A high-strength phenol-formaldehyde resin and a method for producing the same

Abstract

The application relates to the technical field of phenolic resin, and discloses a high-strength phenolic resin and a preparation method thereof; the resin is prepared by introducing furfurylamine-based polymer and hyperbranched polyamide as a composite modifier into phenol and formaldehyde as basic raw materials. The application forms a synergistic effect through the rigid reinforcing effect of the furfurylamine-based polymer and the toughening effect of the hyperbranched polyamide, significantly improves the tensile strength, bending strength and impact strength of the phenolic resin, optimizes the thermal stability, and the product is suitable for fields with high comprehensive performance requirements such as mechanical parts, electronic packaging and composite material matrix, and has a wide industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of phenolic resin technology, specifically to a high-strength phenolic resin and its preparation method. Background Technology

[0002] Phenolic resins are a class of polymeric materials formed by the condensation polymerization of phenols and aldehydes (usually formaldehyde). They possess excellent mechanical strength, thermal stability, chemical resistance, and electrical insulation, and are widely used in machinery manufacturing, electronics, building materials, and many other fields. However, traditional phenolic resins suffer from defects such as high brittleness and insufficient tensile and impact strength, limiting their application in high-end products and scenarios with stringent mechanical performance requirements. Current technologies often employ the addition of reinforcing fillers or the introduction of modifiers to improve the strength of phenolic resins, but these methods present several problems: adding a single filler can easily lead to uneven dispersion, negatively impacting the overall resin performance; and modifiers have poor compatibility with the phenolic resin matrix, making it difficult to achieve an effective synergistic reinforcing effect. Therefore, developing a high-strength phenolic resin with a reasonable formulation, simple preparation, and significantly improved mechanical properties is of significant practical importance. Summary of the Invention

[0003] Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a high-strength phenolic resin and its preparation method, which has good mechanical properties, good flame retardant effect, and a simple preparation process.

[0004] Technical solution To achieve the above objectives, the present invention provides the following technical solution: a method for preparing high-strength phenolic resin, comprising the following steps: S1. Add itaconic anhydride to a reaction flask containing toluene, purge with argon gas for protection, stir mechanically until fully dissolved, then slowly add furfurylamine dropwise. After the addition is complete, react at room temperature for 4-7 hours. After the reaction is complete, filter under vacuum, wash the precipitate 2-4 times with anhydrous diethyl ether, and dry under vacuum to obtain intermediate 1. S2. Add 12-15g of p-allylphenol and 8-9g of triethylamine to 95-110mL of ethyl acetate, stir to dissolve, and continue to add 9.5-9.8g of phenylphosphodichlorodichloride dissolved in 35-40mL of ethyl acetate. Under nitrogen protection, after the addition is complete, heat the mixture for 22-24h. After the reaction is complete, filter the mixture, wash the filtrate 4-5 times with saturated brine, concentrate it, and obtain the alkenylphenol compound. S3. Add 7-8 mmol of N-isopropylacrylamide, 0.4-0.5 g of intermediate 1, 0.76-0.8 g of alkenylphenol compound, 0.02-0.03 g of azobisisobutyronitrile, and 35-40 mL of 1,4-dioxane solvent to the reaction flask. Then, evacuate the flask under vacuum and purge with argon to remove oxygen. React at 65-70 °C. After the reaction is complete, concentrate the solution by rotary evaporation, precipitate with anhydrous diethyl ether, filter, and dry under vacuum to obtain furfurylamine polymer. S4. Add diethylenetriamine to the reaction flask, then slowly add succinic anhydride, heat the mixture at 50-55℃ for 2-2.5h, then raise the temperature to 135-140℃ and hold for 4-5h, and finally, rapidly cool the mixture to room temperature to obtain hyperbranched polyamide. S5. Add 50-60g of phenol, 45-50g of distilled water and 25-27g of sodium hydroxide solution to a flask, slowly add 75-80g of formaldehyde solution, heat at 90-93℃ for 52-55min, then add 22-24g of formaldehyde solution and 5-6g of sodium hydroxide solution, continue heating at 90-93℃ for 30-40min, when the resin viscosity reaches 130-140mPa·s, quickly cool the resin to 40℃ to obtain phenolic resin; S6. Disperse furfurylamine polymer and hyperbranched polyamide in phenolic resin, and stir magnetically at 55-60℃ for 1-2 hours to obtain high-strength phenolic resin.

[0005] Furthermore, in S1, the ratio of toluene, itaconic anhydride, and furfural is 50-65 mL: 4.1-4.5 g: 3.9-4.0 g.

