A cashew phenol-based bisphenol, its preparation method and application

Abstract

This invention discloses a cashew nut shell bisphenol and its preparation method and application. The preparation method of the bisphenol is as follows: First, cashew nut shell phenol, formaldehyde, and an alkaline catalyst are mixed and stirred evenly, and reacted at a certain temperature to obtain hydroxymethylated product A; product A is washed with water several times until the pH is neutral, and then centrifuged to remove water to obtain product B; product B is mixed with phenol and an acidic catalyst and stirred evenly, and reacted at a certain temperature to obtain product C after the phenol-alcohol reaction; product C is washed with water until neutral, and then distilled under reduced pressure to obtain the cashew nut shell bisphenol product. This invention utilizes the structural characteristics of cashew nut shell phenol, which has both a benzene ring and an alkane chain, to obtain a bisphenol structure that combines the rigidity of the benzene ring with the toughness of the long alkane chain on cashew nut shell phenol, while protecting the highly reactive phenolic hydroxyl group. Moreover, this bisphenol is green and low in toxicity, meeting the requirements of environmental protection and sustainable development. The epoxy coating prepared using this bisphenol has high crosslinking density, good corrosion resistance, and excellent mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of bisphenol materials technology, specifically relating to a cashew phenol-based bisphenol, its preparation method, and its application. Background Technology

[0002] Compared to monophenols, bisphenols (such as bisphenol A) typically possess multiple benzene rings, resulting in resins with significantly increased rigidity, higher benzene ring content, and improved thermal stability. Furthermore, the presence of two phenolic hydroxyl groups in bisphenols provides additional active sites, enhancing reactivity. Therefore, bisphenol materials hold broad application prospects in life sciences, composite materials, coatings, and other fields.

[0003] Currently, most existing bisphenols are petroleum-based materials, which have drawbacks such as non-renewability and persistent reproductive toxicity. The few natural bio-based bisphenols, such as cardanol, have low yields and are difficult to extract, failing to meet market demand. Furthermore, due to the linear molecular chains and rigid benzene rings of existing petroleum-based bisphenol materials, the resulting resins exhibit poor flowability and flexibility, and high viscosity, making them difficult to meet construction requirements. Using bio-based cashew nut shell extract with its own flexible carbon chains as a raw material to synthesize polyphenol materials is one effective way to solve these problems.

[0004] Cashew nut shell oil is a plant polyene phenol extracted from natural cashew nut shell oil. It is often used to replace or partially replace phenol in the synthesis of epoxy resins, epoxy curing agents, and phenolic resins. While possessing the molecular characteristics of phenol, cashew nut shell oil also exhibits many properties different from phenol: it contains a benzene ring structure and has a larger molecular weight, resulting in high-temperature resistance; the phenolic hydroxyl groups on the benzene ring provide wetting and activity to the contact surfaces; the carbon-15 straight chain with unsaturated double bonds at the meta position on the benzene ring provides good toughness, excellent hydrophobicity, low permeability, and self-drying properties, making it an ideal biomass feedstock. Currently reported methods for synthesizing bisphenols from cashew nut shell oil mainly utilize the carbon-carbon double bonds in the carbon-15 chain of cashew nut shell oil to add to other monophenolic materials such as phenol to obtain bisphenol materials. However, due to the presence of various carbon-carbon double bonds in the cashew phenol R chain, which have different activities, the bisphenol material suffers from problems such as uncontrollable structure, poor component uniformity, and low yield. Furthermore, the bisphenol molecules generated by the R chain carbon-carbon double bond addition method lose their toughening effect due to the R chain's participation in cross-linking, resulting in a significant decrease in resin viscosity and toughness. Consequently, this type of material cannot replace the application of petroleum-based materials.

[0005] The present invention addresses the aforementioned problems existing in the prior art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a cashew nut phenol-based bisphenol, its preparation method, and its applications. This invention yields a cashew nut phenol-based bisphenol structure with a high yield, possessing both a flexible alkane chain and a rigid benzene ring, along with highly active sites, through simple experimental steps. This resin material combines rigidity and toughness, exhibiting low viscosity and high toughness, which can greatly expand the application of cashew nut phenol-based biomaterials in composite materials, life sciences, surfactants, and friction powders.

