A rosin-based bio-based benzoxazine, a high-thermal-conductivity liquid-crystal benzoxazine resin, and a preparation method and applications thereof

Abstract

The application provides a rosin-based bio-based benzoxazine, a high-thermal-conductivity liquid crystal benzoxazine resin and a preparation method and application thereof. First, a binary phenol, an amine and paraformaldehyde are used as raw materials to obtain a double benzoxazine through a Mannich reaction; the double benzoxazine is subjected to an amidation reaction with an amino-containing rosin derivative to obtain a bio-based benzoxazine monomer. The bio-based benzoxazine monomer is subjected to thermal curing to obtain a benzoxazine resin containing a rosin side group. The benzoxazine resin containing the rosin side group has a liquid crystal structure, high heat resistance and high thermal conductivity, and has a good application prospect in the fields of integrated circuits, (LED) lighting and the like. The synthesis process of the application is simple, the reaction condition is mild, the yield is high, the equipment requirement is low, and the application is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to a rosin-based bio-based benzoxazine, a high thermal conductivity liquid crystal benzoxazine resin, its preparation method and application, belonging to the field of polymer materials technology. Background Technology

[0002] With the rapid development of electronic devices in terms of reliability, functionality and miniaturization, how to effectively dissipate the excessive heat generated by electronic devices during operation has become a serious problem.

[0003] As a crucial component of electronic packaging, high thermal conductivity (λ) polymers are attracting increasing attention due to their ease of processing and electrical insulation properties. However, polymers generally possess an amorphous structure, resulting in low λ values. There are two main approaches to improving thermal conductivity: adding thermally conductive fillers and enhancing intrinsic heat transfer capabilities by controlling the microstructure. The former commonly employs thermally conductive fillers directly, such as metals, ceramics, and carbon-based fillers. Typically, achieving a high λ value using this method requires a high filler content, leading to poor mechanical properties in the composite material. The latter involves using polymers such as polyesters and polyamides containing crystalline and liquid crystal structures to improve the intrinsic thermal conductivity of the polymer.

[0004] Benzoxazine resins are a novel type of thermosetting resin with extremely high heat resistance and low cost. They also exhibit excellent dimensional stability and do not release any byproducts during ring-opening polymerization or crosslinking. By modifying the functional groups of phenols, aldehydes, amines, and other components, benzoxazine resins with specific functions can be prepared, offering extremely high flexibility in molecular design. However, a large portion of benzoxazine resources are petroleum-based. The global energy crisis and environmental protection pressures demand that scientists prioritize green chemistry. Therefore, the research and development of green, sustainable, bio-based benzoxazine resins has become a hot topic. Furthermore, liquid crystal benzoxazine monomers typically lose their liquid crystal structure during polymerization, thus failing to effectively improve the intrinsic thermal conductivity of the polymer.

[0005] Therefore, developing a liquid crystal bio-based benzoxazine resin with high thermal conductivity is of great significance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a rosin-based bio-based benzoxazine, a high thermal conductivity liquid crystal benzoxazine resin, its preparation method, and its applications. This invention first uses carboxyl-containing diphenols, amines, and paraformaldehyde as raw materials to obtain bisbenzoxazine via the Mannich reaction. The bisbenzoxazine is then amidated with an amino-containing rosin derivative to prepare a bio-based benzoxazine monomer. The bio-based benzoxazine monomer is then thermocured to obtain a benzoxazine resin containing rosin side groups. The rosin-side-group-containing benzoxazine resin of this invention possesses a liquid crystal structure, exhibiting high heat resistance and high thermal conductivity, showing promising application prospects in integrated circuits, (LED) lighting, and other fields. The synthesis process of this invention is simple, the reaction conditions are mild, the yield is high, and the equipment requirements are low, making it suitable for large-scale production.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] A rosin-based bio-based benzoxazine having the structure shown in Formula I or Formula II:

[0009]

[0010] R1 is selected from one of the following: -CH3, -(CH2) 11 CH3, -CH2CH2OH, -CH2-CH=CH2, -CH=CH2, R2 is selected from one of the following: -CH2CH3, -CH3, -CH2CH2OH, -CH2-CH=CH2, -CH(CH3)2; R3 is selected from one of the following: -CH2-, -CH2CH2-, R4 is selected from one of the following: -CH3, -CH2CH3, -OH.

[0011] The above-mentioned method for preparing rosin-based bio-based benzoxazine includes the following steps:

[0012] (1) In a low polarity solvent, carboxyl-containing diphenol III, amine compound R1-NH2, and paraformaldehyde are reacted to obtain bisbenzoxazine IV;

[0013]

[0014] In the structures of carboxyl-containing diphenols III and bisbenzoxazines IV, R4 is selected from one of the following: -CH3, -CH2CH3, -OH; in the structures of amine compounds R1-NH2 and bisbenzoxazines IV, R1 is selected from one of the following: -CH3, -(CH2). 11 CH3, -CH2CH2OH, -CH2-CH=CH2, -CH=CH2,

[0015] (2) In a high-boiling-point solvent, under the action of a catalyst, bisbenzoxazine IV reacts with dehydroabsinoamine derivative V or rosin-based amide compound VI to obtain rosin-based bio-based benzoxazine;

[0016]

[0017] In the structures of dehydroabsinolide derivative V and rosinyl amide compound VI, R2 is selected from one of the following: -CH2CH3, -CH3, -CH2CH2OH, -CH2-CH=CH2, -CH(CH3)2; in the structure of rosinyl amide compound VI, R3 is selected from one of the following: -CH2-, -CH2CH2-,

[0018] According to a preferred embodiment of the present invention, in step (1), the low polarity solvent is one or a combination of two or more of toluene, xylene, ethanol or dioxane; the molar amount of carboxyl-containing diphenol III and the volume ratio of the low polarity solvent are 0.1-1 mol / L.

[0019] According to a preferred embodiment of the present invention, in step (1), the molar ratio of carboxyl-containing diphenol III, amine compound R1-NH2, and paraformaldehyde (calculated as formaldehyde) is 1:2:4-1:2:6.

[0020] According to a preferred embodiment of the present invention, in step (1), the reaction temperature is 70-110°C, the reaction time is 5-25 hours, and the reaction is carried out under reflux stirring conditions.

[0021] According to a preferred embodiment of the present invention, in step (2), the high-boiling solvent is one or a combination of two or more of DMSO, DMF, DMAc or NMP; the molar ratio of bisbenzoxazine IV to the volume ratio of the high-boiling solvent is 0.4-1 mol / L.

[0022] According to a preferred embodiment of the present invention, in step (2), the catalyst is one or a combination of two or more of boric acid, dicyclohexylcarbodiimide phosphine oxide, N,N'-diisopropylcarbodiimide, pyridine or triphenyl phosphate; the molar ratio of the catalyst to bisbenzoxazine IV is 1:0.02-0.6.

[0023] According to a preferred embodiment of the present invention, in step (2), the molar ratio of bisbenzoxazine IV to dehydroabimethamine derivative V or rosinyl amide compound VI is 1-2:1.

