A cashew phenol polyol with phosphorus-bromine synergism and a preparation method and application thereof

Abstract

The application provides a cashew phenol polyol with phosphorus-bromine synergism and a preparation method and application thereof, and solves the technical problems of easy migration and precipitation of an existing additive flame retardant, non-renewability and large carbon footprint of a reaction type flame retardant, and low flame-retardant efficiency of a biomass flame retardant; the cashew phenol polyol with phosphorus-bromine synergism has the structure shown in the following formula (I): wherein n is a positive integer, and 1<=n<=3; m is a positive integer, and 0<=m<=3; the RBr m is a bond line structure; the application further provides a preparation method and application of the cashew phenol polyol with phosphorus-bromine synergism; and the application can be widely applied in the technical field of high polymer flame-retardant materials.

Description

Technical Field

[0001] This application relates to the field of polymer flame retardant materials technology, and in particular to a phosphobromine synergistic cashew phenol polyol, its preparation method and application. Background Technology

[0002] Polyurethane foam materials are widely used in construction, furniture, automotive, and aerospace industries due to their excellent mechanical and thermal insulation properties. However, polyurethane foam is highly flammable, and its combustion releases a large amount of heat and toxic fumes, seriously threatening life and property safety. Therefore, flame-retardant modification of polyurethane foam has become a key research focus in this field.

[0003] Traditional flame retardant systems mainly fall into two categories: additive and reactive. Among them, the bromine-antimony synergistic flame retardant system was once widely used due to its high efficiency. However, these flame retardants may release toxic and harmful substances such as hydrogen bromide and antimony halides during combustion, posing potential risks to the environment and human health. Furthermore, their addition often leads to a significant decrease in the mechanical properties of the material. In addition, many additive flame retardants have poor compatibility with the polyurethane matrix, easily migrating and precipitating, which not only affects the durability of the flame retardant effect but also damages the structural integrity of the foam.

[0004] Existing reactive flame-retardant polyols mostly rely on petroleum-derived raw materials (such as propylene oxide), which have problems such as non-renewability, high cost, and large carbon footprint. Biomass alternatives (such as soybean oil and castor oil-based polyols) are environmentally friendly, but they generally have low flame-retardant efficiency and require the formulation of other flame retardants (such as ammonium polyphosphate) to meet practical requirements. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the above-mentioned technologies and provide a phosphobromine synergistic cashew phenol polyol, its preparation method and application, thereby improving the flame retardant effect of polyurethane foam.

[0006] Therefore, the present invention provides a phosphobromine synergistic cashew phenol polyol having the structure shown in formula (I):

[0007] Where n is a positive integer, and 1≤n≤3; m is a positive integer, and 0≤m≤3; RBr m The bonded structure is shown in any one of the following formulas (II), (III), (IV), and (V):

[0008] Preferably, the cashew phenol polyol with synergistic phosphorus and bromine effects has a Brookfield viscosity of 700–40,000 cPs at 25°C.

[0009] This invention also provides a method for preparing a phosphobromine synergistic cashew phenol polyol, comprising the following steps: Step S1. Cashew nut phenol and organophosphorus chloride are heated and reacted under the action of an alkaline catalyst to obtain phosphorylated cashew nut phenol; Step S2. The phosphorylated cashew phenol obtained in step S1 is reacted with H2O2 under acidic conditions to obtain phosphorylated cashew phenol with epoxy groups whose double bonds on the long aliphatic chain are epoxidized. Step S3. The phosphorylated cashew nut alcohol with epoxy groups obtained in step S2 is reacted with excess bromine to obtain a synergistic phosphorus-bromine cashew nut alcohol polyol.

[0010] In step S1, cashew phenol is reacted with an organophosphorus chloride. Essentially, the phenolic hydroxyl group of cashew phenol is converted into a phenoxy anion in the presence of an alkaline catalyst, which then undergoes a nucleophilic substitution reaction with the chlorine atom on the organophosphorus chloride to prepare phosphorylated cashew phenol. In step S2, the phosphorylated cashew phenol is epoxidized. Essentially, the double bond on the pentadecanyl side chain of cashew phenol is epoxidized to prepare phosphorylated cashew phenol with an epoxy group. In step S3, the phosphorylated cashew phenol with an epoxy group is brominated. Essentially, the strong activation effect of the phenolic hydroxyl group causes it to react with benzene... The increased electron cloud density at the ortho and para positions on the ring facilitates electrophilic substitution. The bromine molecule polarizes into a positively charged bromide ion, which reacts with the hydrogen ions at the ortho and para positions of the phenolic hydroxyl group of cashew phenol to undergo an electrophilic substitution reaction on the aromatic ring. Substitution occurs at a minimum of one reaction site and at most three reaction sites, simultaneously generating hydrobromic acid and ortho- or para- or ortho- or para-bromocainol. On the other hand, the hydrobromic acid ionizes to release hydrogen ions that attack the oxygen atom on the epoxy group of the carbon-pentadecanyl side chain of cashew phenol, while the bromide anion attacks the carbon atom, causing the epoxy ring to open. Finally, a phosphobromine synergistic cashew phenol polyol is prepared.