[0006] Furthermore, in S2, the reaction temperature is 56-60℃.

[0007] Furthermore, in S3, the reaction time is 20-24 hours.

[0008] Furthermore, in S4, the mass ratio of diethylenetriamine to succinic anhydride is 82-84g: 95-100g.

[0009] Furthermore, in step S5, the mass fraction of the sodium hydroxide solution is 38-40%.

[0010] Furthermore, in S6, the ratio of furfurylamine polymer, hyperbranched polyamide dispersion, and phenolic resin is 1-2g, 1.5-3g: 50-55g.

[0011] Furthermore, it is prepared using any one of claims 1-7.

[0012] Beneficial technical effects Furfurylamine-based polymers are polymerized from furfurylamine (containing furan rings and amino groups). The molecules contain active groups such as amino groups and unsaturated bonds, which can undergo hydrogen bonding or chemical reactions with the hydroxyl groups and methylene bridges of phenolic resins to enhance interfacial bonding. Furthermore, the phosphorus element contained therein has a good flame retardant effect.

[0013] Hyperbranched polyamides are prepared by reacting diethylenetriamine and succinic anhydride. The molecules contain numerous amide groups, amino groups, and terminal active sites. The hyperbranched structure provides excellent dispersibility and toughening effects, forming a "rigid-flexible" structure with the rigid framework of phenolic resin. The amino groups of the amine polymer can form hydrogen bonds with the phenolic hydroxyl groups of the phenolic resin, improving compatibility; the amide groups of the hyperbranched polyamide can also bond with the hydroxyl groups of the phenolic resin through hydrogen bonds. Simultaneously, the steric hindrance effect of the hyperbranched structure can prevent excessive cross-linking of phenolic resin molecules, improving toughness; the combination of the two enhances the mechanical properties of phenolic resin. The toughening effect of the hyperbranched polyamide and the rigidity enhancement of the furfurylamine-based polymer can simultaneously improve tensile strength, flexural strength, and impact strength; the furan ring of furfurylamine and the amide bonds of the hyperbranched polyamide can enhance thermal stability and delay thermal decomposition at high temperatures. Attached Figure Description

[0014] Figure 1 This is the reaction formula for intermediate 1.

[0015] Figure 2 It is a reaction formula for alkenylphenol compounds. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific embodiments.

[0018] Example 1 A method for preparing a high-strength phenolic resin includes the following steps: S1. Add 4.1 g itaconic anhydride to a reaction flask containing 50 mL toluene, purge with argon gas, stir mechanically until fully dissolved, then slowly add 3.9 g furfurylamine. After the addition is complete, react at room temperature for 4 h. After the reaction is complete, filter, wash the precipitate twice with anhydrous diethyl ether, and dry under vacuum to obtain intermediate 1. S2. Add 12g of p-allylphenol and 8g of triethylamine to 95mL of ethyl acetate, stir to dissolve, and continue to add 9.5g of phenylphosphodichloro dissolved in 35mL of ethyl acetate. Under nitrogen protection, after the addition is complete, heat to 56℃ and react for 22h. After the reaction is complete, filter, wash the filtrate 4 times with saturated brine, concentrate, and obtain the alkenylphenol compound. S3. Add 7 mmol of N-isopropylacrylamide, 0.4 g of intermediate 1, 0.76 g of alkenylphenol compound, 0.02 g of azobisisobutyronitrile, and 35 mL of 1,4-dioxane solvent to the reaction flask. Then, evacuate the flask under vacuum and purge with argon to remove oxygen. React at 65 °C for 20 h. After the reaction is complete, concentrate the solution by rotary evaporation, precipitate with anhydrous diethyl ether, filter, and dry under vacuum to obtain furfurylamine polymer. S4. Add 82g of diethylenetriamine to the reaction flask, then slowly add 95g of succinic anhydride, heat the mixture at 50°C for 2h, then raise the temperature to 135°C and hold for 4h, and finally rapidly cool the mixture to room temperature to obtain hyperbranched polyamide. S5. Add 50g phenol, 45g distilled water and 25g sodium hydroxide solution (38%) to a flask, slowly add 75g formaldehyde solution, heat at 90℃ for 52min, then add 22g formaldehyde solution and 5g sodium hydroxide solution (38%), continue heating at 90℃ for 30min, when the resin viscosity reaches 130-140mPa·s, quickly cool the resin to 40℃ to obtain phenolic resin; S6. Disperse 1g of furfurylamine polymer and 1.5g of hyperbranched polyamide in 50g of phenolic resin, and stir magnetically at 55℃ for 1h to obtain high-strength phenolic resin.

