A process for the preparation of propoxylated bisphenol a

Abstract

The application provides a preparation method of propoxylated bisphenol A, and belongs to the field of production of propoxylated bisphenol A. The method comprises the following steps: stirring and mixing bisphenol A and an alkaline aqueous solution to obtain a pre-structured system; adding propylene oxide dropwise to the pre-structured system and performing heat preservation reaction to obtain a reaction mixture; adding a water-saturated benzene solvent to the reaction mixture, removing a lower aqueous phase, and obtaining an upper benzene solution; removing the benzene solvent in the upper benzene solution under the protection of an inert gas to obtain an intermediate product; dissolving the intermediate product in a ketone solvent, then adding a core-shell structure adsorbent for adsorption treatment, removing a lower solid phase, and obtaining an upper clear liquid; removing the ketone solvent in the upper clear liquid to obtain propoxylated bisphenol A. The application simultaneously realizes the improvement of the structural regularity and the purity of propoxylated bisphenol A through the synergistic design of "directional regulation of the reaction process to guarantee the structural regularity" and "ladder type precise impurity removal to improve the purity".

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of propoxylated bisphenol A production, and particularly relates to a preparation method of propoxylated bisphenol A. BACKGROUND

[0002] As a key intermediate of high-performance polyester resin and light-cured coating, the molecular structure regularity and product purity of propoxylated bisphenol A (BPA-4PO) directly determine the mechanical strength, weather resistance and optical performance of downstream materials. The ideal structure of BPA-4PO requires to realize the accurate addition of bisphenol A molecules and four propylene oxide units, and the head-to-tail connection ratio needs to be higher than 95%, and at the same time, the free phenol content needs to be controlled below 0.1% and the aldehyde impurity needs to be below 50 ppm.

[0003] However, the existing synthesis technology is difficult to simultaneously realize the accurate structure control and deep purification. Although the traditional process represented by the prior art CN103351286A adopts the propylene oxide dropping and condensation reflux mode, there are the following systematic defects: in terms of structure control, since the pre-structuring reaction field is not constructed, the phenoxide ions are distributed disorderly in the aqueous phase, the local concentration of propylene oxide is uneven, part of the area is excessively self-polymerized to generate polyether by-products, and part of the area is insufficiently reacted to cause bisphenol A residues, and finally the molecular weight distribution of the product is discrete (PDI>1.8); at the same time, the wide reaction temperature range of 20-30℃ leads to the out-of-control of the selectivity of ring-opening sites, a large amount of head-to-head connection isomers are generated, and the hydroxyl value fluctuation exceeds the technical requirement of 205-230 mg KOH / g. In terms of purification, the purification system which simply relies on benzene solvent extraction and ketone solvent fractionation has obvious limitations: the removal rate of strong polar aldehyde impurities is less than 60%, the yellowing index (Δb*) of the product during storage is more than 5; the removal efficiency of free phenol is low, and the residual amount often exceeds 0.5%; and the phenolic hydroxyl oxidation to generate quinone chromophores (ΔE*>3) is induced during the high-temperature desolventization process at 110-130℃, forming secondary pollution. These defects seriously restrict the application effect of BPA-4PO in the field of high-order materials. Therefore, how to simultaneously improve the structure regularity and purity of propoxylated bisphenol A is a technical problem to be solved at present. SUMMARY

[0004] The present application provides a preparation method of propoxylated bisphenol A to solve the technical problem of how to simultaneously improve the structure regularity and purity of propoxylated bisphenol A.

[0005] The present application provides a preparation method of propoxylated bisphenol A, which comprises the following steps:

[0006] S1, stirring and mixing bisphenol A with an alkaline aqueous solution at a temperature of 20-30℃ for 15-30 min to obtain a pre-structuring system;

[0007] S2. Under the conditions of temperature 23-27℃ and reflux, propylene oxide is added dropwise to the prestructured system and the reaction is carried out at this temperature for 3-8 hours to obtain the reaction mixture.

[0008] S3. Add a water-saturated benzene solvent to the reaction mixture, mix, allow to stand and separate into layers, remove the lower aqueous phase to obtain the upper benzene solution; the water-saturated benzene solvent contains 0.04-0.06% by mass of water.

[0009] S4. Under inert gas protection, remove the benzene solvent from the upper benzene solution to obtain an intermediate product;

[0010] S5. Dissolve the intermediate product using a ketone solvent, then add a core-shell structured adsorbent for adsorption treatment, allow it to stand and separate into layers, remove the lower solid phase, and obtain the upper clear liquid; the core layer material of the core-shell structured adsorbent is octadecyl-modified macroporous silica gel, and the shell layer material is amino-modified mesoporous silica gel.

