Hyperbranched bio-based benzoxane resin and preparation method thereof

Abstract

The invention discloses hyperbranched bio-based benzoxane resin and a preparation method thereof, and belongs to the technical field of thermosetting resin. The preparation method comprises the following steps: 1) mixing diphenolic acid with alkyl glycol for reaction, and then adding bio-based diamine and formaldehyde for reaction to obtain a hyperbranched bio-based benzoxazine monomer; and 2) carrying out stepped heating and pressure curing on the obtained hyperbranched bio-based benzoxazine monomer to finally prepare the hyperbranched bio-based benzoxazine resin. Based on a unique three-dimensional topological structure, the hyperbranched bio-based benzoxazine resin prepared by the preparation method disclosed by the invention has excellent mechanical strength and toughness, good thermal stability and flame retardance and outstanding comprehensive performance while keeping the environment-friendly advantage that raw materials are derived from renewable biomass; wide application prospects are shown in the fields of high-performance composite materials, electronic packaging, aerospace and the like.

Description

Technical Field

[0001] This invention belongs to the field of thermosetting resin technology, specifically relating to a hyperbranched bio-based benzoxide resin and its preparation method. Background Technology

[0002] Benzoxazines are a class of oxygen- and nitrogen-containing heterocyclic compounds synthesized from phenols, amines, and paraformaldehyde. Under heating or catalysis, they undergo ring-opening polymerization to form nitrogen-containing, phenolic resin-like network polymers, known as benzoxazine resins or polybenzoxazines. Benzoxazine resins possess excellent mechanical properties, thermal stability, corrosion resistance, and electrical insulation, thus attracting significant attention from scholars and industry professionals both domestically and internationally. Currently, benzoxazine resins are widely used in aerospace, automotive parts, resin transfer molding, and electronic packaging.

[0003] Hyperbranched benzoxazine resins, through the construction of a three-dimensional topological molecular structure, overcome the bottleneck of traditional linear resins' inability to simultaneously achieve processability and mechanical properties, becoming an ideal material for a new generation of high-performance resin systems. With its unique spherical molecular configuration, hyperbranched benzoxazine resins can significantly reduce melt viscosity, achieving excellent process flowability; its internal self-toughening mechanism can effectively improve toughness and impact resistance without sacrificing rigidity and heat resistance. Furthermore, this system fully inherits the intrinsic advantages of benzoxazine resins, such as high thermal stability, high char residue, inherent flame retardancy, and near-zero volume shrinkage, exhibiting excellent comprehensive performance and showing broad application prospects in aerospace, electronic packaging, and high-end composite materials.

[0004] Traditional benzoxazine resins are mainly derived from petroleum resources, but fossil raw materials are non-renewable and environmentally impactful, making the development of bio-based benzoxazine resins increasingly important. Patent (CN201911321743.8) utilizes phloroglucinic acid, furfurylamine, and paraformaldehyde to prepare a fully bio-based benzoxazine resin with a low curing temperature and excellent heat resistance. Patent (CN202011218791.7) discloses a bio-based benzoxazine resin containing a furanamide structure and its preparation method. Using biomass such as furanylformic acid and its derivatives as raw materials, a condensation reaction is used to introduce the furan group, introducing the amide bond, into the phenolic source structure of the benzoxazine resin. Then, a semi-bio-based or fully bio-based benzoxazine resin containing a furanamide structure is prepared via a Mannich reaction with mono- or poly-primary amine compounds such as furanylformamine. However, the above-mentioned bio-based benzoxazine resins all suffer from problems such as limited raw material sources, scarce production volume, and insufficient processability of the resulting materials. Summary of the Invention

[0005] The first technical problem to be solved by this invention is to provide a hyperbranched bio-based benzoxazine resin, which possesses excellent processability, heat resistance, hydrophobicity, and low dielectric properties. The second technical problem to be solved by this invention is to provide a method for preparing the hyperbranched bio-based benzoxazine resin, wherein the method uses bisphenolic acid as the phenol source and compounds such as alkyl diamine, 1,6-hexanediamine, and 1,5-pentanediamine as amine sources to synthesize a hyperbranched bio-based benzoxazine resin via the Mannich reaction. The third technical problem to be solved by this invention is to provide the application of this hyperbranched bio-based benzoxazine resin in adhesives, composite materials, and coatings.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A hyperbranched bio-based benzoxide resin monomer, with the following chemical structural formula:

[0008] or ;

[0009] Where n is 4 to 20.