[0024] According to a preferred embodiment of the present invention, in step (2), the reaction temperature is 80℃-180℃, the reaction time is 2-8 hours, and the reaction is carried out under protective gas and reflux stirring conditions. Preferably, the protective atmosphere is nitrogen or argon.

[0025] According to a preferred embodiment of the present invention, in step (2), the post-treatment method of the reaction solution obtained by the reaction includes the steps of: fully dispersing the reaction solution in methanol, filtering and drying to obtain rosin-based bio-based benzoxazine.

[0026] According to a preferred embodiment of the present invention, in step (2), the method for preparing rosin-based amide compound VI includes the following steps: in a solvent, under the action of triphenyl phosphate, pyridine, and lithium chloride, dehydrorosin acid derivative VII and diamine NH2-R3-NH2 react to obtain rosin-based amide compound VI;

[0027]

[0028] In the dehydrorosin acid derivative VII structure, R2 is selected from one of the following: -CH2CH3, -CH3, -CH(CH3)2, -CH2-CH=CH2, -CH2CH2OH; in the diamine NH2-R3-NH2 structure, R3 is selected from one of the following: -CH2-, -CH2CH2-,

[0029] Preferably, the solvent is one or a combination of two or more of DMSO, DMF, DMAc or NMP; the mass ratio of dehydrorosin acid derivative VII to the volume ratio of the solvent is 0.01-1 mol / L.

[0030] Preferably, the molar ratio of dehydrorosin acid derivative VII to diamine NH2-R3-NH2 is 0.5-1:1; the molar ratio of triphenyl phosphate, pyridine, lithium chloride, and dehydrorosin acid derivative VII is 2-3:24-25:15-20:1.

[0031] Preferably, the reaction temperature is 140℃-180℃, the reaction time is 2-6 hours, and the reaction is carried out under reflux stirring conditions and a protective atmosphere; preferably, the protective atmosphere is nitrogen or argon.

[0032] A high thermal conductivity liquid crystal benzoxazine resin has the structural unit shown in Formula VIII or Formula X as follows:

[0033]

[0034] R1 is selected from one of the following: -CH3, -(CH2) 11 CH3, -CH2CH2OH, -CH2-CH=CH2, -CH=CH2, R2 is selected from one of the following: -CH2CH3, -CH3, -CH2CH2OH, -CH2-CH=CH2, -CH(CH3)2; R3 is selected from one of the following: -CH2-, -CH2CH2-, R4 is selected from one of the following: -CH3, -CH2CH3, -OH.

[0035] The preparation method of the above-mentioned high thermal conductivity liquid crystal benzoxazine resin includes the following steps: rosin-based bio-based benzoxazine is cured to obtain high thermal conductivity liquid crystal benzoxazine resin.

[0036] According to a preferred embodiment of the present invention, the curing temperature is 120℃-280℃ and the curing time is 17min-3h.

[0037] The above-mentioned high thermal conductivity liquid crystal benzoxazine resin is used in heat dissipation materials for integrated circuits or LED lighting electronic packaging.

[0038] The preparation route of the high thermal conductivity liquid crystal benzoxazine resin of the present invention is as follows:

[0039]

[0040] R1 is selected from one of the following: -CH3, -(CH2) 11 CH3, -CH2CH2OH, -CH2-CH=CH2, -CH=CH2, R2 is selected from one of the following: -CH2CH3, -CH3, -CH2CH2OH, -CH2-CH=CH2, -CH(CH3)2; R3 is selected from one of the following: -CH2-, -CH2CH2-, R4 is selected from one of the following: -CH3, -CH2CH3, -OH.

[0041] The technical features and beneficial effects of this invention are as follows:

[0042] 1. The raw materials used in this invention are inexpensive and readily available, resulting in low cost; the synthesis route is simple, the reaction conditions are mild, and the equipment requirements are low; the product yield is high, production is safe, and it is suitable for large-scale production.

[0043] 2. This invention uses carboxyl-containing diphenols, amine compounds, and paraformaldehyde as raw materials to synthesize carboxyl-containing bisbenzoxazine via the Mannich reaction. Then, the bisbenzoxazine undergoes an amidation reaction with an amino-containing rosin derivative to prepare a bio-based benzoxazine monomer. This invention introduces a rosin group into benzoxazine to prepare a bio-based benzoxazine monomer, fully utilizing renewable rosin resources and alleviating the pressure of the energy crisis and environmental protection. In the preparation method of bio-based benzoxazine, the type of rosin derivative must contain an active amino group; the type of solvent, the ratio of reactants, and the reaction conditions all affect the selectivity of the reaction and the yield of the target product. Inappropriate conditions will lead to an increase in side reactions and a decrease in the yield of the target product.

[0044] 3. This invention provides a benzoxazine resin containing rosin side groups obtained by thermosetting a bio-based benzoxazine monomer. By introducing rosin liquid crystal building blocks, the rosin liquid crystal building blocks form an ordered structure within a temperature range of 120℃-280℃, thereby forming a benzoxazine resin with a liquid crystal structure. The bio-based benzoxazine monomer synthesized in this invention can form a liquid crystal structure during polymerization, while conventional liquid crystal benzoxazine monomers usually lose their liquid crystal structure during polymerization. The ordered arrangement of the polybenzoxazine liquid crystal structure in this invention improves the intrinsic thermal conductivity of the material; and different structures of the rosin groups have different effects on the thermal conductivity of the benzoxazine resin. Simultaneously, the benzoxazine resin containing rosin side groups of this invention exhibits high heat resistance. These properties make the benzoxazine resin containing rosin side groups of this invention a promising candidate for applications in integrated circuits, (LED) lighting, and other fields. Attached Figure Description

[0045] Figure 1 It is (A) BZD, (B) BZR and (C) PBZR. 1 HNMR spectrum.

[0046] Figure 2 It is (A) DHA, (B) BZD, (C) RBZ and (D) PRBZ. 1 HNMR spectrum.

[0047] Figure 3 These are the Fourier transform infrared spectra of (a)BZD, (b)BZR, and (c)PBZR.

[0048] Figure 4 These are the Fourier transform infrared spectra of (a) DHA, (b) BZD, (c) RBZ and (d) RPBZ.

[0049] Figure 5 Here are the Fourier transform infrared spectra of BZR at different curing temperatures: (a) room temperature (b) cured at 120℃ (c) 140℃ (d) 160℃ (e) 180℃ (f) 200℃.

[0050] Figure 6 The BZR POM image is cured at a rate of 10°C per minute.

[0051] Figure 7 These are POM images of RBZ cured at a rate of 10°C per minute: (a) 180°C, (b) 200°C, (c) 220°C, (d) 240°C, (e) 260°C, (f) 280°C, (g) 300°C, (h) 320°C.

[0052] Figure 8 It is the DSC curve of (A)BZD(B)BZR(C)PBZR.

[0053] Figure 9 It is the DSC curve of RBZ.

[0054] Figure 10 These are the SAXS curves of BZR before (a) curing and after (b) curing.

[0055] Figure 11 These are SAXS spectra before (a) and after (b) curing of RBZ.

