Remodelable high-toughness phenolic resin and preparation method thereof
By constructing a dynamic covalent network through the sol-gel method and transamination reaction, the brittleness and recycling problems of phenolic resin were solved, resulting in a phenolic resin material that is remodelable, highly tough, heat-resistant, and self-healing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUBEI HANGTAI TECH CO LTD
- Filing Date
- 2026-01-30
- Publication Date
- 2026-05-05
AI Technical Summary
Existing phenolic resin materials are brittle, difficult to recycle and reuse, and lack toughness. Nanoparticle modification can easily cause stress concentration and interfacial debonding, and phenolic hydroxyl groups can easily absorb moisture, leading to deterioration of mechanical properties.
A silica nanonetwork was generated in situ using the sol-gel method, and covalent bonds were established using an aminosilane coupling agent. A dynamic covalent network was constructed by combining the transamination reaction, thereby achieving the remodelability and high toughness of phenolic resin.
The material is reshapeable, highly tough, and heat-resistant. It has self-healing capabilities, restores its mechanical properties to their original level, supports closed-loop recycling, and reduces environmental burden.
Smart Images
Figure CN121975263A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer materials technology, specifically relating to a remodelable, high-toughness phenolic resin and its preparation method. Background Technology
[0002] Thermosetting phenolic resins form an irreversible three-dimensional network structure after curing, making them difficult to recycle and reuse using traditional methods. Unlike thermoplastic resins, they cannot be reshaped by heating, a characteristic that severely limits their sustainable development potential. Simultaneously, the inherent brittleness of the material results in poor impact resistance, making it prone to cracking or even failure under extreme environments with rapid temperature changes. Although dynamic covalent bond design (such as transamination) can impart temporary processability, the recovery of the reshaped structure is often accompanied by irreversible degradation of mechanical strength and heat resistance. While nanoparticle modification can improve the toughness and heat resistance to some extent to address insufficient toughness, the weak interfacial bonding between nanoparticles and the matrix easily leads to stress concentration, accelerating material failure, and the mismatch in thermal expansion coefficients may increase the risk of interfacial debonding. Furthermore, the phenolic hydroxyl groups in the phenolic resin molecular chain readily absorb environmental moisture, leading to deterioration of mechanical properties and affecting long-term service stability.
[0003] Based on the above, this invention proposes an innovative remodelable, high-toughness phenolic resin and its preparation method. Through a composite modification strategy, the cross-linked network is reconstructed at the molecular level. First, in-situ hydrolysis technology is used to chemically cross-link nanoparticles onto the phenolic resin groups. Second, transamination technology is used to construct a dynamic covalent network. Through this synergistic modification strategy, the phenolic resin achieves recycling and remodeling, while also achieving toughening and heat resistance modification. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of existing phenolic resin materials, such as high brittleness and difficulty in recycling, and to provide a remodelable, high-toughness phenolic resin and its preparation method. This resin possesses remodelability, high toughness, and closed-loop recycling capability while also exhibiting heat resistance and strength.
[0005] This invention provides the following technical solution: This invention provides a method for preparing a remodelable, high-toughness phenolic resin, comprising the following steps: S1. Preparation of silica-phenolic resin hybrid resin by sol-gel method; S2. The hybrid resin is vacuum dried and melt-blended with the catalyst; then isocyanate is added to the blend system to react and obtain a prepolymer containing dynamic urethane bonds. S3. Add a curing agent to the prepolymer, mix well, and then heat to cure to obtain the remodelable, high-toughness phenolic resin.
