Preparation method and application of modified phthalonitrile resin with low curing temperature, high crosslinking and high heat resistance
By modifying phthalonitrile resin with melamine-based benzoxazine resin, the problems of high curing temperature and high cost of phthalonitrile resin are solved, and modified phthalonitrile resin with low curing temperature, high cross-linking and high heat resistance is achieved, broadening its application range.
Patent Information
- Application Number
- CN202510793379.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-13
- Publication Date
- 2025-09-26
AI Technical Summary
The high curing temperature of phthalonitrile resin, strict requirements on processing equipment, and complex and high-cost synthesis technology limit its application scope and promotion.
By introducing melamine-based benzoxazine resin to modify phthalonitrile resin, the curing temperature is lowered, the thermal stability and heat resistance are improved, and the melamine-based benzoxazine resin is blended with phthalonitrile resin to catalyze the curing reaction and shorten the gelation time.
The modified phthalonitrile resin has low curing temperature, high cross-linking and high heat resistance, which broadens its processing window, reduces production costs and improves thermal stability and flame retardancy.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of polymer materials, and in particular to a preparation method and application of a modified phthalonitrile resin with low curing temperature, high cross-linking and high heat resistance. Background Art
[0002] High-performance resin-based composite materials, with their low density but high rigidity and strength, have become a commonly used material in lightweight applications and high-load structures. It has not only become one of the most critical structural materials in the aerospace field after metal materials, but has also gradually been widely used in ship transportation, civil engineering and other infrastructure construction. Among them, phthalonitrile resin is a type of high-performance thermosetting resin. Since the entire curing reaction process is a cyclic polymerization reaction and no small molecules are released, the cured resin will not have defects. The main chain structure of the polymerization product is rich in benzene rings, which makes the cured phthalonitrile resin have excellent high temperature resistance, moisture resistance, chemical resistance, radiation resistance, flame retardancy and self-extinguishing properties, outstanding optical and electrical properties, and a high glass transition temperature.
[0003] While phthalonitrile resins have garnered widespread attention due to their impressive array of properties, they still face significant drawbacks, such as their high curing temperature and demanding processing equipment requirements. Furthermore, the complex synthesis technology of commonly used phthalonitrile resin monomers and the high cost of raw materials contribute to the relatively high cost of nitrile-based resins and composites, limiting their application and promotion in the civilian market. Summary of the Invention
[0004] The present invention aims to provide a preparation method and application of a modified phthalonitrile resin with low curing temperature, high crosslinking and high heat resistance. The phthalonitrile resin is modified by using a melamine-based benzoxazine resin. While maintaining the excellent properties of traditional phthalonitrile resins, the curing temperature is lowered, the processing window is widened, and the thermal stability, heat resistance and flame retardancy are increased, thereby providing a new preparation method for the production of phthalonitrile resin materials.
[0005] The object of the present invention is achieved through the following technical solutions:
[0006] A method for preparing a modified phthalonitrile resin with low curing temperature, high crosslinking and high heat resistance comprises the following steps:
[0007] S1. A melamine-based benzoxazine resin (Formula I) obtained by dissolving a certain amount of the melamine-based benzoxazine resin having the R1 group as a phenol source in an organic solvent at room temperature to obtain a melamine-based benzoxazine resin solution;
[0008] S2. The melamine-based benzoxazine resin solution is added to a phthalonitrile resin (Formula II) containing an R2 group in a certain proportion, and the blended resin and an organic solvent are mixed and reacted at a certain temperature for a period of time to obtain a yellowish-brown resin solution having a solid content of 30-60 wt%;
[0009] S3. Dry the yellow-brown resin solution to obtain a modified phthalonitrile resin.
[0010] Wherein, the structures of Formula I and Formula II are shown below:
[0011]
[0012] Preferably, the R1 group can be selected from phenolphthalein, bisphenol A, bisphenol AF, eugenol, and p-aminophenol, and the structure can be selected from the following structures:
[0013]
[0014] Preferably, the R2 group is selected from allyl bisphenol A, bisphenol A, and biphenol.
[0015] The structure can be selected from the following structures:
[0016]
[0017] Preferably, in step S1, the organic solvent is solvent A, or a mixture of solvent A and solvent B; the solvent A is selected from toluene, DMF, NMP, DMSO; and the solvent B is selected from ethanol, acetone, and butanone.
[0018] Preferably, in step S1, the solid content of the melamine-based benzoxazine resin solution is 30-40 wt%.
