A fully bio-based benzoxazine monomer modified rosin-based epoxy resin and a preparation method thereof

Abstract

The application discloses a kind of full biological base benzoxazine monomer modified rosin-based epoxy resin and preparation method thereof, comprising: vanillin, decanediamine, polyformaldehyde are reacted to obtain full biological base benzoxazine monomer;Full biological base benzoxazine monomer and 1,8-are added to solvent and reacted to obtain the Schiff base with amino;The Schiff base with amino and propylene pimaric acid diglycidyl ester are mixed uniformly, then poured into mould, then heated and cured to obtain full biological base benzoxazine monomer modified rosin-based epoxy resin.The full biological base benzoxazine monomer modified rosin-based epoxy resin obtained by the application has strong mechanical properties and good thermal stability, and also has excellent self-repairing, shape memory, recyclability, hydrophobicity and dielectric properties.

Description

Technical Field

[0001] This invention relates to a fully bio-based benzoxazine monomer-modified rosin-based epoxy resin and its preparation method, belonging to the field of natural resource modification technology. Background Technology

[0002] With increasing attention paid to global resource and environmental issues, coupled with the rapid depletion of petroleum energy, the energy crisis and environmental problems have become unavoidable and must be addressed head-on. Finding natural renewable resources to replace traditional petroleum feedstocks in the synthesis of polymer materials has become a research hotspot. 1,8-Phenylenediamine (MDA) and propylene diglycidyl acrylate (AE) are derivatives of turpentine and rosin, both derived from pine resin and representing unique forestry biomass resources in my country. Although 1,8-Phenylenediamine (MDA) can be used as a curing agent for rosin-based epoxy resins, its low crosslinking density, poor thermal stability, high brittleness, difficulty in degradation, and weak mechanical strength limit its applications.

[0003] Benzoxazine resins are a new type of thermosetting resin developed from traditional phenolic resins. They possess advantages such as flexible molecular design, excellent thermal stability, and superior mechanical properties, making them promising for applications in aerospace, hydrophobic flame retardancy, corrosion prevention and antibacterial properties, and electronic communications. Unlike traditional thermosetting resins, benzoxazine resins can be made from natural renewable resources in addition to fossil fuels. Currently, monomers for benzoxazine resins have been synthesized from renewable resources, achieving breakthroughs in raw material sourcing and performance improvement. Their flexible molecular design allows for the introduction of various active groups. Furthermore, the ring-opening process of benzoxazine monomers forms numerous phenolic hydroxyl and tertiary amine groups. The phenolic hydroxyl groups can serve as active sites for transesterification and participate in epoxy group reactions to form cross-linked network structures, while the tertiary amine groups can promote this reaction. Additionally, the benzoxazine skeleton further enhances the rigidity of the molecular chain. Therefore, benzoxazine monomers are excellent epoxy curing agents. Summary of the Invention

[0004] To address the shortcomings of existing rosin-based epoxy resins, such as low mechanical strength and poor thermal stability, this invention provides a fully bio-based benzoxazine monomer-modified rosin-based epoxy resin and its preparation method. The fully bio-based benzoxazine monomer-modified resin increases the crosslinking density and molecular chain rigidity of the resin, thereby giving the resin higher tensile modulus and tensile strength as well as better thermal stability. The introduction of dual dynamic covalent bonds endows the resin with better self-healing properties, shape memory and recyclability. At the same time, the resin also has good hydrophobicity and low dielectric properties.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A fully bio-based benzoxazine monomer modified rosin-based epoxy resin, characterized in that its raw material components include: fully bio-based benzoxazine monomer VD, 1,8-p-menthol diamine MDA and propylene-piperidine diglycidyl ester AE;

[0007] Their structural formulas are as follows:

[0008]

[0009] This invention also provides a method for preparing a fully bio-based benzoxazine monomer-modified rosin-based epoxy resin, comprising the following steps:

[0010] (1) Vanillin, decanediamine and paraformaldehyde were reacted to obtain the all-bio-based benzoxazine monomer VD;

[0011] (2) The all-bio-based benzoxazine monomer and 1,8-p-menthol diamine were added to a solvent and reacted to obtain a Schiff base with an amino group.

[0012] (3) After mixing the amino-containing Schiff base and propylene-piperidine diglycidyl ester evenly, pour the mixture into a mold and then heat and cure it to obtain a fully bio-based benzoxazine monomer modified rosin-based epoxy resin.