[0007] The technical solution of this invention is as follows:

[0008] This invention relates to a cashew phenol-based bisphenol, the structure of which is shown below:

[0009]

[0010] Where the group R is C 15 H 31-2n n = 0 - 3

[0011] When n=0, C 15 H 31 for

[0012] When n=1, C 15 H 29 for

[0013] When n=2, C 15 H 27 for

[0014] When n=3, C 15 H 25 for

[0015] In formula (1), the linking group between the two benzene rings is methylene, which is located at the ortho or para position of the phenolic hydroxyl group on the right benzene ring.

[0016] Preferably, the groups X1 and X2 are the same, and are H or CH2OH.

[0017] This invention also relates to a method for preparing cashew phenol-based bisphenols, comprising the following steps:

[0018] (1) First, cashew phenol, formaldehyde and alkaline catalyst are mixed and stirred evenly, and then reacted at a certain temperature to obtain hydroxymethylated product A;

[0019] (2) Wash product A with water several times until the pH is neutral, then centrifuge to remove water to obtain product B. This step removes unreacted formaldehyde, alkaline catalyst and water.

[0020] (3) Mix product B with excess phenol and acid catalyst until homogeneous, and react at a certain temperature to obtain product C after the phenol-alcohol reaction.

[0021] (4) Wash product C with water until neutral, and then distill under reduced pressure to remove impurities from the product and obtain cashew phenol bisphenol product.

[0022] The synthetic mechanism involved in this preparation method is as follows:

[0023]

[0024]

[0025] The raw material cashew phenol used in this preparation method is a bio-based resource that does not consume food or petroleum resources, aiming to replace petroleum-based materials in related fields. This invention utilizes the structural characteristics of cashew phenol, which combines a benzene ring and an alkane chain, to obtain a bisphenol structure that possesses both the rigidity of a benzene ring and the toughness of the long alkane chain in cashew phenol, while protecting the highly reactive phenolic hydroxyl groups.

[0026] Preferably, in step (1), the molar ratio of cashew phenol to formaldehyde is 1:1 to 1:5, and the mass ratio of cashew phenol to alkaline catalyst is 1:0.001 to 1:0.05.

[0027] Preferably, in step (1), the reaction temperature is 30-90℃ and the reaction time is 1-7h.

[0028] Preferably, in step (1), the alkaline catalyst is at least one of ammonia, triethylamine, barium hydroxide, sodium hydroxide, and magnesium hydroxide. More preferably, the alkaline catalyst is at least one of ammonia, triethylamine, and magnesium hydroxide.

[0029] Preferably, the molar ratio of cashew phenol to phenol in step (3) is 1:1 to 1:12; the amount of acidic catalyst used in step (3) is 0.001-0.05 of the mass of cashew phenol.

[0030] Preferably, in step (3), the reaction temperature is 40-120℃ and the reaction time is 1-7h.

[0031] Preferably, in step (3), the acidic catalyst is at least one of oxalic acid, phosphoric acid, hydrochloric acid, sulfuric acid, dodecylbenzenesulfonic acid, p-hydroxybenzenesulfonic acid, and p-toluenesulfonic acid monohydrate.

[0032] Preferably, in step (4), the vacuum distillation temperature is 60-110℃, the time is 1-7h, and the pressure is 0.1Mpa.

[0033] This invention also relates to a method for preparing cashew phenol-based epoxy resin, which uses cashew phenol-based bisphenol as a raw material, reacts with epichlorohydrin, and performs epoxidation to generate cashew phenol-based bisphenol epoxy resin, comprising the following steps:

[0034] (1) Using cashew phenol bisphenol and epichlorohydrin as raw materials, stir at 50-70℃ for 5-15 min in the presence of quaternary ammonium salt catalyst, then add NaOH solution and keep at a constant temperature for 40-90 min.

[0035] (2) Cool down to 75°C, add more NaOH solution, keep reflux to separate water, test the amount of water recovered, and stop the reaction when it reaches the theoretical amount. Remove epichlorohydrin by vacuum distillation.

[0036] (3) Filter or centrifuge to remove salt;

[0037] (4) Take the filtrate, raise the temperature to 110°C, and further remove epichlorohydrin by vacuum distillation to obtain cashew phenol-based epoxy resin.

[0038] by For example, the synthesis mechanism of cashew phenol-based epoxy resin is as follows:

[0039]

[0040] Preferably, the mass concentration of the NaOH solution used in steps (1) and (2) is 30-60%.

