High performance modified phenolic resin plastic and method for making same

Abstract

The application discloses a kind of high-performance modified phenolic resin plastics and preparation method thereof, belong to the field of phenolic resin.The polyamino polyether with 2-4 amino functional groups and molecular weight 1500-3000 is added in phenolic prepolymer, C-N-C crosslinking network is formed by reacting at 85-90 DEG C for 1-1.5 h, and 20-50 nm nano boron nitride and toughening agent are added in batches, and are prepared by twice pressure reduction dehydration and 160-170 DEG C curing.The carbon residue rate of product is 75.0%-80.0%, the thermal decomposition temperature is 420.0 DEG C-440.0 DEG C, the tensile strength is 82.5-92.0 MPa, the elongation at break is 3.6%-4.2%, and the micropore volume is 0.012-0.020 cm 3 / g, the thermal stability and mechanical properties are significantly improved.It is suitable for aerospace and high-performance composite material field, and has the advantages of low cost, long service life and the like.

Description

Technical Field

[0001] This invention relates to the technical field of phenolic resins, and in particular to high-performance modified phenolic resin plastics and their preparation methods. Background Technology

[0002] With the rapid development of aerospace, automotive manufacturing, and high-performance composite materials, the demand for materials with high temperature resistance, ablation resistance, and high carbon residue is increasing. Phenolic resin, as a traditional thermosetting resin, is widely used in brake friction materials, ablation-resistant coatings, and high-temperature structural components due to its excellent mechanical properties, thermal stability, and low cost. In recent years, with technological advancements, researchers have significantly improved the thermal properties of phenolic resins by introducing inorganic elements (such as boron and phosphorus) or modifying them with modifiers to optimize the molecular structure.

[0003] For example, Chinese patent (CN107513144 A) discloses a boron-modified phenolic resin and its preparation method. Although the thermal oxidation of boron to generate B2O3 can form a glassy barrier, if the intermolecular cross-linking is insufficient or impurities interfere, the carbonization process is prone to micropores or defects, which limits the further optimization of the residual carbon rate. Summary of the Invention

[0004] This application provides a method for preparing high-performance modified phenolic resin plastics, including the following technical steps:

[0005] Step S1. Add phenol, formaldehyde, and catalyst in a stoichiometric ratio to the reactor, stir, and heat to 85-90℃. Maintain this temperature for 2.5-3.5 hours via polycondensation to generate a phenolic prepolymer. Step S2. Add polyamino polyether to the phenolic prepolymer, maintaining the temperature at 85-90℃, and stir for 1-1.5 hours to form a modified prepolymer through the polycondensation reaction of the amino group and the phenolic prepolymer. Step S3. Adjust the vacuum degree of the reactor to 0.06-0.07 MPa for the first dehydration under reduced pressure. After dehydration, heat to 100-110℃. Step S4. Add nano-boron nitride and toughening agent in batches at 100-110℃, with 10-15 minute intervals, and continue the reaction for 1-1.5 hours. Heat to 130-140℃ and maintain this temperature for 0.5-1 hour. Step S5. Adjust the vacuum degree of the reactor to 0.04-0.05 MPa. MPa, perform a second decompression dehydration; step S6. continue heating to 160-170℃, discharge the material, and obtain the high-performance modified phenolic resin plastic.

[0006] It should be noted that in step S1, phenol and formaldehyde undergo a polycondensation reaction at 85-90℃ under the action of a catalyst to generate a phenolic prepolymer with hydroxymethyl groups, providing active sites for subsequent modification. In step S2, polyamino polyether is introduced, whose polyamino functional groups form CNC bonds with the hydroxymethyl or benzene rings of the phenolic prepolymer through a polycondensation reaction, constructing a high-density cross-linked network, enhancing the flexibility and thermal stability of the molecular chain, and reducing the formation of micropores during high-temperature carbonization. In step S3, water generated during the reaction is removed by vacuum dehydration at 0.06-0.07 MPa, reducing side reactions and improving the purity of the prepolymer. In step S4, nano-boron nitride (BN) and toughening agents are added in batches. The excellent thermal conductivity and high-temperature stability of nano-boron nitride synergistically form a dense BN-carbon composite network with the modified prepolymer, and the toughening agent further improves the mechanical properties. The batch addition (10-15 minutes apart) ensures uniform dispersion of the nanofiller. The reaction is carried out for 1-1.5 hours, and the temperature is raised to 130-140℃ and held to promote the completion of cross-linking. Step S5 involves a second vacuum dehydration at 0.04-0.05 MPa to further remove residual moisture and low-molecular-weight byproducts, thereby increasing the molecular weight and material density. Step S6 involves heating to 160-170℃ to complete curing, yielding a high-performance modified phenolic resin plastic.