[0011] S6. Under inert gas protection, remove the ketone solvent from the supernatant to obtain propoxylated bisphenol A.

[0012] Optionally, in step S1, the ratio of the mass M of bisphenol A to the volume V of the alkaline aqueous solution, M:V, is 1:(1.5~3), where M is in g and V is in mL.

[0013] The alkaline aqueous solution is a sodium hydroxide or potassium hydroxide aqueous solution with a mass fraction of 5-10%.

[0014] Optionally, in step S2, the molar ratio of bisphenol A to propylene oxide is 1:(4.0-4.4).

[0015] Optionally, in step S3, the volume ratio of the reaction mixture to the water-saturated benzene solvent is 1:(0.8-1.5), and the water-saturated benzene solvent is water-saturated toluene.

[0016] Optionally, in step S5, the mass ratio of the ketone solvent to the intermediate product is (3-6):1, and the ketone solvent is methyl isobutyl ketone.

[0017] Optionally, in step S5, the amount of the core-shell structured adsorbent is 0.1 to 0.5% of the total mass of the intermediate product and the ketone solvent.

[0018] Optionally, in step S5, the adsorption treatment temperature is 40–60°C and the time is 20–30 min.

[0019] Optionally, in step S5, the preparation method of the core-shell structured adsorbent includes:

[0020] S501. Under inert atmosphere and reflux conditions, vacuum-activated large-pore mesoporous silica gel is modified with octadecylsilane reagent to obtain core layer material.

[0021] S502. The core layer material is dispersed in a mixed solution of ethanol and water, and then tetraethyl orthosilicate and 3-aminopropyltriethoxysilane are added. A co-condensation reaction is carried out under alkaline catalytic conditions to form an amino-modified shell mesoporous silica gel on the surface of the core layer material, thereby obtaining the core-shell structure adsorbent.

[0022] Optionally, the pore size of the large-pore mesoporous silica gel is 8–15 nm;

[0023] The octadecylsilane reagent is octadecyltrichlorosilane;

[0024] The molar ratio of the tetraethyl orthosilicate to the 3-aminopropyltriethoxysilane is (4-6):1;

[0025] The pore size of the shell mesoporous silica gel is 3-5 nm;

[0026] The modification reaction is carried out at a temperature of 70℃~85℃ for a time of 10~14h.

[0027] The co-condensation reaction is carried out at a temperature of 20℃ to 40℃ for a time of 20 to 28 hours.

[0028] Optionally, in step S4, the removal temperature of the benzene solvent is 90–110°C;

[0029] In step S6, the removal temperature of the ketone solvent is 80–100°C.

[0030] The technical solutions provided in this application have the following advantages compared with the prior art:

[0031] This application provides a method for preparing propoxylated bisphenol A. Through the synergistic design of "directionally controlling the reaction process to ensure structural regularity" and "step-by-step precise impurity removal to improve purity," the method simultaneously improves the structural regularity and purity of propoxylated bisphenol A. The specific mechanism is explained in detail from the following two aspects:

[0032] On the one hand, this application constructs a pre-structured system through S1 and precisely controls the reaction process through S2, ensuring the regularity of the product chain structure from the molecular addition stage.

[0033] In S1, the temperature conditions of 20–30°C and the stirring time of 15–30 min create the core prerequisites for the directional reaction: the alkaline aqueous solution promotes the dehydrogenation of the phenolic hydroxyl group of bisphenol A to generate phenoxy anions (the active site for reaction with propylene oxide). Since phenoxy anions possess both a hydrophilic oxygen anion end and a hydrophobic benzene ring end, they self-assemble into dynamic and uniform micelles or aggregates. This structure acts like a "nanoreactor," actively enriching the subsequently added PO. Because PO is a weakly polar molecule, it preferentially dissolves in the hydrophobic microregions of the micelles, significantly increasing the local effective concentration ratio of phenoxy anions to PO. This avoids "local over-reaction" or "local under-reaction" caused by uneven dispersion of PO in the aqueous phase, providing spatial constraints for directional addition.

[0034] S2 further enhances the directionality of the reaction through triple precise parameter control: First, a narrow temperature range of 23–27°C allows for precise regulation of reaction activity, promoting PO ring-opening via the SN2 mechanism. Phenoxy anions preferentially attack the secondary carbons of PO molecules with less steric hindrance, generating well-ordered ether chains with a very high head-to-tail linkage ratio, effectively avoiding the disorder of PO ring-opening sites at high temperatures (such as attacking primary carbons to generate disordered head-to-head linkages). Second, PO is added dropwise, which controls the PO supply rate to match the density of active sites of phenoloxy anions in the micelles, preventing a sudden increase in PO concentration due to a single addition (thus avoiding the formation of short-chain polyether byproducts from intermolecular self-polymerization of PO molecules, or uneven chain lengths caused by excessive PO binding to the monophenolic hydroxyl groups of bisphenol A). Third, reflux condensation conditions, considering that the boiling point of PO is only 34°C, prevent PO volatilization, maintain a precise bisphenol A to PO feed ratio, and avoid "incomplete bisphenol A reaction" or "insufficient PO units" due to PO loss. Ultimately, this series of designs ensures that the two phenolic hydroxyl groups of each bisphenol A molecule can stably bind to two PO units, forming a molecular structure with consistent chain length and regular connection.