[0056] Figure 12 These are POM images of BZR cured isothermally at 160℃ for different times: (a) 1 minute; (b) 3 minutes; (c) 6 minutes; (d) 17 minutes; (e) 30 minutes; (f) 60 minutes.

[0057] Figure 13 These are POM images of RBZ cured isothermally at 260℃ for different times: (a) 1 minute; (b) 3 minutes; (c) 6 minutes; (d) 17 minutes; (e) 30 minutes; (f) 60 minutes; (g) 120 minutes; (h) 240 minutes.

[0058] Figure 14 This refers to the thermal conductivity (TC) of BZD and PBZR.

[0059] Figure 15 It is the thermal conductivity (TC) of BZD and PRBZ.

[0060] Figure 16 These are the DMA curves for (a) PBZR and (b) PRBZ.

[0061] Figure 17 These are TGA heatmaps for BZD, BZR, and PBZR.

[0062] Figure 18 This is a TGA analysis chart of BZD, RBZ, and PRBZ. Detailed Implementation

[0063] The present invention will be further described below with reference to specific embodiments. However, it is not limited thereto.

[0064] Furthermore, the experimental methods described in the following examples are conventional methods unless otherwise stated; reagents, materials, and apparatus are all commercially available unless otherwise stated.

[0065] Example 1

[0066] Synthesis of a rosin-based bio-based benzoxazine:

[0067] (1) Synthesis of bisbenzoxazine IV (BZD, where R1 is -(C6H5) and R4 is -CH3)

[0068] In a flask, 0.023 mol of 4,4′-bis(4-hydroxyphenyl)valerate, 0.046 mol of aniline, 0.092 mol of paraformaldehyde (based on formaldehyde), and 75 mL of dioxane were thoroughly mixed and stirred under reflux at 80 °C for 6 h. After the reaction was stopped, the resulting reaction solution was added to ice water to precipitate the precipitate. The precipitate was filtered and dried in a vacuum oven at 60 °C to obtain the product bisbenzoxazine IV (yield 92%).

[0069] (2) Rosinyl amide compound VI(DHA, where R2 is -CH(CH3)2, R3 is... Synthesis of

[0070] In a flask, dehydrorosin acid (4.06 mmol), triphenyl phosphate (Tpp, 2.9 g, 0.0089 mol), and pyridine were added.

[0071] A mixture of 8.2 mL (0.1 mol) of rosinyl amide (BVA) and lithium chloride (3.28 g, 0.077 mol), and 40 mL of NMP was heated at 40 °C until dissolved. Then, 4.06 mmol of diaminodiphenylmethane was added, and the mixture was refluxed and stirred at 160 °C for 5 hours under nitrogen protection. The resulting reaction solution was precipitated in methanol, filtered, and dried overnight to give rosinyl amide compound VI. Yield: 90%.

[0072] (3) Rosin-based bio-based benzoxazine II (RBZ), wherein R1 is -(C6H5), R2 is -CH(CH3)2, and R3 is... Synthesis of R4 (-CH3)

[0073] In a flask, bisbenzoxazine (4.06 mmol), a rosin-based amide compound (4.06 mmol), triphenyl phosphate (Tpp, 2.96 mL, 0.01 mol), and NMP (5 mL) were mixed thoroughly and refluxed with stirring at 115 °C under a nitrogen atmosphere for 4 hours. The reaction mixture was then thoroughly dispersed in methanol, and the precipitate was filtered and dried overnight to give a rosin-based bio-based benzoxazine (yield 85%).

[0074] Example 2

[0075] Synthesis of a rosin-based bio-based benzoxazine:

[0076] (1) Synthesis of bisbenzoxazine IV (BZD, where R1 is -(C6H5) and R4 is -CH3) is the same as in Example 1;

[0077] (2) Rosin-based bio-based benzoxazine I (BZR, where R1 is -(C6H5), R2 is -CH(CH3)2, and R4 is -CH3)

[0078] In a flask, bisbenzoxazine IV (4.06 mmol), dehydroabimethamine derivative V (R2: -CH(CH3)2, 4.06 mmol), triphenyl phosphate (Tpp, 2.96 mL, 0.01 mol), pyridine (8 mL, 0.1 mol), and NMP (10 mL) were mixed thoroughly and refluxed with stirring at 120 °C under a nitrogen atmosphere for 4 hours. The reaction mixture was then thoroughly dispersed in methanol, and the precipitate was filtered and dried overnight to give rosin-based bio-based benzoxazine I. The yield was 80%.

[0079] Example 3

[0080] 4,4′-bis(4-hydroxyphenyl)valerate polybenzoxazine (PRBZ) with rosin side groups, wherein R1 is -(C6H5), R2 is -CH(CH3)2, and R3 is... Synthesis of R4 (-CH3)

[0081] The rosin-based bio-based benzoxazine II prepared in Example 1 was cured in an air-circulating oven under the following curing conditions: heating to 120°C for 2 hours, heating to 140°C for 2 hours, heating to 160°C for 2 hours, heating to 180°C for 2 hours, and finally heating to 200°C for 2 hours.

[0082] Example 4

[0083] Synthesis of 4,4′-bis(4-hydroxyphenyl)valerate polybenzoxazine (PBZR, where R1 is -(C6H5), R2 is -CH(CH3)2, and R4 is -CH3) with rosin side groups

[0084] The rosin-based bio-based benzoxazine I prepared in Example 2 was cured in an air-circulating oven under the following curing conditions: heating to 120°C for 2 hours, heating to 140°C for 2 hours, heating to 160°C for 2 hours, heating to 180°C for 2 hours, and finally heating to 200°C for 2 hours.

[0085] Example 5

[0086] Synthesis of a rosin-based bio-based benzoxazine:

[0087] (1) Synthesis of bisbenzoxazine IV (BZD2, where R1 is -CH3 and R4 is -CH3)

[0088] In a flask, 0.023 mol of 4,4′-bis(4-hydroxyphenyl)valeric acid, 0.046 mol of methylamine, 0.092 mol of paraformaldehyde (based on formaldehyde), and 75 mL of dioxane were thoroughly mixed and stirred under reflux at 75 °C for 9 h. After the reaction was stopped, the resulting reaction solution was added to ice water to precipitate the precipitate. The precipitate was filtered and dried in a vacuum oven at 60 °C to obtain the product bisbenzoxazine (yield 90%).

[0089] (2) Rosinyl amide compound VI (DHA2, where R2 is -CH3, R3 is...) Synthesis of

[0090] In a flask, a dehydrorosin acid derivative (R2: -CH3, 4.06 mmol), triphenyl phosphate (Tpp, 2.9 g, 0.0089 mol), pyridine (8.2 mL, 0.1 mol), lithium chloride (3.28 g, 0.077 mol), and 40 mL of NMP were mixed and heated at 40 °C until dissolved. Then, diaminodiphenylmethane (4.06 mmol) was added, and the mixture was refluxed and stirred at 160 °C for 5 hours under nitrogen protection. The resulting reaction solution was precipitated in methanol, filtered, and dried overnight to give rosinyl amide compound VI. The yield was 88%.