[0019] Preferably, in the blended resin in step S2, the content of the melamine-based benzoxazine resin solution is 2-30 wt%.
[0020] Preferably, in step S2, the reaction temperature is 80-120° C., and the reaction time is 2-6 h.
[0021] In addition, to achieve the above-mentioned purpose, the present invention also provides an application of a modified phthalonitrile resin in preparing a polymer film, specifically, curing the yellow-brown resin solution obtained in step S2 at a certain temperature to obtain a polymer film.
[0022] Preferably, the curing temperature is not less than 200°C.
[0023] Furthermore, to achieve the above-mentioned object, the present invention further provides a use of a modified phthalonitrile resin in preparing a composite material, specifically, coating the blended resin solution obtained in step S2 on a fiber cloth, and then drying and pressing the resulting composite material. The composite material is prepared by drying, hot pressing, and other steps under a certain temperature, time, and pressure.
[0024] The fiber cloth includes glass fiber cloth, carbon fiber cloth, aramid fiber cloth or quartz fiber cloth.
[0025] The drying time is 30-90 minutes and the drying temperature is 80-120°C;
[0026] The hot pressing temperature is 200-260°C; the hot pressing pressure is 15-30 MPa; and the hot pressing time is 2-4 hours.
[0027] Compared with the prior art, the present invention has the following beneficial effects:
[0028] 1. The present invention utilizes a melamine-based benzoxazine resin to modify an o-phthalonitrile resin to produce a modified o-phthalonitrile resin with a low curing temperature, high crosslinking, and high heat resistance. This resin enhances curing reactivity, significantly shortens gelation time, reduces the curing temperature of thermosetting resins, and significantly improves thermal stability and heat resistance, enabling it to meet a wider range of processing requirements. This will provide technical and practical reference for expanding the application range of such high-performance thermosetting resins and promoting their use in the civilian market.
[0029] 2. Compared with traditional phthalonitrile resins, the amino groups introduced into melamine-based benzoxazine resins can catalyze the curing reaction, significantly reducing its curing temperature and shortening its curing time. The introduction of melamine-based benzoxazine resins can achieve autocatalysis of phthalonitrile resins and also improve their heat resistance and thermal stability. The introduction of melamine-based benzoxazine resins can also increase the flame retardancy of phthalonitrile resins. The introduction of melamine-based benzoxazine resins improves the processability of hot pressing and molding of prepreg cloth. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 The comparative viscosity growth curves of the phthalonitrile monomers prepared in Example 1 and Comparative Example 5 are shown;
[0031] Figure 2 The comparative gelation time curves of the phthalonitrile monomers prepared in Example 1 and Comparative Example 5 are shown. DETAILED DESCRIPTION
[0032] Implementation 1
[0033] Step 1: Add melamine-based benzoxazine resin synthesized using bisphenol A as a phenol source to 10 g of DMF organic solvent to obtain a melamine-based benzoxazine resin solution having a solid content of 30 wt%.
[0034] Step 2: adding the melamine-based benzoxazine resin solution to the bisphenol A-type benzoxazine phthalonitrile resin to obtain a blended resin; the content of the melamine-based benzoxazine resin solution in the blended resin is 5 wt %.
[0035] Step 3: The blended resin was mixed with the DMF solution to obtain a yellow-brown resin solution with a solid content of 40 wt%.
[0036] Step 4: The obtained yellow-brown resin solution was poured into deionized water for washing 5 times, and then dried in a forced air oven for 24 hours to obtain a yellow-brown powder, namely, bisphenol A type benzoxazine phthalonitrile resin monomer.
[0037] Step 5: The obtained yellow-brown resin solution was cured at 240° C. to obtain a polymer film.
[0038] Step 6: The blended resin obtained in step 2 is evenly coated on the aramid fiber cloth, and then dried in a vacuum oven at 120° C. for 10 minutes to obtain a prepreg cloth.
[0039] Step 7: 16 layers of prepreg cloth obtained in step 6 were hot-pressed and cured in a press at 240° C. for three hours to obtain a laminate with a thickness of approximately 0.7 mm.
[0040] The obtained bisphenol A type benzoxazine phthalonitrile resin monomer has a gelation time of 234s, an initial curing temperature of 220℃, a thermal enthalpy of 100.7J / g, a viscosity increase temperature of 179.9℃, and a polymer film T cured at 240℃. d5 The temperature is 405℃, the carbon residue rate is 70.91%, and the dielectric constant is 3.83.