[0013] The reaction process is as follows:

[0014]

[0015] Preferably, the reaction temperature in step (1) is 90℃~100℃ and the reaction time is 8~16h.

[0016] Preferably, the reaction temperature in step (2) is 60℃~90℃ and the reaction time is 2~5h.

[0017] Preferably, the molar ratio of the aldehyde group of the fully bio-based benzoxazine monomer to the amino group of 1,8-para-mendanediamine is 1:2.

[0018] Preferably, the molar ratio of the active hydrogen of the amino-containing Schiff base to the epoxy group of the propylene piroctone ester diglycidyl group is 0.6-1:1.

[0019] Preferably, the curing reaction in step (3) is an autocatalytic reaction system.

[0020] Preferably, the vanillin, decanediamine, paraformaldehyde, 1,8-p-mentholdiamine and propylene-piperidine diglycidyl ester are derived from lignin, castor oil, bio-methanol, turpentine and rosin, respectively.

[0021] Preferably, the temperature curing process is as follows:

[0022] After pre-curing at 60–100℃ for 12–18 hours, cure at 100–160℃ for 4–6 hours, and finally cure at 160–220℃ for 2–4 hours, then cool down.

[0023] Preferably, the cooling process involves cooling to room temperature at a rate of 5–8 °C / min.

[0024] Any techniques not mentioned in this invention are based on existing technologies.

[0025] (1) The fully bio-based benzoxazine monomer-modified rosin-based epoxy resin of the present invention has strong mechanical properties and good thermal stability, as well as excellent self-healing, shape memory, recyclability, hydrophobicity and dielectric properties. The tensile strength at room temperature is 48 MPa and the tensile modulus reaches 680 MPa. The temperature at which 5% of the thermal weight loss occurs is higher than 273°C, and the char rate at 800°C is 12%, both of which far exceed those of 1,8-p-menthananediamine (MDA)-cured rosin-based epoxy resin (P-AE-MDA) without the addition of benzoxazine monomer (VD). At the same time, the repair rate can reach 98.2% after heating for 45 min, the water contact angle is as high as 108°, and the dielectric constant and dielectric loss are 3.0 and 0.014, respectively.

[0026] (2) The preparation method of the fully bio-based benzoxazine monomer modified rosin-based epoxy resin of the present invention involves adding an amino-containing Schiff base (MV) formed by benzoxazine monomer (VD) and 1,8-para-menthol diamine (MDA) to propylene piroctone ester (AE) for curing. This method simultaneously applies three bio-based products to the synthesis of thermosetting resins, avoiding the use of petroleum-based compounds, which is in line with the concept of green development. The resulting fully bio-based benzoxazine monomer modified epoxy soybean oil resin can be applied to Vitrimer materials, carbon fiber reinforced composite materials, electronic packaging and other fields. Attached Figure Description

[0027] Figure 1 These are FT-IR plots of VD, MDA, MV, AE, and P-AE-MV;

[0028] Figure 2 These are DMA diagrams for P-AE-MV and P-AE-MDA;

[0029] Figure 3 These are stretched images of P-AE-MV at different scales;

[0030] Figure 4 These are TGA diagrams of P-AE-MV at different scales;

[0031] Figure 5 P-AE-MDA and P-AE-MV before and after immersion in water for one week 1.0 Water contact angle diagram;

[0032] Figure 6 It is P-AE-MV 1.0 Dielectric property diagram;

[0033] Figure 7 shows the P-AE-MV at different temperatures. 1.0 a) Stress relaxation diagram, b) Fitting curve;

[0034] Figure 8 It is P-AE-MV 1.0 Self-healing and shape memory maps;

[0035] Figure 9 It is P-AE-MV 1.0 Original, sheared, and physically recycled stretch graphs;

[0036] Figure 10 It is P-AE-MV 1.0 FT-IR images before and after degradation in n-butylamine. Detailed Implementation

[0037] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0038] FT-IR (Fourier Transform Infrared Spectroscopy) was performed using a Nicolet IS50 infrared spectrometer, with scanning wavelengths starting from 4000 cm⁻¹. -1 -400cm -1 .

[0039] Tensile testing was conducted according to the GB13022-91 standard.