[0091] (3) Rosin-based bio-based benzoxazine II (RBZ2, where R1 is -CH3, R2 is -CH3, and R3 is... Synthesis of R4 (-CH3)

[0092] In a flask, bisbenzoxazine (4.06 mmol), rosin-based amide compound (4.06 mmol), triphenyl phosphate (Tpp, 2.96 mL, 0.01 mol), and NMP (5 mL) were mixed thoroughly and refluxed with stirring at 115 °C under a nitrogen atmosphere for 4 hours. The resulting reaction solution was added to methanol to precipitate, and the precipitate was then filtered and dried overnight to obtain rosin-based bio-based benzoxazine (yield 80%).

[0093] Example 6

[0094] Synthesis of a rosin-based bio-based benzoxazine:

[0095] (1) The synthesis of bisbenzoxazine IV (BZD2, where R1 is -CH3 and R4 is -CH3) is the same as in Example 5;

[0096] (2) Rosin-based bio-based benzoxazine I (BZR2, where R1 is -CH3, R2 is -CH3, and R4 is -CH3)

[0097] In a flask, bisbenzoxazine IV (4.06 mmol), dehydroabimethamine derivative V (R2: -CH3, 4.06 mmol), triphenyl phosphate (Tpp, 2.96 mL, 0.01 mol), pyridine (8 mL), and NMP (10 mL) were mixed thoroughly and refluxed with stirring at 120 °C under a nitrogen atmosphere for 4 hours. The resulting reaction solution was added to methanol to precipitate, and the precipitate was then filtered and dried overnight to obtain rosin-based bio-based benzoxazine I (yield 82%).

[0098] Example 7

[0099] 4,4′-bis(4-hydroxyphenyl)valerate polybenzoxazine (PRBZ2, wherein R1 is -CH3, R2 is -CH3, and R3 is -CH3) with rosin side groups. Synthesis of R4 (-CH3)

[0100] The rosin-based bio-based benzoxazine II prepared in Example 5 was cured in an air-circulating oven under the following curing conditions: heating to 120°C for 2 hours, heating to 140°C for 2 hours, heating to 160°C for 2 hours, heating to 180°C for 2 hours, and finally heating to 200°C for 2 hours.

[0101] Example 8

[0102] Synthesis of 4,4′-bis(4-hydroxyphenyl)valerate polybenzoxazine (PBZR2, where R1 is -CH3, R2 is -CH3, and R4 is -CH3) with rosin side groups

[0103] The rosin-based bio-based benzoxazine I prepared in Example 6 was cured in an air-circulating oven under the following curing conditions: heating to 120°C for 2 hours, heating to 140°C for 2 hours, heating to 160°C for 2 hours, heating to 180°C for 2 hours, and finally heating to 200°C for 2 hours.

[0104] Example 9

[0105] Synthesis of a rosin-based bio-based benzoxazine:

[0106] (1) Synthesis of bisbenzoxazine IV (BZD3, where R1 is -CH2CH2OH and R4 is -CH3)

[0107] In a flask, 0.023 mol of 4,4′-bis(4-hydroxyphenyl)valeric acid, 0.046 mol of ethanolamine, 0.092 mol of paraformaldehyde (calculated as formaldehyde), 75 mL of a mixture of ethanol and dioxane (in a volume ratio of 2:1) were thoroughly mixed and stirred under reflux at 85 °C for 9 h. After the reaction was stopped, the resulting reaction solution was added to ice water to precipitate the precipitate. The precipitate was filtered and dried in a vacuum oven at 60 °C to obtain the product bisbenzoxazine (yield 91%).

[0108] (2) Rosinyl amide compound VI (DHA3, where R2 is -CH2CH2OH, and R3 is...) Synthesis of

[0109] In a flask, a dehydrorosin acid derivative (R2: -CH2CH2OH, 4.06 mmol), triphenyl phosphate (Tpp, 2.9 g, 0.0089 mol), pyridine (8.2 mL, 0.1 mol), lithium chloride (3.28 g, 0.077 mol), and 40 mL of NMP were mixed and heated at 40 °C until dissolved. Then, diaminodiphenylmethane (4.06 mmol) was added, and the mixture was refluxed and stirred at 180 °C for 3 hours under nitrogen protection. The resulting reaction solution was precipitated in methanol, filtered, and dried overnight to give rosinyl amide compound VI. The yield was 77%.

[0110] (3) Rosin-based bio-based benzoxazine II (RBZ3, where R1 is -CH2CH2OH, R2 is -CH2CH2OH, and R3 is... Synthesis of R4 (-CH3)

[0111] In a flask, bisbenzoxazine (4.06 mmol), a rosin-based amide compound (4.06 mmol), triphenyl phosphate (Tpp, 2.96 mL, 0.01 mol), and NMP (5 mL) were mixed thoroughly and refluxed with stirring at 125 °C under a nitrogen atmosphere for 3 hours. The resulting reaction solution was added to methanol to precipitate the precipitate, which was then filtered and dried overnight to obtain a rosin-based bio-based benzoxazine (yield 75%).

[0112] Example 10

[0113] Synthesis of a rosin-based bio-based benzoxazine:

[0114] (1) The synthesis of bisbenzoxazine IV (BZD3, where R1 is -CH2CH2OH and R4 is -CH3) is the same as in Example 9;

[0115] (2) Rosin-based bio-based benzoxazine I (BZR3, where R1 is -CH2CH2OH, R2 is -CH2CH2OH, and R4 is -CH3)

[0116] In a flask, bisbenzoxazine IV (4.06 mmol), dehydroabimethamine derivative V (R2: -CH2CH2OH, 4.06 mmol), triphenyl phosphate (Tpp, 2.96 mL, 0.01 mol), pyridine (8 mL), and NMP (10 mL) were mixed thoroughly and refluxed with stirring at 150 °C under a nitrogen atmosphere for 3 hours. The resulting reaction solution was added to methanol to precipitate the precipitate, which was then filtered and dried overnight to obtain rosin-based bio-based benzoxazine I (yield 72%).

[0117] Example 11

[0118] 4,4′-bis(4-hydroxyphenyl)valerate polybenzoxazine (PRBZ3, wherein R1 is -CH2CH2OH, R2 is -CH2CH2OH, and R3 is -CH2CH2OH) with rosin side groups. Synthesis of R4 (-CH3)

[0119] The rosin-based bio-based benzoxazine II prepared in Example 9 was cured in an air-circulating oven under the following curing conditions: heating to 120°C for 2 hours, heating to 140°C for 2 hours, heating to 160°C for 2 hours, heating to 180°C for 2 hours, and finally heating to 200°C for 2 hours.

[0120] Example 12

[0121] Synthesis of 4,4′-bis(4-hydroxyphenyl)valerate polybenzoxazine (PBZR3, where R1 is -CH2CH2OH, R2 is -CH2CH2OH, and R4 is -CH3) with rosin side groups

[0122] The rosin-based bio-based benzoxazine I prepared in Example 10 was cured in an air-circulating oven under the following curing conditions: heating to 120°C for 2 hours, heating to 140°C for 2 hours, heating to 160°C for 2 hours, heating to 180°C for 2 hours, and finally heating to 200°C for 2 hours.

