A bio-based main-chain benzoxide resin and its preparation method

Abstract

This invention discloses a bio-based main-chain benzoxazine resin and its preparation method. The specific preparation process includes the following steps: ① Reacting natural phenol and terminal hydrogen organosiloxane in the presence of a catalyst, and removing the catalyst to obtain silanized diphenol. ② Reacting the silanized diphenol, alkyl diamine, and formaldehyde, and purifying the mixture to obtain a benzoxazine precursor. ③ Curing the obtained precursor to obtain the bio-based main-chain benzoxazine resin. This invention introduces organosiloxane chains and bulky alkyl rings into the structure of benzoxazine resin, achieving intrinsic toughening and low dielectric properties. Simultaneously, using natural phenols and turpentine-derived amine compounds as raw materials, it possesses characteristics such as low cost, simple operation, and environmental friendliness. The obtained resin is expected to be applied in composite materials, electronic insulation materials, electronic packaging materials, and other fields.

Description

Technical Field

[0001] This invention relates to a method for preparing a bio-based main-chain benzoxazine resin, and more particularly to a turpentine-derived benzoxazine resin and its preparation method. Background Technology

[0002] Benzoxazine resins are a class of oxygen-nitrogen heterocyclic intermediates synthesized from phenolic compounds, amines, and paraformaldehyde. Under heating or catalytic action, they undergo ring-opening polymerization to form nitrogen-containing, phenolic resin-like network polymers, known as benzoxazine resins or polybenzoxazine resins. Benzoxazine resins possess excellent corrosion resistance, electrical insulation, and flame retardancy, while also exhibiting excellent mechanical properties and flexible molecular design capabilities, leading to their application in aerospace and electronic packaging. However, while the high crosslinking density contributes to the high performance of benzoxazine resins, it also results in drawbacks such as brittleness and poor fracture toughness. Furthermore, the dielectric properties of benzoxazine resins do not meet the requirements of precision microelectronic devices. Therefore, improving benzoxazine resins to broaden their applications is receiving increasing attention.

[0003] Toughening of benzoxazine resins can be achieved by designing the structure, adjusting the ratio of rigid to flexible structures, and reducing the crosslinking density. Intrinsically toughened benzoxazine resin systems have minimal impact on the curing process, thermal properties, mechanical properties, and other properties of benzoxazine resins. This avoids the problems caused by poor compatibility between additive toughening agents and the matrix resin, and allows the introduction of flexible groups into the system, thus achieving superior performance. Zhang et al. synthesized a series of cashew phenol-based aromatic diamine-type benzoxazine (BZ-Xc) monomers using cashew phenol, formaldehyde aqueous solution, and -CH2- and -SiO2- aromatic diamines with different bridging groups as raw materials, and studied their curing behavior, viscosity, thermal properties, and mechanical properties. The results showed that the plasticizing effect of BZ-Xc and the flexibility of the alkyl side chains reduced the melt viscosity of the cured product and improved its toughness. Meanwhile, it had minimal impact on the heat resistance and mechanical properties of the copolymer. Kiskan et al. synthesized oligomeric siloxanes containing thermosetting benzoxazine units in the main chain and prepared flexible self-supporting films on polytetrafluoroethylene plates using a solvent casting method with dichloromethane solution. These films can maintain their shape and certain toughness after curing at 100–180 °C.

[0004] Low dielectric modification of benzoxazine resins can be achieved by introducing atoms and groups that reduce molecular polarizability into their structure, such as fluorine atoms, silicon atoms, oxazole rings, and aliphatic rings (chains). Zeng et al. synthesized an aliphatic backbone-type benzoxazine resin film. The presence of the aliphatic chain structure allows the resin film to maintain a low dielectric constant at high frequencies, with dielectric constants of 2.65 and 2.54 at 5 GHz and 10 GHz, respectively. Lu Fei et al. prepared a novel dicyclopentadiene-type benzoxazine resin. Due to the bridging ring structure in dicyclopentadiene, this resin exhibits a low dielectric constant (2.96) and dielectric loss (0.019). Summary of the Invention