[0006] This invention employs a sol-gel method to generate a silica nanonetwork in situ within a phenolic resin system, effectively avoiding phase aggregation and stress concentration caused by simple physical blending. Simultaneously, an aminosilane coupling agent is used as a "molecular bridge" in the sol-gel reaction. The amino group reacts with the phenolic hydroxyl groups of the phenolic resin or the curing agent, thereby establishing a strong covalent bond between the two phases. Subsequently, the phenolic resin is functionalized through a transamination reaction, constructing a modified system with the synergistic effect of the nanoparticle topological cross-linking structure and the dynamic covalent bond network. This achieves recyclability and self-healing ability of the phenolic resin while maintaining its original excellent properties, significantly improving the material's toughness. The structural formula is as follows, where R is isocyanate and R1 is a silane coupling agent.
[0007]
[0008] Furthermore, the steps for preparing the silica-phenolic resin hybrid resin are as follows: Linear phenolic resin was dissolved in anhydrous ethanol under heating and stirring conditions to form a homogeneous resin solution. Tetraethyl orthosilicate, anhydrous ethanol, deionized water, acidic catalyst and aminosilane coupling agent were mixed in proportion and stirred at 25~40 °C to carry out a pre-hydrolysis reaction to obtain silane hydrolysis sol. The silane hydrolysate sol was slowly added dropwise to the homogeneous resin solution, and the reaction was continuously stirred at 40-60 °C for 2-4 h. The reaction solution was then rotary evaporated at 50-60 °C under reduced pressure to obtain a silica-phenolic resin hybrid resin.
[0009] Furthermore, the homogeneous resin solution contains 30-50 wt% phenolic resin, the heating and stirring temperature is 50-60 °C, and the hydroxyl value of the linear phenolic resin is 120 mg KOH / g.
[0010] Furthermore, the amount of tetraethyl orthosilicate used is 5% to 20% of the mass of phenolic resin, and the molar ratio (R value) of water to tetraethyl orthosilicate is 4 to 10.
[0011] Furthermore, the volume ratio of tetraethyl orthosilicate to anhydrous ethanol is 1:4.
[0012] Furthermore, the acidic catalyst is hydrochloric acid, and the amount of acidic catalyst used is 0.5% to 2% of the mass of tetraethyl orthosilicate, and the pre-hydrolysis time is 30 to 120 min.
[0013] Furthermore, the aminosilane coupling agent is KH-550, accounting for 0.5% to 1.5% of the mass of tetraethyl orthosilicate.
[0014] Further, in step S2, the vacuum drying temperature is 60 ℃, the drying time is 12 h, the catalyst is zinc acetate, the amount of which is 1~2% of the mass of phenolic resin, and the melt blending temperature is 120 ℃.
[0015] Furthermore, the isocyanate is hexamethylene diisocyanate or isophorone diisocyanate, the reaction temperature is 80 °C, and the ratio of n(-NCO) / n(-OH) is 0.8~1.0.
[0016] Further, in step S3, the curing agent is hexamethylenetetramine, and the amount of curing agent used is 6%~15% of the mass of the linear phenolic resin; the temperature curing treatment is a stepped temperature curing treatment, and the curing program is 100 ℃ / 2h, 120 ℃ / 2h, and 150 ℃ / 2h in a vacuum drying oven.
[0017] The present invention also provides a remodelable, high-toughness phenolic resin prepared by the above preparation method, wherein the remodelability of the phenolic resin occurs at a temperature >200°C.
[0018] This modified phenolic resin system achieves a performance breakthrough through a dual enhancement mechanism of dynamic covalent network and nanoparticle topological cross-linking structure. Under high-temperature service conditions, the dynamic covalent bonds exhibit a dynamic and reversible bonding-dissociation process, maintaining a stable overall cross-linking density through dynamic equilibrium. Simultaneously, the cross-linking network constructed by nanoparticles interpenetrates in three-dimensional space without hindering the material's macroscopic flow characteristics. This unique synergistic mechanism endows the material with low viscosity and high fluidity, similar to liquids, enabling it to possess excellent deformation adaptability, crack self-healing function, and secondary molding processing capabilities.