[0123] Example 13

[0124] Synthesis of a rosin-based bio-based benzoxazine:

[0125] (1) Synthesis of bisbenzoxazine IV (BZD4, where R1 is -CH=CH2 and R4 is -CH3)

[0126] In a flask, 0.023 mol of 4,4′-bis(4-hydroxyphenyl)valeric acid, 0.046 mol of vinylamine, 0.092 mol of paraformaldehyde (based on formaldehyde), 75 mL of a mixture of ethanol and dioxane (in a volume ratio of 2:1) were thoroughly mixed and stirred under reflux at 80 °C for 10 h. After the reaction was stopped, the resulting reaction solution was added to ice water to precipitate the precipitate. The precipitate was filtered and dried in a vacuum oven at 60 °C to obtain the product bisbenzoxazine (yield 93%).

[0127] (2) Rosinyl amide compound VI (DHA4, where R2 is -CH2-CH=CH2, and R3 is... Synthesis of

[0128] In a flask, a dehydrorosin acid derivative (R2: -CH2-CH=CH2, 4.06 mmol), triphenyl phosphate (Tpp, 2.9 g, 0.0089 mol), pyridine (8.2 mL, 0.1 mol), lithium chloride (3.28 g, 0.077 mol), and 40 mL of NMP were mixed and heated at 40 °C until dissolved. Then, diaminodiphenylmethane (4.06 mmol) was added, and the mixture was refluxed and stirred at 175 °C for 4 hours under nitrogen protection. The resulting reaction solution was precipitated in methanol, filtered, and dried overnight to give rosinyl amide compound VI. Yield: 75%.

[0129] (3) Rosin-based bio-based benzoxazine II (RBZ4, where R1 is -CH=CH2, R2 is -CH2-CH=CH2, and R3 is... Synthesis of R4 (-CH3)

[0130] In a flask, bisbenzoxazine (4.06 mmol), a rosin-based amide compound (4.06 mmol), triphenyl phosphate (Tpp, 2.96 mL, 0.01 mol), and NMP (5 mL) were mixed thoroughly and refluxed with stirring at 115 °C under a nitrogen atmosphere for 3.5 h. The resulting reaction solution was added to methanol to precipitate the precipitate, which was then filtered and dried overnight to obtain a rosin-based bio-based benzoxazine (yield 79%).

[0131] Example 14

[0132] Synthesis of a rosin-based bio-based benzoxazine:

[0133] (1) The synthesis of bisbenzoxazine IV (BZD4, where R1 is -CH=CH2 and R4 is -CH3) is the same as in Example 13;

[0134] (2) Rosin-based bio-based benzoxazine I (BZR4, where R1 is -CH=CH2, R2 is -CH2-CH=CH2, and R4 is -CH3)

[0135] In a flask, bisbenzoxazine IV (4.06 mmol), dehydrorosinamine derivative V (R2: -CH2-CH=CH2, 4.06 mmol), triphenyl phosphate (Tpp, 2.96 mL, 0.01 mol), pyridine (8 mL), and NMP (10 mL) were mixed thoroughly and refluxed with stirring at 140 °C under a nitrogen atmosphere for 4 hours. The resulting reaction solution was added to methanol to precipitate, and the precipitate was then filtered and dried overnight to obtain rosin-based bio-based benzoxazine I (yield 73%).

[0136] Example 15

[0137] 4,4′-bis(4-hydroxyphenyl)valerate polybenzoxazine (PRBZ4, wherein R1 is -CH=CH2, R2 is -CH2-CH=CH2, and R3 is... Synthesis of R4 (-CH3)

[0138] The rosin-based bio-based benzoxazine II prepared in Example 13 was cured in an air-circulating oven under the following curing conditions: heating to 120°C for 2 hours, heating to 140°C for 2 hours, heating to 160°C for 2 hours, heating to 180°C for 2 hours, and finally heating to 200°C for 2 hours.

[0139] Example 16

[0140] Synthesis of 4,4′-bis(4-hydroxyphenyl)valerate polybenzoxazine (PBZR4, where R1 is -CH=CH2, R2 is -CH2-CH=CH2, and R4 is -CH3) with rosin side groups

[0141] The rosin-based bio-based benzoxazine I prepared in Example 14 was cured in an air-circulating oven under the following curing conditions: heating to 120°C for 2 hours, heating to 140°C for 2 hours, heating to 160°C for 2 hours, heating to 180°C for 2 hours, and finally heating to 200°C for 2 hours.

[0142] Example 17

[0143] Synthesis of a rosin-based bio-based benzoxazine:

[0144] (1) Synthesis of bisbenzoxazine IV (BZD5, where R1 is -(CH2)) 11 CH3, R4 is -CH3)

[0145] In a flask, 0.023 mol of 4,4′-bis(4-hydroxyphenyl)valeric acid, 0.046 mol of dodecylamine, 0.092 mol of paraformaldehyde (calculated as formaldehyde), 75 mL of a mixture of ethanol and dioxane (in a volume ratio of 2:1) were thoroughly mixed and stirred under reflux at 90 °C for 24 h. After the reaction was stopped, the resulting reaction solution was added to ice water to precipitate the precipitate. The precipitate was filtered and dried in a vacuum oven at 60 °C to obtain the product bisbenzoxazine (yield 70%).

[0146] (2) Rosinyl amide compound VI (DHA5, where R2 is -CH2CH3, and R3 is...) Synthesis of

[0147] In a flask, a dehydrorosin acid derivative (R2: -CH2CH3, 4.06 mmol), triphenyl phosphate (Tpp, 2.9 g, 0.0089 mol), pyridine (8.2 mL, 0.1 mol), lithium chloride (3.28 g, 0.077 mol), and 40 mL of NMP were mixed and heated at 40 °C until dissolved. Then, diaminodiphenylmethane (4.06 mmol) was added, and the mixture was refluxed and stirred at 165 °C for 5 hours under nitrogen protection. The resulting reaction solution was precipitated in methanol, filtered, and dried overnight to give arosinyl amide compound VI. The yield was 79%.

[0148] (3) Rosin-based bio-based benzoxazine II (RBZ5, where R1 is -(CH2)) 11 CH3, R2 is -CH2CH3, R3 is Synthesis of R4 (-CH3)

[0149] In a flask, bisbenzoxazine (4.06 mmol), a rosin-based amide compound (4.06 mmol), triphenyl phosphate (Tpp, 2.96 mL, 0.01 mol), and NMP (5 mL) were mixed thoroughly and refluxed with stirring at 140 °C under a nitrogen atmosphere for 2 hours. The resulting reaction solution was added to methanol to precipitate the precipitate, which was then filtered and dried overnight to obtain a rosin-based bio-based benzoxazine (yield 73%).