[0005] In view of the shortcomings of current benzoxazine materials, this invention, based on the flexible molecular design of benzoxazine, uses a series of biophenols as phenol sources and turpentine oil derivatives. Using alkyldiamine as the amine source, an intrinsically toughened, low-dielectric main-chain benzoxazine resin was synthesized via hydrosilylation and Mannich reaction. This resin exhibits a low curing temperature and excellent thermodynamic properties, hydrophobicity, and moisture resistance. The synthesis process of this invention is simple, the resin has good processability and low production cost, allowing for large-scale production and applications in composite materials, electronic insulation materials, and electronic packaging materials.

[0006] The technical solution of the present invention is as follows: A bio-based main-chain benzoxide resin, characterized in that its chemical structural formula is:

[0007]

[0008] Where m = 1–10, n = 2–100, and the chemical structure of Ph-R is any one or two of the following structures:

[0009]

[0010] The preparation method of the bio-based main-chain benzoxide resin includes the following steps:

[0011] Step 1: React natural phenolic compounds with organosiloxanes at 60–100°C for 6–12 h under the action of a catalyst; then cool to 70–80°C, add a certain amount of activated carbon, and continue the reaction for 0.5–1 h; after cooling, filter to obtain silanized diphenols. The specific preparation reaction formula is as follows:

[0012]

[0013]

[0014] Where m = 1–10, n = 2–100, and the chemical structure of Ph-R is any one or two of the following structures:

[0015]

[0016] Step 2: Add silanized diphenol, Alkyldiamine and formaldehyde react at 80–110 °C for 4–8 h to obtain a main-chain bio-based benzoxide resin precursor. The specific preparation reaction formula is as follows:

[0017]

[0018]

[0019] Where m = 1–10, n = 2–100, and the chemical structure of Ph-R is any one or two of the following structures:

[0020]

[0021] Step 3: The obtained resin precursor is cured at 150–220℃ for 4–12 hours to obtain a bio-based main-chain benzoxide resin. The specific preparation reaction formula is as follows:

[0022]

[0023] The bio-based main-chain benzo[a]ox resin, wherein the natural phenolic compound in the first step is any one or more of eugenol, isoeugenol, piperol, or their derivatives; the catalyst is any one of Speier catalyst (isopropanol solution of chloroplatinic acid hydrate) and Karstedt catalyst (xylene solution of 1,3-divinyl-1,1,3,3-tetramethyldisiloxaneplatinum(0), Pt content of 2%), wherein the amount of Pt is 30-50 ppm of the mass of the natural phenolic compound; and the organosiloxane is a terminal hydrogen organosiloxane, wherein the amount is 0.5-0.6 times the amount of the natural phenolic substance.

[0024] The bio-based main-chain benzoxide resin, in the second step, contains formaldehyde, which is any one or both of paraformaldehyde or formaldehyde aqueous solution, and the dosage is... It is 4 to 4.05 times the mass of alkyldiamine.

[0025] Beneficial effects

[0026] (1) Based on the flexible molecular design capability of benzoxazine, this invention introduces highly regular, large-volume, low-polarity siloxanes and aliphatic rings into the benzoxazine resin structure through hydrosilylation and Mannich reaction. While maintaining the excellent performance of the resin, it achieves intrinsic toughening and low dielectric modification of the resin, thus expanding the application range of benzoxazine resin.

[0027] (2) The siloxane segments in the bio-based main chain benzo[a]ox resin structure created by this invention have excellent conformational flexibility, which can increase the spatial mobility of the molecular chain, thereby reducing the melting point of the resin precursor and reducing the curing temperature of the resin.

[0028] (3) The bio-based main chain benzoxide resin created in this invention has excellent thermodynamic properties, insulation, and antioxidant properties. The preparation process is simple, the reaction conditions are mild, and it is suitable for large-scale production.

