline washing solution and wash it with deionized water until neutral. Separate the aqueous phase and the organic phase with a separatory funnel. Remove the solvent from the organic phase with a rotary evaporator to obtain a dark yellow liquid, which is the benzoxazine hyperbranched organosilicon resin.

[0095] (8) The benzoxazine-based hyperbranched organosilicon resin obtained in step (7) is loaded into a mold and kept at 120°C for 3 hours, 150°C for 2 hours, 180°C for 2 hours, 200°C for 2 hours, and 250°C for 1 hour in sequence to obtain polybenzoxazine-based hyperbranched organosilicon resin.

[0096] Example 5

[0097] The synthesis of a high-viscosity benzoxazine-based hyperbranched organosilicon resin impregnating material includes the following steps:

[0098] (1) Add 50 ml of N,N-dimethylacetamide, 50 ml of dimethyl sulfoxide solution and 48 g of furfural to a 500 ml three-necked flask equipped with a condenser and a mechanical stirrer. Stir at 30 °C for 10 min to obtain an aldehyde dispersion.

[0099] (2) Dissolve 40g HPSi-NH2, 0.05mol 4,4'-bis(3-aminophenoxy)biphenyl and 0.05mol 4,4'-diaminobenzophenone in 50ml N,N-dimethylformamide and 50ml dimethyl sulfoxide solution to obtain an amine compound solution.

[0100] (3) Dissolve 55g of catechol in 50ml of N,N-dimethylformamide and 50ml of dimethyl sulfoxide solution to obtain a phenolic compound solution.

[0101] (4) The amine compound solution was slowly added dropwise to the paraformaldehyde dispersion at 30°C and the mixture was stirred for 10 min.

[0102] (5) Add the phenolic compound solution slowly at 30°C to the product obtained in step (4) and stir for 10 min.

[0103] (6) The product obtained in step (5) is heated to 100°C and refluxed for 24 hours to obtain a pale yellow benzoxazine hyperbranched organosilicon solution.

[0104] (7) Pour the benzoxazine hyperbranched organosilicon solution obtained in step (6) into an alkaline washing solution and wash it with deionized water until neutral. Separate the aqueous phase and the organic phase with a separatory funnel. Remove the solvent from the organic phase with a rotary evaporator to obtain a brownish-yellow liquid, which is the benzoxazine hyperbranched organosilicon resin.

[0105] (8) The benzoxazine-based hyperbranched organosilicon resin obtained in step (7) is loaded into a mold and kept at 120°C for 3 hours, 150°C for 2 hours, 180°C for 2 hours, 200°C for 2 hours, and 250°C for 1 hour in sequence to obtain polybenzoxazine-based hyperbranched organosilicon resin.

[0106] Example 6

[0107] The synthesis of a bio-based benzoxazine-based hyperbranched organosilicon resin impregnating material includes the following steps:

[0108] (1) Add 50 ml of N-methylpyrrolidone, 50 ml of chloroform solution and 76 g of vanillin to a 500 ml three-necked flask equipped with a condenser and a mechanical stirrer, and stir at 100 °C for 20 min to obtain a paraformaldehyde dispersion.

[0109] (2) Dissolve 20g HPSi-NH2, 0.1mol 2,5-bis(4-aminophenyl)pyridine and 0.1mol 2,6'-diaminopyridine in 50ml N-methylpyrrolidone and 50ml chloroform solution to obtain an amine compound solution.

[0110] (3) Dissolve 34g of 4-isopropylphenol in 50ml of N-methylpyrrolidone and 50ml of chloroform solution to obtain a phenolic compound solution.

[0111] (4) The amine compound solution was slowly added dropwise to the paraformaldehyde dispersion at 100°C and the mixture was stirred for 1 hour.

[0112] (5) The phenolic compound solution was slowly added dropwise to the product obtained in step (4) at 100°C, and the mixture was stirred for 1 hour.

[0113] (6) The product obtained in step (5) is heated to 100°C and refluxed for 24 hours to obtain a yellow benzoxazine hyperbranched organosilicon solution.