[0011] Preferably, in step S1, the preparation method of phosphorylated cashew nut phenol includes: weighing cashew nut phenol, an appropriate amount of triethylamine catalyst and an appropriate amount of organic solvent and adding them to a three-necked flask, installing a reflux condenser and starting stirring, adding organophosphorus chloride dropwise into the system at a constant temperature of 0°C, and after the addition is complete, raising the temperature to 40-50°C to react fully, cooling to room temperature after the reaction is complete, and obtaining phosphorylated cashew nut phenol after post-treatment; wherein, the molar ratio of cashew nut phenol to organophosphorus chloride is 1:1.

[0012] Preferably, in step S1, the post-treatment method includes: filtering to remove the white precipitate, washing the filtrate with pure water, separating the liquid, repeating the washing process multiple times, drying the organic layer with anhydrous magnesium sulfate and filtering, removing the organic solvent from the organic layer by vacuum distillation, wherein the temperature is controlled at 40 to 80°C and the pressure is controlled at -0.07 to -0.1 MPa, and the brown viscous product is phosphorylated cashew nut shell powder.

[0013] Preferably, in step S2, the preparation method of phosphorylated cashew nut phenol with epoxy groups includes: weighing the phosphorylated cashew nut phenol prepared in step S1 and adding an appropriate amount of formic acid into a reaction vessel; measuring an aqueous H2O2 solution and adding it dropwise at a constant temperature of 0°C; after the addition is complete, raising the temperature to 50-70°C to allow the reaction to proceed fully; after the reaction is completed, cooling to room temperature, allowing it to stand and separate into layers, and separating to obtain an orange-yellow oily liquid, which is phosphorylated cashew nut phenol with epoxy groups; wherein, the molar ratio of phosphorylated cashew nut phenol to H2O2 in the aqueous H2O2 solution is 1:2 to 1:3.

[0014] Preferably, in step S3, the preparation method of the phosphorus-bromine synergistic cashew phenol polyol includes: weighing 100 parts by weight of the phosphorylated cashew phenol with epoxy groups prepared in step S2, measuring an appropriate amount of organic solvent and adding it to a four-necked flask, maintaining the temperature at 5-10 °C, and adding an acetic acid solution containing 18-53 parts by weight of bromine dropwise through a constant pressure funnel, completing the addition within 1-3 h; after the addition is completed, maintaining the temperature of the mixture at 20-30 °C and the reflux time at 1-3 h, terminating the reaction, and allowing the reaction solution to stand and separate into layers, taking the oil phase, and after post-processing, obtaining the phosphorus-bromine synergistic cashew phenol polyol.

[0015] Preferably, in step S3, the post-processing method includes: washing the obtained oil phase sequentially with sodium sulfite aqueous solution, alkaline solution and pure water, allowing it to stand and separate into layers to obtain the oil phase; drying the obtained oil phase with anhydrous sodium sulfate and filtering it; removing the organic solvent from the oil phase by vacuum distillation, wherein the temperature is controlled at 40 to 80°C and the pressure is controlled at -0.07 to -0.1 MPa, to obtain the phosphobromine synergistic cashew phenol polyol.

[0016] Preferably, the organophosphorus chloride includes one or more of diphenyl chlorinated phosphine, diphenylphosphine chloride, and diphenyl chlorinated phosphate.

[0017] Preferably, the organic solvent includes one or more of carbon tetrachloride, dichloromethane, dichloroethane, dichloropropane, trichloroethane, and chloroform.

[0018] Application of the phosphobromine synergistic cashew phenol polyol prepared according to the above-described phosphobromine synergistic cashew phenol polyol or any of the above-described methods as a flame retardant in the preparation of flame retardant polyurethane foam materials.

[0019] This invention provides a phosphobromine synergistic cashew phenol polyol, its preparation method, and its application, which mainly have the following beneficial effects: (1) Using cashew phenol polyol with phosphorus and bromine synergy as a flame retardant can replace or partially replace petroleum-based bromine flame retardants such as decabromodiphenyl ethane, which changes the limitation that all flame-retardant polyurethane compositions are derived from petroleum. Using cashew phenol polyol with phosphorus and bromine synergy as a raw material for preparing flame-retardant polyurethane foam has the advantages of safety and environmental protection. Cashew phenol polyol with phosphorus and bromine synergy is a low viscosity liquid with good fluidity. Compared with existing technologies such as decabromodiphenyl ethane and antimony trioxide powders, it is more convenient to add and use, thereby ensuring the molding process of polyurethane foam and the overall toughness of the foam.