[0041] Preferably, the quaternary ammonium salt catalyst is added in solution form, and the quaternary ammonium salt catalyst is tetraethylammonium bromide.

[0042] Preferably, the time for removing epichlorohydrin by vacuum distillation in step (2) is 1-3 hours; the time for further removing epichlorohydrin by vacuum distillation in step (4) is 1-3 hours.

[0043] The present invention also relates to a cashew phenol-based epoxy resin, which is prepared by the above-described preparation method.

[0044] A method for preparing an anti-corrosion coating based on cashew phenol-based epoxy resin includes the following steps:

[0045] (1) Cashew phenol-based epoxy resin and curing agent are mixed in a certain proportion, heated and stirred evenly. The mixing temperature is 20-50℃ and the mixing time is 5min-15min to obtain product a; wherein the curing agent is an amine-based curing agent.

[0046] (2) After sonicating product a for several minutes, place it in a vacuum drying oven to remove bubbles and obtain product b.

[0047] (3) Apply product b to the substrate and cure it in an oven at 30-90℃ to obtain the final product.

[0048] The beneficial effects of this invention are:

[0049] (1) This invention uses cashew monophenol, formaldehyde and phenol as raw materials to synthesize a novel bisphenol material. This material achieves a molecular double benzene ring, thereby increasing molecular rigidity and thermal stability, while retaining the degree of freedom of the R chain, so that the resin material made from it has low viscosity and high toughness. This novel bio-based bisphenol material has both high strength and high toughness in its molecular structure, and is expected to replace petroleum-based bisphenol materials in the fields of composite materials, coatings, surfactants, friction powders, biomedicine and other fields, and has great application prospects.

[0050] (2) The preparation method of the present invention is simple and reliable, and can produce bisphenol molecules that have both the rigidity of benzene ring and the toughness of the long chain of alkane on cashew phenol. The purity of the prepared product can reach 85%, and the bisphenol is green and low in toxicity, which meets the requirements of environmental protection and sustainable development.

[0051] (3) Cashew phenol-based bisphenol is used to prepare an epoxy coating in two steps. First, cashew phenol-based phenol-based epoxy resin is prepared using cashew phenol-based bisphenol as raw material. Then, a bio-based shape memory epoxy resin coating is prepared using cashew phenol-based phenol-based epoxy resin. This coating has high crosslinking density, good hydrophobicity, good corrosion resistance, and excellent mechanical properties, including high toughness, high adhesion and impact resistance. Attached Figure Description

[0052] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0053] Figure 1 This is a gas chromatography-mass spectrum of cashew phenol raw material and a partial magnified image;

[0054] Figure 2 This is a gas chromatogram of the hydroxymethylation intermediate product of the phenol-formaldehyde reaction;

[0055] Figure 3 This is the gas chromatography-mass spectrum of the hydroxymethylation intermediate product of the phenol-formaldehyde reaction;

[0056] Figure 4 This is a gas chromatogram of the cashew bisphenol product, which is the product of the phenol-alcohol reaction.

[0057] Figure 5 This is one of the gas chromatography-mass spectra of the cashew bisphenol product, a product of the phenol-alcohol reaction.

[0058] Figure 6 This is the second gas chromatography-mass spectrum of the cashew bisphenol product, a product of the phenol-alcohol reaction.

[0059] Figure 7This is the third gas chromatography-mass spectrum of the cashew bisphenol product, which is the product of the phenol-alcohol reaction.

[0060] Figure 8 This is the fourth gas chromatographic mass spectrum of the cashew bisphenol product, which is the product of the phenol-alcohol reaction.

[0061] Figure 9 This is the 1H NMR spectrum of the cashew bisphenol product, which is the product of the phenol-alcohol reaction.

[0062] Figure 10 This is the carbon NMR spectrum of the cashew bisphenol product, a product of the phenol-alcohol reaction.

[0063] Figure 11 These are Fourier transform infrared spectra of cashew phenol-based bisphenol and cashew phenol-based epoxy resin.