[0035] On the other hand, this application uses a layered strategy of S3 primary impurity removal and S5 deep impurity removal to remove different types of impurities in stages, while ensuring that the target product is not lost, and ultimately achieves improved purity.

[0036] In S3, a water-saturated benzene solvent with a water mass fraction of 0.04–0.06% is added to the reaction mixture. The core principle is to build a highly efficient separation system based on the "polarity difference": benzene solvents (such as toluene) are weakly polar, which highly matches the solubility of the weakly polar crude propoxylated bisphenol A, allowing the crude product to completely dissolve and form the upper organic phase; while the strongly polar impurities remaining from the reaction (such as unreacted sodium hydroxide / potassium hydroxide, generated inorganic salts, and aldehyde byproducts that cause yellowing of the product) naturally tend to enter the strongly polar aqueous phase due to the principle of "like dissolves like". Among them, the trace amount of water in the solvent plays a key "impurity capture" role. Water molecules can actively combine with strongly polar impurities through hydrogen bonds: forming "water-base" complexes with hydroxyl groups, "water-aldehyde" complexes with the carbonyl groups of aldehydes, and "water-ion" complexes with inorganic salts. These complexes have extremely low solubility in benzene solvents and will be completely removed with the lower aqueous phase, completing the primary impurity removal while significantly reducing the burden of subsequent deep impurity removal.

[0037] S5 achieves deep impurity removal without product loss through a unique core-shell structure adsorbent design: the shell layer is amino-modified mesoporous silica gel with pores smaller than the molecular size of propoxylated bisphenol A, forming a "physical barrier" that prevents the target product from entering the adsorbent, fundamentally avoiding product loss. Simultaneously, the amino groups on the shell surface adsorb residual polar small molecule impurities (such as unreacted free phenols, trace aldehydes, and residual moisture) through hydrogen bonding. The core layer is octadecyl-modified macroporous silica gel with pores of 8–15 nm, capable of accommodating non-polar impurities (such as alkane byproducts) not captured by the shell. The long octadecyl chains on the core surface, due to their strong hydrophobicity, fix non-polar impurities within the core layer through hydrophobic interactions. This design, where the shell sieves the product and the core adsorbs different impurities, thoroughly removes various impurities affecting purity while ensuring zero product loss, ultimately achieving high-purity propoxylated bisphenol A. Attached Figure Description

[0038] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic flowchart illustrating a method for preparing propoxylated bisphenol A, as provided in an embodiment of this application. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] Figure 1 This is a schematic flowchart illustrating a method for preparing propoxylated bisphenol A, as provided in an embodiment of this application.

[0043] like Figure 1 As shown in the embodiments of this application, a method for preparing propoxylated bisphenol A is provided, the method comprising the following steps:

[0044] S1. Under the temperature conditions of 20-30℃, bisphenol A and alkaline aqueous solution are stirred and mixed for 15-30 min to obtain a prestructured system;

[0045] S2. Under the conditions of temperature 23-27℃ and reflux, propylene oxide is added dropwise to the prestructured system and the reaction is carried out at this temperature for 3-8 hours to obtain the reaction mixture.

[0046] S3. Add a water-saturated benzene solvent to the reaction mixture, mix, allow to stand and separate into layers, remove the lower aqueous phase to obtain the upper benzene solution; the water-saturated benzene solvent contains 0.04-0.06% by mass of water.

[0047] S4. Under inert gas protection, remove the benzene solvent from the upper benzene solution to obtain an intermediate product;

[0048] S5. Dissolve the intermediate product using a ketone solvent, then add a core-shell structured adsorbent for adsorption treatment, allow it to stand and separate into layers, remove the lower solid phase, and obtain the upper clear liquid; the core layer material of the core-shell structured adsorbent is octadecyl-modified macroporous silica gel, and the shell layer material is amino-modified mesoporous silica gel.

[0049] S6. Under inert gas protection, remove the ketone solvent from the supernatant to obtain propoxylated bisphenol A.

[0050] In some embodiments, in step S1, the ratio of the mass M of bisphenol A to the volume V of the alkaline aqueous solution, M:V, is 1:(1.5-3), where M is in g and V is in mL.