[0020] (2) Using cashew phenol polyol, a phosphorus-bromine synergistic compound made from cashew phenol, as a flame retardant exhibits highly efficient flame retardant properties. On one hand, phosphorus mainly functions in the condensed phase, promoting char formation in the polyurethane matrix to create a dense and stable char layer that isolates heat and oxygen. Bromine mainly functions in the gas phase, capturing free radicals generated during combustion and interrupting the combustion chain reaction. The synergistic effect of both achieves a dual flame retardant mechanism of "solid-gas phase," which is far more efficient than a single flame retardant. Due to the synergistic effect of phosphorus and bromine, the total amount of flame retardant required to achieve the same flame retardant rating is significantly reduced. This helps to reduce the negative impact on the mechanical properties of the polyurethane matrix.

[0021] (3) Using cashew nut shell phenol polyol prepared from cashew nut shell phenol as a raw material as a flame retardant provides a stable flame retardant effect. Phosphorus and bromine elements are directly bonded to the molecular skeleton of the cashew nut shell phenol polyol. At the same time, the hydroxyl groups on the cashew nut shell phenol polyol make it compatible with the main conventional polyols and can also react with isocyanates to become part of rigid or flexible polyurethane foam. This "reactive" flame retardant method avoids the problems of poor flame retardant performance and material aging caused by the easy migration and precipitation of traditional "additive" flame retardants (such as halogenated and phosphate esters), and achieves a stable flame retardant effect. At the same time, applying this invention to the field of polyurethane enables polyurethane compositions to have a phosphorus-bromine synergistic flame retardant system, which can play a flame retardant role in different stages of combustion, thereby greatly improving the flame retardant efficiency of polyurethane foam. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application.

[0023] Figure 1 Infrared spectra of cashew phenol raw material, phosphorylated cashew phenol prepared in Example 1, phosphorylated cashew phenol with epoxy groups prepared in Example 2, and cashew phenol polyol with synergistic phosphorus and bromide effects prepared in Example 3. Detailed Implementation

[0024] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0025] Unless otherwise specified, all methods used in this invention are conventional methods; all raw materials and equipment used are commercially available products unless otherwise specified. Cashew phenol was purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd., with a purity greater than 99%; diphenyl chlorophosphate was purchased from Maclean's Ltd.

[0026] This invention provides a phosphobromine synergistic cashew phenol polyol having the structure shown in formula (I):

[0027] Where n is a positive integer, and 1 ≤ n ≤ 3; m is a positive integer, and 0 ≤ m ≤ 3; RBr m The bonded structure is shown in any one of the following formulas (II), (III), (IV), and (V):

[0028] Among numerous biomaterial matrices, cashew nut shell phenol (C15) possesses a unique chemical structure combining a benzene ring, phenolic hydroxyl groups, and an unsaturated straight-chain C15 structure. The benzene ring exhibits rigidity, while the C15 straight-chain provides good toughness. It is precisely this combination of rigidity and flexibility that has made cashew nut shell phenol a research hotspot in the field of bio-based materials in recent years. Cashew nut shell phenol has reactive phenolic hydroxyl groups and unsaturated long alkyl chains. As an agricultural byproduct, it is extracted from natural cashew nut shell oil, offering advantages such as abundant supply, low price, and renewability. Typically, cashew nut shell phenol is a mixture of four alkylphenols with different degrees of saturation: 3% saturated hydrocarbon cashew nut shell phenol, 36% mono-olefin cashew nut shell phenol, 20% diene-olefin cashew nut shell phenol, and 41% tri-olefin cashew nut shell phenol. Its structural diagram is shown below:

[0029] Phosphorus-based flame retardants primarily exert their flame-retardant effect in the condensed phase by promoting char formation, while bromine-based flame retardants interrupt the combustion chain reaction in the gas phase by capturing free radicals. Combining phosphorus and bromine allows for simultaneous flame-retardant action in both the gas and solid phases, achieving synergistic effects. This reduces the amount of flame retardant required while improving flame-retardant efficiency and better preserving the physical and mechanical properties of the matrix material. This invention utilizes chemical modification to covalently integrate flame-retardant elements such as phosphorus and bromine into the cashew nut phenol molecular chain, developing an intrinsically flame-retardant bio-based polyol. This fundamentally solves the problems of flame retardant migration, precipitation, and poor compatibility with the matrix, achieving a balance between flame retardancy and mechanical properties.

