Polymerizable benzoxazine surfactants, methods of making and using the same

Abstract

The application provides a polymerizable benzoxazine surfactant and a preparation method and application thereof. The application takes biomass phenolic compounds I containing long aliphatic chain structures, amine compounds II containing hydroxyl groups and formaldehyde as raw materials, and obtains biomass benzoxazine monomers III containing hydroxyl groups through reaction; the biomass benzoxazine monomers III containing hydroxyl groups and maleic anhydride are reacted to introduce double bonds, and the polymerizable benzoxazine surfactant is obtained. When the polymerizable benzoxazine surfactant is used as an emulsifier, not only can a core-shell toughening agent be prepared, but also the polymerizable benzoxazine surfactant can be copolymerized on the core-shell toughening agent, so that the surfactant does not need to be further washed, the purity of the core-shell toughening agent is improved, energy is saved, and the environment is protected. The obtained core-shell toughening agent has excellent toughening effect, can effectively toughen epoxy resin, and improves the heat resistance of the epoxy resin.

Description

Technical Field

[0001] This invention belongs to the field of surfactant technology, specifically relating to polymerizable benzoxazine surfactants, their preparation methods, and applications. Background Technology

[0002] Epoxy resin, one of the three major thermosetting resins, is widely used in flooring, coatings, adhesives, circuit boards, and other fields due to its excellent mechanical strength, thermal stability, and chemical stability. However, its high degree of cross-linking leads to brittleness and insufficient toughness. To improve the toughness of epoxy resin, researchers have studied toughening methods, mainly categorized as core-shell polymer toughening, rubber elastomer toughening, hyperbranched polymer toughening, and inorganic nanoparticle toughening. Currently, core-shell toughening agents are quite popular. In industrial production, the emulsifier is obtained through a saponification reaction using oleic acid. After the core-shell toughening agent is prepared, the emulsifier in the system affects subsequent processing performance and the performance of the final product. Therefore, a water washing step is required to remove the emulsifier, which not only increases production costs but also generates a large amount of wastewater.

[0003] Benzoxazine surfactants possess strong molecular designability; by introducing hydrophobic aliphatic chains and hydrophilic groups onto phenolic or amine source materials, they can be designed and synthesized. To date, most reported benzoxazine surfactants are nonionic surfactants. For example: Researchers synthesized mono- and bicyclic benzoxazine surfactants via the Mannich reaction using bisphenol A and tert-butylphenol as phenolic sources and a polyether monoamine (M-1000) with a molecular weight of 1000 as the amine source. These surfactants were then used to prepare stable aqueous epoxy resin emulsions. Ishida et al. reported the synthesis of the benzoxazine surfactant IV-a-Jeff using vanillin from biomass as the phenolic source. A fine emulsion with stability up to two weeks was prepared using IV-a-Jeff surfactant and polystyrene monomer. For ionic benzoxazine surfactants, Mahfud et al. used aliphatic primary amines of different chain lengths as amine sources and reacted them with p-hydroxybenzoic acid and paraformaldehyde via the Mannich reaction to synthesize benzoxazine monomers with carboxyl groups, subsequently obtaining benzoxazine resin surfactants with sodium carboxylate groups. Wang et al. synthesized the all-biomass ionic benzoxazine resin surfactant Ca-g using cashew phenol, sodium amino acid, and paraformaldehyde, preparing a high internal phase emulsion (HIPE) with a stable styrene volume fraction up to 90%.

[0004] The benzoxazine surfactants reported above do not contain double bonds and cannot copolymerize with monomers containing double bonds during free radical emulsion polymerization. When using these benzoxazine surfactants to prepare core-shell toughening agents, the system will contain this surfactant, which will affect subsequent processing performance and the performance of the final product. Although the surfactant can be washed away with water, this not only increases production costs but also generates a large amount of wastewater. Furthermore, the surfactant cannot be completely washed away, leaving residues in the system that affect subsequent processing performance and the performance of the final product. Therefore, this invention is proposed. Summary of the Invention

[0005] To address the shortcomings of existing surfactants, particularly those used in the production of core-shell toughening agents, which require subsequent surfactant removal and inevitably leave residual surfactants that can negatively impact the agent's performance, this invention aims to provide a biomass surfactant, specifically a polymerizable benzoxazine surfactant, along with its preparation method and application. This solution resolves the need for subsequent surfactant removal during core-shell toughening agent production and improves the purity of the toughening agent. The surfactant used in this invention for preparing core-shell toughening agents is energy-saving and environmentally friendly. The resulting core-shell toughening agent exhibits excellent toughening effects, effectively toughening epoxy resins and improving their heat resistance.

[0006] This invention uses hydroxyl-containing amines as raw materials to synthesize monocyclic benzoxazine monomers, which are then reacted with maleic anhydride to obtain benzoxazine surfactants containing double bonds. When used as emulsifiers, these surfactants can not only be used to prepare core-shell toughening agents, but also copolymerized onto them without the need for further surfactant removal.

[0007] To address the issue of surfactant removal during the production of core-shell toughening agents, this invention designs and synthesizes a polymerizable benzoxazine surfactant containing double bonds, which can copolymerize with the core-shell toughening agent without the need for subsequent surfactant removal.

[0008] To improve the yield of copolymerization of surfactant and core-shell toughening agent, this invention uses maleic anhydride as the source of double bonds. Because maleic anhydride has the characteristics of being copolymerizable but difficult to homopolymerize, it enables the surfactant to copolymerize onto the core-shell toughening agent in high yield.

[0009] To address the problems arising from the depletion of petroleum resources, this invention utilizes biomass phenol sources to synthesize biomass benzoxazine surfactants.

[0010] The technical solution of the present invention is as follows:

[0011] Polymerizable benzoxazine surfactants have the structure shown in Formula IV:

[0012]

[0013] in,

[0014] R1 is -(CH2)2-, -(CH2)3-, -CH2-CH(CH3)-, -(CH2)4-, -C(CH3)2-CH2-, -CH(CH3)-(CH2)2-, -CH2-CH(CH3)-CH2- or -(CH2)2-O-(CH2)2-;

[0015] R2 is -H, -OH, or -CH3;

[0016] R3 is -C 15 H 31-2n , n = 0 - 3.

[0017] The above-mentioned method for preparing polymerizable benzoxazine surfactants includes the following steps:

[0018] (1) Using biomass phenolic compound I containing a long fatty chain structure, amine compound II containing hydroxyl groups and formaldehyde as raw materials, hydroxyl-containing biomass benzoxazine monomer III was obtained through reaction;

[0019]

[0020] Among them, R1, R2, and R3 have the same meaning as R1, R2, and R3 in Formula IV compound;

[0021] (2) A double bond is introduced into the hydroxyl-containing biomass benzoxazine monomer III and maleic anhydride through a reaction to obtain a polymerizable benzoxazine surfactant, namely compound IV.

[0022] According to the present invention, preferably, in step (1), the biomass phenolic compound I containing a long fatty chain structure is any one of cashew phenol, urushiol, cardiotonic phenol or m-pentadecanylphenol.

[0023] According to the present invention, preferably, in step (1), the amine compound II containing a hydroxyl group is any one of ethanolamine, propanolamine, isopropanolamine, butanolamine, isobutanolamine, 2-aminobutanol, 3-aminobutanol or diethylene glycolamine.

[0024] According to the present invention, preferably, in step (1), the formaldehyde used is an aqueous solution of formaldehyde with a mass concentration of 36.5-38%.

[0025] 38 According to the present invention, preferably, in step (1), the molar ratio of the biomass phenolic compound I containing a long fatty chain structure, the amine compound II containing a hydroxyl group, and formaldehyde is 1:1:(2-2.5).