[0040] Dynamic thermodynamic analysis (DMA) was performed using a TADMAQ800 dynamic thermodynamic analyzer in tensile mode. The specimens were cut into rectangular strips with a cross-section of 5 mm × 1 mm, and the distance between the clamps was 18 mm. Analysis was conducted at a heating rate of 3 °C / min within a range of -50 to 150 °C at a frequency of 1 Hz, and the changes in storage modulus, loss modulus, and tanδ were recorded.

[0041] TGA (Thermogravimetric Analysis) uses nitrogen as a protective gas and a heating rate of 10℃ / min, from 25℃ to 800℃.

[0042] The contact angle was measured using a Drop Meter A-200 contact angle meter.

[0043] Dielectric properties were tested using an Agilent 4294A precision impedance analyzer, with a frequency range of 1MHz to 30MHz.

[0044] Stress relaxation was performed by cutting the film into 25 mm (length) × 5 mm (width) × 1 mm (height) specimens and conducting stress relaxation tests on the specimens in tensile mode on a TA Instruments Q800 analyzer. Isothermal measurements were performed at 160 °C, 140 °C, 120 °C, and 100 °C. A constant strain of 1% was applied to each sample, and the change in relaxation modulus was monitored.

[0045] Shape memory is at the glass transition temperature (T). g ) and topological freezing transition temperature (T v The sample strip was then subjected to triple shape fixation and restoration near the sample area.

[0046] Example 1

[0047] A fully bio-based benzoxazine monomer, the synthetic route of which is as follows:

[0048]

[0049] A method for preparing a fully bio-based benzoxazine monomer includes the following steps:

[0050] 15.9 g of vanillin (DA), 9 g of decanediamine (DAD), and 6.27 g of paraformaldehyde were added to a round-bottom flask and reacted at 90 °C for 12 h. After cooling to room temperature, the mixture precipitated in ethanol to obtain a white powder: a fully bio-based benzoxazine monomer (VD).

[0051] The preparation process of the fully bio-based benzoxazine monomer-modified rosin-based epoxy resin is as follows: 2.34 g of fully bio-based benzoxazine monomer (VD) and 1.53 g of 1,8-p-menthol diamine (MDA) were dissolved in DMSO and added to a single-necked flask. After reacting at 80°C for 3 hours, an amino-containing Schiff base MV was obtained. Then, 8 g of propylene-piperidine diglycidyl ester (AE) was added to make it a homogeneous system. After evaporating the solvent, the mixture was poured into a mold and pre-cured at 80°C for 12 hours, then cured at 140°C for 5 hours, cured at 180°C for 4 hours, and finally cured at 220°C for 2 hours. The temperature was then lowered to room temperature at a rate of 6°C / min to obtain the fully bio-based benzoxazine monomer-modified rosin-based epoxy resin (P-AE-MV). 0.6 ).

[0052] FT-IR plots of VD, MDA, MV, AE, and P-AE-MV are shown below. Figure 1 As shown, from Figure 1 As can be seen from this, the characteristic peak of the aldehyde group in MV is at 1685 cm⁻¹. -1 Disappeared at 3357cm -1 and 3278cm -1 The characteristic double peaks of primary amines weakened; simultaneously, at 1640 cm⁻¹... -1The presence of characteristic peaks for carbon-nitrogen double bonds at 960-920 cm⁻¹ confirms the successful preparation of MV; in P-AE-MV, the peaks at 960-920 cm⁻¹... -1 The characteristic peak of the oxazine ring disappeared at 908 cm⁻¹. -1 The characteristic peak of epoxy at 3450 cm⁻¹ disappears, and at the same time, the characteristic peak of epoxy at 3450 cm⁻¹ disappears. -1 The presence of a broad hydroxyl peak nearby indicates that AE and MV have completely cured to form a cross-linked network P-AE-MV.

[0053] Example 2

[0054] The preparation method of the fully bio-based benzoxazine monomer is as described in Example 1.

[0055] The preparation process of the fully bio-based benzoxazine monomer-modified rosin-based epoxy resin is as follows: 3.12 g of fully bio-based benzoxazine monomer (VD) and 2.04 g of 1,8-p-menthol diamine (MDA) were dissolved in DMSO and added to a single-necked flask. After reacting at 80°C for 3 hours, an amino-containing Schiff base MV was obtained. Then, 8 g of propylene-piperidine diglycidyl ester (AE) was added to make it a homogeneous system. After evaporating the solvent, the mixture was poured into a mold and pre-cured at 80°C for 12 hours, then cured at 140°C for 5 hours, cured at 180°C for 4 hours, and finally cured at 220°C for 2 hours. The temperature was then lowered to room temperature at a rate of 6°C / min to obtain the fully bio-based benzoxazine monomer-modified rosin-based epoxy resin (P-AE-MV). 0.8 ).