[0030] Example Example 1: Example 1 provides a method for preparing phosphorylated cashew nut shellac, comprising the following preparation steps: Weigh 156 g (0.5 mol) of cashew nut shell powder, 50.5 g (0.5 mol) of triethylamine, and 300 g of dichloromethane into a three-necked flask. Install a reflux condenser and start stirring. Add 124 g (0.5 mol) of diphenyl chlorophosphate dropwise to the system at 0 °C. After the addition is complete, raise the temperature to allow the reaction to proceed fully, controlling the temperature at 40–50 °C and the reaction time at 4–8 h. After the reaction is complete, cool to room temperature, filter to remove the white precipitate, and wash the filtrate with 300 g of deionized water. Separate the layers, repeating the washing process three times. Dry the organic layer with 10 g of anhydrous magnesium sulfate and filter. Then, remove the organic solvent dichloromethane from the organic layer by vacuum distillation, controlling the temperature at 40–80 °C and the pressure at -0.07–-0.1 MPa, to obtain phosphorylated cashew nut shell powder.

[0031] The molar ratio of cashew phenol to diphenyl chlorophosphate was 1:1. The synthesized phosphorylated cashew phenol was a brown, low-viscosity liquid with a yield of 82%, a phosphorus content of 5.9%, and a Brookfield viscosity of 800 CPS at 25°C.

[0032] Example 2: Example 2 provides a method for preparing phosphorylated cashew nut shells with epoxy groups, wherein three phosphorylated cashew nut shell products with epoxy groups of different epoxy equivalents are prepared, designated as A, 2A, and 3A, respectively, and the preparation steps are as follows: (1) Phosphorylated cashew nut alcohol A with epoxy group Weigh 100 g (0.3 mol) of phosphorylated cashew phenol prepared in Example 1, 6.9 g (0.15 mol) of formic acid, and 75.5 g of 27% H2O2 aqueous solution (0.6 mol of H2O2 in the aqueous solution) and add them dropwise to the system at a constant temperature of 0°C. After the addition is complete, raise the temperature to allow the reaction to proceed fully, controlling the temperature at 50–70°C and the reaction time at 4–8 h. After the reaction is completed, cool to room temperature and allow to stand for separation. The oil phase is phosphorylated cashew phenol A with epoxy groups.

[0033] The molar ratio of phosphorylated cashew nut shell powder to H2O2 in the above-mentioned aqueous solution is 1:2. The synthesized phosphorylated cashew nut shell powder A with epoxy groups is an orange-yellow, low-viscosity liquid. Experimental testing (hydrochloric acid-acetone method) showed that the epoxy equivalent of phosphorylated cashew nut shell powder with epoxy groups is 460 g / equivalent, and the Brookfield viscosity of the product at 25°C is 900 CPS.

[0034] (2) Phosphorylated cashew phenol 2A with epoxy groups The difference between this preparation process and that of phosphorylated cashew nut shell acid A with epoxy groups is that 100 g (0.3 mol) of phosphorylated cashew nut shell acid prepared in Example 1, 6.9 g (0.15 mol) of formic acid, and 90.4 g of a 27% H2O2 aqueous solution (0.72 mol of H2O2 in the aqueous solution) are added dropwise to the system at a constant temperature of 0°C; the other contents are the same and will not be repeated here.

[0035] The molar ratio of phosphorylated cashew nut shell powder to H2O2 in the above-mentioned aqueous solution is 1:2.4. The synthesized phosphorylated cashew nut shell powder 2A with epoxy groups has an epoxy equivalent of 402 g / equivalent.

[0036] (3) Phosphorylated cashew phenol 3A with epoxy groups The difference between this preparation process and that of phosphorylated cashew nut shell acid A with epoxy groups is that 100 g (0.3 mol) of phosphorylated cashew nut shell acid prepared in Example 1, 6.9 g (0.15 mol) of formic acid, and 113 g of 27% H2O2 aqueous solution (0.9 mol of H2O2 in the H2O2 aqueous solution) are weighed and added dropwise to the system at a constant temperature of 0°C; the other contents are the same and will not be repeated here.

[0037] The molar ratio of phosphorylated cashew nut shell powder to H2O2 in the above-mentioned aqueous solution is 1:3. The synthesized phosphorylated cashew nut shell powder 3A with epoxy groups has an epoxy equivalent of 322 g / equivalent.