[0010] Furthermore, the hyperbranched bio-based benzoxide resin prepared from the aforementioned hyperbranched bio-based benzoxide resin monomer has the following chemical structural formula:

[0011] or ;

[0012] Where n is 4 to 20.

[0013] Furthermore, the preparation method of the hyperbranched bio-based benzoxazine resin monomer includes the following steps: reacting bisphenolic acid with alkyl diol at 150~180℃ for 3~4h, then adding bio-based diamine and formaldehyde and reacting at 80℃ for 10~12h to obtain the hyperbranched bio-based benzoxazine monomer.

[0014] Furthermore, the bio-based amine is selected from any one or a combination of cyclohexanediamine, 1,6-hexanediamine, and 1,5-pentanediamine.

[0015] Furthermore, the amount of the bio-based amine is 0.99 to 1.05 times the molar number of phenolic hydroxyl groups in the bisphenolic acid.

[0016] Furthermore, the formaldehyde is paraformaldehyde or an aqueous solution of formaldehyde.

[0017] Furthermore, the amount of formaldehyde used is 2.0 to 2.1 times the molar number of phenolic hydroxyl groups in bisphenol A.

[0018] Furthermore, the method for preparing hyperbranched bio-based benzoxazine resin from the hyperbranched bio-based benzoxazine resin monomer includes the steps of: subjecting the hyperbranched bio-based benzoxazine monomer to stepwise heating and pressure curing to finally obtain the hyperbranched bio-based benzoxazine resin.

[0019] Furthermore, the step-heating and pressure curing procedure is as follows: maintain at 100~150℃ for 1~2 hours, and then gradually increase the temperature to 160~200℃ for 2~3 hours for curing.

[0020] Furthermore, the application of hyperbranched bio-based benzoxane resin prepared from the hyperbranched bio-based benzoxane resin monomer in adhesives, composite materials, and coatings.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) This invention uses bio-based raw materials to prepare hyperbranched benzoxazine resin. By introducing a highly branched three-dimensional topological molecular structure, it fundamentally breaks through the bottleneck of mutual restriction between the processing performance and mechanical properties of traditional linear thermosetting resins, and provides a new technical direction for the cutting-edge development of benzoxazine resin system.

[0023] (2) The preparation process of the present invention is simple, the reaction conditions are mild, and it is suitable for large-scale production.

[0024] (3) The hyperbranched benzoxazine resin prepared by the present invention has a low curing temperature and excellent heat resistance and flame retardancy, and can be applied to adhesives, composite materials and coatings. Attached Figure Description

[0025] Figure 1 The reaction route for preparing hyperbranched bio-based benzoxazine resins for this application is shown below;

[0026] Figure 2 The FT-IR spectrum of the hyperbranched benzoxazine monomer prepared in Example 1 of this application is shown below.

[0027] Figure 3 The DSC curing curve of the hyperbranched benzoxazine monomer prepared in Example 1 of this application;

[0028] Figure 4 The thermogravimetric curve of the hyperbranched benzoxazine resin prepared in Example 1 of this application. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are implemented based on the technical solutions of the present invention, and it should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0030] Bisphenolic acid, alkyl diol, formaldehyde, 1,5-pentanediamine, 1,6-hexanediamine and ethanol were all analytical grade and purchased from Aladdin Reagent (Shanghai) Co., Ltd.; cyclohexanediamine was provided by Linyi University.