[0007] In a preferred embodiment of a method for preparing high-performance modified phenolic resin plastics, the raw materials in step S1 include, by mass parts:

[0008] Phenol: 70-80 parts;

[0009] Formaldehyde: 45-55 parts;

[0010] Catalyst: 0.3-0.5 parts; wherein the catalyst is hydrochloric acid, phosphoric acid, or a combination thereof.

[0011] It should be noted that the hydroxyl groups on the benzene ring of phenol activate the ortho and para carbon atoms through a conjugation effect. Under the action of an acidic catalyst (hydrochloric acid or phosphoric acid), the carbonyl group of formaldehyde is protonated to form an electrophilic carbocation, which undergoes electrophilic addition with the active site of phenol to generate hydroxymethylphenol intermediates. These intermediates further undergo dehydration condensation reactions to form phenolic prepolymer molecular chains linked by methylene bridges (-CH2-). Hydrochloric acid, as a strong acid catalyst, can accelerate the electrophilic addition and dehydration reactions, while the mild acidity of phosphoric acid helps to control the reaction rate and reduce the formation of by-products. The combined use can optimize the molecular weight distribution and structural uniformity of the prepolymer. The ratio of phenol to formaldehyde (70-80:45-55) ensures that the reaction generates an appropriate amount of hydroxymethyl functional groups, providing sufficient reaction sites for the condensation reaction of the amino groups and hydroxymethyl groups of the polyamino polyether in the subsequent step S2, while avoiding excessive cross-linking that leads to excessively rigid molecular chains.

[0012] In a preferred embodiment of a method for preparing high-performance modified phenolic resin plastics, the polyamino polyether in step S2 is a polyamino polyether with a molecular weight of 1500-3000 and containing 2-4 amino functional groups, and the amount added is 3-6 parts by mass.

[0013] It should be noted that the amino groups in polyamino polyethers act as nucleophiles, undergoing nucleophilic addition reactions with the hydroxymethyl groups (-CH2OH) in phenolic prepolymers to form CNC bonds, simultaneously releasing water molecules and forming a highly cross-linked network structure. The molecular weight (1500-3000) of polyamino polyethers ensures that their flexible backbone can introduce flexibility into the rigid framework of phenolic resins, improving the material's toughness and elongation at break. The 2-4 amino functional groups provide multiple reaction sites, enhancing the cross-linking density with phenolic prepolymers and reducing micropore formation during high-temperature carbonization.

[0014] In a preferred embodiment of a method for preparing high-performance modified phenolic resin plastics, the main chain of the polyamino polyether is a polypropylene oxide or polyethylene oxide structure, the amino functional group is a primary amine or a secondary amine, and the amino functionality is 2.5-3.5.

[0015] It should be noted that the primary amine (-NH2) or secondary amine (-NHR) of polyamino polyether acts as a nucleophile. Its lone pair electrons attack the carbon atom of the hydroxymethyl group (-CH2OH) in the phenolic prepolymer, forming a CNC bond and releasing water molecules. Through polycondensation, the flexible segments of the polyamino polyether are integrated into the rigid network of the phenolic resin. The polypropylene oxide or polyethylene oxide backbone imparts flexibility to the molecular chain, reducing the brittleness of the phenolic resin and improving the elongation at break and impact strength. The amino functionality of 2.5-3.5 ensures that each polyamino polyether molecule has multiple (2.5-3.5) active amino groups, which react with the hydroxymethyl group of the phenolic prepolymer at multiple points to form a high-density cross-linked network, enhancing thermal stability and reducing micropore formation during high-temperature carbonization.

[0016] In a preferred embodiment of a method for preparing high-performance modified phenolic resin plastics, the particle size of boron nitride nanoparticles in step S4 is 20-50 nm, the addition amount is 1-4 parts by mass, and the toughening agent is polyethersulfone, polyimide or a combination thereof, the addition amount is 2-5 parts by mass.

[0017] It should be noted that by adding the product in batches and reacting it at 100-110℃ for 1-1.5 hours and then raising the temperature to 130-140℃ and holding it for 0.5-1 hours, a dense boron nitride-carbon composite network is formed in synergy with the polyamino polyether modified prepolymer, which significantly improves the residual carbon rate, thermal decomposition temperature and mechanical properties, while reducing the micropore volume.

[0018] In a preferred embodiment of a method for preparing high-performance modified phenolic resin plastics, the mass ratio of polyamino polyether to nano-boron nitride in step S4 is 1.5:1 to 3:1.

[0019] It should be noted that by optimizing the ratio, the flexible cross-linked network of polyamino polyether and the dense boron nitride-carbon composite network of nano boron nitride can be ensured to work synergistically, significantly improving the performance of phenolic resin plastics.

[0020] In a preferred embodiment of a method for preparing high-performance modified phenolic resin plastics, the first dehydration time in step S3 is 30-45 minutes, and the second dehydration time in step S5 is 20-30 minutes.