[0038] Example 3: Example 3 provides a method for preparing a phosphobromine synergistic cashew phenol polyol, comprising the following preparation steps: 100 g of phosphorylated cashew phenol 2A with epoxy groups prepared in Example 2 and 200 g of dichloromethane were weighed and added to a four-necked flask. The mixture was kept at 5–10 °C. An acetic acid solution containing 34 g of bromine was added dropwise through a constant-pressure funnel over 1–3 h. After the addition was complete, the mixture was kept at 20–30 °C and refluxed for 1–3 h to terminate the reaction. The reaction solution was then allowed to stand at room temperature. Subsequently, the mixture was washed sequentially with 100 g of 10% sodium sulfite aqueous solution, 100 g of 3% sodium hydroxide solution, and 200 g of deionized water. The oil phase was separated into layers, dried with 10 g of anhydrous sodium sulfate, and filtered. The dichloromethane solvent was then removed from the oil phase by vacuum distillation at 40–80 °C and -0.07–-0.1 MPa to obtain the phosphorus-bromine synergistic cashew phenol polyol.

[0039] To further verify the successful synthesis of the phosphobromine synergistic cashew phenol polyol, the following were characterized by infrared spectroscopy: cashew phenol as the raw material, phosphorylated cashew phenol prepared in Example 1, phosphorylated cashew phenol 2A with epoxy groups prepared in Example 2, and the phosphobromine synergistic cashew phenol polyol prepared in Example 3. The infrared spectra are shown below. Figure 1 As shown: In the infrared spectrum of cashew phenol raw material, 3280 cm⁻¹ -1 The broad band at 3008 cm⁻¹ is produced by the stretching of -OH groups. -1 The absorption peak at 2922 cm⁻¹ is attributed to the stretching of the unsaturated double bond (C=C) of the long aliphatic side chain; -1 and 2850cm -1 The signals are attributed to the antisymmetric and symmetric stretching vibrations of the -CH3 and -CH2 groups, respectively; located at 1153 cm⁻¹. -1 The spectral bands belong to the stretching vibration of CO between the phenolic hydroxyl group and the benzene ring group.

[0040] Compared to the infrared spectrum of the cashew phenol raw material, the infrared spectrum of phosphorylated cashew phenol shows the following differences: characteristic groups belonging to diphenyl chlorophosphate are observed, such as P=O (1173 cm⁻¹). -1 ), PO-Ph (958-1130cm) -1 ), and 3280 cm -1 The disappearance of the phenolic hydroxyl signal indicates that a substitution reaction has occurred between the phenolic hydroxyl groups of diphenyl chlorophosphate and cashew phenol. Combined with the fact that the phosphorus content of the product was 5.9% as determined by molybdate spectrophotometry, the successful synthesis of phosphorylated cashew phenol was confirmed.

[0041] Compared to the infrared spectrum of the cashew nutmeg raw material, the difference in the infrared spectrum of phosphorylated cashew nutmeg with epoxy groups is: 3008 cm⁻¹ -1 The absorption peak of the unsaturated double bond of the long aliphatic side chain disappears at 3404 cm⁻¹. -1 A stretching peak appears at the hydroxyl group of the alcohol. Formic acid reacts reversibly with hydrogen peroxide under acid catalysis to produce peroxyformic acid. Peroxyformic acid and the double bond on the cashew nutshell chain undergo a Prilezhaev reaction to generate a three-membered ring epoxy structure. The determination of the epoxy equivalent of the product confirms the successful synthesis of phosphorylated cashew nutshell with epoxy groups.

[0042] The difference compared to the infrared spectrum of cashew phenol raw material is: 3008 cm⁻¹ -1 The absorption peak of the unsaturated double bond of the long aliphatic side chain disappears at 3404 cm⁻¹. -1The appearance of a stretching peak at the hydroxyl group and the measurement of the bromine content of the product (25.3%) confirm that the bromination reaction of the cashew phenol polyol with synergistic phosphorus and bromine reaction has been completed. Furthermore, the cashew phenol polyol with synergistic phosphorus and bromine reaction still exhibits the characteristic absorption peak of the diphenyl chlorophosphate group, P=O (1173 cm⁻¹). -1 ), PO-Ph (958-1130cm) -1 The phosphorus content of the product was determined to be 4.4% by molybdate spectrophotometry, which proved that the phosphorylated cashew nut alcohol with epoxy groups completed the bromination reaction to obtain the above-mentioned phosphorus-bromine synergistic cashew nut alcohol polyol of formula (I).

[0043] Example 4: Example 4 provides a method for preparing cashew phenol polyols with different bromine contents and phosphorus-bromine synergy, and three cashew phenol polyol products with different bromine contents and phosphorus-bromine synergy are prepared respectively, designated as B, 2B and 3B.

[0044] (1) Preparation of cashew phenol polyol B with synergistic effects of phosphorus and bromide: The difference between the preparation process of the phosphobromine synergistic cashew phenol polyol B in Example 3 and that in Example 3 is that the acetic acid solution containing 18 g of bromine is added dropwise through a constant pressure funnel. The other contents are the same and will not be repeated. Finally, the phosphobromine synergistic cashew phenol polyol B is obtained.