[0051] The alkaline aqueous solution is a sodium hydroxide or potassium hydroxide aqueous solution with a mass fraction of 5-10%.

[0052] In some embodiments, in step S2, the molar ratio of bisphenol A to propylene oxide is 1:(4.0 to 4.4).

[0053] In some embodiments, in step S3, the volume ratio of the reaction mixture to the water-saturated benzene solvent is 1:(0.8-1.5), and the water-saturated benzene solvent is water-saturated toluene.

[0054] In some embodiments, in step S5, the mass ratio of the ketone solvent to the intermediate product is (3-6):1, and the ketone solvent is methyl isobutyl ketone.

[0055] In some embodiments, in step S5, the amount of the core-shell structured adsorbent is 0.1 to 0.5% of the total mass of the intermediate product and the ketone solvent.

[0056] In some embodiments, in step S5, the adsorption treatment is carried out at a temperature of 40–60°C for a time of 20–30 min.

[0057] In some embodiments, step S5, the preparation method of the core-shell structured adsorbent includes:

[0058] S501. Under inert atmosphere and reflux conditions, vacuum-activated large-pore mesoporous silica gel is modified with octadecylsilane reagent to obtain core layer material.

[0059] S502. The core layer material is dispersed in a mixed solution of ethanol and water, and then tetraethyl orthosilicate and 3-aminopropyltriethoxysilane are added. A co-condensation reaction is carried out under alkaline catalytic conditions to form an amino-modified shell mesoporous silica gel on the surface of the core layer material, thereby obtaining the core-shell structure adsorbent.

[0060] In some embodiments, the pore size of the macroporous silica gel is 8–15 nm;

[0061] The octadecylsilane reagent is octadecyltrichlorosilane;

[0062] The molar ratio of the tetraethyl orthosilicate to the 3-aminopropyltriethoxysilane is (4-6):1;

[0063] The pore size of the shell mesoporous silica gel is 3-5 nm;

[0064] The modification reaction is carried out at a temperature of 70℃~85℃ for a time of 10~14h.

[0065] The co-condensation reaction is carried out at a temperature of 20℃ to 40℃ for a time of 20 to 28 hours.

[0066] In some embodiments, in step S4, the removal temperature of the benzene solvent is 90–110°C;

[0067] In step S6, the removal temperature of the ketone solvent is 80–100°C.

[0068] In some embodiments, the preparation method of water-saturated benzene solvent includes: placing a benzene solvent (such as toluene) and excess deionized water in a separatory funnel, vigorously shaking and mixing at room temperature (20-25°C) for 10-15 minutes to ensure sufficient contact, and then allowing the mixture to stand for at least 30 minutes to separate the phases. After the two phases have completely separated, the lower aqueous phase is removed, and the resulting upper organic phase is the desired water-saturated benzene solvent.

[0069] It should be noted that step S1 involves premixing bisphenol A with an alkaline aqueous solution. The core function of this step is to construct a "nanoreactor" through molecular regulation, laying the foundation for the subsequent directional addition of propylene oxide (PO). Under conditions of 20–30°C, bisphenol A and the alkaline aqueous solution are stirred and mixed for 15–30 minutes. This not only promotes the dehydrogenation of the phenolic hydroxyl group of bisphenol A to generate phenoxy anions that participate in the addition reaction, but also utilizes the amphiphilic nature of the phenoxy anion (hydrophilic oxy anion end + hydrophobic benzene ring end) to self-assemble into dynamic and uniform micelles / aggregates in the aqueous phase, i.e., the "pre-structured system".

[0070] A temperature of 20–30°C maintains the stability of the micelle structure while ensuring the efficient generation of phenolic anions; a stirring time of 15–30 min ensures that bisphenol A reacts fully with the alkali to form a homogeneous pre-structured system; a bisphenol A mass to alkali volume ratio of 1:(1.5–3) provides a sufficient aqueous environment for micelle self-assembly and allows bisphenol A to dissolve completely, avoiding undissolved substances from affecting subsequent reactions; a 5–10% sodium hydroxide / potassium hydroxide aqueous solution can efficiently promote the dehydrogenation of phenolic hydroxyl groups to generate phenolic anions, providing sufficient active sites for subsequent PO addition.

[0071] Step S2 is the dropwise addition and heat preservation reaction of propylene oxide. This step is the key to the formation of the BPA-4PO main chain structure. Its role is to achieve the precise addition of "PO-phenolic anion" in the prestructured system and generate a crude product with a regular structure.