[0019] This modified phenolic resin exhibits unique sustainable recycling and self-healing capabilities: waste phenolic resin-based composite materials (such as brake friction pads, electronic circuit boards, and other typical application components) can be efficiently recycled through a high-temperature, high-pressure regeneration process after pulverization and pretreatment, restoring their mechanical properties to the level of the original material. This technological breakthrough provides an innovative path for the closed-loop recycling of phenolic resins, significantly reducing the environmental burden. Furthermore, microcracks generated during the material's service life can be self-repaired in situ through a thermally induced dynamic rearrangement reaction of urethane groups, effectively restoring mechanical strength and extending service life. The material also possesses excellent secondary processing performance, supporting hot-press welding for integrated component connections. The cured products can also be reshaped into complex, high-precision structural parts, demonstrating excellent processing flexibility and sustainable application potential.
[0020] This modified phenolic resin introduces a dynamic covalent bond network without sacrificing the structural reliability of traditional phenolic resins under high-temperature conditions. This characteristic gives it a dual advantage in aerospace and other fields.
[0021] The present invention has the following beneficial effects: This invention utilizes a dynamic covalent network, in which dynamic bonds undergo a reversible "break-recombination" reaction at a trigger temperature. Although individual bonds are constantly changing, the total number of crosslinking points in the entire network remains in dynamic equilibrium, resulting in a resin with high toughness, remodelability, and closed-loop recyclability.
[0022] This invention utilizes the pre-hydrolysis of tetraethyl orthosilicate and its mixing with a phenolic resin solution to form a nano-silica reinforcing phase. The modified phenolic resin is then subjected to a transamination reaction with isocyanate in the presence of a catalyst, introducing a dynamic urethane bond crosslinking network. This constructs a modified system where the dynamic covalent bond network and the nanoparticle topological crosslinking structure work synergistically. This achieves a phenolic resin that retains the excellent properties of thermosetting phenolic resin while also possessing the characteristics of thermoplastic phenolic resin, exhibiting recyclability and self-healing capabilities, and significantly improving material toughness. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 A schematic diagram of a polymer structure with a dynamic covalent structure obtained by modifying phenolic resin through transamination reaction by combining isocyanate with phenolic resin. Figure 2 This is a schematic diagram of the polymer structure obtained by topologically crosslinking silica nanoparticles onto phenolic resin using a silane coupling agent to toughen and modify phenolic resin. Figure 3 A schematic diagram illustrating the synergistic modification of phenolic resin by combining isocyanate modification and silane coupling agent crosslinking of silica nanoparticles to fully utilize the inherent groups of phenolic resin and obtain a dynamically covalently crosslinked-inorganic filler-reinforced polymer structure. Figure 4 This is a schematic diagram of traditional phenolic resin products; Figure 5 This is a schematic diagram of a phenolic resin product prepared by dynamic covalent crosslinking and synergistic modification with inorganic fillers. Detailed Implementation
[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0026] The reaction formula for the hydrolysis of alkoxy groups (OR) of silane coupling agent KH-550 to generate silanol in this invention is shown below:
[0027] In this invention, the silanol generated by the hydrolysis of the silane coupling agent undergoes condensation polymerization with the silanol on the surface of the silica generated by in-situ hydrolysis, forming a strong Si-O-Si covalent bond.
[0028]
[0029] The reaction formula for the combination of the organic terminal amino group of the silane coupling agent and the hydroxymethyl group of the phenolic resin in this invention is shown below:
[0030] The reaction formula for the formation of a carbamate bond between the isocyanate group (-NCO) and the phenolic hydroxyl group of the phenolic resin in this invention is shown below:
[0031] In summary, this invention achieves a tight bond between the phenolic resin and silica by combining the organic-terminal amino group of the silane coupling agent with the hydroxymethyl group of the phenolic resin, and attaching the other end to silica generated by in-situ hydrolysis. The phenolic hydroxyl group of the phenolic resin then undergoes a transamination reaction with the isocyanate group (-NCO). The reaction formula for synergistically enhancing the phenolic resin through modification is shown below:
[0032] like Figure 1 The diagram shows a polymer structure with a dynamic covalent structure obtained by modifying phenolic resin through transamination reaction by combining isocyanate and phenolic resin. The transamination reaction makes the molecular connections of the polymer material more compact and strong. At the trigger temperature, the dynamic bonds undergo a reversible "break-recombination" reaction. Although individual bonds are constantly changing, the total number of crosslinking points in the entire network maintains a dynamic equilibrium. The resulting resin has remodeling ability, closed-loop recycling capability, and a certain degree of improved toughness.