[0029] (4) The novel bio-based main chain benzo[a]ox resin constructed by the present invention using natural phenolic compounds and turpentine-derived amine compounds as raw materials has advantages such as environmental friendliness and renewability, and is expected to be applied in the fields of composite materials, electronic insulation materials, and electronic packaging materials. Attached Figure Description

[0030] Figure 1 The NMR spectrum of the bio-based main-chain benzoxide resin precursor prepared in Example 1;

[0031] Figure 2 The DSC curing curve of the bio-based main-chain benzoxide resin prepared in Example 1.

[0032] Figure 3 SEM image of the bio-based main-chain benzoxide resin prepared in Example 1;

[0033] Figure 4 The thermogravimetric curve of the bio-based main-chain benzoxide resin prepared in Example 1. Detailed Implementation

[0034] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0035] A bio-based main-chain benzo[a]ox resin and its preparation method. Natural phenolic compounds are reacted with organosiloxanes via hydrosilylation to obtain silanized diphenols, which are then further reacted with… Alkanediamine and formaldehyde react to obtain a benzoxazine resin precursor, which is then heated and polymerized to obtain a bio-based main-chain benzoxazine resin.

[0036] A method for preparing a bio-based main-chain benzoxide resin.

[0037] Step 1: React natural phenolic compounds with organosiloxanes at 60–100°C for 6–12 h under the action of a catalyst; then cool to 70–80°C, add a certain amount of activated carbon, and continue the reaction for 0.5–1 h; after cooling, filter to obtain silanized diphenols. The specific preparation reaction formula is as follows:

[0038]

[0039] Where m = 1–10, n = 2–100, and the chemical structure of Ph-R is any one or two of the following structures:

[0040]

[0041] Step 2: Add silanized diphenol, Alkyldiamine and formaldehyde react at 80–110 °C for 4–8 h to obtain a main-chain bio-based benzoxide resin precursor. The specific preparation reaction formula is as follows:

[0042]

[0043] Where m = 1–10, n = 2–100, and the chemical structure of Ph-R is any one or two of the following structures:

[0044]

[0045] Step 3: The obtained precursor is cured at 150–220°C for 4–12 hours to obtain a bio-based main-chain benzoxide resin. The specific preparation reaction formula is as follows:

[0046]

[0047]

[0048] The bio-based main-chain benzo[a]ox resin, wherein the natural phenolic compound in the first step is any one or more of eugenol, piperine, or their derivatives; the catalyst is any one of Speier catalyst (isopropanol solution of chloroplatinic acid hydrate) and Karstedt catalyst (xylene solution of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum(O), Pt content of 2%), wherein the amount of Pt is 30-50 ppm of the mass of the natural phenolic compound; and the organosiloxane is a terminal hydrogen organosiloxane, wherein the amount is 0.5-0.6 times the amount of the natural phenolic substance.

[0049] The bio-based main-chain benzoxide resin, in the second step, contains formaldehyde, which is any one or both of paraformaldehyde or formaldehyde aqueous solution, and the dosage is... It is 4 to 4.05 times the mass of alkyldiamine.

[0050] Example 1 Based on eugenol and Preparation method of alkyldiamine synthesis main-chain benzoxazine resin

[0051] (1) Add 82.1g of eugenol and 50ppm of Karstedt catalyst to a 500mL four-necked round-bottom flask equipped with a stirrer, thermometer and reflux condenser. After purging with nitrogen for 15 minutes, add 35.3g of 1,1,3,3-tetramethyldisiloxane. Heat to 70℃ with stirring and react for 12h. Then add 5g of activated carbon and continue the reaction for 1h. Filter to remove the activated carbon to obtain silanized diphenol.

[0052] (2) Take 46.2g and 17.0g of the above-mentioned silanized diphenol. Alkyldiamine and 12.0 g of paraformaldehyde were reacted at 90 °C for 6 h to obtain a main-chain benzoxide resin precursor.

[0053] (3) Using a stepped heating method, the resin precursor obtained in step (2) is placed into a mold and cured at 150℃ and 180℃ for 4 hours each to obtain a main chain benzoxide resin.