[0056] Example 3

[0057] The preparation method of the fully bio-based benzoxazine monomer is as described in Example 1.

[0058] The preparation process of the fully bio-based benzoxazine monomer-modified rosin-based epoxy resin is as follows: 3.90 g of fully bio-based benzoxazine monomer (VD) and 2.55 g of 1,8-p-menthol diamine (MDA) were dissolved in DMSO and added to a single-necked flask. After reacting at 80°C for 3 hours, an amino-containing Schiff base MV was obtained. Then, 8 g of propylene-piperidine diglycidyl ester (AE) was added to make it a homogeneous system. After evaporating the solvent, the mixture was poured into a mold and pre-cured at 80°C for 12 hours, then cured at 140°C for 5 hours, cured at 180°C for 4 hours, and finally cured at 220°C for 2 hours. The temperature was then lowered to room temperature at a rate of 6°C / min to obtain the fully bio-based benzoxazine monomer-modified rosin-based epoxy resin (P-AE-MV). 1.0 ).

[0059] Comparative Example

[0060] The preparation method of the fully bio-based benzoxazine monomer is as described in Example 1.

[0061] The preparation process of 1,8-p-menthalanediamine (MDA) cured rosin-based epoxy resin is as follows: 1.28 g of 1,8-p-menthalanediamine (MDA) and 8 g of propylene-piperidine diglycidyl ester (AE) are added to a single-necked flask and stirred mechanically to form a homogeneous system. The mixture is then poured into a mold and pre-cured at 80 °C for 12 h, followed by curing at 140 °C for 4 h, and finally at 160 °C for 2 h. The temperature is then lowered to room temperature at a rate of 6 °C / min to obtain 1,8-p-menthalanediamine (MDA) cured rosin-based epoxy resin (P-AE-MDA, with an active hydrogen to epoxy group ratio of 1:1).

[0062] The DMA diagrams for P-AE-MV and P-AE-MDA are shown below. Figure 2 As shown in the figure, both P-AE-MV and P-AE-MDA exhibit a transition from a glassy state to a rubbery state. At 25°C, the storage modulus (E′) of P-AE-MV is 2089 MPa, while that of P-AE-MDA is only 985 MPa, less than half that of P-AE-MV. Furthermore, the Tg of P-AE-MV is 78.1°C, significantly lower than that of P-AE-MDA (151.7°C).

[0063] Stretched images of P-AE-MV at different scales are shown below Figure 3 As shown in the figure, the tensile strength, elongation at break, and tensile modulus of P-AE-MV all increase with the increase of MV content. 1.0 At its maximum, the tensile strength and tensile modulus are 48 MPa and 680 MPa, respectively, and its tensile strength is 28 times that of the resin without benzoxazine (P-AE-MDA).

[0064] TGA diagrams of P-AE-MV at different scales are shown below Figure 4 As shown in the figure, the thermal stability of P-AE-MV increases with the increase of benzoxazine addition. Compared with P-AE-MDA without benzoxazine, P-AE-MV... 1.0 T d5 (Confirmed to be T) d5 Or T 5％ The temperature was increased from 240℃ to 273℃, an increase of 33℃. Moreover, the char residue at 800℃ was 5 times that of P-AE-MDA, thanks to the introduction of benzoxazine, which increased the crosslinking density of the resin.

[0065] P-AE-MDA and P-AE-MV before and after immersion in water for one week 1.0 Water contact angle diagram as shown Figure 5 As shown in the figure, P-AE-MV 1.0Before immersion in water, the water contact angle of P-AE-MDA was slightly higher, at 108°. After immersion in water for one week, P-AE-MV... 1.0 The water contact angle of the resin decreased slightly, but the water contact angle of P-AE-MDA decreased significantly, from 99° to 58°, indicating that the resin with the addition of benzoxazine has better hydrophobicity.