[0021] It should be noted that the first decompression dehydration in step S3 effectively removes the moisture and low molecular weight byproducts generated in the polycondensation reaction in steps S1 and S2 through a moderate vacuum environment, reducing the risk of side reactions caused by residual moisture in the system, ensuring the uniform molecular weight distribution of the phenolic prepolymer and the polyamino polyether modified prepolymer, and providing a stable reaction environment for the uniform dispersion of subsequent nano-boron nitride and toughening agent; the second decompression dehydration in step S5 further removes the moisture and residual low molecular weight substances generated in the reaction in step S4, enhances the molecular chain crosslinking density and structural compactness of the modified phenolic resin plastic, thereby significantly improving the residual carbon rate, thermal decomposition temperature, mechanical properties, and reducing the micropore volume.

[0022] In addition, this application prepares high-performance modified phenolic resin plastics using the above-described preparation method.

[0023] The beneficial effects of this application are that the high-performance modified phenolic resin plastic and its preparation method of the present invention significantly improve the material's performance by introducing synergistic modification of polyamino polyether and nano-boron nitride: the residual carbon content is increased to 75.0%-80.0%, the thermal decomposition temperature is increased to 420.0℃-440.0℃, the tensile strength reaches 82.5-92.0 MPa, the elongation at break is increased to 3.6%-4.2%, and the impact strength is increased to 11.5-14.0 kJ / m. 2 The micropore volume was reduced to 0.012-0.020 cm³. 3 / g, compared to the unmodified control sample (carbon residue approximately 75.0%, thermal decomposition temperature approximately 400.0℃, tensile strength approximately 72.0 MPa, elongation at break approximately 2.8%, impact strength approximately 8.5 kJ / m²), 2 The micropore volume is approximately 0.035 cm³. 3The polyether backbone exhibits excellent thermal stability and mechanical properties. Furthermore, the high-density cross-linked network of CNC bonds reduces the formation of micropores during high-temperature carbonization, the flexibility of the polyether backbone improves the toughness of the material, and the addition of nano-boron nitride enhances thermal conductivity and oxidation barrier effect, thereby reducing production costs, improving high-temperature resistance and service life, and making it suitable for aerospace, automotive manufacturing and high-performance composite materials. Attached Figure Description

[0024] Figure 1 The infrared spectrum is that of the modified prepolymer prepared in step S2 of Example 1. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments. Example 1

[0028] Example 1 provides a method for preparing high-performance modified phenolic resin plastics, including the following technical steps:

[0029] Step S1: In a reaction vessel coated with polytetrafluoroethylene (PTFE), add 75 parts phenol, 50 parts formaldehyde (37 wt% aqueous solution), and 0.4 parts hydrochloric acid (36 wt%). Mix thoroughly with stirring at 250 rpm, slowly raise the temperature to 88°C, and maintain a constant temperature for 3 hours to induce a polycondensation reaction. Phenol and formaldehyde undergo electrophilic addition and dehydration polycondensation under hydrochloric acid catalysis to generate hydroxymethylphenol intermediates and low molecular weight phenolic prepolymers, providing active sites for subsequent modification.

[0030] Step S2: Add 4 parts of polyamino polyether (molecular weight 2000, polyoxypropylene backbone, containing 3 primary amine functional groups, functionality 3.0) to the phenolic prepolymer, maintain the temperature at 88℃, stir at 250 rpm, and react for 1.2 hours. The amino groups of the polyamino polyether and the hydroxymethyl groups of the prepolymer form CNC bonds through a condensation reaction, introducing flexible segments to generate a modified prepolymer, improving toughness and thermal stability.

[0031] Step S3: Adjust the vacuum degree of the reactor to 0.065 MPa, and use a vacuum pump to evacuate for 40 minutes to perform the first decompression dehydration, removing the water and a small amount of low molecular weight byproducts generated in the reaction. After dehydration, raise the temperature to 105℃ to ensure the purity of the system and prepare for the addition of nanofillers.

[0032] Step S4: At 105℃, add 2 parts of surface-modified nano-boron nitride (particle size 20-50 nm, KH-550 treated, 1 part each time, 12 minutes apart) and 3 parts of polyethersulfone (polyamino polyether: nano-boron nitride = 2:1) in two batches, stirring at 180 rpm. After reacting for 1.2 hours, raise the temperature to 135℃ and hold for 0.8 hours. Nano-boron nitride and modified prepolymer form a dense boron nitride-carbon composite network, and polyethersulfone enhances mechanical properties.

[0033] Step S5: Adjust the vacuum level to 0.045 MPa and perform a second decompression dehydration for 25 minutes to further remove residual moisture and by-products and increase the molecular chain crosslinking density.