[0041] The bisphenol A type benzoxazine phthalonitrile resin monomer aramid fiber reinforced composite laminate has a flexural strength of 503 MPa, a flexural modulus of 3.7 GPa, a CTE of 75 ppm / ℃, and a glass transition temperature of 280℃.
[0042] Example 2
[0043] Step 1: Phenolphthalein-type melamine-based benzoxazine is added to a mixed organic reagent of 8 g toluene and 2 g methanol to obtain a melamine-based benzoxazine resin solution having a solid content of 35%.
[0044] Step 2: adding the melamine-based benzoxazine resin solution to the allyl bisphenol A-type benzoxazine phthalonitrile resin to obtain a blended resin; the content of the melamine-based benzoxazine resin solution in the blended resin is 30 wt%.
[0045] Step 3: Mix the blended resin with the toluene solution to obtain a yellow-brown resin solution with a solid content of 30 wt%.
[0046] Step 4: The obtained yellow-brown resin solution was poured into deionized water for washing 4 times, and then dried in a forced air oven for 24 hours to obtain a yellow-brown powder, namely, allyl bisphenol A type benzoxazine phthalonitrile resin monomer.
[0047] Step 5: The obtained yellow-brown resin solution was cured at 240° C. to obtain a polymer film.
[0048] Step 6: The blended resin obtained in step 2 is evenly coated on the glass fiber cloth, and then dried in a vacuum oven at 100° C. for 20 minutes to obtain a prepreg cloth.
[0049] Step 7: 16 layers of prepreg cloth obtained in step 6 were hot-pressed and cured in a press at 240°C for two hours to obtain a laminate with a thickness of approximately 0.3 mm.
[0050] The gelation time of the obtained allyl bisphenol A type benzoxazine phthalonitrile resin monomer is 306s, the initial curing temperature is 225℃, the thermal enthalpy is 227J / g, and the polymer film T d5 The temperature is 415℃, the carbon residue rate is 75.23%, and the dielectric constant is 4.53.
[0051] The allyl bisphenol A type benzoxazine phthalonitrile resin monomer glass fiber reinforced composite laminate has a flexural strength of 400 MPa, a flexural modulus of 5.6 GPa, a CTE of 60 ppm / ℃, and a glass transition temperature of 260℃.
[0052] Example 3
[0053] Step 1: Add eugenol-based melamine-based benzoxazine to a mixed organic reagent of 14 g NMP and 5 g ethanol to obtain a melamine-based benzoxazine resin solution having a solid content of 35%.
[0054] Step 2: Add the melamine-based benzoxazine resin solution to the biphenyl-type benzoxazine phthalonitrile resin to obtain a blended resin. The content of the melamine-based benzoxazine resin solution in the blended resin is 20 wt%.
[0055] Step 3: The blended resin is mixed with the NMP solution to obtain a yellow-brown resin solution with a solid content of 40 wt%.
[0056] Step 4: The obtained yellow-brown resin solution was poured into deionized water for washing 5 times, and then dried in a forced air oven for 24 hours to obtain a yellow-brown powder, i.e., a biphenyl-type benzoxazine phthalonitrile resin monomer.
[0057] Step 5: The obtained yellow-brown resin solution was cured at 220° C. to obtain a polymer film.
[0058] Step 6: The blended resin obtained in step 2 is evenly coated on the glass fiber cloth, and then dried in a vacuum oven at 120° C. for 30 minutes to obtain a prepreg cloth.
[0059] Step 7: 16 layers of prepreg cloth obtained in step 6 were hot-pressed and cured in a press at 220°C for two hours to obtain a laminate with a thickness of approximately 0.4 mm.
[0060] The obtained biphenyl type benzoxazine phthalonitrile resin monomer has a gelation time of 280s, an initial curing temperature of 210℃, a thermal enthalpy of 150.4J / g, and a polymer film T cured at 240℃. d5 The temperature is 423℃, the carbon residue rate is 69.82%, and the dielectric constant is 4.22.
[0061] The glass fiber reinforced composite laminate has a flexural strength of 420 MPa, a flexural modulus of 4.7 GPa, and a fracture toughness greater than 190 J / m 2 , CTE is 46ppm / ℃, and glass transition temperature is 240℃.
[0062] Example 4
[0063] Step 1: Add resorcinol-type melamine-based benzoxazine to a mixed organic reagent of 10 g DMSO and 2 g acetone to obtain a melamine-based benzoxazine resin solution having a solid content of 35%.