[0066] P-AE-MV 1.0 The dielectric properties diagram is as follows Figure 6 As shown in the figure, P-AE-MV 1.0 With a dielectric constant of 3.0 and a dielectric loss of 0.014 at 10MHz, it exhibits excellent dielectric properties and is suitable for circuit boards used in high-frequency communication.

[0067] P-AE-MV at different temperatures 1.0 The stress relaxation diagram is as follows Figure 7a As shown in the figure, P-AE-MV 1.0 The relaxation rate increases with increasing temperature. At 160°C, the relaxation time τ is only 12s, enabling rapid and efficient topology rearrangement without external catalysts.

[0068] P-AE-MV at different temperatures 1.0 The stress fitting curve is shown in the figure. Figure 7b As shown in the figure, the relaxation behavior follows the Arrhenius equation. The activation energy of dynamic bond exchange, Ea = 48.1 kJ / mol, can be calculated from the slope of the fitted curve. This value is lower than the activation energy of dynamic ester exchange and closer to the activation energy of Schiff base exchange. This is because the rearrangement rate of Schiff base exchange is faster than that of ester exchange at the same temperature.

[0069] P-AE-MV 1.0 Self-healing and shape memory diagrams, such as Figure 8 As shown, a) is P-AE-MV 1.0 The sample was scratched with a blade, then heated in an oven at 180°C. The changes in the scratches over different time periods were observed under a microscope. After heating for 45 minutes, the scratches decreased from an initial 44.3 μm to 0.8 μm (self-healing rate of 98.2%). (b) Rectangular sample P-AE-MV 1.0 Based on T g and T v The triple shape memory process.

[0070] The shape memory process for all-bio-based benzoxazine monomer-modified rosin-based epoxy resin is as follows: The permanent rectangular sample P-AE-MV... 1.0Heated to 120°C (above the glass transition temperature Tg) and bent into an "S" shape, then cooled to room temperature to obtain a temporarily fixed "S" shape. The "S" shaped sample was then placed at 120°C, and the sample returned to its original rectangular shape.

[0071] P-AE-MV 1.0 The triple shape memory process is as follows: The rectangular sample P-AE-MV... 1.0 The sample was bent into the shape of the letter "L" at 180℃ (above the topological freeze-thaw temperature Tv) and held for 30 minutes. It was then cooled to room temperature to permanently form the letter "L". The "L" sample was then deformed into the letter "O" at 120℃ and cooled to room temperature, maintaining this shape. The cooled "O" sample was then placed at 120℃, and it slowly returned to its original "L" shape. Finally, the "L" shaped sample was heated to 180℃, and it returned to its original rectangular shape.

[0072] P-AE-MV 1.0 The original, sheared and physically recycled stretch diagrams are as follows Figure 9 As shown in the figure, P-AE-MV 1.0 After welding at 180℃ and physical recycling, the post-weld stress decreased by 3 MPa and the strain decreased by 1.5%. This was achieved through hot-pressing and reshaping of the physically recycled block-shaped P-AE-MV. 1.0 The stress after the first recycling was reduced by 8 MPa and the strain by 1.7%. After the second recycling, the stress was reduced by 10 MPa and the strain by 2%.

[0073] The degradation process of the fully bio-based benzoxazine monomer modified rosin-based epoxy resin is as follows: 5g sample P-AE-MV 1.0 Add the sample to a single-necked flask, then add 10 ml of n-butylamine, heat to 60 °C, stir thoroughly, and after the sample has fully degraded, evaporate the solvent to obtain P-AE-MV. 1.0 Degradation products.

[0074] P-AE-MV 1.0 FT-IR spectra before and after degradation in n-butylamine are shown below. Figure 10 As shown in the figure, P-AE-MV 1.0 The infrared spectrum of the degradation products is at 3359 cm⁻¹ -1 and 3280cm -1 The appearance of characteristic peaks representing the double peaks of primary amines at 1720 cm⁻¹ proves that bond exchange occurred between n-butylamine and the Schiff base, exposing the amino group on MDA. -1 The characteristic peak of the ester bond at 1642 cm⁻¹ weakened. -1The appearance of the characteristic amide peak at the position indicates that n-butylamine undergoes partial ester bond amidation during transesterification with Schiff bases, thus achieving a rapid degradation process.