[0034] Step S6: Continue heating to 165℃, maintain stirring speed at 150 rpm, discharge and cool to room temperature to obtain high-performance modified phenolic resin plastic. Example 2

[0035] Example 2 provides a method for preparing high-performance modified phenolic resin plastic, comprising the following technical steps:

[0036] Step S1: Add 70 parts phenol, 45 parts formaldehyde (37wt% aqueous solution), and 0.3 parts phosphoric acid (85wt%) to a polytetrafluoroethylene-coated reactor. Mix thoroughly with stirring at 200 rpm, heat to 85°C, and maintain the temperature for 2.5 hours to carry out the polycondensation reaction. Phosphoric acid gently catalyzes the formation of oligomeric phenolic prepolymers, ensuring appropriate hydroxymethylation and providing reaction sites for subsequent modification.

[0037] Step S2: Add 3 parts of polyamino polyether (molecular weight 1500, polyethylene oxide backbone, containing 2 secondary amine functional groups, functionality 2.5), maintain temperature at 85℃, stir at 200 rpm, and react for 1 hour. The secondary amine of the polyamino polyether condenses with hydroxymethyl groups to form CNC bonds, enhancing the flexibility of the molecular chain and generating a modified prepolymer.

[0038] Step S3: Adjust the vacuum to 0.06 MPa, perform the first dehydration under reduced pressure for 30 minutes to remove moisture and byproducts, and then raise the temperature to 100℃ to optimize the system's reaction activity.

[0039] Step S4: At 100℃, add 1 part of surface-modified nano-boron nitride (particle size 20-50 nm, KH-550 treated, 0.5 part each time, 10 minutes apart) and 2 parts of polyimide (polyamino polyether: nano-boron nitride = 3:1) in two batches, stirring at 150 rpm. After reacting for 1 hour, raise the temperature to 130℃ and hold for 0.5 hours. Nano-boron nitride enhances thermal stability, while polyimide improves mechanical properties.

[0040] Step S5: Adjust the vacuum level to 0.04 MPa, and dehydrate under reduced pressure for 20 minutes to remove residual moisture and increase crosslinking density.

[0041] Step S6: Heat to 160℃, stir at 120 rpm, discharge and cool to obtain high-performance modified phenolic resin plastic. Example 3

[0042] Example 3 provides a method for preparing high-performance modified phenolic resin plastics, including the following technical steps:

[0043] Step S1: Add 80 parts phenol, 55 parts formaldehyde (37wt% aqueous solution), and 0.5 parts catalyst (a mixture of hydrochloric acid and phosphoric acid in a 1:1 mass ratio, with hydrochloric acid concentration of 36wt% and phosphoric acid concentration of 85wt%) to the reactor. Mix at a stirring rate of 300 rpm, heat to 90℃, and maintain the temperature for 3.5 hours to carry out the polycondensation reaction. The mixed catalyst is used to balance the reaction rate and control byproducts, generating a highly active phenolic prepolymer.

[0044] Step S2: Add 6 parts of polyamino polyether (molecular weight 3000, polyoxypropylene backbone, containing 4 primary amine functional groups, functionality 3.5), maintain temperature at 90℃, stir at 300 rpm, and react for 1.5 hours. The primary amine and hydroxymethyl group undergo efficient polycondensation to form a highly crosslinked modified prepolymer, improving thermal stability.

[0045] Step S3: Adjust the vacuum to 0.07 MPa, perform the first dehydration under reduced pressure for 45 minutes to remove moisture, and then raise the temperature to 110℃ to ensure the purity of the system.

[0046] Step S4: At 110℃, add 4 parts of surface-modified nano-boron nitride (particle size 20-50 nm, KH-550 treated, 1.33 parts each time, 15 minutes apart) and 5 parts of a mixture of polyethersulfone and polyimide (mass ratio 1:1, polyamino polyether: nano-boron nitride = 1.5:1) in three portions, stirring at 200 rpm. After reacting for 1.5 hours, raise the temperature to 140℃ and hold for 1 hour. Nano-boron nitride and toughening agent synergistically optimize thermal and mechanical properties.

[0047] Step S5: Adjust the vacuum level to 0.05 MPa, and perform a second dehydration under reduced pressure for 30 minutes to further improve the molecular weight and density.

[0048] Step S6: Heat to 170℃, stir at 180 rpm, discharge and cool to obtain high-performance modified phenolic resin plastic. Example 4

[0049] Example 4 provides a method for preparing high-performance modified phenolic resin plastics, including the following technical steps:

[0050] Step S1: Add 72 parts phenol, 48 parts formaldehyde (37wt% aqueous solution), and 0.35 parts hydrochloric acid (36wt% concentration) to a reactor, mix at a stirring rate of 220 rpm, heat to 87℃, and maintain the temperature for 2.8 hours to carry out the polycondensation reaction. The hydrochloric acid catalyzes the formation of a homogeneous phenolic prepolymer, which is moderately hydroxymethylated.