[0019] Example 2 A method for preparing a high-strength phenolic resin includes the following steps: S1. Add 4.5 g itaconic anhydride to a reaction flask containing 65 mL toluene, purge with argon gas, stir mechanically until fully dissolved, then slowly add 4.0 g furfurylamine. After the addition is complete, react at room temperature for 7 h. After the reaction is complete, filter, wash the precipitate 4 times with anhydrous diethyl ether, and dry under vacuum to obtain intermediate 1. S2. Add 15g of p-allylphenol and 9g of triethylamine to 110mL of ethyl acetate, stir to dissolve, and continue to add 9.8g of phenylphosphodichlorodichloride dissolved in 40mL of ethyl acetate. Under nitrogen protection, after the addition is complete, heat to 60℃ and react for 24h. After the reaction is complete, filter, wash the filtrate 5 times with saturated brine, concentrate, and obtain the alkenylphenol compound. S3. Add 8 mmol of N-isopropylacrylamide, 0.5 g of intermediate 1, 0.8 g of alkenylphenol compound, 0.03 g of azobisisobutyronitrile, and 40 mL of 1,4-dioxane solvent to the reaction flask. Then, evacuate the flask under vacuum and purge with argon to remove oxygen. React at 70 °C for 24 h. After the reaction is complete, concentrate the solution by rotary evaporation, precipitate with anhydrous diethyl ether, filter, and dry under vacuum to obtain furfurylamine polymer. S4. Add 84g of diethylenetriamine to the reaction flask, then slowly add 100g of succinic anhydride, heat the mixture at 55℃ for 2.5h, then raise the temperature to 140℃ and hold for 5h, and finally, rapidly cool the mixture to room temperature to obtain hyperbranched polyamide. S5. Add 60g phenol, 50g distilled water and 27g sodium hydroxide solution (40%) to a flask, slowly add 80g formaldehyde solution, heat at 93℃ for 55min, then add 24g formaldehyde solution and 6g sodium hydroxide solution (40%), continue heating at 93℃ for 40min, when the resin viscosity reaches 140mPa·s, quickly cool the resin to 40℃ to obtain phenolic resin; S6. Disperse 2g of furfurylamine polymer and 3g of hyperbranched polyamide in 55g of phenolic resin, and stir magnetically at 60°C for 2h to obtain high-strength phenolic resin.

[0020] Example 3 A method for preparing a high-strength phenolic resin includes the following steps: S1. Add 4.3 g itaconic anhydride to a reaction flask containing 60 mL toluene, purge with argon gas, stir mechanically until fully dissolved, then slowly add 3.95 g furfurylamine. After the addition is complete, react at room temperature for 6 h. After the reaction is complete, filter, wash the precipitate 3 times with anhydrous diethyl ether, and dry under vacuum to obtain intermediate 1. S2. Add 14g of p-allylphenol and 8.5g of triethylamine to 100mL of ethyl acetate, stir to dissolve, and continue to add 9.7g of phenylphosphodichlorodichloride dissolved in 38mL of ethyl acetate. Under nitrogen protection, after the addition is complete, raise the temperature to 56℃ and react for 23h. After the reaction is complete, filter, wash the filtrate four times with saturated brine, concentrate, and obtain the alkenylphenol compound. S3. Add 7.5 mmol of N-isopropylacrylamide, 0.45 g of intermediate 1, 0.78 g of alkenylphenol compound, 0.02 g of azobisisobutyronitrile, and 37 mL of 1,4-dioxane solvent to the reaction flask. Then, evacuate the flask under vacuum and purge with argon to remove oxygen. React at 68 °C for 22 h. After the reaction is complete, concentrate the solution by rotary evaporation, precipitate with anhydrous diethyl ether, filter, and dry under vacuum to obtain furfurylamine polymer. S4. Add 83g of diethylenetriamine to the reaction flask, then slowly add 98g of succinic anhydride, heat the mixture at 52℃ for 2.3h, then raise the temperature to 137℃ and hold for 5h, and finally rapidly cool the mixture to room temperature to obtain hyperbranched polyamide. S5. Add 55g phenol, 48g distilled water and 26g sodium hydroxide solution (40%) to a flask, slowly add 78g formaldehyde solution, heat at 92℃ for 53min, then add 23g formaldehyde solution and 5.5g sodium hydroxide solution (40%), continue heating at 93℃ for 40min, when the resin viscosity reaches 135mPa·s, quickly cool the resin to 40℃ to obtain phenolic resin; S6. Disperse 1g of furfurylamine polymer and 3g of hyperbranched polyamide in 55g of phenolic resin, and stir magnetically at 58℃ for 2h to obtain high-strength phenolic resin.