[0064] Figure 12 It is the electrochemical spectrum of the coating prepared using cashew phenol-based epoxy resin;

[0065] Figure 13 This is a flowchart of the synthesis of cashew phenol-based epoxy resin;

[0066] Figure 14 This is a flowchart of the preparation of epoxy coating using cashew phenol-based epoxy resin. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0068] Example 1

[0069] 105.312 g of cashew nut shellac, 0.105 g of ammonia water (containing 25%-28% ammonia), and 11.444 g of paraformaldehyde were added to a 500 mL four-necked flask. The temperature was raised to 30 °C and the reaction was carried out for 1 h. The mixture was then washed with water several times until the pH was neutral, and centrifuged to remove water. The temperature was then raised to 40 °C, and 0.105 g (0.00117 mol) of oxalic acid and 33.033 g (0.351 mol) of phenol were added to carry out a phenol-alcohol condensation reaction for 1 h. The mixture was then washed with water several times until the pH was neutral. Finally, the mixture was distilled under reduced pressure at 0.1 MPa and 60 °C for 1 h to obtain the product (cashew nut shellac bisphenol purity of 60%).

[0070] Example 2

[0071] 46.182 g of cashew nut shell powder, 0.924 g (0.00913 mol) of triethylamine, and 15.055 g of paraformaldehyde were added to a 500 mL four-necked flask. The temperature was raised to 60 °C and the reaction was carried out for 3 h. The mixture was then washed with water several times until the pH was neutral, and centrifuged to remove water. The temperature was then raised to 100 °C, and 0.924 g (0.00943 mol) of phosphoric acid and 86.915 g (0.924 mol) of phenol were added to carry out a phenol-alcohol condensation reaction for 3 h. The mixture was then washed with water several times until the pH was neutral. Finally, the mixture was distilled under reduced pressure at 0.1 MPa and 90 °C for 3 h to obtain the product (cashew nut shell powder bisphenol purity was 67%).

[0072] Example 3

[0073] 27.740 g of cashew nut shell powder, 1.387 g (0.0347 mol) of sodium hydroxide, and 15.072 g of paraformaldehyde were added to a 500 mL four-necked flask. The temperature was raised to 90 °C and the reaction was carried out for 7 h. The mixture was then washed with water several times until the pH was neutral, and centrifuged to remove water. The temperature was then raised to 160 °C, and 1.387 g (0.00425 mol) of dodecylbenzenesulfonic acid and 104.414 g (1.110 mol) of phenol were added to carry out a phenol-alcohol condensation reaction for 7 h. The mixture was then washed with water several times until the pH was neutral. Finally, the mixture was distilled under reduced pressure at 0.1 MPa and 110 °C for 6 h to obtain the product (cashew nut shell powder bisphenol purity of 70%).

[0074] Example 4

[0075] 46.182 g of cashew nut shellac, 0.924 g (0.00913 mol) of triethylamine, and 15.055 g of paraformaldehyde were added to a 500 mL four-necked flask. The temperature was raised to 60 °C and the reaction was carried out for 3 h. The mixture was then washed with water several times until the pH was neutral, and centrifuged to remove water. The temperature was then raised to 100 °C, and 0.924 g (0.00943 mol) of sulfuric acid and 86.915 g (0.924 mol) of phenol were added to carry out a phenol-alcohol condensation reaction for 3 h. The mixture was then washed with water several times until the pH was neutral. Finally, the mixture was distilled under reduced pressure at 0.1 MPa and 90 °C for 3 h to obtain the product (cashew nut shellac bisphenol purity was 79%).

[0076] Example 5

[0077] 46.182 g of cashew nut shell powder, 0.924 g (0.00539 mol) of barium hydroxide, and 15.055 g of paraformaldehyde were added to a 500 mL four-necked flask. The temperature was raised to 60 °C and the reaction was carried out for 3 h. The mixture was then washed with water several times until the pH was neutral, and centrifuged to remove water. The temperature was then raised to 100 °C, and 0.924 g (0.00943 mol) of sulfuric acid and 86.915 g (0.924 mol) of phenol were added to carry out a phenol-alcohol condensation reaction for 3 h. The mixture was then washed with water several times until the pH was neutral. Finally, the mixture was distilled under reduced pressure at 0.1 MPa and 90 °C for 3 h to obtain the product (cashew nut shell powder bisphenol purity of 85%).