[0064] Step 2: Add the melamine-based benzoxazine resin solution to the allyl bisphenol A-type benzoxazine phthalonitrile resin to obtain a blended resin. The content of the melamine-based benzoxazine resin solution in the blended resin is 10 wt%.
[0065] Step 3: The blended resin was mixed with the DMSO solution to obtain a yellow-brown resin solution with a solid content of 35 wt%.
[0066] Step 4: The obtained yellow-brown resin solution was poured into deionized water and washed five times, and then dried in a forced air oven for 24 hours to obtain a yellow-brown powder, namely, allyl bisphenol A type benzoxazine phthalonitrile resin monomer.
[0067] Step 5: The obtained yellow-brown resin solution was cured at 240° C. to obtain a polymer film.
[0068] Step 6: The blended resin obtained in step 2 is evenly coated on the carbon fiber cloth, and then dried in a vacuum oven at 110° C. for 30 minutes to obtain a prepreg cloth.
[0069] Step 7: 16 layers of prepreg cloth obtained in step 6 were hot-pressed and cured in a press at 240°C for four hours to obtain a laminate with a thickness of approximately 0.5 mm.
[0070] The gelation time of the obtained allyl bisphenol A type benzoxazine phthalonitrile resin monomer is 256s, the initial curing temperature is 230℃, the thermal enthalpy is 100.2J / g, and the polymer film T d5 The temperature is 431.3℃, the carbon residue rate is 71%, and the dielectric constant is 3.16.
[0071] The carbon fiber reinforced composite laminate has a flexural strength of 607 MPa, a flexural modulus of 5.8 GPa, a CTE of 46 ppm / °C, and a glass transition temperature of 265°C.
[0072] Comparative Example 1:
[0073] Melamine-based benzoxazine resin: J. Shi, X. Zheng, L. Xie, F. Cao, Y. Wu, and W. Liu, “Film-Forming Characteristics and Thermal Stability of Low Viscosity Benzoxazines Derived From Melamine,” European Polymer Journal 49, no. 12 (2013): 4054-4061, reported a benzoxazine resin synthesized from bisphenol A, paraformaldehyde, and melamine. The T 5％ The temperature is 357℃ and the carbon residue rate is 44%.
[0074] Comparative Example 2:
[0075] Phthalonitrile resin containing benzoxazine resin (BAph): Reference Q.Li, S.Zhang, J.Ye, X.Liu, Multiple catalytic polymerization of phthalonitrile resin bearing benzoxazinemoiety: Greatly reduced curing temperature, European Polymer Journal 180 (2022). Before the addition of modified DCS, the gelation time was 1464s and the initial exothermic temperature of the system was 222.9°C. When the DCA mass fraction was 3%, the initial decomposition temperature (T d5 ) is 412℃, and the residual carbon rate (Yc) at 800℃ is 72.09%.
[0076] Comparative Example 3:
[0077] Phthalonitrile resin containing benzoxazine resin (BAph): Reference J.Ye, S.Zhang, M.Wu, X.Liu, X.Liu, Thermal, mechanical and dielectric property enhancement of benzoxazine-containing phthalonitrile resin: The effect of functional oligomericpolyphenyl ether, Polymer 280 (2023). Two oligomeric polyphenyl ethers (PPE) with different functional groups (hydroxyl and allyl) were introduced into benzoxazine-containing phthalonitrile resin. The initial exothermic temperature of the system without adding PPE was 249.1℃. The gelation time was 426s, and the T of Poly(MBP) under nitrogen atmosphere was 2.38kJ / cm2. 5％ The temperature is 406℃ and the carbon residue rate is 71.8%.
[0078] Comparative Example 4:
[0079] Benzoxazine resin: Reference S. Zhang, P. He, Y. Liu, G. Chen, R. Han, Polybenzoxazine modified by phenolphthalein-based poly(arylene ether nitrile): Better thermal, mechanical, and dielectric properties, Journal of Applied Polymer Science 140(45)(2023). The onset exothermic temperature of the monomer is 254.9°C, and the T of Poly(BA-a) under nitrogen atmosphere is 200. 5％ The temperature is 312.7℃ and the carbon residue rate is 28.0%.
[0080] Comparative Example 5:
[0081] Compared with Example 1, the content of the melamine-based benzoxazine resin solution in the blended resin was changed to 0 wt %, and the remaining parameters and steps were the same as those in Example 1.
[0082] Comparing the data in Comparative Examples 1 to 4 with the present invention, the following conclusions can be drawn:
[0083] Comparative Example 1: Comparison with the TGA of the benzoxazine-type phthalonitrile resin used in this patent shows that the phthalonitrile resin has higher heat resistance.