[0075] The fully bio-based benzoxazine monomer-modified rosin-based epoxy resin prepared by this invention exhibits strong mechanical properties and good thermal stability, along with excellent self-healing, shape memory, recyclability, hydrophobicity, and dielectric properties. Its tensile strength at room temperature is 48 MPa, and its tensile modulus reaches 680 MPa. The temperature at which it loses 5% of its weight is above 273°C, and its char residue at 800°C is 12%, both significantly exceeding those of 1,8-p-menthanediamine (MDA)-cured rosin-based epoxy resin (P-AE-MDA) without the addition of benzoxazine monomer (VD). Furthermore, the repair rate reaches 98.2% after heating for 45 minutes, the water contact angle is as high as 108°, and the dielectric constant and dielectric loss are 3.0 and 0.014, respectively.

[0076] 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 technical principles 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 fully bio-based benzoxazine monomer-modified rosin-based epoxy resin, characterized in that, Its raw material components include: fully bio-based benzoxazine monomer VD, 1,8-p-menthol diamine MDA and propylene piroctone ester diglycidyl ester AE; Their structural formulas are as follows: ， ， ； A method for preparing rosin-based epoxy resin modified with a fully bio-based benzoxazine monomer includes the following steps: (1) Vanillin, decanediamine and paraformaldehyde were reacted to obtain a fully bio-based benzoxazine monomer; (2) The all-bio-based benzoxazine monomer and 1,8-p-mentanediamine were added to a solvent and reacted to obtain a Schiff base with an amino group. (3) After mixing the amino-containing Schiff base and the diglycidyl propylene-piperidine, pour the mixture into a mold and then heat it to cure to obtain the fully bio-based benzoxazine monomer modified rosin-based epoxy resin.

2. The method for preparing the fully bio-based benzoxazine monomer-modified rosin-based epoxy resin according to claim 1, characterized in that, Includes the following steps: (1) Vanillin, decanediamine and paraformaldehyde were reacted to obtain a fully bio-based benzoxazine monomer; (2) The all-bio-based benzoxazine monomer and 1,8-p-mentanediamine were added to a solvent and reacted to obtain a Schiff base with an amino group. (3) After mixing the amino-containing Schiff base and the diglycidyl propylene-piperidine, pour the mixture into a mold and then heat it to cure to obtain the fully bio-based benzoxazine monomer modified rosin-based epoxy resin.

3. The method for preparing the fully bio-based benzoxazine monomer-modified rosin-based epoxy resin according to claim 2, characterized in that, The reaction temperature in step (1) is 90℃~100℃ and the reaction time is 8~16h.

4. The method for preparing the all-bio-based benzoxazine monomer-modified rosin-based epoxy resin according to claim 2, characterized in that, The reaction temperature in step (2) is 60℃~90℃, and the reaction time is 2~5h.

5. The method for preparing the all-bio-based benzoxazine monomer-modified rosin-based epoxy resin according to claim 2, characterized in that, The molar ratio of the aldehyde group to the amino group of 1,8-p-menthol diamine in the fully bio-based benzoxazine monomer is 1:

2.

6. The method for preparing the fully bio-based benzoxazine monomer-modified rosin-based epoxy resin according to claim 2, characterized in that, The molar ratio of the active hydrogen of the amino-containing Schiff base to the epoxy group of the propylene piroctone ester diglycidyl group is 0.6-1:

1.

7. The method for preparing the fully bio-based benzoxazine monomer-modified rosin-based epoxy resin according to claim 2, characterized in that, The curing reaction in step (3) is a self-catalytic reaction system.

8. The method for preparing the all-bio-based benzoxazine monomer-modified rosin-based epoxy resin according to claim 2, characterized in that, Vanillin, decanediamine, paraformaldehyde, 1,8-p-menthanediamine, and propylene piroctone ester diglycidyl ester are derived from lignin, castor oil, bio-methanol, turpentine, and rosin, respectively.

9. The method for preparing the all-bio-based benzoxazine monomer-modified rosin-based epoxy resin according to claim 2, characterized in that, The temperature curing procedure is as follows: After pre-curing at 60~100℃ for 12~18 h, cure at 100~160℃ for 4~6 h, and finally cure at 160~220℃ for 2~4 h, then cool down.

10. The method for preparing the fully bio-based benzoxazine monomer-modified rosin-based epoxy resin according to claim 9, characterized in that, The cooling process involves reducing the temperature to room temperature at a rate of 5~8℃ / min.

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