[0072] Temperatures of 23–27°C enhance the SN2 mechanism of PO ring-opening, allowing phenolic anions to preferentially attack the secondary carbons of PO with less steric hindrance, resulting in a well-ordered chain structure with a very high head-to-tail connection ratio. PO is added dropwise, allowing it to be continuously enriched by the hydrophobic microregions of the pre-structured system and precisely bind to the active sites. The molar ratio of bisphenol A to PO is 1:(4.0–4.4), satisfying the theoretical requirement of each of the two phenolic hydroxyl groups of bisphenol A molecule adding two PO units, while also ensuring complete reaction of bisphenol A. A 3–8 hour incubation period allows PO to fully combine with phenolic anions, ensuring a complete addition reaction. Reflux condensation prevents PO volatilization, maintains a precise bisphenol A to PO feed ratio, and provides a proportional guarantee for the formation of the target structure.

[0073] The prestructured system in this application is a "dynamic nanoreactor" formed by molecular self-assembly after the reaction of bisphenol A with an alkaline aqueous solution. Its core functions are reflected in two aspects: First, the enrichment and directional supply of active sites. The amphiphilic nature of phenolic anions allows them to self-assemble into micelles in the aqueous phase. The hydrophobic microregions of the micelles can actively enrich the subsequently added PO, significantly increasing the local effective concentration of phenolic anions and PO, avoiding uneven dispersion of PO in the aqueous phase, and significantly improving the reaction rate. Second, the directional reaction regulation. The micellar structure provides "spatial constraint" for the ring-opening of PO, restricting the disordered movement of PO. Combined with a temperature of 23-27℃, it can promote PO to preferentially attack secondary carbons via the SN2 mechanism to generate a structurally regular BPA-4PO main chain, while inhibiting side reactions such as PO self-polymerization, ensuring the uniformity of the product chain structure from the source.

[0074] Step S3 involves layering in a water-saturated benzene solvent. The purpose of this step is to actively capture polar impurities using a "functional solvent" to achieve efficient separation of the "organic phase (crude product) - aqueous phase (impurities)," thus reducing the burden on subsequent precise purification.

[0075] A water-saturated benzene solvent with a water mass fraction of 0.04–0.06% is used. The trace amounts of water in the solvent can form a hydrogen bond network with unreacted polar impurities such as alkalis and aldehydes, constructing a "water-alkali-impurity" complex, which promotes the entry of impurities into the aqueous phase. The volume ratio of the reaction mixture to the solvent is 1:(0.8–1.5), which ensures that the benzene solvent completely dissolves the crude BPA-4PO, allowing the impurities to be fully dispersed and enter the aqueous phase. Water-saturated toluene is chosen as the solvent because its weak polarity matches that of BPA-4PO, it has strong dissolving power, and its boiling point is moderate (110.6℃), making it easy to remove later. At the same time, its density difference with water is significant, which facilitates clear stratification.

[0076] The core of water-saturated benzene solvent separation lies in achieving efficient separation through "polarity difference" and "directional capture of trace water." Benzene solvents (such as toluene) are weakly polar, matching the solubility of the weakly polar crude BPA-4PO, allowing the crude product to completely dissolve and form the upper organic phase. Meanwhile, strongly polar impurities remaining from the reaction (such as basic catalysts, inorganic salts, and aldehyde byproducts) tend to adhere to the strongly polar aqueous phase due to the principle of "like dissolves like." The key is the "water-saturated" trace water (0.04–0.06% by mass), which actively binds to strongly polar impurities through hydrogen bonds. For example, it forms stable "water-base" complexes with basic catalysts and "water-aldehyde" complexes with the carbonyl groups of aldehydes, allowing these impurities to more thoroughly enter the lower aqueous phase and preventing them from remaining in the organic phase. Simultaneously, the density difference between benzene solvents and water (e.g., toluene's density is less than water) allows for rapid and clear separation of the two phases, facilitating the removal of impurities from the aqueous phase. From the perspective of process integration, this step can also terminate the previous reaction and remove most of the highly polar impurities in advance, reducing the burden on subsequent adsorption steps and laying the foundation for subsequent purification.

[0077] Step S4 is the removal of benzene-based solvents under inert gas protection. The purpose of this step is to remove benzene-based solvents from the organic phase to obtain a pure BPA-4PO intermediate product, while avoiding oxidation and deterioration of the intermediate product.

[0078] The desolvation temperature of 90-110℃ is highly matched with the boiling point of toluene, which can efficiently remove toluene under normal pressure or slight reduced pressure without causing thermal damage to the intermediate product. The protection of inert gas (such as high-purity nitrogen) can isolate oxygen, prevent the phenolic hydroxyl groups in the intermediate product from being oxidized to generate colored impurities, ensure the chemical integrity of the intermediate product, and provide a pure matrix for subsequent adsorption and purification.