[0021] Example 4 A method for preparing a high-strength phenolic resin includes the following steps: S1. Add 4.1 g itaconic anhydride to a reaction flask containing 50 mL toluene, purge with argon gas, stir mechanically until fully dissolved, then slowly add 3.9 g furfurylamine. After the addition is complete, react at room temperature for 4 h. After the reaction is complete, filter, wash the precipitate twice with anhydrous diethyl ether, and dry under vacuum to obtain intermediate 1. S2. Add 12g of p-allylphenol and 8g of triethylamine to 95mL of ethyl acetate, stir to dissolve, and continue to add 9.5g of phenylphosphodichloro dissolved in 35mL of ethyl acetate. Under nitrogen protection, after the addition is complete, heat to 56℃ and react for 22h. After the reaction is complete, filter, wash the filtrate 4 times with saturated brine, concentrate, and obtain the alkenylphenol compound. S3. Add 8 mmol of N-isopropylacrylamide, 0.5 g of intermediate 1, 0.8 g of alkenylphenol compound, 0.03 g of azobisisobutyronitrile, and 40 mL of 1,4-dioxane solvent to the reaction flask. Then, evacuate the flask under vacuum and purge with argon to remove oxygen. React at 70 °C for 24 h. After the reaction is complete, concentrate the solution by rotary evaporation, precipitate with anhydrous diethyl ether, filter, and dry under vacuum to obtain furfurylamine polymer. S4. Add 84g of diethylenetriamine to the reaction flask, then slowly add 100g of succinic anhydride, heat the mixture at 55℃ for 2.5h, then raise the temperature to 140℃ and hold for 5h, and finally, rapidly cool the mixture to room temperature to obtain hyperbranched polyamide. S5. Add 55g phenol, 48g distilled water and 26g sodium hydroxide solution (40%) to a flask, slowly add 78g formaldehyde solution, heat at 92℃ for 53min, then add 23g formaldehyde solution and 5.5g sodium hydroxide solution (40%), continue heating at 93℃ for 40min, when the resin viscosity reaches 135mPa·s, quickly cool the resin to 40℃ to obtain phenolic resin; S6. Disperse 1g of furfurylamine polymer and 3g of hyperbranched polyamide in 55g of phenolic resin, and stir magnetically at 60°C for 2h to obtain high-strength phenolic resin.

[0022] Comparative Example 1 The difference between this comparative example and Example 4 is that furfurylamine is used instead of the furfurylamine-based polymer.

[0023] Comparative Example 2 The difference between this comparative example and Example 4 is that diethylenetriamine was used instead of hyperbranched polyamide.

[0024] Tensile properties shall be tested according to ISO 527-2; flexural properties shall be tested according to ISO 178; impact properties shall be tested according to ISO 180. The limiting oxygen index of the material is tested using an oxygen index meter, and the flammability rating of the material is tested using a horizontal-vertical combustion meter.

[0025] Tensile strength test method: Specimen specifications: Type I dumbbell-shaped specimens, total length 150mm, effective working section length 25mm, width 6mm, thickness 4mm. Test equipment: Electronic universal testing machine (accuracy ±0.5%), equipped with an extensometer. Test parameters: Tensile rate 1mm / min, test temperature 23℃±2℃, record the maximum load at specimen fracture.

[0026] Calculation method: Tensile strength σ (MPa) = maximum load F (N) / effective cross-sectional area of ​​specimen A (mm²), take the arithmetic mean of parallel specimens and retain 1 decimal place.