[0114] (7) Pour the benzoxazine hyperbranched organosilicon solution obtained in step (6) into an alkaline washing solution and wash it with deionized water until neutral. Separate the aqueous phase and the organic phase using a separatory funnel. Remove the solvent from the organic phase using a rotary evaporator to obtain a pale yellow liquid, which is the benzoxazine hyperbranched organosilicon resin.

[0115] (8) The benzoxazine-based hyperbranched organosilicon resin described in step (7) is loaded into a mold and kept at 120°C for 3 hours, 150°C for 2 hours, 180°C for 2 hours, 200°C for 2 hours, and 250°C for 1 hour in sequence to obtain polybenzoxazine-based hyperbranched organosilicon resin.

[0116] Example 7

[0117] The synthesis of a benzoxazine-based hyperbranched organosilicon resin molding powder includes the following steps:

[0118] (1) Add 50 ml of tetrahydrofuran, 50 ml of ethanol solution and 78 g of 1-naphthaldehyde to a 500 ml three-necked flask equipped with a condenser and a mechanical stirrer, and stir at 30 °C for 20 min to obtain a paraformaldehyde dispersion.

[0119] (2) Dissolve 60g HPSi-NH2 in 50ml tetrahydrofuran and 50ml ethanol solution to obtain an amine compound solution.

[0120] (3) Dissolve 115g of bisphenol A in 50ml of tetrahydrofuran and 50ml of ethanol solution to obtain a phenolic compound solution.

[0121] (4) The amine compound solution was slowly added dropwise to the paraformaldehyde dispersion at 30°C and the mixture was stirred for 1 hour.

[0122] (5) The phenolic compound solution was slowly added dropwise to the product obtained in step (4) at 30°C, and the mixture was stirred for 1 hour.

[0123] (6) The product obtained in step (5) is heated to 150°C and refluxed for 24 hours to obtain a yellow benzoxazine-based hyperbranched organosilicon solution.

[0124] (7) Pour the benzoxazine hyperbranched organosilicon solution obtained in step (6) into an alkaline washing solution and then wash it with deionized water until neutral. Separate the aqueous phase and the organic phase using a separatory funnel. Remove the solvent from the organic phase using a rotary evaporator to obtain a light yellow powder, which is the benzoxazine hyperbranched organosilicon resin molding powder.

[0125] (8) The benzoxazine-based hyperbranched organosilicon resin obtained in step (7) is loaded into a mold, placed under a flat vulcanizing machine, and molded at 160°C for 1 hour under a pressure of 10 MPa to obtain polybenzoxazine-based hyperbranched organosilicon resin.

[0126] Figures 10-11 The thermal stability of polybenzoxazine-based hyperbranched silicone resin was demonstrated, showing that its T0.05 under a nitrogen atmosphere is [not specified]. 5％ At 270℃, the residual weight at 1000℃ is 52%. In an oxygen atmosphere, its T... 5％ At 264℃, the residual weight at 1000℃ is 19%.

[0127] Comparative Example 1

[0128] The remaining steps of this comparative example were the same as in Example 1, except that the amino hyperbranched silicone resin (HPSi-NH2) was replaced with amino silicone oil. The results showed that the residual carbon content and thermal decomposition temperature of the material decreased significantly.

[0129] Comparative Example 2

[0130] The remaining steps of this comparative example are the same as those of Example 1, except that the amino hyperbranched silicone resin (HPSi-NH2) is replaced with aniline. The results showed that although the material had a high high-temperature carbon residue in a nitrogen atmosphere, the carbon residue rate in an air atmosphere was low and the antioxidant capacity was insufficient.

[0131] Comparative Example 3

[0132] The remaining steps of this comparative example are the same as those in Example 1, except that the amino hyperbranched silicone resin (HPSi-NH2) is replaced with KH550 and phenol is replaced with bisphenol A. The results showed that the temperature resistance of the material decreased significantly and the material was in a solid powder state with insufficient flowability.

[0133] Comparative Example 4

[0134] The remaining steps of this comparative example are the same as those in Example 1, except that the amino hyperbranched silicone resin (HPSi-NH2) is replaced with furfurylamine. As a result, the temperature resistance of the material is significantly reduced.