[0051] Step S2: Add 5 parts of polyamino polyether (molecular weight 2500, polyethylene oxide backbone, containing 3 secondary amine functional groups, functionality 3.0), maintain temperature at 87℃, stir at 220 rpm, and react for 1.3 hours. The secondary amine and hydroxymethyl condensate to form a modified prepolymer, optimizing flexibility and crosslinking density.

[0052] Step S3: Adjust the vacuum to 0.062 MPa, perform the first dehydration under reduced pressure for 35 minutes to remove moisture, and then raise the temperature to 102℃ to provide a pure system for subsequent steps.

[0053] Step S4: At 102℃, add 3 parts of surface-modified nano-boron nitride (particle size 20-50 nm, KH-550 treated, 1 part each time, 13 minutes apart) and 4 parts of polyethersulfone (polyamino polyether: nano-boron nitride = 1.67:1) in three portions, stirring at 170 rpm. After reacting for 1.3 hours, raise the temperature to 138℃ and hold for 0.7 hours. Nano-boron nitride and polyethersulfone synergistically enhance thermal stability and mechanical properties.

[0054] Step S5: Adjust the vacuum level to 0.042 MPa, and perform a second decompression dehydration for 22 minutes to remove residual by-products and improve the material density.

[0055] Step S6: Heat to 168℃, stir at 140 rpm, discharge and cool to obtain high-performance modified phenolic resin plastic.

[0056] Compare with Example 1

[0057] The difference between Comparative Example 1 and Example 1 is that no polyamino polyether is added, and its preparation method includes:

[0058] Step S1: Add 75 parts phenol, 50 parts formaldehyde (37wt% aqueous solution) and 0.4 parts hydrochloric acid (36wt%) to a polytetrafluoroethylene coated reactor, stir at 250 rpm, heat to 88℃, and keep at this temperature for 3 hours to generate phenolic prepolymer.

[0059] Step S2: Omit the addition of polyamino polyether and proceed directly to step S3. Maintain 88°C and stir for 1.2 hours (250 rpm) to maintain a consistent thermal history.

[0060] Step S3: Adjust the vacuum to 0.065 MPa, dehydrate under reduced pressure for 40 minutes, and raise the temperature to 105℃.

[0061] Step S4: At 105℃, add 2 parts of nano boron nitride (particle size 20-50 nm, KH-550 treated, 1 part each time, 12 minutes apart) and 3 parts of polyethersulfone in two batches, stirring at 180 rpm, react for 1.2 hours, then heat to 135℃ and hold for 0.8 hours.

[0062] Step S5: Adjust the vacuum level to 0.045 MPa, and perform a second dehydration under reduced pressure for 25 minutes.

[0063] Step S6: Heat to 165℃, stir at 150 rpm, discharge and cool to obtain phenolic resin plastic.

[0064] Compare with Example 2

[0065] The difference between Comparative Example 2 and Example 1 is that no nano-boron nitride is added, and its preparation method includes:

[0066] Step S1: Add 75 parts phenol, 50 parts formaldehyde (37wt% aqueous solution) and 0.4 parts hydrochloric acid (36wt%) to a polytetrafluoroethylene coated reactor, stir at 250 rpm, heat to 88℃, and keep at this temperature for 3 hours to generate phenolic prepolymer.

[0067] Step S2: Add 4 parts of polyamino polyether (molecular weight 2000, polyoxypropylene backbone, 3 primary amine functional groups, functionality 3.0), 88℃, stirring speed 250 rpm, react for 1.2 hours to form a modified prepolymer.

[0068] Step S3: Adjust the vacuum to 0.065 MPa, dehydrate under reduced pressure for 40 minutes, and raise the temperature to 105℃.

[0069] Step S4: At 105°C, add only 3 parts of polyethersulfone (omitting nano boron nitride), stir at 180 rpm, react for 1.2 hours, then heat to 135°C and hold for 0.8 hours.

[0070] Step S5: Adjust the vacuum level to 0.045 MPa, and perform a second dehydration under reduced pressure for 25 minutes.

[0071] Step S6: Heat to 165℃, stir at 150 rpm, discharge and cool to obtain phenolic resin plastic.

[0072] Compare with Example 3

[0073] The difference between Comparative Example 3 and Example 1 is that the polyamino polyether backbone is replaced with a polyester structure, and its preparation method includes:

[0074] Step S1: Add 75 parts phenol, 50 parts formaldehyde (37wt% aqueous solution) and 0.4 parts hydrochloric acid (36wt%) to a polytetrafluoroethylene coated reactor, stir at 250 rpm, heat to 88℃, and keep at this temperature for 3 hours to generate phenolic prepolymer.