[0079] Step S5 involves dissolving the ketone solvent and adsorbing it with the core-shell adsorbent. This step is crucial for achieving a "high-purity, low-color" product. Its function is to selectively remove residual free phenols, trace amounts of aldehydes, moisture, and other small molecule impurities from the intermediate product without losing the target product.

[0080] A mass ratio of ketone solvent (preferably methyl isobutyl ketone, MIBK) to intermediate product of 3–6:1 ensures complete dissolution of the intermediate product to form a homogeneous solution, allowing impurities to disperse sufficiently and facilitating adsorbent contact. The core-shell structure adsorbent is used at 0.1–0.5% of the total material mass, effectively adsorbing impurities while avoiding excessive dosage that could increase costs. An adsorption temperature of 40–60°C improves the diffusion rate of impurities in the solvent, accelerating their migration to the active sites of the adsorbent. An adsorption time of 20–30 minutes ensures sufficient binding between impurities and the adsorbent, achieving adsorption equilibrium.

[0081] Core-shell structured adsorbents achieve "precise impurity removal + zero product loss" through a gradient mechanism of "physical sieving + synergistic adsorption of functional groups." The core principle is as follows:

[0082] The shell is made of amino-modified mesoporous silica gel with a pore size of 3-5 nm, allowing for precise sieving. The target product, BPA-4PO, has a molecular size larger than 5 nm and cannot enter the shell, fundamentally preventing product loss. Simultaneously, the amino groups on the shell surface actively capture small polar molecule impurities (such as free phenols, aldehydes, and moisture) that enter the shell through hydrogen bonding, completing the "first stage of impurity removal." Tetraethyl orthosilicate and 3-aminopropyltriethoxysilane are co-condensed in a molar ratio of (4-6):1, which allows for control of the amino group density, ensuring that polar impurities are fully adsorbed.

[0083] The core layer is octadecyl (C18) modified macroporous silica gel with a pore size of 8–15 nm, capable of accommodating nonpolar small molecule impurities not captured by the shell layer. The C18 long-chain alkyl groups on the core layer surface are strongly hydrophobic, enabling them to adsorb nonpolar impurities (such as alkane byproducts) through hydrophobic interactions, thus completing a "secondary impurity removal." The modification reaction at 70–85 °C for 10–14 h ensures full grafting of the C18 long chains onto the silica gel surface, forming a dense hydrophobic layer and improving the adsorption efficiency of nonpolar impurities.

[0084] The synergistic effect of the "amino shell + C18 core layer" makes the adsorbent's removal efficiency for impurities far superior to that of single-function adsorbents. The sieving effect of the shell layer prevents large molecular impurities from occupying the adsorption sites of the core layer, while the hydrophobic adsorption of the core layer supplements the removal of non-polar impurities. The combination of the two can comprehensively remove impurities that affect the product's color, acid value, and moisture content, while ensuring no product loss and significantly improving the purity and storage stability of BPA-4PO.

[0085] Step S6 involves removing ketone solvents under an inert gas atmosphere. This step removes ketone solvents to obtain a pure BPA-4PO product, while ensuring that the product does not oxidize or degrade in subsequent processing and maintains its excellent performance.

[0086] The solvent removal temperature of 80-100℃ matches the boiling point of MIBK (115℃), enabling efficient solvent removal under slight reduced pressure without causing thermal decomposition of the product. The inert gas protection continuously isolates oxygen, preventing the oxidation of phenolic hydroxyl groups and ether bonds in the product, ensuring that the product is colorless or very light yellow in appearance, and that the hydroxyl value remains stable within the target range of 205-230 mgKOH / g. Hot discharge and sealed packaging under a nitrogen atmosphere can continue the oxygen-free protection, further ensuring the stability of the product during storage and delaying yellowing.

[0087] In summary, the method for preparing propoxylated bisphenol A described in this application has significant advantages in reaction control, impurity purification, product stability, and industrial application.

[0088] At the reaction control level, by constructing a pre-structured system, a dynamic nanoreactor is formed by utilizing the self-assembly characteristics of phenolic anions. This allows for the directional enrichment of propylene oxide. Combined with precise temperature control and dropwise addition, propylene oxide can be guided to open the ring and precisely add to bisphenol A via a specific mechanism. This effectively reduces side reactions, ensures the regularity of the product's main chain structure, and improves reaction efficiency and product structure uniformity from the source.

[0089] In the impurity purification stage, this method employs a dual strategy of "primary layering + precise adsorption" to achieve efficient and lossless impurity removal. First, a water-saturated benzene solvent is used for layering, leveraging the polarity difference and the directional binding of trace amounts of water to actively capture polar impurities in the system, completing preliminary purification. Then, utilizing the special design of the core-shell structured adsorbent, the physical sieving function of the shell layer prevents product loss, while the different functional groups in the shell and core layers specifically adsorb polar and non-polar small molecule impurities, achieving comprehensive and precise deep purification and significantly improving product purity.