[0135] Comparative Example 5

[0136] The remaining steps of this comparative example are the same as those in Example 1, except that the amino hyperbranched silicone resin (HPSi-NH2) is replaced with 4-nitrophthalonitrile. As a result, the residual weight of the material in air atmosphere is significantly reduced.

[0137] Table 1. TG performance tests under different atmospheres

[0138]

[0139]

[0140] As can be seen from Table 1, among the above embodiments, Embodiment 1 is the optimal embodiment, exhibiting the best temperature resistance and ablation resistance.

Claims

1. A method for preparing a benzoxazine-based hyperbranched organosilicon resin, characterized in that, Includes the following steps: Step 1: Dissolve the amino hyperbranched organosilicon resin in an organic solvent by stirring to obtain a hyperbranched organosilicon solution. Phenolic compounds are added to an organic solvent and stirred to dissolve, resulting in a phenolic compound solution. Step 2: Add the hyperbranched organosilicon solution and amine compound solution dropwise to the aldehyde compound solution, and stir the reaction at 0℃~100℃ for 10min~24h. Step 3: Add the phenolic compound solution dropwise to the product obtained in Step 2, and stir the mixture at 0℃~100℃ for 10min~24h. Step 4: Heat the product obtained in Step 3 under reflux at 50℃~150℃ for 1h~24h to obtain a benzoxazine-based hyperbranched organosilicon solution. Step 5: Wash the benzoxazine-based hyperbranched organosilicon solution with alkaline washing solution and deionized water until neutral, separate the aqueous phase and organic phase, and remove the solvent by rotary evaporation of the organic phase to obtain benzoxazine-based hyperbranched organosilicon resin. Step 6: Curing or hot pressing at 120℃~250℃ to obtain polybenzoxazine-based hyperbranched silicone resin; The benzoxazine-based hyperbranched organosilicon resin is a pale yellow liquid; The preparation method of the amino hyperbranched organosilicon resin is as follows: 0.1 mol of phenyltrimethoxysiloxane, 1 mol of aminotrimethoxysiloxane, and 30 wt% anhydrous methanol are added to a 500 mL three-necked flask equipped with a mechanical stirrer and a condenser, and the mixture is stirred at 0°C for 4 h to mix evenly; 0.55 mol of water is slowly added dropwise to the reaction system to carry out the reaction at 0°C for 24 h; the solvent is removed by vacuum distillation at 40°C and a pressure of -0.1 MPa for 3 h. The molar ratio of the amine compound, phenol compound, aldehyde compound, and organic solvent is 1:0.1~4:0.1~4:0.1~10.

2. The method for preparing a benzoxazine-based hyperbranched organosilicon resin according to claim 1, characterized in that: The amine compound is one or more of the following: p-phenylenediamine, 4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 2,6'-diaminopyridine, 4,4'-diaminodiphenyl sulfone, m-phenylenediamine, 4,4'-diaminodiphenyl sulfide, 4,4'-bis(3-aminophenoxy)biphenyl, 2,5-bis(4-aminophenyl)pyridine, and 4,4'-diaminobenzophenone.

3. The method for preparing a benzoxazine-based hyperbranched organosilicon resin according to claim 1, characterized in that: The aldehyde compounds are one or more of formaldehyde, 1-naphthaldehyde, paraformaldehyde, vanillin, furfural, benzaldehyde, p-hydroxybenzaldehyde, and 4-ethynylbenzaldehyde.

4. The method for preparing a benzoxazine-based hyperbranched organosilicon resin according to claim 1, characterized in that: The phenolic compounds are one or more of alkyl-substituted phenols, alkoxy-substituted phenols, isopropenyl-substituted phenols, aryl-substituted phenols, and polyhydroxy-substituted phenols.

5. The method for preparing a benzoxazine-based hyperbranched organosilicon resin according to claim 1, characterized in that: The organic solvent is one or more of acetone, butanone, ethanol, tetrahydrofuran, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, ethyl acetate, dichloromethane, chloroform, and toluene.

6. A benzoxazine-based hyperbranched organosilicon resin, characterized in that, It is prepared by the preparation method described in claim 1.

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