[0075] Step S2: Add 4 parts of polyamino polyester (molecular weight 2000, polyester backbone, containing 3 primary amine functional groups, functionality 3.0), 88℃, stirring speed 250 rpm, react for 1.2 hours, and form a modified prepolymer through condensation polymerization of amino and hydroxymethyl groups.

[0076] Step S3: Adjust the vacuum to 0.065 MPa, dehydrate under reduced pressure for 40 minutes, and raise the temperature to 105℃.

[0077] Step S4: At 105℃, add 2 parts of nano boron nitride (particle size 20-50 nm, KH-550 treated, 1 part each time, 12 minutes apart) and 3 parts of polyethersulfone in two batches, stirring at 180 rpm, react for 1.2 hours, then heat to 135℃ and hold for 0.8 hours.

[0078] Step S5: Adjust the vacuum level to 0.045 MPa, and perform a second dehydration under reduced pressure for 25 minutes.

[0079] Step S6: Heat to 165℃, stir at 150 rpm, discharge and cool to obtain modified phenolic resin plastic.

[0080] Compare with Example 4

[0081] The difference between Comparative Example 4 and Example 1 is that the amino functional group is replaced with a tertiary amine, and its preparation method includes:

[0082] Step S1: Add 75 parts phenol, 50 parts formaldehyde (37wt% aqueous solution) and 0.4 parts hydrochloric acid (36wt%) to a polytetrafluoroethylene coated reactor, stir at 250 rpm, heat to 88℃, and keep at this temperature for 3 hours to generate phenolic prepolymer.

[0083] Step S2: Add 4 parts of polyamino polyether (molecular weight 2000, polyoxypropylene backbone, containing 3 tertiary amine functional groups, functionality 3.0), 88℃, stirring speed 250 rpm, react for 1.2 hours. Due to the low reactivity of tertiary amine, the polycondensation reaction is limited, and a partially modified prepolymer is formed.

[0084] Step S3: Adjust the vacuum to 0.065 MPa, dehydrate under reduced pressure for 40 minutes, and raise the temperature to 105℃.

[0085] Step S4: At 105℃, add 2 parts of nano boron nitride (particle size 30 nm, KH-550 treated, hydroxyl content 1.0 mmol / g, 1 part each time, 12 minutes apart) and 3 parts of polyethersulfone in two batches, stirring at 180 rpm, react for 1.2 hours, then heat to 135℃ and hold for 0.8 hours.

[0086] Step S5: Adjust the vacuum level to 0.045 MPa, and perform a second dehydration under reduced pressure for 25 minutes.

[0087] Step S6: Heat to 165℃, stir at 150 rpm, discharge and cool to obtain modified phenolic resin plastic.

[0088] Performance testing methods

[0089] 1. Residual carbon content

[0090] Test method: Thermogravimetric analysis (TGA) was used to determine the carbon residue. The sample was placed in a thermogravimetric analyzer and heated from room temperature to 800-1000℃ at a heating rate of 10℃ / min under nitrogen or inert atmosphere. The mass loss of the sample at the high temperature was recorded. The carbon residue was calculated as the percentage of the remaining mass of the sample at a specified temperature (e.g., 800℃) relative to the initial mass.

[0091] 2. Thermal decomposition temperature

[0092] Test method: The thermal decomposition temperature is determined using a thermogravimetric analyzer (TGA) or differential scanning calorimetry (DSC). Under a nitrogen atmosphere, the sample is heated at a heating rate of 5-10 °C / min, and the temperature at which the sample begins to lose significant weight (usually defined as a mass loss of 5%) is recorded as the thermal decomposition temperature (Td).

[0093] 3. Mechanical properties (tensile strength, elongation at break, impact strength)

[0094] Test methods: Tensile strength and elongation at break were tested according to ASTM D638 standard. A universal testing machine was used to perform tensile tests on standard dumbbell-shaped specimens, and the maximum tensile strength and elongation at break were recorded. Impact strength was tested according to ASTM D256 standard. A pendulum impact tester was used to perform notched impact tests, and the impact energy absorbed per unit area was determined.

[0095] 4. Micropore volume

[0096] Test method: The micropore volume was determined by nitrogen adsorption-desorption (BET) method. A specific surface area and porosity analyzer was used to conduct nitrogen adsorption experiments at 77 K to obtain the adsorption-desorption isotherms of the samples. The micropore volume was calculated using the BJH model or DFT method.