[0026] According to the present invention, preferably, in step (1), the reaction is carried out in a solvent; the solvent is one or a combination of two or more of toluene, chloroform, dioxane or ethanol; the mass ratio of the biomass phenolic compound I containing the long aliphatic chain structure to the volume ratio of the solvent is 1:3-5 g / mL.

[0027] According to the present invention, preferably, in step (1), the reaction temperature is 60-120°C and the reaction time is 4-12 hours.

[0028] According to the present invention, preferably, in step (1), the post-treatment method of the reaction solution obtained by the reaction is as follows: the reaction solution is removed from the solvent, then washed, and vacuum dried to obtain viscous hydroxyl-containing biomass benzoxazine monomer III.

[0029] According to the present invention, preferably, in step (2), the molar ratio of hydroxyl-containing biomass benzoxazine monomer III and maleic anhydride is 1:1.1-1.4.

[0030] According to the present invention, preferably, in step (2), the reaction is carried out in a solvent under the action of a catalyst; the solvent is one of chloroform or dichloromethane; the mass ratio of maleic anhydride to the volume ratio of the solvent is 1:3-5 g / mL; the catalyst is p-toluenesulfonic acid, 4-dimethylaminopyridine or concentrated sulfuric acid with a mass concentration of 98%; the molar ratio of the catalyst to the hydroxyl-containing biomass benzoxazine monomer III is 1:100-130.

[0031] According to the present invention, preferably, in step (2), the reaction temperature is 70-120°C and the reaction time is 3-10 hours.

[0032] According to the present invention, preferably, in step (2), after the reaction, the pH value of the system is adjusted to 7.0 using a saturated sodium bicarbonate aqueous solution.

[0033] According to the present invention, preferably, in step (2), the post-treatment method of the reaction solution obtained from the reaction is as follows: the reaction solution is washed with deionized water, and the organic phase is taken; the organic phase is dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain a solid product; the solid product is dissolved in methanol, and a saturated sodium bicarbonate aqueous solution is added dropwise until the pH of the system is 7.0, and rotary evaporated to obtain a polymerizable benzoxazine surfactant. Preferably, the mass ratio of the solid product to the volume ratio of methanol is 1:2-3 g / ml.

[0034] According to the present invention, a preferred embodiment of the preparation method of polymerizable benzoxazine surfactant includes the following steps:

[0035] (1) Dissolve biomass phenolic compound I containing long aliphatic chain structure, amine compound II containing hydroxyl group and formaldehyde aqueous solution with mass concentration of 36.5-38% in toluene, stir and react at 60-120℃ for 4-12 hours, remove solvent from reaction solution, wash and vacuum dry to obtain hydroxyl-containing biomass benzoxazine monomer III.

[0036] (2) Mix hydroxyl-containing biomass benzoxazine monomer III, maleic anhydride and chloroform, add catalyst, mix thoroughly and stir under reflux at 70-120℃ for 3-10h; wash the resulting reaction solution with deionized water and take the organic phase; dry the organic phase with anhydrous magnesium sulfate, filter and rotary evaporate to obtain solid product; dissolve the solid product in methanol, add saturated sodium bicarbonate aqueous solution dropwise until the pH of the system is 7.0, rotary evaporate to obtain polymerizable benzoxazine surfactant.

[0037] The above-mentioned polymerizable benzoxazine surfactants are used as surfactants in the preparation of core-shell toughening agents.

[0038] According to the present invention, preferably, the preparation method of the core-shell toughening agent includes the following steps:

[0039] Deionized water, butyl acrylate, 1,4-butanediol diacrylate, and polymerizable benzoxazine surfactant were thoroughly mixed and dispersed. Under stirring and protective gas protection, an initiator was added, and the reaction was carried out to obtain a polyacrylate seed emulsion. Then, under stirring and protective gas protection, methyl methacrylate was added dropwise to carry out the reaction. Finally, the core-shell toughening agent was obtained by freeze drying.

[0040] Preferably, the mass ratio of deionized water, butyl acrylate, 1,4-butanediol diacrylate, polymerizable benzoxazine surfactant, and methyl methacrylate is 20:3:0.03:0.03:2.

[0041] Preferably, the protective gas is either nitrogen or argon.

[0042] Preferably, the stirring speed is 200-300 r / min.

[0043] Preferably, the initiator is a 3%-5% potassium persulfate aqueous solution; the molar ratio of the initiator to butyl acrylate is 1:100-110.

[0044] Preferably, the reaction temperature after adding the initiator is 60-80℃, and the reaction time is 3-8h.

[0045] Preferably, the reaction temperature after adding methyl methacrylate is 60-80℃, and the reaction time is 0.5-3h.

[0046] According to the present invention, a preferred embodiment of the preparation method of the core-shell toughening agent includes the following steps:

[0047] Deionized water, butyl acrylate, 1,4-butanediol diacrylate, and polymerizable benzoxazine surfactant were added to a four-necked flask equipped with a mechanical stirrer. High-purity nitrogen was introduced, and the mixture was stirred at 200-300 rpm. When the temperature reached 60-70°C, an initiator was added, and the reaction was carried out for 4-6 hours to obtain a polyacrylate seed emulsion. Then, under stirring at 200-300 rpm and nitrogen protection, methyl methacrylate was added dropwise. After the addition was completed in 1-2 hours, the mixture was reacted at 70-75°C for 1-2 hours. The emulsion was then directly freeze-dried to obtain a core-shell toughening agent.

[0048] The present invention also provides an epoxy-core-shell toughening agent cured product, comprising: epoxy resin, core-shell toughening agent and curing agent; the mass of the curing agent is 20%-30% of the mass of the epoxy resin; the mass of the core-shell toughening agent is 2.5%-10% of the total mass of the epoxy resin, core-shell toughening agent and curing agent.

[0049] According to the present invention, preferably, the curing agent is 4,4-diaminodiphenylmethane.

[0050] The preparation method of the above-mentioned epoxy-core-shell toughening agent cured product includes the following steps:

[0051] The core-shell toughening agent and epoxy resin are thoroughly mixed, and then the curing agent is added. The mixture is then cured at 100℃, 150℃, 200℃, and 250℃ for 2 hours respectively to obtain the epoxy-core-shell toughening agent cured product.

[0052] The synthetic route for polymerizable benzoxazine surfactants of this invention is shown below:

[0053]

[0054] in,

[0055] R1 is -(CH2)2-, -(CH2)3-, -CH2-CH(CH3)-, -(CH2)4-, -C(CH3)2-CH2-, -CH(CH3)-(CH2)2-, -CH2-CH(CH3)-CH2- or -(CH2)2-O-(CH2)2-;

[0056] R2 is -H, -OH, or -CH3;

[0057] R3 is -C 15 H 31-2n , n = 0 - 3.

[0058] The technical features and beneficial effects of this invention are as follows:

[0059] 1. To address the problems arising from the depletion of petroleum resources, this invention utilizes biomass phenolic sources to synthesize biomass benzoxazine surfactants. Using amine compounds containing hydroxyl groups and biomass phenolic compounds with long aliphatic chains as raw materials, this invention designs and synthesizes hydroxyl-containing biomass benzoxazine monomers, meeting the requirements of green and sustainable development materials.