[0054] Example 2 based on isoeugenol and Preparation method of alkyldiamine synthesis main-chain benzoxazine resin

[0055] (1) Add 82.1g of isoeugenol and 30ppm of Karstedt catalyst to a 500mL four-necked round-bottom flask equipped with a stirrer, thermometer and reflux condenser. After purging with nitrogen for 15 minutes, add 70.65g of 1,1,1,3,5,7,7,7-octamethyltetrasiloxane. Heat to 100℃ with stirring and react for 6h. Then add 5.0g of activated carbon and continue the reaction for 1h. Filter to remove the activated carbon to obtain silanized diphenol.

[0056] (2) Take 61.1g and 17.0g of the above-mentioned silanized diphenol. Alkyldiamine and 12.6 g of paraformaldehyde were reacted at 80 °C for 8 h to obtain a main-chain benzoxide resin precursor.

[0057] (3) Using a stepped heating method, the resin precursor obtained in step (2) is placed into a mold and kept at 150℃ for 2 hours, 180℃ for 2 hours, 200℃ for 2 hours, and 220℃ for 1 hour each to obtain the main chain type benzoxide resin.

[0058] Example 3 is based on piperol and Preparation method of alkyldiamine synthesis main-chain benzoxazine resin

[0059] (1) Add 67.2g of pepper phenol and 40ppm of Karstedt catalyst to a 500mL four-necked round-bottom flask equipped with a stirrer, thermometer and reflux condenser. After purging with nitrogen for 15 minutes, add 52.1g of hydrogen-terminated poly(dimethylsiloxane). Heat to 60°C with stirring and react for 12h. Then add 5g of activated carbon and continue the reaction for 1h. Filter to remove the activated carbon to obtain silanized diphenol.

[0060] (2) In a 500mL four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, add 47.7g and 17.0g of the above-mentioned silanized diphenol. Alkyldiamine and 12.0 g of paraformaldehyde were heated to 80 °C with stirring and reacted for 8 h to obtain a main-chain benzoxide resin precursor.

[0061] (3) Using a stepped heating method, the precursor obtained in step (2) is placed into a mold and cured at 150℃, 180℃, 200℃ and 220℃ for 2 hours each to obtain a main chain benzoxide resin.

[0062] Example 4 Based on eugenol and Preparation method of alkyldiamine synthesis main-chain benzoxazine resin

[0063] (1) Add 82.1g of eugenol and 50ppm of Karstedt catalyst to a 500mL four-necked round-bottom flask equipped with a stirrer, thermometer and reflux condenser. After purging with nitrogen for 15 minutes, add 270g of hydrogen-terminated polydimethylsiloxane. Heat to 80℃ with stirring and react for 12h. Then add 6g of activated carbon and continue the reaction for 0.5h. Filter to remove activated carbon and obtain silanized diphenol.

[0064] (2) Take 140.8g and 17.0g of the above-mentioned silanized diphenol. Alkyldiamine and 12.0 g of paraformaldehyde were reacted at 110 °C for 6 h to obtain a bio-based main-chain benzoxide resin precursor.

[0065] (3) Using a stepped heating method, the resin precursor obtained in step (2) is placed into a mold and cured at 150℃ and 180℃ for 4 hours each to obtain a main chain benzoxide resin.

[0066] Example 5 is based on isoeugenol and Preparation method of alkyldiamine synthesis main-chain benzoxazine resin

[0067] (1) Add 82.1g of isophenol and 50ppm of Karstedt catalyst to a 500mL four-necked round-bottom flask equipped with a stirrer, thermometer and reflux condenser. After purging with nitrogen for 15 minutes, add 35.3g of 1,1,3,3-tetramethyldisiloxane. Heat to 70℃ with stirring and react for 12h. Then add 5g of activated carbon and continue the reaction for 1h. Filter to remove the activated carbon to obtain silanized diphenol.

[0068] (2) Take 46.2g and 17.0g of the above-mentioned silanized diphenol. Alkyldiamine and 12.0 g of paraformaldehyde were reacted at 90 °C for 6 h to obtain a main-chain benzoxide resin precursor.