[0033] like Figure 2The diagram shows a schematic of the polymer structure obtained by topologically crosslinking silica nanoparticles onto phenolic resin using a silane coupling agent to toughen and modify the resin. Compared to physically adding nanoparticle fillers, this method effectively solves the agglomeration phenomenon caused by the mismatch of thermal expansion coefficients during mixing, which is beneficial for obtaining uniformly dispersed and well-bonded filler-modified polymers, achieving excellent toughening effects and greatly improving the toughness of phenolic resin.
[0034] like Figure 3 The diagram illustrates a synergistic modification of phenolic resin by combining isocyanate modification and silane coupling agent crosslinking of silica nanoparticles to fully utilize the inherent functional groups of the phenolic resin, resulting in a dynamically covalently crosslinked-inorganic filler-reinforced polymer structure. This composite modification method yields remodelable, recyclable, and highly tough high-performance phenolic resins.
[0035] like Figure 4 The diagram shows a traditional phenolic resin product. Traditional thermosetting phenolic resins are brittle, have poor impact resistance, and are prone to cracking and failure under thermal shock conditions, making them difficult to meet the requirements.
[0036] like Figure 5 The diagram shows a phenolic resin product prepared through dynamic covalent cross-linking and synergistic modification with inorganic fillers. The modified phenolic resin possesses characteristics of thermoplastic phenolic resins and can be reshaped under high temperature and pressure. Although individual bonds at the microscopic level continuously change dynamically, the total number of cross-linking points in the entire network remains in dynamic equilibrium. Furthermore, the presence of silica further enhances the degree of cross-linking of the polymer, improving not only the material's recyclability but also its toughness, resulting in a material with higher performance that can be reused.
[0037] Example 1 This embodiment provides a remodelable, high-toughness phenolic resin, the preparation method of which includes the following steps: (1) Take 10 g of linear phenolic resin in 15 mL of anhydrous ethanol, heat and stir at 55 °C until completely mixed, and prepare a 40 wt% homogeneous solution; 1 g tetraethyl orthosilicate, 0.5 mL deionized water, 0.01 mL catalyst (0.1 M hydrochloric acid) and 0.01 g silane coupling agent (KH-550) were mixed in 4 mL anhydrous ethanol and pre-hydrolyzed by heating and stirring at 35 °C for 90 min until the solution became a homogeneous and transparent sol. The pre-hydrolyzed sol was slowly added dropwise to the phenolic resin solution, and the reaction was continued to be stirred at 50 °C for 3 h. The reaction solution was transferred to a rotary evaporator, and the solvent ethanol and the reaction byproduct ethanol were slowly evaporated at 50 °C and under reduced pressure to obtain the modified phenolic resin. (2) The modified phenolic resin was vacuum dried at 60 °C for 12 h to completely remove moisture; 0.15 g of catalyst (zinc acetate) was melt-blended with the dried modified phenolic resin at 120 °C and stirred continuously until completely dispersed. Subsequently, 1.682 g of hexamethylene diisocyanate was slowly added to the above continuously stirred melt blend at 80 °C to react and obtain the prepolymer; (3) Add 1.2 g of curing agent (hexamethylenetetramine) to the viscous prepolymer obtained above, and then pour it into a polytetrafluoroethylene mold. Place it in a vacuum drying oven and cure it using a stepped heating method. The curing program is 100 ℃ / 2 h, 120 ℃ / 2 h, and 150 ℃ / 2 h. After curing, allow it to cool naturally to room temperature to obtain a high-performance remodelable phenolic resin with a dense structure and a light yellow transparent appearance.