[0031] Figure 1 The reaction route for preparing hyperbranched bio-based benzoxazine resin for this application includes the following steps:

[0032] 1) Bisphenolic acid and alkyl diol are reacted at 150~180℃ for 3~4h, and then bio-based diamine and formaldehyde are added and reacted at 80℃ for 10~12h to obtain hyperbranched bio-based benzoxazine monomer;

[0033] 2) The hyperbranched bio-based benzoxazine monomer obtained in step 1) is subjected to step-heating and pressure curing. The step-heating and pressure curing procedure is as follows: hold at 100~150℃ for 1~2h, and then gradually increase the temperature to 160~200℃ for 2~3h to finally obtain hyperbranched bio-based benzoxazine resin.

[0034] Example 1

[0035] A method for preparing a hyperbranched bio-based benzoxide resin includes the following steps:

[0036] (1) 28.6 g of bisphenolic acid and 10.1 g of 1,12-dodecanediol were added to a 1000 mL four-necked round-bottom flask equipped with a stirrer, thermometer and reflux condenser. After reacting at 170 °C for 3 h, 400 mL of ethanol, 17.1 g of cyclohexanediamine and 12.1 g of paraformaldehyde were added respectively. The reaction system was refluxed at 80 °C for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a yellow solid, which was a hyperbranched bio-based benzoxazine monomer.

[0037] (2) The hyperbranched bio-based benzoxazine monomer obtained in step (1) is subjected to step heating and pressure curing. The curing procedure is as follows: keep it at 100℃ and 140℃ for 1 hour each, and then gradually increase the temperature to 160℃, 180℃ and 200℃ for 2 hours each, and finally obtain hyperbranched bio-based benzoxazine resin.

[0038] Depend on Figure 2 It can be seen that in the infrared spectrum of hyperbranched bio-based benzoxazine monomers, at 1701 cm⁻¹... -1 1175 cm -1 and 922cm -1 Characteristic absorption peaks of carbonyl (C=O), ester (CO) and oxazine rings appeared at the positions, respectively, which together confirmed the successful synthesis of the target monomer.

[0039] Depend on Figure 3It is known that the thermal polymerization of hyperbranched bio-based benzoxazine monomers is a typical single exothermic process, with the curing reaction completed within a temperature range of 120–280 °C. Thanks to the autocatalytic effect of the intramolecular phenolic hydroxyl groups, the monomer can initiate the ring-opening polymerization of the oxazine ring at a relatively low starting temperature (approximately 120 °C), and finally form a highly cross-linked resin network at approximately 280 °C, namely, hyperbranched bio-based benzoxazine resin.

[0040] Depend on Figure 4 It is evident that hyperbranched bio-based benzoxazine resins exhibit excellent thermal stability below 270℃. Their thermal degradation process displays multi-stage characteristics, with significant decomposition rate peaks observed at 360.51℃, 403.72℃, and 560.1℃ in the DTG curves. This is primarily due to the differences in the thermal behavior of various functional groups within the resin, including ester bonds, amine groups, and benzene rings. The dense cross-linked network within the hyperbranched bio-based benzoxazine resin contributes to its good thermal stability.

[0041] Example 2

[0042] A method for preparing a hyperbranched bio-based benzoxide resin includes the following steps:

[0043] (1) 28.6 g of bisphenolic acid and 10.1 g of 1,12-dodecanediol were added to a 1000 mL four-necked round-bottom flask equipped with a stirrer, thermometer and reflux condenser. After reacting at 170 °C for 4 h, 500 mL of ethanol, 11.6 g of 1,6-hexanediamine and 12.1 g of paraformaldehyde were added respectively. The reaction system was refluxed at 80 °C for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a yellow solid, which was a hyperbranched bio-based benzoxazine monomer.