[0060] 2. This invention involves reacting hydroxyl-containing biomass benzoxazine monomers with maleic anhydride to obtain biomass surfactants, specifically benzoxazine surfactants containing double bonds. The method of this invention utilizes inexpensive and readily available raw materials, resulting in low cost. The polymerizable benzoxazine surfactant containing double bonds of this invention can copolymerize onto a core-shell toughening agent without subsequent water washing to remove the surfactant, saving costs and being environmentally friendly; furthermore, it does not contaminate the toughening agent, facilitating the preparation of high-purity core-shell toughening agents and improving their performance. To improve the yield of the copolymerization of the surfactant and the core-shell toughening agent, this invention uses maleic anhydride as the source of the double bonds. Maleic anhydride has the characteristic of being copolymerizable but difficult to homopolymerize, enabling the surfactant to copolymerize onto the core-shell toughening agent in a high yield. During the preparation of the polymerizable benzoxazine surfactant of this invention, a strictly anhydrous environment must be maintained during the incorporation of double bonds; otherwise, the double bonds cannot be successfully incorporated into the benzoxazine monomer.

[0061] 3. This invention successfully prepared a core-shell toughening agent using a benzoxazine surfactant containing double bonds, which exhibited excellent toughening effects on epoxy resin. The optimal addition amount of the prepared core-shell toughening agent was 7.5 wt%; exceeding or falling short of this optimal addition amount reduced the toughening effect. The maximum elongation at break of the epoxy-core-shell toughening agent cured product toughened with the toughening agent was 17.25%, which was 112% higher than that of the untoughened epoxy resin cured system (8.15%), and the maximum impact strength was 53.5 KJ / m. 2 Compared to the untoughened epoxy resin curing system (20.8 KJ / m²), 2 The maximum elongation at break of commercially available epoxy resin toughened with carboxyl-terminated butadiene-acrylonitrile rubber (CTBN) is around 10%, and the maximum impact strength is around 20 kJ / m. 2 The core-shell toughening agent prepared by the surfactant of this invention has a superior toughening effect compared with commercial toughening agents.

[0062] 4. This invention successfully prepared a PMMA-PBA core-shell toughening agent using a benzoxazine surfactant containing double bonds. When applied to epoxy resin toughening, the epoxy-core-shell toughening agent cured product exhibited the best toughening effect. g All temperatures are above 165℃. The best toughening effect of traditional commercial epoxy resin toughening agents on carboxyl-terminated butadiene-acrylonitrile rubber is achieved when the cured epoxy-core-shell toughening agent has a T0 of... gAt around 100℃. Therefore, the carboxyl-containing benzoxazine biomass toughening agent of the present invention has less heat resistance loss than the epoxy-core-shell toughening agent cured product obtained by commercial toughening agents, and can effectively improve the heat resistance of epoxy resin.

[0063] 5. The present invention uses emulsion polymerization to prepare core-shell toughening agents, in which an inert gas environment must be maintained at all times, otherwise the core-shell structure cannot be formed; the stirring speed should not be too fast (200-300 r / min), otherwise demulsification will occur. Attached Figure Description

[0064] Figure 1 This is the infrared spectrum of the carboxyl-containing benzoxazine monomer DYBZM from Example 1;

[0065] Figure 2 This is the 1H NMR spectrum of the carboxyl-containing benzoxazine monomer DYBZM in Example 1;

[0066] Figure 3 This is the UV absorption spectrum of the unpolymerized raw material mixture and the polymerized core-shell toughening agent in Example 1;

[0067] Figure 4 These are surface tension diagrams of aqueous solutions of surfactants at different concentrations in Example 1;

[0068] Figure 5 This is a transmission electron microscope (TEM) image of the core-shell toughening agent in Example 1;

[0069] Figure 6 This is a comparison of the elongation at break of epoxy resin toughened with different contents of CRS-DYBZM-Na toughening agent in Experiment Example 1.

[0070] Figure 7 This is a comparison chart of the elongation at break of epoxy resin toughened with different contents of CRS-YM-Na toughening agent in Experiment Example 1.

[0071] Figure 8 This is a comparison chart of the impact strength of epoxy resin toughened with different amounts of toughening agent in Experiment Example 1.

[0072] Figure 9 This is a comparison chart of DMA (dynamic thermomechanical analysis) of epoxy resin toughened with different contents of CRS-DYBZM-Na toughening agent in Experiment Example 1.

[0073] Figure 10 This is a comparison chart of DMA (dynamic thermomechanical analysis) of epoxy resin toughened with different contents of CRS-YM-Na toughening agent in Experiment Example 1.

[0074] Figure 11This is a comparison chart of TGA (thermal weight loss analysis) of epoxy resin toughened with different contents of CRS-DYBZM-Na toughening agent in Experiment Example 1.

[0075] Figure 12 This is a comparison chart of TGA (thermal weight loss analysis) of epoxy resin toughened with different contents of CRS-YM-Na toughening agent in Experiment Example 1. Detailed Implementation

[0076] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the embodiments described are only some representative embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention. In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0077] Unless otherwise specified, all raw materials used in the embodiments are conventional raw materials that can be purchased commercially; unless otherwise specified, all methods used in the embodiments are existing technologies.

[0078] Example 1: Preparation method of polymerizable benzoxazine surfactant and core-shell toughening agent based on diethylene glycolamine and cashew nut phenol

[0079] Preparation of polymerizable benzoxazine surfactants

[0080] (1) Diethylene glycolamine, cashew phenol and a 38% aqueous solution of formaldehyde (molar ratio of diethylene glycolamine, cashew phenol and formaldehyde is 1:1:2) were fully dissolved in an organic solvent (toluene, the mass ratio of cashew phenol to solvent is 1:5 g / ml). The mixture was stirred at 90°C for 4 hours. The solvent was removed from the reaction solution, and then the solution was washed with deionized water and dried under vacuum to obtain a viscous hydroxyl-containing biomass benzoxazine monomer with a yield of 85%.

[0081] (2) The hydroxyl-containing biomass benzoxazine monomer and maleic anhydride were placed in a three-necked flask containing chloroform (water removed) (the mass ratio of maleic anhydride to the volume ratio of chloroform was 1:5 g / ml) at a molar ratio of 1:1.3. p-Toluenesulfonic acid (the molar ratio of the hydroxyl-containing biomass benzoxazine monomer to p-toluenesulfonic acid was 100:1) was added and the mixture was thoroughly mixed. The mixture was heated to 70°C and stirred under reflux for 6 hours. The mixture was washed three times with deionized water, and the lower chloroform phase was separated. The mixture was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the carboxyl-containing benzoxazine monomer DYBZM dissolved in methanol (the mass ratio of DYBZM to the volume ratio of methanol was 1:3 g / ml). A saturated sodium bicarbonate aqueous solution was added dropwise until the pH of the aqueous solution was 7.0. The solvent was then evaporated to obtain the polymerizable benzoxazine surfactant DYBZM-Na with a yield of 78%.

[0082] Preparation of core-shell toughening agents

[0083] (3) Add deionized water, butyl acrylate (BA), 1,4-butanediol diacrylate, and DYBZM-Na (the mass ratio of deionized water, butyl acrylate, 1,4-butanediol diacrylate, and DYBZM-Na is 20:3:0.03:0.03) to a 250ml four-necked flask equipped with a mechanical stirrer, purge with high-purity nitrogen, stir at a speed of 200r / min, and when the temperature reaches 70℃, add potassium persulfate initiator (5% by mass). A potassium hydroxide aqueous solution (with a molar ratio of initiator to butyl acrylate of 1:100) was reacted for 5 h to obtain a polyacrylate seed emulsion. Then, methyl methacrylate (MMA, with a mass ratio of methyl methacrylate to butyl acrylate of 2:3) was placed in a constant pressure dropping funnel and added dropwise over 1.5 h under stirring at 200 r / min and nitrogen protection. The reaction was then carried out at 75 °C for 1 h. The emulsion was then freeze-dried to obtain the powdered core-shell toughening agent CRS-DYBZM-Na.