[0038] Example 2 This embodiment provides a remodelable, high-toughness phenolic resin, the preparation method of which includes the following steps: (1) Take 10 g of linear phenolic resin and put it into 23.3 mL of anhydrous ethanol. Heat and stir at 50 °C until completely mixed to prepare a 30 wt% homogeneous solution. Mix 0.5 g tetraethyl orthosilicate, 0.2 mL deionized water, 0.0025 mL catalyst (0.1 M hydrochloric acid), and 0.0025 g silane coupling agent (KH-550) in 2 mL anhydrous ethanol, and heat and stir at 35 °C for 90 min to pre-hydrolyze until the solution becomes a homogeneous and transparent sol. The pre-hydrolyzed sol was slowly added dropwise to the phenolic resin solution, and the reaction was continued to be stirred at 50 °C for 3 h. The reaction solution was transferred to a rotary evaporator, and the solvent ethanol and the reaction byproduct ethanol were slowly evaporated at 50 °C and under reduced pressure to obtain the modified phenolic resin. (2) The modified phenolic resin was vacuum dried at 60 °C for 12 h to completely remove moisture. 0.1 g of catalyst (zinc acetate) was melt-blended with the dried modified phenolic resin at 120 °C and stirred continuously until completely dispersed; Subsequently, 1.514 g of hexamethylene diisocyanate was slowly added to the above continuously stirred melt blend at 80 °C to react and obtain the prepolymer; (3) Add 0.6 g of curing agent (hexamethylenetetramine) to the viscous prepolymer obtained above, and then pour it into a polytetrafluoroethylene mold. Place it in a vacuum drying oven and cure it using a stepped heating method. The curing program is 100 ℃ / 2 h, 120 ℃ / 2 h, and 150 ℃ / 2 h. After curing, allow it to cool naturally to room temperature to obtain a high-performance remodelable phenolic resin with a dense structure and a light yellow transparent appearance.
[0039] Example 3 This embodiment provides a remodelable, high-toughness phenolic resin, the preparation method of which includes the following steps: (1) Take 10 g of linear phenolic resin and put it into 10 mL of anhydrous ethanol. Heat and stir at 60 °C until completely mixed to prepare a 50 wt% homogeneous solution. 2 g tetraethyl orthosilicate, 1.7 mL deionized water, 0.04 mL catalyst (0.1 M hydrochloric acid) and 0.03 g silane coupling agent (KH-550) were mixed in 8 mL anhydrous ethanol and pre-hydrolyzed by heating and stirring at 35 °C for 90 min until the solution became a homogeneous and transparent sol. The pre-hydrolyzed sol was slowly added dropwise to the phenolic resin solution, and the reaction was continued to be stirred at 50 °C for 3 h. The reaction solution was transferred to a rotary evaporator, and the solvent ethanol and the reaction byproduct ethanol were slowly evaporated at 50 °C and under reduced pressure to obtain the modified phenolic resin. (2) The modified phenolic resin was vacuum dried at 60 °C for 12 h to completely remove moisture. 0.2 g of catalyst (zinc acetate) was melt-blended with the dried modified phenolic resin at 120 °C and stirred continuously until completely dispersed; Subsequently, 1.85 g of hexamethylene diisocyanate was slowly added to the above continuously stirred melt blend at 80 °C to react and obtain the prepolymer; (3) Add 1.5 g of curing agent (hexamethylenetetramine) to the viscous prepolymer obtained above, and then pour it into a polytetrafluoroethylene mold. Place it in a vacuum drying oven and cure it using a stepped heating method. The curing program is 100 ℃ / 2 h, 120 ℃ / 2 h, and 150 ℃ / 2 h. After curing, allow it to cool naturally to room temperature to obtain a high-performance remodelable phenolic resin with a dense structure and a light yellow transparent appearance.