[0027] Table 1: Performance Tests Example 1 30.28 V-0 88.4 128 22.8 432 Example 2 33.66 V-0 91.8 135 24.9 450 Example 3 31.51 V-0 90.6 132 24.1 446 Example 4 30.57 V-0 92.4 131 23.7 449 Comparative Example 1 22.16 V-1 73.1 78 12.8 341 Comparative Example 2 23.24 V-1 68.4 73 11.2 332 Table 1 shows that the phenolic resin prepared by this invention has good flame retardant properties, impact resistance, and tensile properties. Comparative Example 1: Furfurylamine replacing furfurylamine-based polymer: Loss of rigidity reinforcement and flame retardant synergy; Structural level: Furfurylamine is a small molecule monomer containing only a single furan ring and amino group, unable to form a long-chain polymer structure, making it difficult to form a stable hydrogen bond network with the hydroxyl and methylene bridges of the phenolic resin, resulting in a significant weakening of interfacial bonding; Mechanical properties: Lacking the rigid skeleton support of the furfurylamine-based polymer, tensile strength and flexural strength are reduced; Thermal stability: The single furan ring is difficult to delay thermal decomposition, and the structure is easily destroyed at high temperatures. Comparative Example 2: Diethylenetriamine replacing hyperbranched polyamide: Structural level: Diethylenetriamine is a small molecule amine, lacking the "multi-terminal active sites and steric hindrance structure" of hyperbranched polyamide, unable to form a "rigid-flexible" composite system with the phenolic resin. The lack of a hyperbranched structure reduces impact strength and tensile strength. The low number of amino groups in diethylenetriamine results in weak hydrogen bonding with the phenolic hydroxyl groups of phenolic resin, leading to uneven dispersion and further weakening mechanical properties. The lack of amide bonds in hyperbranched polyamides enhances thermal stability and lowers the glass transition temperature.

[0028] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0029] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0030] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A method for preparing a high-strength phenolic resin, characterized in that, Includes the following steps: S1. Add itaconic anhydride to a reaction flask containing toluene, purge with argon gas, stir mechanically until fully dissolved, then slowly add furfurylamine. After the addition is complete, react at room temperature for 4-7 hours. After the reaction is complete, filter, wash the precipitate 2-4 times with anhydrous diethyl ether, and dry under vacuum to obtain intermediate 1. S2. Add 12-15g of p-allylphenol and 8-9g of triethylamine to 95-110mL of ethyl acetate, stir to dissolve, and continue to add 9.5-9.8g of phenylphosphodichlorodichloride dissolved in 35-40mL of ethyl acetate. Under nitrogen protection, after the addition is complete, heat the mixture for 22-24h. After the reaction is complete, filter the mixture, wash the filtrate 4-5 times with saturated brine, concentrate it, and obtain the alkenylphenol compound. S3. Add 7-8 mmol of N-isopropylacrylamide, 0.4-0.5 g of intermediate 1, 0.76-0.8 g of alkenylphenol compound, 0.02-0.03 g of azobisisobutyronitrile, and 35-40 mL of 1,4-dioxane solvent to the reaction flask. Then, evacuate the flask under vacuum and purge with argon to remove oxygen. React at 65-70 °C. After the reaction is complete, concentrate the solution by rotary evaporation, precipitate with anhydrous diethyl ether, filter, and dry under vacuum to obtain furfurylamine polymer. S4. Add diethylenetriamine to the reaction flask, then slowly add succinic anhydride, heat the mixture at 50-55℃ for 2-2.5h, then raise the temperature to 135-140℃ and hold for 4-5h, and finally, rapidly cool the mixture to room temperature to obtain hyperbranched polyamide. S5. Add 50-60g of phenol, 45-50g of distilled water and 25-27g of sodium hydroxide solution to a flask, slowly add 75-80g of formaldehyde solution, heat at 90-93℃ for 52-55min, then add 22-24g of formaldehyde solution and 5-6g of sodium hydroxide solution, continue heating at 90-93℃ for 30-40min, when the resin viscosity reaches 130-140mPa·s, quickly cool the resin to obtain phenolic resin; S6. Disperse furfurylamine polymer and hyperbranched polyamide in phenolic resin, and stir magnetically at 55-60℃ for 1-2 hours to obtain high-strength phenolic resin; In step S1, the ratio of toluene, itaconic anhydride, and furfurylamine is 50-65 mL. 4.1-4.5g: 3.9-4.0g.

2. The method for preparing high-strength phenolic resin according to claim 1, characterized in that, In the S2 reaction, the reaction temperature is 56-60℃.

3. The method for preparing high-strength phenolic resin according to claim 1, characterized in that, In S3, the reaction time is 20-24 hours.

4. The method for preparing high-strength phenolic resin according to claim 1, characterized in that, In S4, the mass ratio of diethylenetriamine to succinic anhydride is 82-84g: 95-100g.

5. The method for preparing high-strength phenolic resin according to claim 1, characterized in that, In S5, the mass fraction of sodium hydroxide solution is 38-40%.

6. The method for preparing high-strength phenolic resin according to claim 1, characterized in that, In S6, the ratio of furfurylamine polymer and hyperbranched polyamide dispersed in phenolic resin is 1-2g: 1.5-3g: 50-55g.

7. A high-strength phenolic resin, characterized in that, It is prepared by the method for preparing high-strength phenolic resin as described in any one of claims 1-6.

Images