[0084] Comparative Example 2: It shows that before adding a catalyst or a modifier, the gelation time of the PN resin is very long and the reaction activity is very low.
[0085] Comparative Example 3: Compared with other types of phthalonitrile resins, it is shown that the gelation time of the benzoxazine-type phthalonitrile resin used in this patent is shortened while maintaining a certain heat resistance.
[0086] Comparative Example 4: Comparison with the TGA of the benzoxazine-type phthalonitrile resin used in this patent shows that the heat resistance of the phthalonitrile resin is maintained at a certain temperature and the reaction activity is improved.
[0087] The viscosity growth curves of the phthalonitrile monomers prepared in Example 1 and Comparative Example 5 are shown in FIG. Figure 1 As shown; the comparative gelation time curves of the phthalonitrile monomers prepared in Example 1 and Comparative Example 5 are as shown Figure 2 shown.
[0088] pass Figure 1 and Figure 2It can be seen that the introduction of melamine-based benzoxazine can increase the number of active groups and improve the reactivity of the resin, thereby shortening the gelation time of the phthalonitrile resin, reducing the curing temperature, and maintaining a certain processing window.
[0089] Since benzoxazine-type phthalonitrile has two curing exothermic peaks, one is the ring-opening reaction of benzoxazine and the other is the polymerization reaction of cyano group. Figure 1 and Figure 2 It can be seen that after adding melamine-based benzoxazine, the reaction activity is greatly improved and its curing temperature is reduced.
Claims
1. A method for preparing a modified phthalonitrile resin with low curing temperature, high crosslinking and high heat resistance, characterized in that: The steps include: S1. A melamine-based benzoxazine resin (Formula I) obtained by dissolving a certain amount of the melamine-based benzoxazine resin having the R1 group as a phenol source in an organic solvent at room temperature to obtain a melamine-based benzoxazine resin solution; S2. The melamine-based benzoxazine resin solution is added to the phthalonitrile resin containing the R2 group (Formula II), and then the blended resin and the organic solvent are mixed and reacted at a certain temperature for a period of time to obtain a yellowish-brown resin solution having a solid content of 30-60wt%; S3. Dry the yellow-brown resin solution to obtain a modified phthalonitrile resin. Wherein, the structures of Formula I and Formula II are shown below:
2. The method for preparing a modified phthalonitrile resin with low curing temperature, high crosslinking and high heat resistance according to claim 1, wherein: The R1 group can be selected from phenolphthalein, bisphenol A, bisphenol AF, eugenol, and p-aminophenol.
3. The method for preparing a modified phthalonitrile resin with low curing temperature, high crosslinking and high heat resistance according to claim 1, wherein: The R2 group is selected from allyl bisphenol A, bisphenol A, and biphenol.
4. The method for preparing a modified phthalonitrile resin with low curing temperature, high crosslinking and high heat resistance according to claim 1, wherein: In step S1, the organic solvent is solvent A, or a mixture of solvent A and solvent B; the solvent A is selected from toluene, DMF, NMP, and DMSO; and the solvent B is selected from ethanol, acetone, and butanone.
5. The method for preparing a modified phthalonitrile resin with low curing temperature, high crosslinking and high heat resistance according to claim 1, wherein: In step S1, the solid content of the melamine-based benzoxazine resin solution is 30-40 wt%.
6. The method for preparing a modified phthalonitrile resin with low curing temperature, high crosslinking and high heat resistance according to claim 1, wherein: In the blended resin of step S2, the content of the melamine-based benzoxazine resin solution is 2-30 wt%.
7. The method for preparing a modified phthalonitrile resin with low curing temperature, high crosslinking and high heat resistance according to claim 1, wherein: In step S2, the reaction temperature is 80-120° C., and the reaction time is 2-6 h.
8. Use of the modified phthalonitrile resin according to any one of claims 1 to 7 in preparing polymer films, characterized in that: The yellow-brown resin solution obtained in step S2 is solidified at a certain temperature to obtain a polymer film.
9. Use of the modified phthalonitrile resin according to claim 8 in preparing a polymer film, characterized in that: The curing temperature is not less than 200℃.
10. Use of the modified phthalonitrile resin according to any one of claims 1 to 7 in preparing a composite material, characterized in that: The blended resin obtained in step S2 is coated on a fiber cloth, and a composite material is prepared after drying and hot pressing.