[0040] Comparative Example 1 This comparative example provides a single inorganic nanoparticle-reinforced phenolic resin based on Example 2, and its preparation method is as follows: (1) Take 10 g of linear phenolic resin and put it into 23.3 mL of anhydrous ethanol. Heat and stir at 50 °C until completely mixed to prepare a 30 wt% homogeneous solution. Mix 0.14 g of nano silica, 0.2 mL of deionized water, 0.0025 mL of catalyst (0.1 M hydrochloric acid) and 0.0025 g of silane coupling agent (KH-550) in 2 mL of anhydrous ethanol, and heat and stir at 35 °C for 90 min to pre-hydrolyze until the solution becomes a homogeneous and transparent sol. The pre-hydrolyzed sol was slowly added dropwise to the phenolic resin solution, and the reaction was continued to be stirred at 50 °C for 3 h. (2) Add 0.6 g of curing agent (hexamethylenetetramine) to the modified material obtained above, and then pour it into a polytetrafluoroethylene mold. Place it in a vacuum drying oven and cure it using a stepped heating method. The curing program is 100 ℃ / 2 h, 120 ℃ / 2 h, and 150 ℃ / 2 h. After curing, allow it to cool naturally to room temperature to obtain the modified phenolic resin. This material maintains its heat resistance while improving its mechanical properties. However, due to the different coefficients of thermal expansion of the materials, stress concentration is easily generated, and the filler is prone to agglomeration.
[0041] Comparative Example 2 This comparative example provides a dynamically covalently transaminated phenolic resin based on Example 2, the preparation method of which is as follows: (1) Take 10 g of linear phenolic resin and put it into 23.3 mL of anhydrous ethanol. Heat and stir at 50 °C until completely mixed to prepare a 30 wt% homogeneous solution. (2) The phenolic resin was vacuum dried at 60 °C for 12 h to completely remove moisture. 0.1 g of catalyst (zinc acetate) was melt-blended with the dried phenolic resin at 120 °C and stirred continuously until completely dispersed; Subsequently, 1.514 g of hexamethylene diisocyanate was slowly added to the above continuously stirred melt blend at 80 °C to react and obtain the prepolymer; (3) Add 0.6 g of curing agent (hexamethylenetetramine) to the viscous prepolymer obtained above, and then pour it into a polytetrafluoroethylene mold. Place it in a vacuum drying oven and cure it using a stepped heating method. The curing program is 100 ℃ / 2 h, 120 ℃ / 2 h, and 150 ℃ / 2 h. After curing, allow it to cool naturally to room temperature to obtain a dynamically covalently transaminated phenolic resin. The material has high-temperature and high-pressure remodeling properties and closed-loop recycling capability, but it will lead to a decrease in the mechanical properties and loss of heat resistance of the material.
[0042] Existing traditional thermosetting phenolic resins have fixed molecular chains linked by permanent covalent bonds, resulting in high rigidity and high heat resistance. However, they are brittle (poor toughness) and cannot be reshaped once molded, making them highly susceptible to brittle fracture. Heating causes the material to decompose rather than melt, such as... Figure 4 As shown.
[0043] This invention utilizes Figure 1 and Figure 2 Chemical modification of phenolic resins is achieved by combining various modification methods (such as...). Figure 3(As shown). The introduction of dynamic covalent bonds allows the urethane bonds within the material to undergo exchange reactions with adjacent hydroxyl or amino groups under heating and pressure, enabling breakage and reconnection, and topological rearrangement. Simultaneously, the topological crosslinking of silica effectively prevents the loss of mechanical properties at high temperatures due to the introduction of dynamic bonds, improving the material's toughness and heat resistance (e.g., Figure 5 As shown in the figure. At the trigger temperature (>200℃), the dynamic bonds undergo a reversible "break-recombination" reaction. Although individual bonds are constantly changing, the total number of crosslinking points in the entire network remains in dynamic equilibrium. The resulting resin has high toughness, remodelability and closed-loop recycling capability.