[0090] In terms of product stability, the inert gas protection throughout the process can effectively isolate oxygen, prevent the active groups in the product from being oxidized, and avoid the product color from darkening. At the same time, the mild desolvation temperature matched with the boiling point of the solvent can completely remove the solvent without causing thermal damage to the product, ensuring that the product appearance remains excellent and that key performance indicators remain stable for a long time, thus extending the shelf life.

[0091] In addition, the process has good industrial feasibility: the preparation of water-saturated benzene solvents is simple, the core-shell structure adsorbent can be achieved by a two-step grafting method, the process is mature and easy to replicate; the key operations in each step do not require extreme conditions, the parameter control range is reasonable, and it is easy to stabilize and control in actual production, which can meet the needs of mass production of high-quality propoxylated bisphenol A.

[0092] The propoxylated bisphenol A prepared in this application has a wide range of applications and is of key value in the field of high-performance materials. It is commonly used in UV-curable coating systems and is a major raw material for synthesizing chemically resistant polyester resins, especially indispensable in the manufacture of alkali-resistant polyester resins. Furthermore, it possesses excellent thermal stability, imparting good heat resistance to the synthesized resins and subsequent coatings. In addition, acrylic monomers produced based on ethoxylated and propoxylated bisphenol A can significantly improve the flexibility of coatings and allow the coating to possess both hydrophobic and hydrophilic properties. Hydrophobicity helps enhance the coating's water resistance, while hydrophilicity ensures adhesion between the coating and the substrate. These acrylic monomers also possess high curing activity, accelerating the curing efficiency of UV-curable coatings. Besides the above core applications, propoxylated bisphenol A can also be used in the manufacture of paints, adhesives, and other products, providing support for the corrosion resistance, flexibility, and curing performance of these products.

[0093] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards / industry standards / the disclosure herein; if there are no corresponding national standards / industry standards / the disclosure herein, they are performed according to generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer.

[0094] Example 1

[0095] This embodiment provides a method for preparing propoxylated bisphenol A, which may specifically include the following steps:

[0096] S11. Add 100.0g of bisphenol A and 200mL of 8% sodium hydroxide aqueous solution to a dry reaction vessel, and stir for 22min at 25℃ to form a milky white prestructured system.

[0097] S21. Maintaining the system temperature at 25°C, under reflux conditions, add 244.0 g of propylene oxide dropwise to the prestructured system obtained in step S11. The molar ratio of bisphenol A to propylene oxide is 1:4. After the addition is complete, continue the reaction at this temperature for 5 hours to obtain the reaction mixture.

[0098] S31. Add 115 mL of water-saturated toluene to the reaction mixture obtained in step S21. The volume ratio of the reaction mixture to water-saturated toluene is 1:1.2, and the mass fraction of water in the water-saturated toluene is 0.05%. After mixing, stir for 18 min, then let stand to separate into layers, remove the lower aqueous phase, and obtain the upper benzene solution.

[0099] S41. Under the protection of high-purity nitrogen, the upper benzene solution obtained in step S31 is treated, and the temperature is controlled at 100℃ to remove toluene and obtain an intermediate product.

[0100] S51. Dissolve the intermediate product obtained in step S41 using methyl isobutyl ketone, with a mass ratio of methyl isobutyl ketone to intermediate product of 4.5:1; after dissolution, add a core-shell structured adsorbent, with the amount of core-shell structured adsorbent being 0.3% of the total mass of intermediate product and methyl isobutyl ketone, and perform adsorption treatment at a temperature of 50°C for 25 min; after adsorption treatment, allow the mixture to stand and separate into layers, remove the lower solid phase, and obtain the upper clear liquid.

[0101] The preparation method of the core-shell structured adsorbent includes the following steps:

[0102] S501, Preparation of core layer material: 10nm macroporous silica gel (purchased from Beijing Huideyi Technology, product model DIOLMB100-75 / 200) was vacuum activated at 120℃ for 2h, and then placed under nitrogen atmosphere and reflux conditions to undergo a modification reaction with octadecyltrichlorosilane (CAS No. 112-04-9). The reaction temperature was 77℃ and the reaction time was 12h to obtain octadecyl-modified macroporous silica gel (core layer material).

[0103] S502, Shell Material Construction: The core material from S501 was dispersed in a mixed solution of ethanol and water (volume ratio of ethanol to water: 4:1), followed by the addition of tetraethyl orthosilicate (CAS No. 78-10-4) and 3-aminopropyltriethoxysilane (CAS No. 919-30-2), with a molar ratio of tetraethyl orthosilicate to 3-aminopropyltriethoxysilane of 5:1. A co-condensation reaction was carried out under alkaline catalytic conditions (ammonia as catalyst, concentration 0.3 mol / L) at 30°C for 24 h, forming an amino-modified mesoporous silica gel (shell material) with a pore size of 4 nm on the surface of the core material, thus obtaining a core-shell structured adsorbent.