[0078] Figure 1 The images show the gas chromatography-mass spectra and partial magnifications of the cashew nut shell extract raw materials used in Examples 1-5. Magnifying the peak near 302 reveals substances at 298, 300, 302, and 304, corresponding to n = 3, 2, 1, and 0 respectively, indicating that the cashew nut shell extract raw materials themselves are a mixture. Furthermore, from... Figure 1 It can also be seen that many of the peaks marked with numbers are not single peaks, but have other peaks nearby, which further indicates that the cashew phenol raw material is a mixture.

[0079] The structures of the cashew phenol-based bisphenol resin samples obtained in Examples 1-5 were determined using the following methods: 1H and 1C NMR spectra were used to characterize whether the new structural framework conformed to the expected results; gas chromatography-mass spectrometry (GC-MS) was used to determine the unique molecular weight structure, thus confirming the intermediate and product structures. Taking Example 5 as an example, the corresponding spectrum is as follows:

[0080] Figure 2 This is a gas chromatogram of the hydroxymethylation intermediate product from the phenol-formaldehyde reaction. Figure 3 These are two gas chromatography-mass spectra of the phenolic reaction product and the hydroxymethylation product. The substance appearing at 21.035 min in the corresponding GC-MS gas chromatogram corresponds to... Figure 3 The first figure shows a content of 92.43%, representing the monohydroxymethylated intermediate product; the peak appearing at 22.055 min in the corresponding GC-MS gas chromatogram corresponds to... Figure 3 The second graph shows a content of 5.54%, representing the trihydroxymethylated intermediate product. The corresponding GC-MS gas chromatogram shows other peaks including unreacted cashew phenol and solvent impurities, present in very small quantities. Based on the GC-MS chromatogram, formaldehyde and cashew phenol successfully underwent an addition reaction, producing only two products besides the cashew phenol mass spectrum. These two products are identified as intermediates of the target product, and their structural formulas are as follows: Figure 3 As shown.

[0081] Figure 4 This is a gas chromatogram of the cashew bisphenol product, which is the product of the phenol-alcohol reaction. Figures 5 to 8 This is the gas chromatography-mass spectrum (GC-MS) of the cashew bisphenol product, a product of the phenol-alcohol reaction. In the corresponding GC-MS gas chromatogram, the substance at 7.608 min is unreacted phenol, and the peaks at 23.265 and 24.206 min correspond to the following mass spectra: Figure 5 and Figure 6 The mass spectrum corresponding to the substance at 24.701 min in the gas chromatogram of GC-MS is as follows: Figure 7 It is the main product, accounting for a large proportion, and is inferred to be bisphenol converted from monohydroxymethylation product; the peak at 26.033 min in the gas chromatogram of GC-MS corresponds to the mass spectrum of Figure 8 It is inferred that the product is a bisphenol converted from a trihydroxymethylation product. Based on the GCMS spectrum, it can be determined that the product contains both bisphenol converted from a monohydroxymethylation product and a bisphenol converted from a trihydroxymethylation product.

[0082] Figure 9 The image shows the 1H NMR spectrum of the cashew bisphenol product, a product of the phenol-alcohol reaction. Based on the 1H NMR spectrum of the sample, the chemical shift of the hydrogen corresponding to the methylene group is 3.5-4.5 ppm, confirming the presence of the methylene group.

[0083] Figure 10 This is the carbon NMR spectrum of the cashew bisphenol product, a product of the phenol-alcohol reaction. Based on the 12C NMR of the sample, a chemical shift of C at 27-32 ppm can be observed in C-CH2-C. Combining the C and H spectra, it can be determined that the product contains the structure of the target product we need.

[0084] Cashew phenol bisphenol was prepared according to the method in Example 5. Epoxy resin was then prepared using cashew phenol bisphenol as a raw material, as detailed in the following process: Figure 13 As shown.

[0085] Example 6: Synthesis of Epoxy Resin

[0086] (1) Etherification: Weigh cashew phenol bisphenol (50.7g), epichlorohydrin (55.2g), tetraethylammonium bromide (0.063g, the catalyst was dissolved in 0.063g of deionized water) and add them to a four-necked flask. Stir at 50°C for 10 min, then add 4g of 33wt.% NaOH solution and keep at a constant temperature for 40 min.

[0087] (2) Closed loop: Heat to 75℃, add 22.533g of 33wt.% NaOH solution dropwise, keep reflux to separate water, test the amount of water recovered, and stop the reaction when it reaches the theoretical amount. Remove epichlorohydrin by vacuum distillation for 1h.

[0088] (3) Filtration to remove salt.