[0150] Example 18

[0151] Synthesis of a rosin-based bio-based benzoxazine:

[0152] (1) Synthesis of bisbenzoxazine IV (BZD5, where R1 is -(CH2)) 11 CH3, R4 is -CH3) Same as in Example 17;

[0153] (2) Rosin-based bio-based benzoxazine I (BZR5, where R1 is -(CH2)11 CH3, R2 is -CH2CH3, R4 is -CH3)

[0154] In a flask, bisbenzoxazine IV (4.06 mmol), dehydroabimethamine derivative V (R2: -CH2CH3, 4.06 mmol), triphenyl phosphate (Tpp, 2.96 mL, 0.01 mol), pyridine (8 mL), and NMP (10 mL) were mixed thoroughly and refluxed with stirring at 180 °C under a nitrogen atmosphere for 3 hours. The resulting reaction solution was added to methanol to precipitate, and the precipitate was then filtered and dried overnight to obtain rosin-based bio-based benzoxazine I (yield 70%).

[0155] Example 19

[0156] 4,4′-bis(4-hydroxyphenyl)valerate polybenzoxazine (PRBZ5, where R1 is -(CH2)) with rosin side groups. 11 CH3, R2 is -CH2CH3, R3 is Synthesis of R4 (-CH3)

[0157] The rosin-based bio-based benzoxazine II prepared in Example 17 was cured in an air-circulating oven under the following curing conditions: heating to 120°C for 2 hours, heating to 140°C for 2 hours, heating to 160°C for 2 hours, heating to 180°C for 2 hours, and finally heating to 200°C for 2 hours.

[0158] Example 20

[0159] 4,4′-bis(4-hydroxyphenyl)valerate polybenzoxazine (PBZR5, where R1 is -(CH2)) with rosin side groups. 11 Synthesis of CH3, R2 being -CH2CH3, and R4 being -CH3

[0160] The rosin-based bio-based benzoxazine I prepared in Example 18 was cured in an air-circulating oven under the following curing conditions: heating to 120°C for 2 hours, heating to 140°C for 2 hours, heating to 160°C for 2 hours, heating to 180°C for 2 hours, and finally heating to 200°C for 2 hours.

[0161] Test case

[0162] Figure 1 It is (A) BZD, (B) BZR and (C) PBZR (prepared by the method in Example 4). 1 HNMR spectrum. In Figure 1In A, the characteristic resonance peaks of Ar-CH2-N(d)O-CH2-N(e) and -CH3(c) appear at 4.49 ppm, 5.25 ppm, and 1.44 ppm, respectively. Their integral ratio is 1.97:1.99:3.06, consistent with the theoretical value of 2:2:3, indicating the formation of an oxazine ring. The peaks at 1.95 ppm(b) and 2.30 ppm(a) are protons of the -CH2 and -CH2-COOH groups in valeric acid. The peaks from 6.67 ppm(f) to 7.16 ppm(g) are aromatic protons. Figure 1 In B, the new peak at 9.24 ppm indicates that an amide bond has formed between BZD and the dehydroabsinoamine derivative V. Figure 1 C indicates that ring-opening polymerization occurred, and the target product was obtained.

[0163] Figure 2 It is (A) DHA, (B) BZD, (C) RBZ and (D) PRBZ (prepared by the method in Example 3). 1 HNMR spectrum. In Figure 2 In A, the peak at 9.22 ppm indicates that an amide bond has been formed between dehydrorosin acid and diaminodiphenylmethane; Figure 2 C indicates that BZD and DHA reacted to form an amide bond; Figure 2 D indicates that a ring-opening polymerization reaction has occurred.

[0164] Figure 3 The FTIR spectra of (a) BZD, (b) BZR, and (c) PBZR (prepared by the method in Example 4) are shown. Figure 3 a and 3b and Figure 3 Compared to c, the 904 cm corresponding to the oxazine ring -1 The peak at that location disappears, while the peak at 1460 cm⁻¹ corresponding to the tetrasubstituted benzene ring disappears. -1 The peak at 3670 cm⁻¹ increases. -1 The new peak at that location corresponds to the phenolic hydroxyl groups that appear after ring-opening polymerization. Figure 3 In b, at 1501cm -1 and 3265cm -1 The peaks at these locations correspond to the stretching and bending vibrations of the C=O group of the amide group, respectively. Figure 3 In b and 3c, the carboxyl group is at 1710 cm⁻¹ -1 The disappearance of the characteristic carbonyl peak indicates that the dehydroabimethamine derivative V was successfully grafted with a carboxyl group through the formation of an amide bond. These results demonstrate that the target product has been successfully synthesized.

[0165] Figure 4 The Fourier transform infrared spectra of (a) DHA, (b) BZD, (c) RBZ, and (d) RPBZ (prepared by the method in Example 3) are shown. Figure 4 In a, 1514cm-1 and 3315cm -1 The peak at that point corresponds to the bending and stretching vibrations of the carbonyl group in the DHA amide bond. Figure 4 In d, the peak corresponding to the oxazine ring disappeared, and at 3630 cm⁻¹, after ring-opening polymerization, the peak value disappeared. -1 A peak corresponding to the phenolic hydroxyl group of the benzene ring appeared at that location. Figure 4 b and Figure 4 c and Figure 4 Compared to d, the 904 cm corresponding to the oxazine ring -1 The peak at that location disappeared, while the peak at 1460 cm⁻¹ corresponding to the tetrasubstituted benzene ring disappeared. -1 The peak at 3670cm increased. -1 The new peak corresponds to the phenolic hydroxyl groups that appear after ring-opening polymerization. All these findings indicate that the target product was successfully synthesized.

[0166] To investigate the curing behavior, the samples were subjected to thermogravimetric analysis at 10 °C / min. -1 The mixture is heated rapidly in N2 and then quickly cooled to room temperature. Figure 5 The Fourier transform infrared spectra of BZR at different temperatures during the heating process are shown: (a) room temperature, (b) 120℃, (c) 140℃, (d) 160℃, (e) 180℃, and (f) 200℃, with a curing time of 1 hour at each temperature. The spectrum at room temperature is used for comparison. After curing at 140℃ for 1 hour, the bending and stretching vibrations of the carbonyl group of the amide bond are observed at 1501 cm⁻¹. -1 and 3265cm -1 A new peak begins to appear at this point, while the oxazine ring reaches 904 cm⁻¹. -1 The peak value decreases slightly, indicating that the ring-opening reaction begins at this stage. As the temperature increases from 140℃ to 180℃, the tetrasubstituted benzene ring reaches a peak value of 1460 cm⁻¹. -1 The peak intensity at that location increases relatively. Furthermore, the peak intensity at 3670 cm⁻¹ corresponds to the phenolic hydroxyl group. -1 The peak intensity also significantly increased. All these changes indicate that the ring-opening polymerization of BZR was completed after curing at 200°C for 1 hour.

[0167] Figure 6 The image shows POM images of BZR cured at a temperature increase rate of 10°C per minute. No LC structure appears at 100°C, indicating an amorphous phase. A bright structure appears at 120°C, and the bright area increases with increasing temperature. After 240°C, the bright structure no longer increases with further temperature increases.

[0168] Figure 7Images of POM cured by RBZ at 10°C for 1 minute are shown. No LC structure appeared when heated to 180°C, indicating it is an amorphous phase. A bright structure appeared when heated to 200°C, and the bright area increased with increasing temperature. Above 280°C, the bright structure no longer increased with increasing temperature. It was observed that the sample exhibited a bright structure throughout the temperature range of 200°C–280°C.