[0045] (2) Preparation of cashew phenol polyol 2B with synergistic effects of phosphorus and bromide: This refers to the phosphobromine synergistic cashew phenol polyol prepared in Example 3.

[0046] (3) Preparation of cashew phenol polyol 3B with synergistic effect of phosphorus and bromide: The difference between the preparation process of the phosphobromine synergistic cashew phenol polyol B in Example 3 and that in Example 3 is that the acetic acid solution containing 53 g of bromine is added dropwise through a constant pressure funnel. The other contents are the same and will not be repeated. Finally, the phosphobromine synergistic cashew phenol polyol 3B is obtained.

[0047] The bromine content (refer to "4.2 Determination of Bromine Content" in test standard Q / 0700STY103-2019) and the Brookfield viscosity (refer to "5.4 Operating Procedures" in test standard GB / T 11145-2014) of the above three synergistic phosphorus and bromine cashew polyol products are shown in Table 1.

[0048] Table 1. Test data on bromine content and viscosity of three types of brominated cashew phenols.

[0049] Table 1 shows the results of Brookfield viscosity determination of cashew phenol polyols with different bromine contents (15.2-34.6%). Cashew phenol polyols with synergistic effects of phosphorus and bromine have good viscosity and applications.

[0050] Comparative Example 1: Comparative Example 1 provides a method for preparing brominated cashew phenol. The difference between this method and the preparation process of the synergistic phosphorus and bromide cashew phenol polyol in Example 3 is that the phosphorylated cashew phenol 2A with epoxy groups prepared in Example 2 is replaced with an equal mass of cashew phenol. All other contents are the same and will not be repeated here. Brominated cashew phenol can then be obtained.

[0051] Application Examples The phosphorylated cashew phenol prepared in Example 1, the phosphobromine synergistic cashew phenol polyol prepared in Example 3, and the brominated cashew phenol prepared in Comparative Example 1 were respectively used as polymeric flame retardants in flame-retardant polyurethane materials, and limiting oxygen index tests were conducted.

[0052] Application Example 1: Application Example 1 provides a method for preparing a flame-retardant polyurethane composition containing phosphorylated cashew nut shell powder, comprising the following preparation steps: (1) Preparation of flame-retardant polyurethane composition white material: According to the formulation design, 8g of phosphorylated cashew phenol, 20g of polyether polyol, 0.16g of processing aid water-soluble silicone oil, 0.5g of distilled water, 0.01g of triethylenediamine, and 0.01g of dibutyltin dilaurate prepared in Example 1 were weighed. The temperature of the constant temperature device was set to control the temperature of the liquid at 25℃±2℃. Then, the mixture was stirred and mixed at 800r / min for 2 minutes to obtain the flame-retardant polyurethane composition white material.

[0053] (2) Preparation of flame-retardant polyurethane composition foam: Polymethylene polyphenyl isocyanate (PAPI) was used as the black component in the flame-retardant polyurethane composition. According to the formulation design, 20g of the black component was added to a disposable plastic cup containing the white component. The mixture of black and white components was first stirred slowly to avoid splashing and affecting the ratio; after 2-3 seconds, it was stirred at full speed for 8-10 seconds. Then, the stirred material was quickly poured into a clean mold for free foaming. After foaming stopped, it was placed in an aging chamber at 50℃ for 8 hours.

[0054] Application Example 2: Application Example 2 provides a method for preparing a flame-retardant polyurethane composition containing a phosphorus-bromine synergistic cashew phenol polyol. The only difference from Application Example 1 is that the phosphorylated cashew phenol prepared in Example 1 is replaced with an equal mass of the phosphorus-bromine synergistic cashew phenol polyol prepared in Example 3. All other contents are the same as those in Application Example 1 and will not be repeated here.

[0055] Application Example 3: Application Example 3 provides a method for preparing a flame-retardant polyurethane composition containing brominated cashew phenol as a raw material. The only difference from Application Example 1 is that the phosphorylated cashew phenol prepared in Example 1 is replaced with an equal mass of brominated cashew phenol prepared in Comparative Example 1. All other contents are the same as those in Application Example 1 and will not be repeated here.

[0056] For each of the above application examples 1-3, standard samples were prepared for LOI testing: For the LOI foam material testing standard, the standard dimensions of the specimen (length × width × thickness) should be 70-150mm × 10±0.5mm × 10±0.5mm. (Test standard: GB / T2406.3-2022 standard, determination of limiting oxygen index of foamed plastics) Test method: The standard sample is vertically clamped in a transparent combustion cylinder containing an upward-flowing mixture of oxygen and nitrogen in a specific ratio. The upper part of the sample is ignited, and the subsequent combustion phenomenon is observed. The duration of combustion or the distance burned is recorded. If the combustion time exceeds 3 minutes or the flame front exceeds the 50 mm mark, the oxygen concentration is reduced. If the combustion time is less than 3 minutes or the flame front does not reach the mark, the oxygen concentration is increased. This process is repeated, gradually approaching the specified value from both the top and bottom until the concentration difference is less than 0.5%.