[0069] (3) Using a stepped heating method, the resin precursor obtained in step (2) is placed into a mold and kept at 150℃ for 4 hours, 180℃ for 4 hours, 200℃ for 2 hours, and 220℃ for 2 hours each to obtain the main chain type benzoxide resin.

[0070] Example 6 Based on eugenol and Preparation method of alkyldiamine synthesis main-chain benzoxazine resin

[0071] (1) Add 82.1g of eugenol and 50ppm of Karstedt catalyst to a 500mL four-necked round-bottom flask equipped with a stirrer, thermometer and reflux condenser. After purging with nitrogen for 15 minutes, add 70.65g of 1,1,1,3,5,7,7,7-octamethyltetrasiloxane. Heat to 100℃ with stirring and react for 4h. Then add 5.0g of activated carbon and continue the reaction for 1h. Filter to remove the activated carbon to obtain silanized diphenol.

[0072] (2) Take 61.1g and 17.0g of the above-mentioned silanized diphenol. Alkyldiamine and 12.6 g of paraformaldehyde were reacted at 80 °C for 8 h to obtain a main-chain benzoxide resin precursor.

[0073] (3) Using a stepped heating method, the resin precursor obtained in step (2) is placed into a mold and kept at 150℃ for 2 hours, 180℃ for 2 hours, 200℃ for 2 hours, and 220℃ for 1 hour each to obtain the main chain type benzoxide resin.

[0074] The tensile strength of benzoxazine resin was determined according to the method specified in national standard GB / T 2567-2008. The water absorption of benzoxazine resin was determined according to the method specified in national standard GB / T 1034-2008. The dielectric constant of the resin was determined by the parallel plate capacitance method at a test frequency of 10MHz.

[0075] Comparison table of tensile strength, tensile modulus, dielectric constant and water absorption of benzoxazine resins prepared in Examples 1-6

[0076] Test Project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Tensile strength (MPa) 9.81 11.5 12.5 9.41 11.0 11.5 Tensile modulus (MPa) 938 1010 1130 986 875 1123 Dielectric constant 3.46 3.41 3.42 3.32 3.45 3.33 Water absorption rate (%) 0 0 0 0 0 0

[0077] As can be seen from the table above, the bio-based benzoxazine resin prepared by the method of the present invention has excellent mechanical properties, dielectric properties and moisture resistance.

[0078] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a bio-based main-chain benzoxazine resin, characterized in that, The steps are as follows: Step 1: React natural phenolic compounds with terminal hydrogen-containing organosiloxanes at 60-100℃ for 6-12 hours under the action of a catalyst; then cool to 70-80℃, add a certain amount of activated carbon, and continue the reaction for 0.5-1 hour; after cooling, filter to obtain silanized diphenols; the natural phenolic compounds are any one of eugenol, isoeugenol, or piperine, and their molecular structures are as follows: or or The aforementioned terminal hydrogen-containing organosiloxane has the following chemical structural formula: Where m = 1~10; Step 2: Silyl diphenol, methyl methacrylate diamine, and formaldehyde are reacted at 80-110°C for 4-8 hours to obtain a bio-based main-chain benzoxide resin precursor. The formaldehyde is either paraformaldehyde or an aqueous formaldehyde solution. The structure of the methyl methacrylate diamine is as follows: ; Step 3: The obtained resin precursor is cured at 150~220℃ for 4~12 h to obtain a bio-based main chain benzoxazine resin.

2. The method for preparing bio-based main-chain benzoxazine resin according to claim 1, characterized in that, The catalyst mentioned in the first step is either a Speier catalyst or a Karstedt catalyst, and the amount of Pt used is 30-50 ppm of the mass of the natural phenolic compound.

3. The method for preparing bio-based main-chain benzoxazine resin according to claim 1, characterized in that, The amount of terminal hydrogen-containing organosiloxanes used is 0.5 to 0.6 times that of natural phenolic substances.

4. The method for preparing bio-based main-chain benzoxazine resin according to claim 1, characterized in that, The amount of formaldehyde used is 4 to 4.05 times the amount of diammonium oxane.

Images