[0097] Table 1

[0098]

[0099] In conjunction with Example 1 and Figure 1 It can be seen that a significant broad peak appears in the 3400-3350 cm⁻¹ range. -1 The peak value is approximately 1.0, attributed to the NH or OH stretching vibrations of hydroxyl (-OH) and primary / secondary amines (-NH2 / -NHR), indicating residual polar groups and partially unreacted amino groups; 1075 cm⁻¹ -1 The high-intensity peak (peak value approximately 1.4) at 1050 cm⁻¹ -1 The combined peaks confirmed the CNC bond (CN stretching vibration) and the CO stretching vibration of hydroxymethyl (-CH2OH), strongly supporting the conclusion that CNC bonds are formed by the condensation polymerization of amino groups in polyamino ethers and hydroxymethyl groups in phenolic prepolymers; 1475-1500 cm⁻¹ -1 and 1600 cm -1 The moderate intensity peak (peak value approximately 0.6-0.8) at 1150 cm⁻¹ corresponds to the C=C stretching vibration of the benzene ring, indicating the stability of the aromatic structure; -1 and 1225 cm -1 The intermediate peaks at 1700 cm⁻¹ (peak value approximately 0.5–0.4) are attributed to COC stretching of the polyether backbone and ether bonds, respectively, reflecting the introduction of flexible segments in the polyamino polyether; -1 The weak peak (peak value around 0.2) may originate from the carbonyl group (C=O), indicating trace byproducts.

[0100] As can be seen from Examples 1 to 4 and Table 1, this high-performance modified phenolic resin plastic exhibits a stable optimization range in key performance indicators: residual carbon content (800℃, N2 atmosphere) ranges from 75.0% to 80.0%, thermal decomposition temperature (5% mass loss) ranges from 420.0℃ to 440.0℃, tensile strength fluctuates between 82.5 MPa and 92.0 MPa, elongation at break ranges from 3.6% to 4.2%, and impact strength ranges from 11.5 kJ / m. 2 Up to 14.0 kJ / m 2 The micropore volume was controlled at 0.012 cm³. 3 / g to 0.020 cm 3 / g. These data ranges reflect the comprehensive improvement in thermal stability, mechanical properties, and microstructure density achieved through the synergistic effect of polyamino polyether modification and nano-boron nitride.

[0101] Based on Example 1, Comparative Example 1, Comparative Example 2, and Table 1, it can be seen that Example 1 exhibits the following characteristics: residual carbon content (78.5%), thermal decomposition temperature (430.0℃), tensile strength (88.0 MPa), elongation at break (4.0%), and impact strength (13.0 kJ / m²). 2 ) and micropore volume (0.015 cm) 3 In terms of properties such as g, it is superior to control example 1 (corresponding indicators are 75.0%, 400.0℃, 72.0MPa, 2.8%, and 8.5 kJ / m). 2 0.035 cm 3 / g) and Control Example 2 (75.2%, 410.0℃, 77.0 MPa, 3.2%, 10.0 kJ / m 2 0.030 cm 3 The improvement in thermal stability and mechanical properties is particularly significant, with a 3.5%-3.3% increase in residual carbon content, a 30℃-20℃ increase in thermal decomposition temperature, a 16 MPa-11 MPa increase in tensile strength, a 1.2%-0.8% increase in elongation at break, and a 4.5 kJ / m increase in impact strength. 2 -3.0 kJ / m 2 The micropore volume decreased by 0.020 cm³. 3 / g-0.015 cm 3 / g; In Example 1, a high-density CNC crosslinked network was formed by the condensation reaction of the amino functional groups of polyamino polyether with the hydroxymethyl group of phenolic prepolymer. Flexible segments were introduced to improve toughness and reduce micropore formation during high-temperature carbonization. At the same time, the addition of nano-boron nitride constructed a dense BN-carbon composite structure, which improved thermal conductivity and barrier effect, and synergistically inhibited thermal decomposition and oxidation. In contrast, the absence of polyamino polyether in Control Example 1 resulted in insufficient crosslinking density, excessively high molecular chain rigidity and increased micropores. The absence of nano-boron nitride in Control Example 2 weakened thermal stability and composite reinforcement, thus deteriorating the overall performance.

[0102] Combining Example 1, Comparative Example 3, and Table 1, it can be seen that Example 1 achieved the following results: residual carbon content (78.5%), thermal decomposition temperature (430.0℃), tensile strength (88.0 MPa), elongation at break (4.0%), and impact strength (13.0 kJ / m²). 2 ) and micropore volume (0.015 cm) 3 In terms of properties such as g / m², it is superior to control example 3 (corresponding indicators are 75.5%, 415.0℃, 80.0 MPa, 3.4%, and 10.5 kJ / m², respectively). 2 0.028 cm 3 The thermal stability and mechanical properties were significantly improved, with a 3.0% increase in residual carbon content, a 15.0℃ increase in thermal decomposition temperature, an 8.0 MPa increase in tensile strength, a 0.6% increase in elongation at break, and a 2.5 kJ / m increase in impact strength. 2 The micropore volume decreased by 0.013 cm. 3 / g; From a mechanistic perspective, Example 1 uses polyamino polyether (polyoxypropylene backbone, primary amine functional group) and phenolic prepolymer hydroxymethyl high-efficiency polycondensation to form a high-density CNC crosslinking network, introducing flexible segments to improve toughness and suppress micropore formation during high-temperature carbonization. At the same time, the addition of nano boron nitride constructs a dense BN-carbon composite structure, enhancing thermal conductivity and oxidation barrier effect. In contrast, Control Example 3 uses polyamino polyester with polyester backbone, resulting in insufficient flexibility, reduced crosslinking density and weakened reactivity, thereby increasing micropores and deteriorating overall thermal stability and mechanical properties.