[0084] In contrast, cashew phenol was used instead of hydroxyl-containing biomass benzoxazine monomer to directly prepare surfactant YM-Na (i.e., step (1) was omitted, and cashew phenol was used instead of hydroxyl-containing biomass benzoxazine monomer to directly proceed to step (2)), and core-shell toughening agent CRS-YM-Na was prepared according to the above method.

[0085] See Figure 1 and Figure 2 The infrared and nuclear magnetic resonance spectra of DYBZM, a carboxyl-containing benzoxazine monomer prepared in this embodiment. DYBZM is spectral at 3290 cm⁻¹. -1 The peak at 1250 cm⁻¹ is a characteristic peak of the hydroxyl group on the carboxyl group. -1 (COC, asymmetric stretching), 1080cm -1 (COC, symmetrical stretching) and 960cm-1 The characteristic peaks at (oxazine ring skeletal vibration and CH-face outward bending) indicate the formation of the oxazine ring, at 1711 cm⁻¹. -1 The peak at 4.91 ppm is a carbonyl peak. The peaks at 4.11 ppm are attributed to the signal peaks of O-CH2-N and N-CH2-Ar on the oxazine ring.

[0086] 1 H NMR (400MHz, CDCl3, ppm): 9.51ppm (H,s,-COOH), 6.71-6.96ppm (3H,m,Ar-H), 6.40ppm ( H,s,-CH=CH-), 6.10ppm(H,s,-CH=CH-), 4.91ppm(2H,s,O-CH2-N), 4.11ppm(2H,s,N-CH 2- Ar), 2.71-2.78ppm(2H,t,-CH2-N), 1.52ppm(2H,m,-CH2-CH3), 1.31-1.16ppm(30H,m,-CH2-), 0.88ppm(3H,t,-CH3), 2.98ppm(2H,t,N-CH2-). 4.25ppm(2H,t,-CH2-O), 3.67ppm(2H,s,O-CH2-).

[0087] See Figure 3 The UV-Vis absorption spectra of the core-shell toughening agents CRS-DYBZM-Na and CRS-YM-Na prepared in this embodiment, as well as the mixtures of surfactant and BA, MMA, 1,4-butanediol diacrylate, and deionized water in this embodiment (DYBZM-Na-MMA-BA, CRS-YM-Na-MMA-BA, with the molar ratio of each raw material in the mixture being the same as above) are shown. The surfactant and acrylate mixture that did not undergo polymerization showed a double bond signal peak at 230 nm, and a signal peak belonging to the double bonds in the cashew phenol side chain at 250-300 nm. The synthesized core-shell toughening agent showed no peak at 230 nm, proving that the double bonds belonging to the acrylate were successfully polymerized, and the double bonds belonging to the surfactant were also successfully copolymerized with the core-shell toughening agent.

[0088] See Figure 4 Surface tension maps of aqueous solutions of YM-Na and DYBZM-Na at different concentrations are shown, illustrating the surface tension of these solutions at 25℃. As the concentration of DYBZM-Na increases, the surface tension of its aqueous solution decreases sharply. The surface tension reaches its lowest value (γ) at a concentration of 0.3 g / L. cmcThe surface tension of the DYBZM-Na aqueous solution was 37.8 mN / m. With further increases in the concentration of DYBZM-Na, the surface tension remained essentially stable. Therefore, the concentration of DYBZM-Na at the surface tension inflection point is its critical micelle concentration (cmc). Surface tension tests were performed on the YM-Na aqueous solution using the same method, and the results showed that the cmc of YM-Na was similar to that of γ-ray dimethyl ether (γ-ray dimethyl ether). cmc The concentrations were 0.5 g / L and 42.2 mN / m, respectively. Currently, when preparing oil-in-water emulsions, the HLB value of the surfactant should be between 10 and 15. Therefore, based on comprehensive comparison, the emulsifying ability of the two surfactants prepared is superior to that of commercially available emulsifiers such as sodium dodecyl sulfate. DYBZM-Na exhibits better emulsifying performance than YM-Na, indicating that the ether bond in the amine source used to synthesize the benzoxazine monomer enhances its emulsifying properties. The data are summarized in Table 1.

[0089] Table 1 Emulsifying properties of surfactants

[0090]

[0091] like Figure 5 The morphology and structure of the core-shell toughening agent are shown below. Figure 5 The top and bottom images are transmission electron microscopy (TEM) images of CRS-YM-Na and CRS-DYBZM-Na, respectively. The TEM images show that both CRS-YM-Na and CRS-DYBZM-Na exhibit a distinct core-shell structure, confirming the successful synthesis of these core-shell toughening agents. The average particle sizes of CRS-YM-Na and CRS-DYBZM-Na are 165 nm and 110 nm, respectively. CRS-DYBZM-Na has a smaller particle size than CRS-YM-Na, which allows for better dispersion in epoxy resin systems and results in superior toughening performance.

[0092] Example 2: Preparation method of polymerized benzoxazine surfactant and core-shell toughening agent based on ethanolamine and urushiol. Preparation of polymerizable benzoxazine surfactant.

[0093] (1) Ethanolamine, urushiol and a 36.5% aqueous solution of formaldehyde (molar ratio of ethanolamine, urushiol and formaldehyde is 1:1:2.1) were fully dissolved in an organic solvent (mass ratio of dioxane and cashew phenol to solvent is 1:3 g / ml). The mixture was stirred at 60°C for 12 hours. The solvent was removed from the reaction solution, and then it was washed with tert-butyl ether and dried under vacuum to obtain a viscous hydroxyl-containing biomass benzoxazine monomer with a yield of 87%.

[0094] (2) The hydroxyl-containing biomass benzoxazine monomer and maleic anhydride were placed in a three-necked flask containing chloroform (water removed) (the mass ratio of maleic anhydride to the volume ratio of chloroform was 1:4 g / ml) at a molar ratio of 1:1.3. Concentrated sulfuric acid with a mass concentration of 98% (the molar ratio of the hydroxyl-containing biomass benzoxazine monomer to concentrated sulfuric acid was 120:1) was added and thoroughly mixed. The mixture was heated to 75°C and stirred under reflux for 10 h. The mixture was washed three times with deionized water, and the lower chloroform phase was separated. The mixture was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the carboxyl-containing benzoxazine monomer DYBZM. The DYBZM was dissolved in methanol (the mass ratio of DYBZM to the volume ratio of methanol was 1:2 g / ml). Saturated sodium bicarbonate aqueous solution was added dropwise until the pH of the aqueous solution was 7.0. The solvent was then evaporated to obtain the polymerizable benzoxazine surfactant DYBZM-Na with a yield of 70%.

[0095] Preparation of core-shell toughening agents

[0096] (3) Add deionized water, butyl acrylate (BA), 1,4-butanediol diacrylate, and DYBZM-Na (the mass ratio of deionized water, butyl acrylate, 1,4-butanediol diacrylate, and DYBZM-Na is 20:3:0.03:0.03) to a 250ml four-necked flask equipped with a mechanical stirrer. Purge with high-purity nitrogen and stir at 200r / min. When the temperature reaches 70℃, add potassium persulfate initiator (3% by mass). A potassium hydroxide aqueous solution (with a molar ratio of initiator to butyl acrylate of 1:105) was reacted for 6 hours to obtain a polyacrylate seed emulsion. Then, methyl methacrylate (MMA, with a mass ratio of methyl methacrylate to butyl acrylate of 2:3) was placed in a constant pressure dropping funnel and added dropwise over 2 hours under stirring at 200 r / min and nitrogen protection. After the addition was completed, the reaction was stopped at 70 °C for 1.5 hours. The emulsion was then directly freeze-dried to obtain the powdered core-shell toughening agent CRS-DYBZM-Na.