[0044] (2) The hyperbranched bio-based benzoxazine monomer obtained in step (1) is subjected to step heating and pressure curing. The curing procedure is as follows: keep it at 100℃ and 150℃ for 1 hour each, and then gradually increase the temperature to 160℃, 180℃ and 200℃ for 2 hours each, and finally obtain hyperbranched bio-based benzoxazine resin.

[0045] Example 3

[0046] A method for preparing a hyperbranched bio-based benzoxide resin includes the following steps:

[0047] (1) 28.6 g of bisphenolic acid and 8.7 g of 1,10-decanediol were added to a 1000 mL four-necked round-bottom flask equipped with a stirrer, thermometer and reflux condenser. After reacting at 170 °C for 3 h, 500 mL of ethanol, 17.1 g of alkyl diamine and 32.4 g of formaldehyde solution were added respectively. The reaction system was refluxed at 80 °C for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a yellow solid, which was a hyperbranched bio-based benzoxazine monomer.

[0048] (2) The hyperbranched bio-based benzoxazine monomer obtained in step (1) is subjected to step heating and pressure curing. The curing procedure is as follows: keep it at 120℃ and 150℃ for 2 hours each, and then gradually increase the temperature to 160℃, 180℃ and 200℃ for 2 hours each, and finally obtain hyperbranched bio-based benzoxazine resin.

[0049] Example 4

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

[0051] (1) 28.6 g of bisphenolic acid and 10.1 g of 1,12-dodecanediol were added to a 1000 mL four-necked round-bottom flask equipped with a stirrer, thermometer and reflux condenser. After reacting at 170 °C for 4 h, 450 mL of ethanol, 10.2 g of 1,5-pentanediamine and 12.1 g of paraformaldehyde were added respectively. The reaction system was refluxed at 80 °C for 10 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a yellow solid, which was a hyperbranched bio-based benzoxazine monomer.

[0052] (2) The hyperbranched bio-based benzoxazine monomer obtained in step (1) is subjected to step heating and pressure curing. The curing procedure is as follows: keep it at 100℃ and 150℃ for 1 hour each, and then gradually increase the temperature to 160℃, 180℃ and 200℃ for 2 hours each, and finally obtain hyperbranched bio-based benzoxazine resin.

[0053] Example 5

[0054] A method for preparing a hyperbranched bio-based benzoxide resin includes the following steps:

[0055] (1) In a 1000 mL four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, 28.6 g of bisphenol acid and 8.7 g of 1,10-decanediol were added and reacted at 170 °C for 3 h. Then, 450 mL of ethanol, 10.2 g of 1,5-pentanediamine, and 12.1 g of paraformaldehyde were added, and the reaction system was refluxed at 80 °C for 10 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a yellow solid, which was a hyperbranched bio-based benzoxazine monomer.

[0056] (2) The hyperbranched bio-based benzoxazine monomer obtained in step (1) is subjected to step heating and pressure curing. The curing procedure is as follows: keep it at 120℃ and 150℃ for 2 hours each, and then gradually increase the temperature to 160℃, 180℃ and 200℃ for 2 hours each, and finally obtain hyperbranched bio-based benzoxazine resin.

[0057] Example 6

[0058] A method for preparing a hyperbranched bio-based benzoxide resin includes the following steps:

[0059] (1) 25.8 g of bisphenolic acid and 14.7 g of 1,18-octadecanediol were added to a 1000 mL four-necked round-bottom flask equipped with a stirrer, thermometer and reflux condenser. After reacting at 170 °C for 3 h, 500 mL of anhydrous ethanol, 11.6 g of 1,6-hexanediamine and 12.0 g of paraformaldehyde were added to the flask. The reaction system was refluxed at 80 °C for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a yellow solid, which was a hyperbranched bio-based benzoxazine monomer.

[0060] (2) The hyperbranched bio-based benzoxazine monomer obtained in step (1) is subjected to step heating and pressure curing. The curing procedure is as follows: keep it at 100℃ and 150℃ for 1 hour each, and then gradually increase the temperature to 160℃, 180℃ and 200℃ for 3 hours each, and finally obtain hyperbranched bio-based benzoxazine resin.