[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a remodelable, high-toughness phenolic resin, characterized in that, Including the following steps: S1. Preparation of silica-phenolic resin hybrid resin by sol-gel method; S2. The hybrid resin is vacuum dried and melt-blended with the catalyst; then isocyanate is added to the blend system to react and obtain a prepolymer containing dynamic urethane bonds. S3. Add a curing agent to the prepolymer, mix well, and then heat to cure to obtain the remodelable, high-toughness phenolic resin.
2. The method for preparing the remodelable, high-toughness phenolic resin as described in claim 1, characterized in that: The steps for preparing the silica-phenolic resin hybrid resin are as follows: Linear phenolic resin was dissolved in anhydrous ethanol under heating and stirring conditions to form a homogeneous resin solution. Tetraethyl orthosilicate, anhydrous ethanol, deionized water, acidic catalyst and aminosilane coupling agent were mixed in proportion and stirred at 25~40 °C to carry out a pre-hydrolysis reaction to obtain silane hydrolysis sol. The silane hydrolysate sol was slowly added dropwise to the homogeneous resin solution, and the reaction was continuously stirred for 2-4 hours. The reaction solution was then evaporated under reduced pressure at 50-60 °C to obtain a silica-phenolic resin hybrid resin.
3. The method for preparing the remodelable, high-toughness phenolic resin as described in claim 2, characterized in that: The homogeneous resin solution contains 30-50 wt% phenolic resin, and the heating and stirring temperature is 50-60 °C.
4. The method for preparing the remodelable, high-toughness phenolic resin as described in claim 2, characterized in that: The amount of tetraethyl orthosilicate used is 5% to 20% of the mass of phenolic resin, the molar ratio of water to tetraethyl orthosilicate is 4 to 10, and the volume ratio of tetraethyl orthosilicate to anhydrous ethanol is 1:
4.
5. The method for preparing the remodelable, high-toughness phenolic resin as described in claim 2, characterized in that: The acidic catalyst is hydrochloric acid, and the amount of acidic catalyst used is 0.5% to 2% of the mass of tetraethyl orthosilicate. The pre-hydrolysis time is 30 to 120 min.
6. The method for preparing the remodelable, high-toughness phenolic resin as described in claim 1, characterized in that: The aminosilane coupling agent is KH-550, which accounts for 0.5% to 1.5% of the mass of tetraethyl orthosilicate.
7. The method for preparing the remodelable, high-toughness phenolic resin as described in claim 1, characterized in that: In step S2, the vacuum drying temperature is 60 ℃, the drying time is 12 h, the catalyst is zinc acetate, the amount of which is 1~2% of the mass of phenolic resin, and the melt blending temperature is 120 ℃.
8. The method for preparing the remodelable, high-toughness phenolic resin as described in claim 1, characterized in that: The isocyanate is hexamethylene diisocyanate or isophorone diisocyanate, the reaction temperature is 80 ℃, and the ratio of n(-NCO) / n(-OH) is 0.8~1.
0.
9. The method for preparing the remodelable, high-toughness phenolic resin as described in claim 1, characterized in that: In step S3, the curing agent is hexamethylenetetramine, and the amount of curing agent used is 6%~15% of the mass of the linear phenolic resin; the temperature curing treatment is a stepped temperature curing treatment, and the curing program is 100 ℃ / 2 h, 120 ℃ / 2 h, and 150 ℃ / 2 h in a vacuum drying oven.
10. The remodelable, high-toughness phenolic resin prepared by any one of claims 1 to 9, characterized in that, The remodelable, high-toughness phenolic resin exhibits remodelability under conditions where the temperature is >200 ℃.