[0103] Combining Example 1, Comparative Example 4, and Table 1, it can be seen that Example 1 exhibits the following characteristics: residual carbon content (78.5%), thermal decomposition temperature (430.0℃), tensile strength (88.0 MPa), elongation at break (4.0%), and impact strength (13.0 kJ / m²). 2 ) and micropore volume (0.015 cm) 3 In terms of performance indicators such as g / m², it was significantly better than control example 4 (corresponding indicators are 75.0%, 405.0℃, 74.0 MPa, 3.0%, and 9.0 kJ / m²). 2 0.032 cm3 Specifically, this resulted in a 3.5% increase in residual carbon content, a 25.0℃ increase in thermal decomposition temperature, a 14.0 MPa increase in tensile strength, a 1.0% increase in elongation at break, a 4.0 kJ / m² increase in impact strength, and a 0.017 cm³ decrease in micropore volume. 3 / g. Example 1 uses polyamino polyether (polypropylene oxide backbone, containing 3 primary amine functional groups, functionality 3.0). Its primary amine and the hydroxymethyl group of the phenolic prepolymer undergo efficient condensation to form CNC bonds, constructing a high-density cross-linked network. The flexible polypropylene oxide backbone significantly improves the brittleness of the phenolic resin, enhances its toughness and elongation at break, and reduces micropore formation during high-temperature carbonization. The addition of nano-boron nitride (particle size 20-50 nm) further forms a dense BN-carbon composite network, enhancing thermal conductivity and thermal oxidation barrier effect, and increasing thermal decomposition temperature and residual carbon content. In contrast, Control Example 4 uses polyamino polyether containing tertiary amine functional groups. Due to the lack of active hydrogen in the tertiary amine, the condensation reaction activity is significantly reduced, resulting in insufficient cross-linking density, increased micropore volume, and significant deterioration in thermal stability and mechanical properties.

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. 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 high-performance modified phenolic resin plastics, characterized in that, The technical steps include the following: Step S1. Add 70-80 parts of phenol, 45-55 parts of formaldehyde and 0.3-0.5 parts of catalyst in a reaction vessel according to the stoichiometric ratio, stir and heat to 85-90℃, and maintain the temperature for 2.5-3.5h through polycondensation reaction to generate phenolic prepolymer; wherein, the catalyst is hydrochloric acid, phosphoric acid or a combination thereof; Step S2. Add polyamino polyether to the phenolic prepolymer, maintain the temperature at 85-90℃, and stir for 1-1.5 hours to form a modified prepolymer through the polycondensation reaction of amino groups with the phenolic prepolymer; wherein the polyamino polyether is a polyamino polyether with a molecular weight of 1500-3000 and containing 2-4 amino functional groups, and the amount added is 3-6 parts by mass, and the main chain of the polyamino polyether is a polypropylene oxide or polyethylene oxide structure, and the amino functional groups are primary amines or secondary amines; Step S3. Adjust the vacuum degree of the reactor to 0.06-0.07 MPa, perform the first decompression dehydration, and then raise the temperature to 100-110℃; Step S4. Add nano boron nitride and toughening agent in batches at 100-110℃, with an interval of 10-15 minutes, and continue the reaction for 1-1.5 hours. Then raise the temperature to 130-140℃ and keep it at that temperature for 0.5-1 hour. Step S5. Adjust the vacuum degree of the reactor to 0.04-0.05 MPa and perform a second decompression dehydration; Step S6. Continue heating to 160-170℃, then discharge the material to obtain the high-performance modified phenolic resin plastic.

2. The preparation method according to claim 1, characterized in that, The amino functionality is 2.5-3.

5.

3. The preparation method according to claim 1, characterized in that, In step S4, the particle size of the nano boron nitride is 20-50 nm, and the amount added is 1-4 parts by mass. The toughening agent is polyethersulfone, polyimide, or a combination thereof, and the amount added is 2-5 parts by mass.

4. The preparation method according to claim 3, characterized in that, In step S4, the mass ratio of polyamino polyether to nano-boron nitride is 1.5:1 to 3:

1.

5. The preparation method according to claim 1, characterized in that, The first dehydration time in step S3 is 30-45 minutes, and the second dehydration time in step S5 is 20-30 minutes.

6. High-performance modified phenolic resin plastics are prepared based on the preparation method described in claim 1.

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