[0061] The hyperbranched bio-based benzoxazine resins prepared in Examples 1-6 were subjected to performance testing. The curing initiation temperature was determined using a PerkinElmer DSC 8000 instrument with a heating rate of 5°C / min. -1 The temperature range was 30-300 ℃, and the test was conducted under a nitrogen atmosphere. The glass transition temperature was determined in shear mode using a TA Instruments DMA Q800 dynamic thermomechanical analyzer. The sample size was 50×4×1 mm. 3 At a frequency of 1 Hz and a temperature of 3 °C·min -1 The heating rate was from 0 °C to 200 °C. The water contact angle was measured using a Dropmeter A-200 contact angle system from MAIST Vision Inspection & Measurement Co., Ltd. (China), and each result is the average of three tests. Dielectric constant measurements were performed at room temperature using a 4294A precision impedance analyzer (Agilent Technologies, USA) in the frequency range of 40–10 MHz. The results are shown in Table 1.

[0062] Table 1. Performance tests of the hyperbranched bio-based benzoxazine resins prepared in Examples 1-6

[0063]

[0064] As shown in Table 1, the hyperbranched benzoxazine resin prepared by this invention has excellent processability, heat resistance, hydrophobicity and low dielectric properties, and can be applied in adhesives, composite materials and coatings. Therefore, it is an ideal basic material for next-generation high-frequency electronic devices and advanced packaging, with broad application prospects.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hyperbranched bio-based benzoxoxa resin monomer, characterized in that, The chemical structural formula is: or ; Where n is 4 to 20.

2. The hyperbranched bio-based benzoxane resin prepared from the hyperbranched bio-based benzoxane resin monomer according to claim 1, characterized in that, The chemical structural formula is: or ; Where n is 4 to 20.

3. The method for preparing hyperbranched bio-based benzoxide resin monomer according to claim 1, characterized in that: The process includes the following steps: reacting bisphenolic acid with alkyl diol at 150-180°C for 3-4 hours, then adding bio-based diamine and formaldehyde and reacting at 80°C for 10-12 hours to obtain hyperbranched bio-based benzoxazine monomer.

4. The method for preparing hyperbranched bio-based benzoxide resin monomer according to claim 3, characterized in that: The bio-based amine is selected from any one or a combination of cyclohexanediamine, 1,6-hexanediamine, and 1,5-pentanediamine.

5. The method for preparing hyperbranched bio-based benzoxide resin monomer according to claim 3, characterized in that: The amount of the bio-based amine is 0.99 to 1.05 times the molar number of phenolic hydroxyl groups in bisphenol A.

6. The method for preparing hyperbranched bio-based benzoxide resin monomer according to claim 3, characterized in that: The formaldehyde is paraformaldehyde or an aqueous solution of formaldehyde.

7. The method for preparing hyperbranched bio-based benzoxide resin monomer according to claim 3, characterized in that: The amount of formaldehyde used is 2.0 to 2.1 times the molar number of phenolic hydroxyl groups in bisphenol A.

8. The method for preparing hyperbranched bio-based benzoxide resin from the hyperbranched bio-based benzoxide resin monomer according to claim 2, characterized in that: The process includes the following steps: stepwise temperature and pressure curing of hyperbranched bio-based benzoxazine monomers to finally obtain hyperbranched bio-based benzoxazine resin.

9. The method for preparing hyperbranched bio-based benzoxide resin from the hyperbranched bio-based benzoxide resin monomer according to claim 8, characterized in that: The procedure for step-heating and pressure curing is as follows: maintain at 100~150℃ for 1~2 hours, and then gradually increase the temperature to 160~200℃ for 2~3 hours for curing.

10. The application of hyperbranched bio-based benzoxane resin prepared from the hyperbranched bio-based benzoxane resin monomer according to claim 2 in adhesives, composite materials and coatings.

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