[0089] (4) Take the filtrate, raise the temperature to 110°C, and further remove epichlorohydrin by vacuum distillation for 1 hour, and then discharge the product.

[0090] Example 7 Synthesis of Epoxy Resin

[0091] (1) Etherification: Weigh cashew bisphenol (50.7g), epichlorohydrin (73.6g), and tetraethylammonium bromide (0.084g, the catalyst is dissolved in an equal mass of deionized water) and add them to a four-necked flask. Stir at 60°C for 10 min, then add 6g of 33wt.% NaOH solution and keep at a constant temperature for 50 min.

[0092] (2) Closed loop: Heat to 75℃, add 33.8g of 33wt.% NaOH solution dropwise, keep reflux to separate water, test the amount of water recovered, and stop the reaction when it reaches the theoretical amount. Remove epichlorohydrin by vacuum distillation for 2h.

[0093] (3) Filtration to remove salt.

[0094] (4) Take the filtrate, raise the temperature to 110°C, and further remove epichlorohydrin by vacuum distillation for 1 hour, and then discharge the product.

[0095] Example 8: Synthesis of Epoxy Resin

[0096] (1) Etherification: Weigh cashew polyphenols (50.7g), epichlorohydrin (82.8g), and tetraethylammonium bromide (0.105g, the catalyst is dissolved in an equal mass of deionized water) and add them to a four-necked flask. Stir at 70°C for 10 min, then add 8g of 33wt.% NaOH solution and keep at a constant temperature for 60 min.

[0097] (2) Closed loop: Heat to 75℃, add 45.066g of 33 wt.% NaOH solution dropwise, keep reflux to separate water, test the amount of water recovered, and stop the reaction when it reaches the theoretical amount. Remove epichlorohydrin by vacuum distillation for 3h.

[0098] (3) Filtration to remove salt.

[0099] (4) Take the filtrate, raise the temperature to 110°C, and further remove epichlorohydrin by vacuum distillation for 1 hour, and then discharge the product.

[0100] The cashew phenol-based bisphenol prepared by the method in Example 5 and the cashew phenol-based epoxy resin prepared in Example 7 were characterized, and the corresponding Fourier transform infrared spectra are shown below. Figure 11 As shown, at 3325cm -1 2925cm -1 2843cm -1The characteristic peaks of cashew phenol bisphenol A (CPB) appeared at the peak, corresponding to the stretching vibrations of -OH, -CC, and -CH, respectively. Furthermore, a strong characteristic peak of the epoxy group, at 1250 cm⁻¹, was observed after epoxidation. -1 910cm -1 770cm -1 The peak at that point indicates that bisphenol was successfully epoxidized.

[0101] Cashew phenol-based epoxy resin (EP) was prepared according to the method in Example 6, following... Figure 14 The process shown involves preparing a coating using cashew phenol-based epoxy resin, and then testing the performance of the coated product, as detailed below.

[0102] Example 9 Coating Preparation

[0103] Take 10g of cashew phenol-based epoxy resin and 3.7g of curing agent 718A, add them to a 100mL beaker, raise the temperature to 30℃ and mix and stir for 15min; then put it into an ultrasonic machine and sonicate for 10min, then put it into a vacuum drying oven to remove bubbles; then further scrape it onto a steel plate with a thickness of 100μm, and then put the scraped steel plate into an oven at 30℃ to cure for 12h to obtain the coating product.

[0104] Example 10 Coating Preparation

[0105] Take 10g of cashew phenol-based epoxy resin and 3.7g of curing agent 718A, add them to a 100mL beaker, raise the temperature to 40℃ and mix and stir for 10min; then put it into an ultrasonic machine and sonicate for 10min, then put it into a vacuum drying oven to remove bubbles; then scrape it onto a steel plate with a thickness of 100μm, and then put the scraped steel plate into an oven at 60℃ to cure for 12h to obtain the coating product.

[0106] Example 11 Coating Preparation

[0107] Take 10g of cashew phenol-based epoxy resin and 3.7g of curing agent (PLR718A, Changshu Naisu Biomaterials Technology Co., Ltd.), add them to a 100mL beaker, and mix and stir for 5min after the temperature is raised to 50℃. Then, place it in an ultrasonic machine and sonicate for 10min. After that, place it in a vacuum drying oven to remove bubbles. Then, coat it onto a steel plate with a thickness of 100μm. Finally, place the coated steel plate in a 90℃ oven to cure for 12h to obtain the coating product.