[0097] Example 3: Preparation method of polymerizable benzoxazine surfactant and core-shell toughening agent based on propanolamine and m-pentadecanylphenol

[0098] Preparation of polymerizable benzoxazine surfactants

[0099] (1) Propanolamine, m-pentadecanylphenol and a 38% aqueous solution of formaldehyde (molar ratio of propanolamine, m-pentadecanylphenol and formaldehyde is 1:1:2.3) were fully dissolved in an organic solvent (chloroform, the mass ratio of cashew phenol to solvent is 1:4 g / ml). The mixture was stirred at 85°C for 11 hours. The solvent was removed from the reaction solution, and then the solution was washed with ether and dried under vacuum to obtain a viscous hydroxyl-containing biomass benzoxazine monomer with a yield of 79%.

[0100] (2) The hydroxyl-containing biomass benzoxazine monomer and maleic anhydride were placed in a three-necked flask containing dichloromethane (water removed) (the mass ratio of maleic anhydride to the volume ratio of dichloromethane was 1:5 g / ml) at a molar ratio of 1:1.3. 4-Dimethylaminopyridine (the molar ratio of the hydroxyl-containing biomass benzoxazine monomer and 4-dimethylaminopyridine was 130:1) was added and thoroughly mixed. The mixture was heated to 95°C and stirred under reflux for 6 hours. The mixture was washed three times with deionized water, and the lower chloroform phase was separated. The mixture was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the carboxyl-containing benzoxazine monomer DYBZM. The DYBZM was dissolved in methanol (the mass ratio of DYBZM to the volume ratio of methanol was 1:2 g / ml). A saturated sodium bicarbonate aqueous solution was added dropwise until the pH of the aqueous solution was 7.0. The solvent was then evaporated to obtain the polymerizable benzoxazine surfactant DYBZM-Na with a yield of 75%.

[0101] Preparation of core-shell toughening agents

[0102] (3) Deionized water, butyl acrylate (BA), 1,4-butanediol diacrylate, and DYBZM-Na (mass ratio of deionized water, butyl acrylate, 1,4-butanediol diacrylate, and DYBZM-Na is 20:3:0.03:0.03) were added to a 250ml four-necked flask equipped with a mechanical stirrer. High-purity nitrogen gas was introduced, and the mixture was stirred at a speed of 300r / min. When the temperature reached 70℃, potassium persulfate initiator (mass concentration of 3.5%) was added. A potassium persulfate aqueous solution (with an initiator and butyl acrylate molar ratio of 1:110) was reacted for 6 hours to obtain a polyacrylate seed emulsion. Then, methyl methacrylate (MMA, with a mass ratio of methyl methacrylate to butyl acrylate of 2:3) was placed in a constant pressure dropping funnel and added dropwise over 1 hour under stirring at 300 r / min and nitrogen protection. The reaction was then carried out at 70°C for 2 hours. The emulsion was then freeze-dried to obtain the powdered core-shell toughening agent CRS-DYBZM-Na.

[0103] Example 4: Preparation method of polymerizable benzoxazine surfactant and core-shell toughening agent based on isopropanolamine and cashew nut phenol.

[0104] Preparation of polymerizable benzoxazine surfactants

[0105] (1) Isopropanolamine, cashew phenol and a 37% aqueous solution of formaldehyde (molar ratio of isopropanolamine, cashew phenol and formaldehyde is 1:1:2.5) were fully dissolved in an organic solvent (toluene, the mass ratio of cashew phenol to solvent is 1:3.5 g / ml). The mixture was stirred at 90°C for 8 hours. The reaction solution was then removed from the solvent, washed with tert-butyl ether, and dried under vacuum to obtain a viscous hydroxyl-containing biomass benzoxazine monomer with a yield of 86%.

[0106] (2) The hydroxyl-containing biomass benzoxazine monomer and maleic anhydride were placed in a three-necked flask containing dichloromethane (water removed) (the mass ratio of maleic anhydride to the volume ratio of dichloromethane was 1:3.5 g / ml) at a molar ratio of 1:1.1. p-Toluenesulfonic acid (the molar ratio of the hydroxyl-containing biomass benzoxazine monomer to p-toluenesulfonic acid was 105:1) was added, and the mixture was thoroughly mixed. The temperature was raised to 70°C, and the mixture was refluxed and stirred for 6 hours. The mixture was washed three times with deionized water, and the lower chloroform phase was separated. The mixture was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the carboxyl-containing benzoxazine monomer DYBZM. The monomer was dissolved in methanol (the mass ratio of DYBZM to the volume ratio of methanol was 1:3 g / ml). A saturated sodium bicarbonate aqueous solution was added dropwise until the pH of the aqueous solution was 7.0. The solvent was then evaporated to obtain the polymerizable benzoxazine surfactant DYBZM-Na with a yield of 80%.

[0107] Preparation of core-shell toughening agents

[0108] (3) Deionized water, butyl acrylate (BA), 1,4-butanediol diacrylate, and DYBZM-Na (the mass ratio of deionized water, butyl acrylate, 1,4-butanediol diacrylate, and DYBZM-Na is 20:3:0.03:0.03) are added to a 250ml four-necked flask equipped with a mechanical stirrer. High-purity nitrogen gas is introduced, and the mixture is stirred at a speed of 250r / min. When the temperature reaches 70℃, potassium persulfate initiator (4.5% by mass) is added. A potassium hydroxide aqueous solution (with a molar ratio of initiator to butyl acrylate of 1:105) was reacted for 4 h to obtain a polyacrylate seed emulsion. Then, methyl methacrylate (MMA, with a mass ratio of methyl methacrylate to butyl acrylate of 2:3) was placed in a constant pressure dropping funnel and added dropwise over 1.5 h under stirring at 250 r / min and nitrogen protection. The reaction was then carried out at 70 °C for 1.5 h. The emulsion was then freeze-dried to obtain the powdered core-shell toughening agent CRS-DYBZM-Na.

[0109] Example 5: Preparation method of polymerizable benzoxazine surfactant and core-shell toughening agent based on butanolamine and cardiotonic phenol.

[0110] (1) Butanolamine, cardiac glycoside and formaldehyde aqueous solution with a mass concentration of 37% (molar ratio of butanolamine, cardiac glycoside and formaldehyde is 1:1:2.4) were fully dissolved in an organic solvent (mixed solvent of toluene and ethanol, volume ratio of toluene and ethanol is 4:1, mass ratio of cashew phenol to solvent is 1:4 g / ml). The reaction was stirred at 120℃ for 5 hours. The reaction solution was then removed from the solvent, washed with tert-butyl ether, and dried under vacuum to obtain a viscous hydroxyl-containing biomass benzoxazine monomer with a yield of 89%.

[0111] (2) The hydroxyl-containing biomass benzoxazine monomer and maleic anhydride were placed in a three-necked flask containing chloroform (water-free) (the mass ratio of maleic anhydride to the volume ratio of chloroform was 1:4.5 g / ml) at a molar ratio of 1:1.4. p-Toluenesulfonic acid (the molar ratio of the hydroxyl-containing biomass benzoxazine monomer to p-toluenesulfonic acid was 105:1) was added, and the mixture was thoroughly mixed. The mixture was heated to 110°C and stirred under reflux for 5 hours. The mixture was washed three times with deionized water, and the lower chloroform phase was separated. The mixture was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the carboxyl-containing benzoxazine monomer DYBZM. The DYBZM was dissolved in methanol (the mass ratio of DYBZM to the volume ratio of methanol was 1:3 g / ml). A saturated sodium bicarbonate aqueous solution was added dropwise until the pH of the aqueous solution was 7.0. The solvent was then evaporated to obtain the polymerizable benzoxazine surfactant DYBZM-Na with a yield of 81%.