[0057] The average of all experimental data is the final experimental result. The experimental results of Application Examples 1 to 3 are shown in Table 2.

[0058] Table 2. Results of Limiting Oxygen Index Tests in Application Examples 1-3

[0059] As shown in Table 2, when phosphorylated cashew nut shellac, phosphobromine-coated cashew nut shellac polyol, and brominated cashew nut shellac were added in equal mass as flame retardants to prepare polyurethane foam, the limiting oxygen indices of the polyurethane foams prepared using Examples 1-3 were 19.8%, 22.3%, and 21.5%, respectively. Phosphorylated cashew nut shellac and phosphobromine-coated cashew nut shellac polyol exhibited different degrees of flame retardant effects: under the same bromine content, the phosphobromine-coated cashew nut shellac polyol exceeded the limiting oxygen index of the polyurethane foam with the same amount of brominated cashew nut shellac, proving that the phosphobromine-coated cashew nut shellac polyol synthesized in this invention exhibits a synergistic flame retardant effect.

[0060] This invention provides a phosphobromine-coated cashew nut shell polyol, its preparation method, and its application. The phosphobromine-coated cashew nut shell polyol, using cashew nut shell as a raw material, is used as a flame retardant. On one hand, the phosphobromine-coated cashew nut shell polyol can replace or partially replace petroleum-based polyether polyols, overcoming the limitation that flame-retardant polyurethane compositions are entirely petroleum-based. Using the phosphobromine-coated cashew nut shell polyol as a raw material for preparing flame-retardant polyurethane foam has the advantages of safety and environmental friendliness. On the other hand, the phosphobromine-coated cashew nut shell polyol is a low-viscosity liquid with good fluidity, making it convenient to add and use, thus ensuring the molding process and overall toughness of the polyurethane foam.

[0061] It should be noted that: (1) In the preparation of phosphorylated cashew nut shells with epoxy groups, the reaction time, reaction temperature, and amount of formic acid between phosphorylated cashew nut shells and H2O2 can be adjusted according to the actual situation. Formic acid is used as the catalyst, and the amount of formic acid can be adjusted according to the actual situation.

[0062] (2) In addition to triethylamine, the embodiments of the present invention can also use alkaline catalysts such as ferric chloride and aluminum chloride instead.

[0063] (3) In addition to diphenyl chlorinated phosphate, the embodiments of the present invention can also use one or more organophosphorus chlorides such as diphenylphosphine chloride and diphenylphosphine chloride.

[0064] (4) In addition to dichloromethane, the embodiments of the present invention can also use one or more of the organic solvents such as carbon tetrachloride, dichloroethane, dichloropropane, trichloroethane, and chloroform.

[0065] (5) In this embodiment of the invention, an aqueous solution of H2O2 with a mass concentration of 27% is used. The operator can adjust the concentration of H2O2 in the aqueous solution according to the actual situation.

[0066] (6) In this embodiment of the invention, a 10% sodium sulfite aqueous solution is used to wash the reaction solution to remove residual bromine. The operator can adjust the concentration of sodium sulfite in the sodium sulfite aqueous solution according to the actual situation.

[0067] (7) In this embodiment of the invention, a 3% sodium hydroxide solution is used to wash the reaction solution to remove residual acidic substances through a neutralization reaction. Operators can adjust the concentration of sodium hydroxide in the solution according to the actual situation; alternatively, they can use alkaline solutions such as potassium hydroxide solution instead of sodium hydroxide solution.

[0068] (8) In addition to deionized water, pure water such as distilled water can also be used in the embodiments of the present invention.

[0069] (9) In the post-processing of this invention, the washing is usually repeated 2-3 times, and the number of washing times can be increased according to the actual situation.

[0070] (10) The room temperature described in this invention is 25±5℃.

[0071] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A cashew nut phenol polyol with synergistic effects of phosphorus and bromide, characterized in that, It has the structure shown in equation (I): Where n is a positive integer, and 1 ≤ n ≤ 3; m is a positive integer, and 0 ≤ m ≤ 3; the RBr m The bonded structure is shown in any one of the following formulas (II), (III), (IV), and (V): 。 2. The cashew phenol polyol with synergistic phosphorus and bromide effects according to claim 1, characterized in that, The cashew phenol polyol with synergistic phosphorus and bromine effects has a Brookfield viscosity of 700–40,000 cPs at 25°C.