[0169] Figure 8 These are the DSC curves for (A)BZD, (B)BZR, and (C)PBZR (prepared by the method in Example 4). For BZD, the exothermic peak at 170°C corresponds to the ring-opening polymerization reaction. Figure 8 b is the DSC thermogram of BZR. The exothermic temperature range of 140℃-178℃ is related to the occurrence of amidation (the residual reactive monomers in BZR continue to undergo amidation during heating) and ring-opening polymerization. Figure 8 In c, the absence of an exothermic peak corresponds to the complete ring-opening polymerization and amidation reaction.

[0170] Figure 9 The DSC thermal map of RBZ is shown. The two exothermic peaks at 166℃ and 257℃ represent the ring-opening polymerization reaction and the amidation reaction, respectively (the reactive monomers remaining in RBZ continue to undergo amidation reaction during heating).

[0171] Figure 10 These are the SAXS spectra of PBZR before curing (a) and PBZR prepared by the method in Example 4 (b). Figure 10 The spectrum of a shows no obvious peaks, indicating that it has an amorphous structure. After curing, in Figure 10 Two types of peaks can be observed in the spectrum of b. At q1 = 2.73 nm... -1 q2 = 5.38 nm 1 q4 = 10.33 nm -1 and q5 = 12.50nm -1 The wide amorphous hump at q3 represents the short-range ordered hierarchical arrangement of liquid crystal structure 26. (At q3 = 6.71 nm) -1 The sharp peaks appearing at this point correspond to the long-range ordered arrangement of the eutectic C phase structure. Furthermore, the interlayer spacing was calculated to be 2.1 nm according to the Bragg equation (d = 2π / q). This interlayer spacing confirms the extended molecular chains.

[0172] Figure 11 The images are SAXS spectra of RBZ before curing (a) and PRBZ prepared by the method in Example 3 (b). Figure 11 In (b), after curing, the SAXS spectrum is at q1 = 0.97 nm. -1 q2 = 1.28nm -1q3 = 1.88nm -1 q4 = 2.38nm -1 and q5 = 2.56nm -1 The low-angle region exhibits broad peaks with weak reflection intensity. These peaks observed in the low-angle region and their corresponding q-values ​​indicate short-range ordered alignment of the liquid crystal structure. Specifically, the presence of small peaks confirms the presence of a nematic phase in the material.

[0173] Figure 12 These are POM images of BZR cured isothermally at 160℃ for different times: (a) 1 minute; (b) 3 minutes; (c) 6 minutes; (d) 17 minutes; (e) 30 minutes; (f) 60 minutes. Initially, no visible bright structure appeared after 1 minute and 3 minutes of curing, indicating an isotropic phase. However, when the reaction proceeded to 6 minutes (see...),... Figure 12 c) A rope-like layered pattern appeared, indicating the formation of a liquid crystal structure. The fluidity during pressing further confirmed this. Furthermore, after curing for 17 minutes (see...), Figure 12 d) and 30 minutes (see Figure 12 After e), we can observe an increase in the area of ​​the bright region. However, after 60 minutes of curing, the area of ​​the bright region essentially no longer changes, indicating that extending the curing time did not promote further formation of the layered pattern. These POM images show the formation and evolution of the LC structure during curing. This indicates that the amide bond formed between BZD and the dehydrorosinamine derivative V induces the formation of the LC structure. The rope-like layered pattern suggests that it is similar to a eutectic C-type liquid crystal. POM images show the formation and evolution of the LC structure during copolymerization.

[0174] Figure 13 These are POM images of RBZ cured isothermally at 260℃ for different times: (a) 1 minute; (b) 3 minutes; (c) 6 minutes; (d) 17 minutes; (e) 30 minutes; (f) 60 minutes; (g) 120 minutes; (h) 240 minutes. Initially, no visible bright structure was observed after 1 minute and 3 minutes of curing, indicating the presence of an isotropic phase. However, when the reaction proceeded to 6 minutes (see...),... Figure 13 c) Low-concentration structural domains appeared, indicating that a low-concentration structure had formed, which was confirmed by the fluidity observed during pressing. Furthermore, after 17 minutes of curing (see...), Figure 13 d) We can observe that the area of ​​the bright region increases, indicating that the LC structure further develops and the formation of the LC phase continues with the extension of reaction time. After curing for 60 minutes, the area of ​​the bright region basically no longer changes, indicating that the formation of the liquid crystal structure has reached a stable state.

[0175] Figure 14 and 15The thermal conductivity (TC) of BZD, PBZR prepared by the method of Example 4, and PRBZ prepared by the method of Example 3 are shown. The thermal conductivity of PBZR and PRBZ are 0.289 W / mK and 0.295 W / mK, respectively, which are 61% and 64% higher than that of BZD. The high thermal conductivity of PBZR and PRBZ is due to the polymer liquid crystal layered arrangement formed by amide bonds. The lower thermal conductivity of BZD is due to its lack of ordered arrangement and amorphous nature.

[0176] Figure 16 (a) shows the DMA curve of PBZR prepared by the method of Example 4. From the specific peaks in the G" and tanδ curves, the glass transition temperatures are 99 °C and 129 °C, respectively. Figure 16 (b) In the DMA curve of PRBZ, the specific peaks of the G" and tanδ curves are located at 93℃ and 105℃, respectively. The reason for the lower Tg is that the added DHA is brittle.

[0177] Figure 17 The TGA thermal images of BZD, BZR, and PBZR prepared by the method of Example 4 are shown. The 5% weight loss temperature (Td5) and 10% weight loss temperature (Td) of PBZR are also shown. 10 The PBZR and PBZD carbonization rates were 247℃ and 276℃ respectively, higher than BZR and BZD. Furthermore, the PBZR carbonization rate was 41%, higher than BZD (30%) and BZR (34%).

[0178] Figure 18 The TGA thermal maps of BZD, RBZ, and PRBZ prepared by the method of Example 3 are shown. The 5% weight loss temperature (Td5) and 10% weight loss temperature (Td) of PRBZ are also shown. 10 The thermal stability of PRBZ and PBZR is 288℃ and 310℃ respectively, higher than that of BZD and RBZ. Furthermore, the carbonization rate of PRBZ is 30%, higher than that of BZD. Compared to PRBZ, PBZR has lower thermal stability due to the brittleness of the added DHA. The improved thermal stability of PRBZ and PBZR is due to the ordered arrangement of the liquid crystal amide bonds.

[0179] Temperature range for liquid crystal structure formation, TC (thermal conductivity), T g Td5 and Td 10 The char yield data are shown in Table 1 below. The temperature range for liquid crystal structure formation refers to the temperature at which the liquid crystal structure begins to form and the temperature at which the liquid crystal structure no longer changes. The test method for the liquid crystal structure formation temperature range is as follows: Place the sample on the hot platform of a microscope and heat it from room temperature to different temperatures at a heating rate of 10℃ / min. Test the formation of the liquid crystal structure at different temperatures to obtain the temperature range for liquid crystal structure formation.