[0112] Preparation of core-shell toughening agents

[0113] (3) Add deionized water, butyl acrylate (BA), 1,4-butanediol diacrylate, and DYBZM-Na (the mass ratio of deionized water, butyl acrylate, 1,4-butanediol diacrylate, and DYBZM-Na is 20:3:0.03:0.03) to a 250ml four-necked flask equipped with a mechanical stirrer. Purge with high-purity nitrogen and stir at 200r / min. When the temperature reaches 70℃, add potassium persulfate initiator (3% by mass). A potassium hydroxide aqueous solution (with a molar ratio of initiator to butyl acrylate of 1:100) was reacted for 5.5 h to obtain a polyacrylate seed emulsion. Then, methyl methacrylate (MMA, with a mass ratio of methyl methacrylate to butyl acrylate of 2:3) was placed in a constant pressure dropping funnel and added dropwise over 2 h under stirring at 200 r / min and nitrogen protection. After the addition was completed, the reaction was stopped at 70 °C for 1 h. The emulsion was then directly freeze-dried to obtain the powdered core-shell toughening agent CRS-DYBZM-Na.

[0114] Example 6: Preparation method of polymerizable benzoxazine surfactant and core-shell toughening agent based on isobutanolamine and cashew nut phenol.

[0115] Preparation of polymerizable benzoxazine surfactants

[0116] (1) Isobutanolamine, cashew phenol and a 38% aqueous solution of formaldehyde (molar ratio of isobutanolamine, cashew phenol and formaldehyde is 1:1:2.5) were fully dissolved in an organic solvent (toluene, the mass ratio of cashew phenol to solvent is 1:5 g / ml). The mixture was stirred at 100°C for 6 hours. The solvent was removed from the reaction solution, and then the solution was washed with deionized water and dried under vacuum to obtain a viscous hydroxyl-containing biomass benzoxazine monomer with a yield of 88%.

[0117] (2) The hydroxyl-containing biomass benzoxazine monomer and maleic anhydride were placed in a three-necked flask containing chloroform (water removed) (the mass ratio of maleic anhydride to the volume ratio of chloroform was 1:4 g / ml) at a molar ratio of 1:1.3. 4-Dimethylaminopyridine (the molar ratio of the hydroxyl-containing biomass benzoxazine monomer and 4-dimethylaminopyridine was 110:1) was added and mixed thoroughly. The mixture was heated to 110°C and stirred under reflux for 6 hours. The mixture was washed three times with deionized water, and the lower chloroform phase was separated. The mixture was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the carboxyl-containing benzoxazine monomer DYBZM. The DYBZM was dissolved in methanol (the mass ratio of DYBZM to the volume ratio of methanol was 1:3 g / ml). A saturated sodium bicarbonate aqueous solution was added dropwise until the pH of the aqueous solution was 7.0. The solvent was then evaporated to obtain the polymerizable benzoxazine surfactant DYBZM-Na with a yield of 75%.

[0118] Preparation of core-shell toughening agents

[0119] (3) Deionized water, butyl acrylate (BA), 1,4-butanediol diacrylate, and DYBZM-Na (the mass ratio of deionized water, butyl acrylate, 1,4-butanediol diacrylate, and DYBZM-Na is 20:3:0.03:0.03) were added to a 250ml four-necked flask equipped with a mechanical stirrer. High-purity nitrogen gas was introduced, and the mixture was stirred at a speed of 300r / min. When the temperature reached 70℃, potassium persulfate initiator (mass concentration of 4.5%) was added. A potassium sulfate aqueous solution (with an initiator and butyl acrylate molar ratio of 1:110) was reacted for 4 hours to obtain a polyacrylate seed emulsion. Then, methyl methacrylate (MMA, with a mass ratio of methyl methacrylate to butyl acrylate of 2:3) was placed in a constant pressure dropping funnel and added dropwise over 1.5 hours under stirring at 300 r / min and nitrogen protection. The reaction was then carried out at 70°C for 2 hours. The emulsion was then directly freeze-dried to obtain the powdered core-shell toughening agent CRS-DYBZM-Na.

[0120] Example 7: Preparation method of polymerizable benzoxazine surfactant and core-shell toughening agent based on 2-aminobutanol and cardiotonic phenol.

[0121] Preparation of polymerizable benzoxazine surfactants

[0122] (1) 2-Aminobutanol, cardiotonic phenol and formaldehyde aqueous solution with a mass concentration of 38% (the molar ratio of 2-aminobutanol, cardiotonic phenol and formaldehyde is 1:1:2.5) were fully dissolved in an organic solvent (the mass ratio of dioxane and cashew phenol to the volume of the solvent is 1:4.5 g / ml). The reaction was stirred at 85°C for 12 hours. The reaction solution was then removed from the solvent, washed with deionized water and dried under vacuum to obtain a viscous hydroxyl-containing biomass benzoxazine monomer with a yield of 84%.

[0123] (2) The hydroxyl-containing biomass benzoxazine monomer and maleic anhydride were placed in a three-necked flask containing chloroform (excluding water) (the mass ratio of maleic anhydride to the volume ratio of chloroform was 1:3.5 g / ml) at a molar ratio of 1:1.3. p-Toluenesulfonic acid (the molar ratio of the hydroxyl-containing biomass benzoxazine monomer to p-toluenesulfonic acid was 130:1) was added, and the mixture was thoroughly mixed. The mixture was heated to 115°C and stirred under reflux for 8 hours. The mixture was washed three times with deionized water, and the lower chloroform phase was separated. The mixture was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the carboxyl-containing benzoxazine monomer DYBZM. The DYBZM was dissolved in methanol (the mass ratio of DYBZM to the volume ratio of methanol was 1:3 g / ml). A saturated sodium bicarbonate aqueous solution was added dropwise until the pH of the aqueous solution was 7.0. The solvent was then evaporated to obtain the polymerizable benzoxazine surfactant DYBZM-Na with a yield of 72%.

[0124] Preparation of core-shell toughening agents

[0125] (3) Add deionized water, butyl acrylate (BA), 1,4-butanediol diacrylate, and DYBZM-Na (the mass ratio of deionized water, butyl acrylate, 1,4-butanediol diacrylate, and DYBZM-Na is 20:3:0.03:0.03) to a 250ml four-necked flask equipped with a mechanical stirrer, purge with high-purity nitrogen, stir at a speed of 250r / min, and when the temperature reaches 60℃, add potassium persulfate initiator (3% persulfate by mass). A potassium aqueous solution (with a molar ratio of initiator to butyl acrylate of 1:110) was reacted for 5 h to obtain a polyacrylate seed emulsion. Then, methyl methacrylate (MMA, with a mass ratio of methyl methacrylate to butyl acrylate of 2:3) was placed in a constant pressure dropping funnel and added dropwise over 1.5 h under stirring at 250 r / min and nitrogen protection. The reaction was then carried out at 70 °C for 1.5 h. The emulsion was then freeze-dried to obtain the powdered core-shell toughening agent CRS-DYBZM-Na.

[0126] Example 8: Preparation method of polymerizable benzoxazine surfactant and core-shell toughening agent based on 3-aminobutanol and cashew nut phenol.