[0108] Comparative Example 1: Coating Preparation

[0109] Take 10g of petroleum-based epoxy resin E51, 3.7g of curing agent (PLR718A, Changshu Naisu Biomaterials Technology Co., Ltd.), and 0.5g of acetone, add them to a 100mL beaker, raise the temperature to 30℃ and mix and stir for 10min; then put it into an ultrasonic machine and sonicate for 10min, then put it into a vacuum drying oven to remove bubbles; then further scrape it onto a steel plate with a thickness of 100μm, and then put the scraped steel plate into an oven at 30℃ to cure for 12h to obtain the coating product.

[0110] Figure 12 The electrochemical spectrum of the coating prepared using cashew phenol-based epoxy resin in Example 11 is shown. After 10 days of testing at 0.01 Hz, the impedance of the steel substrate coated with the coating is 10^7.5. The electrochemical spectrum indicates that the anti-corrosion coating exhibits high impedance performance, proving that it has good anti-corrosion properties.

[0111] The mechanical properties of the coating prepared in Example 11 and the coating prepared in Comparative Example 1 were tested, and the specific mechanical property comparison results are shown in Table 1.

[0112] Table 1

[0113]

[0114] As can be seen from Table 1, compared with the petroleum-based epoxy resin (E51) coating, the coating prepared using cashew phenol-based epoxy resin (EP) has significantly improved adhesion, flexibility, and impact resistance.

[0115] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A cashew phenol-based bisphenol, characterized in that, The structure is as follows: （1） Where the group R is C 15 H 31-2n n=0-3, When n=0, C 15 H 31 for , When n=1, C 15 H 29 for , When n=2, C 15 H 27 for , When n=3, C 15 H 25 for ; In formula (1), the linking group between the two benzene rings is methylene, which is located at the ortho or para position of the phenolic hydroxyl group on the right benzene ring; The groups X1 and X2 are the same, which are H or CH2OH.

2. A method for preparing cashew phenol-based bisphenols, characterized in that, Includes the following steps: (1) First, cashew phenol, formaldehyde and alkaline catalyst are mixed and stirred evenly, and then reacted at a certain temperature to obtain hydroxymethylated product A; (2) Wash product A with water several times until the pH is neutral, then centrifuge to remove water to obtain product B; (3) Mix product B with phenol and acid catalyst and stir evenly, and react at a certain temperature to obtain product C after the phenol-alcohol reaction; (4) Wash product C with water until neutral, then distill under reduced pressure to obtain cashew phenol bisphenol product.

3. The method for preparing cashew phenol-based bisphenol according to claim 2, characterized in that, In step (1), the molar ratio of cashew phenol to formaldehyde is 1:1 to 1:5, and the mass ratio of cashew phenol to alkaline catalyst is 1:0.001 to 1:0.

05.

4. The method for preparing cashew phenol-based bisphenol according to claim 2, characterized in that, In step (1), the reaction temperature is 30-90℃ and the reaction time is 1-7h.

5. The method for preparing cashew phenol-based bisphenol according to claim 2, characterized in that, In step (1), the alkaline catalyst is at least one of ammonia, triethylamine, barium hydroxide, sodium hydroxide, and magnesium hydroxide.

6. The method for preparing cashew phenol-based bisphenol according to claim 2, characterized in that, The molar ratio of cashew phenol to phenol in step (3) is 1:1 to 1:12; the amount of acidic catalyst used in step (3) is 0.001-0.05 of the mass of cashew phenol.

7. The method for preparing cashew phenol-based bisphenol according to claim 2, characterized in that, In step (3), the reaction temperature is 40-120℃ and the reaction time is 1-7h.

8. The method for preparing cashew phenol-based bisphenol according to claim 2, characterized in that, In step (3), the acidic catalyst is at least one of oxalic acid, phosphoric acid, hydrochloric acid, sulfuric acid, dodecylbenzenesulfonic acid, p-hydroxybenzenesulfonic acid, and p-toluenesulfonic acid monohydrate.

9. The method for preparing cashew phenol-based bisphenol according to claim 2, characterized in that, In step (4), the vacuum distillation temperature is 60-110℃, the time is 1-7h, and the pressure is 0.1MPa.

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