[0180] Table 1 Performance data of different samples

[0181]

[0182]

[0183]

[0184] As shown in Table 1, the temperature ranges for liquid crystal formation during the curing process of BZR and RBZ are 120℃-240℃ and 200℃-280℃, respectively. The liquid crystal structure is an ordered structure formed through amide bonds. The temperature range of the liquid crystal in this invention exceeds that of ordinary liquid crystals, which means that the polymer of this invention will not lose its liquid crystal structure during polymerization like ordinary polymers, and its thermal conductivity is also higher than that of ordinary liquid crystal polymers. The glass transition temperature (Tg≥105℃) is much higher than that of ordinary liquid crystal copolymers. Therefore, the bio-based resin designed and synthesized in this invention has better heat resistance than ordinary resins and can meet the requirements for high heat resistance.

[0185] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Other changes, modifications, substitutions, and simplifications that do not depart from the spirit and principles of the present invention are all equivalent substitution methods and fall within the protection scope of the present invention. The liquid crystal bio-based polybenzoxazine synthesized according to the present invention can be used in green chemistry, integrated circuits, electronics, LED lighting, and liquid crystal displays.

Claims

1. A rosin-based bio-based benzoxazine, characterized in that, It has the structure shown in Equation I or Equation II: R1 is selected from one of the following: -CH3, -(CH2) 11 CH3, -CH2CH2OH, -CH2-CH=CH2, -CH=CH2, , R2 is selected from one of the following: -CH2CH3, -CH3, -CH2CH2OH, -CH2-CH=CH2, -CH(CH3)2; R3 is selected from one of the following: -CH2-, -CH2CH2-, , R4 is selected from one of the following: -CH3, -CH2CH3, -OH.

2. The method for preparing rosin-based bio-based benzoxazine as described in claim 1, comprising the steps of: (1) In a low polarity solvent, a carboxyl-containing diphenol III, an amine compound R1-NH2, and paraformaldehyde are reacted to obtain bisbenzoxazine IV; the low polarity solvent is one or a combination of two or more of toluene, xylene, ethanol, or dioxane. in, In the structures of carboxyl-containing diphenols III and bisbenzoxazines IV, R4 is selected from one of the following: -CH3, -CH2CH3, -OH; in the structures of amine compounds R1-NH2 and bisbenzoxazines IV, R1 is selected from one of the following: -CH3, -(CH2). 11 CH3, -CH2CH2OH, -CH2-CH=CH2, -CH=CH2, , ; (2) In a high-boiling-point solvent, under the action of a catalyst, bisbenzoxazine IV reacts with dehydroabimethamine derivative V or rosin-based amide compound VI to obtain a rosin-based bio-based benzoxazine; the high-boiling-point solvent is one or a combination of two or more of DMSO, DMF, DMAc or NMP; the catalyst is one or a combination of two or more of boric acid, dicyclohexylcarbodiimide phosphine oxide, N,N'-diisopropylcarbodiimide, pyridine or triphenyl phosphate; In the structures of dehydroabsinolide derivative V and rosinyl amide compound VI, R2 is selected from one of the following: -CH2CH3, -CH3, -CH2CH2OH, -CH2-CH=CH2, -CH(CH3)2; in the structure of rosinyl amide compound VI, R3 is selected from one of the following: -CH2-, -CH2CH2-, , .

3. The method for preparing rosin-based bio-based benzoxazine according to claim 2, characterized in that, Step (1) includes one or more of the following conditions: i. The molar ratio of carboxyl-containing diphenol III to the volume ratio of low-polarity solvent is 0.1-1 mol / L; ii. The molar ratio of carboxyl-containing diphenols III, amine compounds R1-NH2, and paraformaldehyde (calculated as formaldehyde) is 1:2:4-1:2:6; iii. The reaction temperature is 70-110℃, the reaction time is 5-25 hours, and the reaction is carried out under reflux and stirring conditions.

4. The method for preparing rosin-based bio-based benzoxazine according to claim 2, characterized in that, Step (2) includes one or more of the following conditions: i. The molar ratio of bisbenzoxazine IV to the volume ratio of the high-boiling solvent is 0.4-1 mol / L; ii. The molar ratio of catalyst to bisbenzoxazine IV is 1:0.02-0.6; iii. The molar ratio of bisbenzoxazine IV to dehydroafungin derivative V or rosinyl amide compound VI is 1-2:1; iv. The reaction temperature is 80℃-180℃, the reaction time is 2-8 hours, and the reaction is carried out under protective gas and reflux stirring conditions; the protective atmosphere is nitrogen or argon. v. The post-processing method of the reaction solution obtained from the reaction includes the following steps: the reaction solution is fully dispersed in methanol, filtered and dried to obtain rosin-based bio-based benzoxazine.

5. The method for preparing rosin-based bio-based benzoxazine according to claim 2, characterized in that, In step (2), the preparation method of rosin-based amide compound VI includes the following steps: in a solvent, under the action of triphenyl phosphate, pyridine, and lithium chloride, dehydrorosin acid derivative VII and diamine NH2-R3-NH2 react to obtain rosin-based amide compound VI; In the dehydrorosin acid derivative VII structure, R2 is selected from one of the following: -CH2CH3, -CH3, -CH(CH3)2, -CH2-CH=CH2, -CH2CH2OH; in the diamine NH2-R3-NH2 structure, R3 is selected from one of the following: -CH2-, -CH2CH2-, , .

6. The method for preparing rosin-based bio-based benzoxazine according to claim 5, characterized in that, Includes one or more of the following conditions: i. The molar ratio of dehydrorosin acid derivative VII to the volume ratio of solvent is 0.01-1 mol / L; ii. The molar ratio of dehydrorosin acid derivative VII and diamine NH2-R3-NH2 is 0.5-1:1; the molar ratio of triphenyl phosphate, pyridine, lithium chloride, and dehydrorosin acid derivative VII is 2-3:24-25:15-20:

1. iii. The reaction temperature is 140℃-180℃, the reaction time is 2-6 hours, and the reaction is carried out under reflux stirring conditions and a protective atmosphere; the protective atmosphere is nitrogen or argon.

7. A high thermal conductivity liquid crystal benzoxazine resin, characterized in that, It has the structural unit shown in Equation VIII or Equation X as follows: R1 is selected from one of the following: -CH3, -(CH2) 11 CH3, -CH2CH2OH, -CH2-CH=CH2, -CH=CH2, , R2 is selected from one of the following: -CH2CH3, -CH3, -CH2CH2OH, -CH2-CH=CH2, -CH(CH3)2; R3 is selected from one of the following: -CH2-, -CH2CH2-, , R4 is selected from one of the following: -CH3, -CH2CH3, -OH.

8. The method for preparing the high thermal conductivity liquid crystal benzoxazine resin as described in claim 7, comprising the step of: curing the rosin-based bio-based benzoxazine as described in claim 1 to obtain the high thermal conductivity liquid crystal benzoxazine resin.

9. The method for preparing the high thermal conductivity liquid crystal benzoxazine resin according to claim 8, characterized in that, The curing temperature is 120℃-280℃, and the curing time is 17min-3h.

10. The application of the high thermal conductivity liquid crystal benzoxazine resin as described in claim 7 in heat dissipation materials for integrated circuits or LED lighting electronic packaging.

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