[0127] Preparation of polymerizable benzoxazine surfactants

[0128] (1) 3-aminobutanol, cashew phenol and formaldehyde aqueous solution with a mass concentration of 36.5% (molar ratio of 3-aminobutanol, cashew phenol and formaldehyde is 1:1:2.4) were fully dissolved in organic solvent (chloroform, mass ratio of cashew phenol to solvent is 1:5 g / ml) and stirred at 115℃ for 10 hours. The reaction solution was then removed from the solvent, washed with sodium hydroxide aqueous solution and vacuum dried to obtain viscous hydroxyl-containing biomass benzoxazine monomer with a yield of 83%.

[0129] (2) The hydroxyl-containing biomass benzoxazine monomer and maleic anhydride were placed in a three-necked flask containing chloroform (water removed) (the mass ratio of maleic anhydride to the volume ratio of chloroform was 1:4 g / ml) at a molar ratio of 1:1.3. p-Toluenesulfonic acid (the molar ratio of the hydroxyl-containing biomass benzoxazine monomer to p-toluenesulfonic acid was 120:1) was added and mixed thoroughly. The mixture was heated to 120°C and stirred under reflux for 6 hours. The mixture was washed three times with deionized water, and the lower chloroform phase was separated. The mixture was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the carboxyl-containing benzoxazine monomer DYBZM. The DYBZM was dissolved in methanol (the mass ratio of DYBZM to the volume ratio of methanol was 1:2.5). A saturated sodium bicarbonate aqueous solution was added dropwise until the pH of the aqueous solution was 7.0. The solvent was then evaporated to obtain the polymerizable benzoxazine surfactant DYBZM-Na with a yield of 69%.

[0130] Preparation of core-shell toughening agents

[0131] (3) Deionized water, butyl acrylate (BA), 1,4-butanediol diacrylate, and DYBZM-Na (the mass ratio of deionized water, butyl acrylate, 1,4-butanediol diacrylate, and DYBZM-Na is 20:3:0.03:0.03) are added to a 250ml four-necked flask equipped with a mechanical stirrer. High-purity nitrogen gas is introduced, and the mixture is stirred at a speed of 200r / min. When the temperature reaches 70℃, potassium persulfate initiator (mass concentration of 5%) is added. A potassium sulfate aqueous solution (with an initiator and butyl acrylate molar ratio of 1:100) was reacted for 6 hours to obtain a polyacrylate seed emulsion. Then, methyl methacrylate (MMA, with a mass ratio of methyl methacrylate to butyl acrylate of 2:3) was placed in a constant pressure dropping funnel and added dropwise over 2 hours under stirring at 200 r / min and nitrogen protection. After the addition was completed, the reaction was stopped at 70°C for 1 hour. The emulsion was then directly freeze-dried to obtain the powdered core-shell toughening agent CRS-DYBZM-Na.

[0132] Experimental Example 1

[0133] The core-shell toughening agents CRS-DYBZM-Na and CRS-YM-Na from Example 1 were thoroughly mixed with epoxy resin (E51). Then, 4,4-diaminodiphenylmethane curing agent (25 parts by weight, epoxy resin 100 parts by weight) was added to obtain an epoxy resin blend. The epoxy resin blend was cured at 100℃, 150℃, 200℃, and 250℃ for 2 hours respectively to obtain the epoxy-core-shell toughening agent cured product. The mass of the core-shell toughening agent was 2.5wt%, 5wt%, 7.5wt%, or 10wt% of the total mass of the raw materials (core-shell toughening agent, epoxy resin, and curing agent). The epoxy-core-shell toughening agent cured product prepared with core-shell toughening agent CRS-DYBZM-Na is abbreviated as CRS-DYBZM-EP; the epoxy-core-shell toughening agent cured product prepared with core-shell toughening agent CRS-YM-Na is abbreviated as CRS-YM-EP.

[0134] Meanwhile, a comparison was made with the epoxy resin cured product prepared without a core-shell toughening agent. The epoxy resin cured product was prepared in the same way as above, except that no core-shell toughening agent was added. The resulting epoxy resin cured product is referred to as Comparative Example 1 or EP.

[0135] Figure 6-7 These are the stress-strain curves of CRS-DYBZM-EP and CRS-YM-EP, respectively. Figure 8 This is a bar chart of the impact strength of EP, CRS-YM-EP, and CRS-DYBZM-EP. The chart shows that the elongation at break of pure epoxy resin is 8.15%, and the tensile strength is 52.1 MPa. After adding CRS-YM-Na and CRS-DYBZM-Na core-shell toughening agents, the toughness of the epoxy resin is significantly improved. For CRS-YM-Na... Figure 8 As the dosage of CRS-YM-Na increases, the elongation at break of the epoxy resin first increases and then decreases. Although the tensile strength is slightly lower than that of pure epoxy resin, it remains essentially unchanged. At a dosage of 5 wt%, the elongation at break reaches a maximum of 14.6%, an increase of 53.3% compared to pure epoxy resin. Compared to the tensile strength of pure epoxy resin, the tensile strength of the toughened epoxy resin at this point is 45.85 MPa, still maintaining a considerably high strength. When the dosage of CRS-YM-Na continues to increase, the elongation at break of the epoxy resin shows a decreasing trend, but still remains at a relatively high value. For CRS-DYBZM-Na... Figure 7 As the dosage of this agent increases, the elongation at break of the epoxy resin first increases significantly and then decreases, while the tensile strength gradually decreases. At a dosage of 7.5 wt%, the elongation at break reaches a maximum of 17.25%, which is 112% higher than that of pure epoxy resin. At this point, the tensile strength is 40.9 MPa. Therefore, it can be seen that the toughening agent CRS-DYBZM-Na of this invention exhibits superior toughening effect compared to CRS-YM-Na while maintaining a high tensile strength of the epoxy resin. Figure 9 It is known that the impact strength of epoxy resin is effectively improved after adding CRS-YM-Na and CRS-DYBZM-Na core-shell toughening agents; and the toughening agent CRS-DYBZM-Na of the present invention has a better toughening effect than CRS-YM-Na.

[0136] Based on the above, the optimal toughening effect of CRS-DYBZM-Na is shown in the toughened epoxy resin having an elongation at break of 17.25% and an impact strength of 53.5 KJ / m. 2 The optimal toughening effect of CRS-YM-Na was observed in the toughened epoxy resin, with an elongation at break of 14.6% and an impact strength of 48.9 KJ / m. 2 The elongation at break and impact strength of CRS-DYBZM-Na are both greater than those of CRS-YM-Na, so its toughening effect is better than that of CRS-YM-Na.

[0137] Figure 9-10 The DMA curves for CRS-DYBZM-EP and CRS-YM-EP are shown below. Figure 11-12 The figures show the TGA curves for CRS-DYBZM-EP and CRS-YM-EP, respectively. As can be seen from the figures, the addition of CRS-YM-Na and CRS-DYBZM-Na generally slightly increases the glass transition temperature (Tg) of the epoxy resin. g Both CRS-YM-EP and CRS-DYBZM-EP exhibited a single-stage degradation process, demonstrating that the core-shell toughening agent formed a homogeneous system with the epoxy resin. Compared to pure epoxy resin, the addition of the toughening agent resulted in a higher TT of the toughened epoxy resin. d5 T d10 The slight increase is due to the addition of the core-shell toughening agent, which increases the crosslinking density of the epoxy resin system, leading to a higher Tg. g The glass transition temperature of CRS-DYBZM-EP increased more significantly because its core-shell structure has a smaller particle size, making it easier to disperse evenly in the epoxy resin system and better increase the crosslinking density.