3. A method for preparing a phosphobromine synergistic cashew phenol polyol, characterized in that, Includes the following steps: Step S1. Cashew nut phenol and organophosphorus chloride are heated and reacted under the action of an alkaline catalyst to obtain phosphorylated cashew nut phenol; Step S2. The phosphorylated cashew nut alcohol obtained in step S1 is reacted with H2O2 under acidic conditions to obtain phosphorylated cashew nut alcohol with epoxy groups whose double bonds on the long aliphatic chain are epoxidized. Step S3. React the phosphorylated cashew phenol with epoxy groups obtained in step S2 with excess bromine to obtain a synergistic phosphorus-bromine cashew phenol polyol.

4. The method for preparing cashew phenol polyol with synergistic phosphorus and bromide effects according to claim 3, characterized in that, In step S1, the method for preparing phosphorylated cashew nut shell alcohol includes: Cashew phenol, an appropriate amount of triethylamine catalyst, and an appropriate amount of organic solvent were weighed and added to a three-necked flask. A reflux condenser was installed and stirring was started. Organophosphorus chloride was added dropwise to the system at a constant temperature of 0°C. After the addition was complete, the temperature was raised to 40-50°C to allow the reaction to proceed fully. After the reaction was completed, the mixture was cooled to room temperature and post-processed to obtain the phosphorylated cashew phenol. The molar ratio of cashew phenol to organophosphorus chloride was 1:

1.

5. The method for preparing a phosphobromine synergistic cashew phenol polyol according to claim 4, characterized in that, In step S1, the post-processing method includes: filtering to remove white precipitate, washing the filtrate with pure water, separating the liquid, repeating the washing process multiple times, drying the organic layer with anhydrous magnesium sulfate and filtering, removing the organic solvent from the organic layer by vacuum distillation, wherein the temperature is controlled at 40-80℃ and the pressure is controlled at -0.07--0.1MPa, and the brown viscous product is the phosphorylated cashew nut shell powder.

6. The method for preparing a phosphobromine synergistic cashew phenol polyol according to claim 3, characterized in that, In step S2, the method for preparing the phosphorylated cashew phenol with epoxy groups includes: Weigh the phosphorylated cashew nut powder prepared in step S1 and add an appropriate amount of formic acid to the reaction vessel. Measure an aqueous H2O2 solution and add it dropwise at a constant temperature of 0°C. After the addition is complete, raise the temperature to 50–70°C to allow the reaction to proceed fully. After the reaction is complete, cool to room temperature, allow to stand and separate into layers, and obtain an orange-yellow oily liquid, which is the phosphorylated cashew nut powder with epoxy groups. The molar ratio of phosphorylated cashew nut powder to H2O2 in the aqueous H2O2 solution is 1:2 to 1:

3.

7. The method for preparing a phosphobromine synergistic cashew phenol polyol according to claim 3, characterized in that, In step S3, the preparation method of the phosphobromine synergistic cashew phenol polyol includes: Weigh 100 parts by weight of the phosphorylated cashew nut shell with epoxy groups prepared in step S2, add an appropriate amount of organic solvent to a four-necked flask, and maintain the temperature at 5-10 °C. Add an acetic acid solution containing 18-53 parts by weight of bromine dropwise through a constant pressure funnel, completing the addition within 1-3 h. After the addition is complete, maintain the temperature of the mixture at 20-30 °C and the reflux time at 1-3 h, terminate the reaction, and allow the reaction solution to stand and separate into layers. Take the oil phase, and after post-processing, obtain the phosphorus-bromine synergistic cashew nut shell polyol.

8. The method for preparing a phosphobromine synergistic cashew phenol polyol according to claim 7, characterized in that, In step S3, the post-processing method includes: washing the obtained oil phase sequentially with sodium sulfite aqueous solution, alkaline solution and pure water, allowing it to stand and separate into layers to obtain the oil phase; drying the obtained oil phase with anhydrous sodium sulfate and filtering it; removing the organic solvent from the oil phase by vacuum distillation, wherein the temperature is controlled at 40-80℃ and the pressure is controlled at -0.07--0.1MPa, to obtain the phosphobromine synergistic cashew phenol polyol.

9. A method for preparing a phosphobromine synergistic cashew phenol polyol according to claim 4 or 7, characterized in that, The organophosphorus chloride includes one or more of diphenylphosphine chloride, diphenylphosphine chloride, and diphenyl chlorinated phosphate; the organic solvent includes one or more of carbon tetrachloride, dichloromethane, dichloroethane, dichloropropane, trichloroethane, and chloroform.

10. The application of the phosphobromine synergistic cashew phenol polyol according to claim 1 or 2, or the phosphobromine synergistic cashew phenol polyol prepared by the method according to any one of claims 3-9, as a flame retardant in the preparation of flame-retardant polyurethane foam materials.

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