[0138] See Table 2 for a summary of the specific data.

[0139] Table 2 Performance parameters of different epoxy resin curing systems

[0140]

[0141] As shown in Table 2:

[0142] (1) The core-shell toughening agents of the present invention all have a toughening effect on epoxy resin. Compared with the epoxy resin curing system without toughening agent (Comparative Example 1), the epoxy resin with added core-shell toughening agent has increased elongation at break, increased impact strength, decreased tensile strength, and slightly increased glass transition temperature.

[0143] (2) With the increase of the core-shell toughening agent CRS-DYBZM content, the elongation at break of the cured epoxy resin first increases and then decreases, the impact strength first increases and then decreases, the tensile strength decreases, and the glass transition temperature first increases and then decreases. Among them, the elongation at break is the largest (17.25%) and the impact strength is the largest (53.5 KJ / m) when the toughening agent content is 7.5%. 2 As the content of the core-shell toughening agent CRS-YM increases, the elongation at break of the epoxy resin initially increases and then decreases. Although the tensile strength is slightly lower than that of pure epoxy resin, it remains essentially unchanged. The elongation at break is highest at 5 wt%, reaching 14.6%, a 53.3% increase compared to pure epoxy resin. Compared to the tensile strength of pure epoxy resin, the toughened epoxy resin at this point has a tensile strength of 45.1 MPa, still maintaining a considerably high strength. When the amount of CRS-YM continues to increase, the elongation at break of the epoxy resin shows a decreasing trend, but still remains at a relatively high value.

[0144] 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 polymerizable benzoxazine surfactant, characterized in that, It has the structure shown in Equation IV: ； in, R1 is -(CH2)2-, -(CH2)3-, -CH2-CH(CH3)-, -(CH2)4-, -C(CH3)2-CH2-, -CH(CH3)-(CH2)2-, -CH2-CH(CH3)-CH2- or -(CH2)2-O-(CH2)2-; R2 is -H, -OH, or -CH3; R3 is -C 15 H 31-2n , n=0-3.

2. The method for preparing the polymerizable benzoxazine surfactant as described in claim 1, comprising the steps of: (1) Using biomass phenolic compound I containing a long fatty chain structure, amine compound II containing hydroxyl groups and formaldehyde as raw materials, hydroxyl-containing biomass benzoxazine monomer III was obtained through reaction; ； in, R1, R2, and R3 have the same meaning as R1, R2, and R3 in compound IV; (2) A double bond is introduced by reacting hydroxyl-containing biomass benzoxazine monomer III and maleic anhydride. After the reaction, the pH value of the system is adjusted by using a saturated sodium bicarbonate aqueous solution to obtain a polymerizable benzoxazine surfactant, namely compound IV.

3. The method for preparing polymerizable benzoxazine surfactant according to claim 2, characterized in that, Step (1) includes one or more of the following conditions: i. The biomass phenolic compound I containing a long fatty chain structure is any one of cashew phenol, urushiol, cardiotonic phenol or m-pentadecanylphenol; ii. The amine compound II containing a hydroxyl group is any one of ethanolamine, propanolamine, isopropanolamine, butanolamine, isobutanolamine, 2-aminobutanol, 3-aminobutanol or diethylene glycolamine; iii. The formaldehyde used is a formaldehyde aqueous solution with a mass concentration of 36.5-38%; iv. The molar ratio of the biomass phenolic compound I containing a long fatty chain structure, the amine compound II containing a hydroxyl group, and formaldehyde is 1:1:(2-2.5); v. The reaction is carried out in a solvent; the solvent is one or a combination of two or more of toluene, chloroform, dioxane or ethanol; the mass ratio of the biomass phenolic compound I containing the long aliphatic chain structure to the volume ratio of the solvent is 1:3-5 g / mL; vi. The reaction temperature is 60-120℃, and the reaction time is 4-12 hours.

4. The method for preparing polymerizable benzoxazine surfactant according to claim 2, characterized in that, Step (2) includes one or more of the following conditions: i. The molar ratio of hydroxyl-containing biomass benzoxazine monomer III to maleic anhydride is 1:1.1-1.4; ii. The reaction is carried out in a solvent under the action of a catalyst; the solvent is either chloroform or dichloromethane; the mass ratio of maleic anhydride to solvent is 1:3-5 g / mL; the catalyst is p-toluenesulfonic acid, 4-dimethylaminopyridine, or concentrated sulfuric acid with a mass concentration of 98%; the molar ratio of the catalyst to the hydroxyl-containing biomass benzoxazine monomer III is 1:100-130. iii. The reaction temperature is 70-120℃, and the reaction time is 3-10 hours; iv. After the reaction, the pH of the system is adjusted to 7.0 using a saturated sodium bicarbonate aqueous solution; v. The post-treatment method of the reaction solution obtained from the reaction is as follows: the reaction solution is washed with deionized water and the organic phase is taken; the organic phase is dried with anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain a solid product; the solid product is dissolved in methanol, and saturated sodium bicarbonate aqueous solution is added dropwise until the pH of the system is 7.0, and rotary evaporated to obtain a polymerizable benzoxazine surfactant; the mass ratio of the solid product to the volume of methanol is 1:2-3 g / ml.

5. The application of the polymerizable benzoxazine surfactant as described in claim 1, wherein the surfactant is used in the preparation of a core-shell toughening agent.

6. The application of the polymerizable benzoxazine surfactant according to claim 5, characterized in that, The preparation method of core-shell toughening agents includes the following steps: Deionized water, butyl acrylate, 1,4-butanediol diacrylate, and polymerizable benzoxazine surfactant were thoroughly mixed and dispersed. Under stirring and protective gas protection, an initiator was added, and the reaction was carried out to obtain a polyacrylate seed emulsion. Then, under stirring and protective gas protection, methyl methacrylate was added dropwise to carry out the reaction. Finally, the core-shell toughening agent was obtained by freeze drying.

7. The application of the polymerizable benzoxazine surfactant according to claim 6, characterized in that, Includes one or more of the following conditions: i. The mass ratio of deionized water, butyl acrylate, 1,4-butanediol diacrylate, polymerizable benzoxazine surfactant, and methyl methacrylate is 20:3:0.03:0.03:2; ii. The protective gases are all nitrogen or argon; iii. The stirring speed is 200-300 r / min; iv. The initiator is a 3%-5% potassium persulfate aqueous solution; the molar ratio of the initiator to butyl acrylate is 1:100-110; v. The reaction temperature after adding the initiator is 60-80℃, and the reaction time is 3-8h; vi. The reaction temperature after adding methyl methacrylate is 60-80℃, and the reaction time is 0.5-3h.

8. An epoxy-core-shell toughening agent cured product, comprising: The epoxy resin, the curing agent, and the core-shell toughening agent as described in any one of claims 5-7; the mass of the curing agent is 20%-30% of the mass of the epoxy resin; the mass of the core-shell toughening agent is 2.5%-10% of the total mass of the epoxy resin, the core-shell toughening agent, and the curing agent.

9. The epoxy-core-shell toughening agent cured product according to claim 8, characterized in that, The curing agent is 4,4-diaminodiphenylmethane.

10. The method for preparing the epoxy-core-shell toughening agent cured product as described in claim 8 or 9, comprising the following steps: The core-shell toughening agent and epoxy resin are thoroughly mixed, and then the curing agent is added. The mixture is then cured at 100℃, 150℃, 200℃, and 250℃ for 2 hours respectively to obtain the epoxy-core-shell toughening agent cured product.

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