[0104] S61. Under the protection of high-purity nitrogen, the supernatant obtained in step S51 is treated, and the temperature is controlled at 90°C to remove methyl isobutyl ketone, finally obtaining a colorless, transparent, viscous liquid, which is propoxylated bisphenol A.

[0105] Example 2

[0106] This embodiment provides a method for preparing propoxylated bisphenol A, which may specifically include the following steps:

[0107] S12. Add 100.0g of bisphenol A and 150mL of 6% potassium hydroxide aqueous solution to a dry reaction vessel, and stir for 18min at 22℃ to form a milky white prestructured system.

[0108] S22. Maintaining the system temperature at 24°C, under reflux conditions, add 248.8 g of propylene oxide dropwise to the prestructured system obtained in step S12. The molar ratio of bisphenol A to propylene oxide is 1:4.1. After the addition is complete, continue the reaction at this temperature for 6 hours to obtain the reaction mixture.

[0109] S32. Add 90 mL of water-saturated toluene to the reaction mixture obtained in step S22. The volume ratio of the reaction mixture to water-saturated toluene is 1:0.9, and the mass fraction of water in the water-saturated toluene is 0.04%. After mixing, stir for 15 min, then let stand to separate the layers, remove the lower aqueous phase, and obtain the upper benzene solution.

[0110] S42. Under the protection of high-purity nitrogen, the upper benzene solution obtained in step S32 is treated, and the temperature is controlled at 95°C to remove toluene and obtain an intermediate product.

[0111] S52. Dissolve the intermediate product obtained in step S42 using methyl isobutyl ketone, with a mass ratio of methyl isobutyl ketone to intermediate product of 3.5:1; after dissolution, add a core-shell structured adsorbent, with the amount of core-shell structured adsorbent being 0.2% of the total mass of intermediate product and methyl isobutyl ketone, and perform adsorption treatment at a temperature of 45°C for 22 min; after adsorption treatment, allow the mixture to stand and separate into layers, remove the lower solid phase, and obtain the upper clear liquid;

[0112] The preparation method of the core-shell structured adsorbent includes the following steps:

[0113] S501, Preparation of core layer material: 8nm macroporous silica gel (purchased from Zhengzhou Huiju Chemical, model SBA-15) was activated under vacuum at 120℃, and then placed under nitrogen atmosphere and reflux conditions to undergo a modification reaction with octadecyltrichlorosilane. The reaction temperature was 75℃ and the reaction time was 11h to obtain octadecyl-modified macroporous silica gel (core layer material).

[0114] S502, Shell Material Construction: The core material from S501 was dispersed in a mixed solution of ethanol and water (volume ratio of ethanol to water: 3:1), followed by the addition of tetraethyl orthosilicate and 3-aminopropyltriethoxysilane, with a molar ratio of tetraethyl orthosilicate to 3-aminopropyltriethoxysilane of 4:1. A co-condensation reaction was carried out under alkaline catalytic conditions (ammonia as catalyst, concentration 0.2 mol / L) at 25°C for 22 hours, forming an amino-modified mesoporous silica gel (shell material) with a pore size of 3 nm on the surface of the core material, thus obtaining a core-shell structured adsorbent.

[0115] S62. Under the protection of high-purity nitrogen, the supernatant obtained in step S52 is treated and the temperature is controlled at 85°C to remove methyl isobutyl ketone, and finally a colorless, transparent, viscous liquid is obtained, which is propoxylated bisphenol A.

[0116] Example 3

[0117] This embodiment provides a method for preparing propoxylated bisphenol A, which may specifically include the following steps:

[0118] S13. Add 100.0g of bisphenol A and 300mL of 10% sodium hydroxide aqueous solution to a dry reaction vessel, and stir for 25min at 28℃ to form a milky white prestructured system.

[0119] S23. Maintaining the system temperature at 26°C, under reflux conditions, add 258.4 g of propylene oxide dropwise to the prestructured system obtained in step S13. The molar ratio of bisphenol A to propylene oxide is 1:4.3. After the addition is complete, continue the reaction at this temperature for 7 hours to obtain the reaction mixture.

[0120] S33. Add 150 mL of water-saturated toluene to the reaction mixture obtained in step S23. The volume ratio of the reaction mixture to water-saturated toluene is 1:1.5, and the mass fraction of water in the water-saturated toluene is 0.06%. After mixing, stir for 20 min, then let stand to separate the layers, remove the lower aqueous phase, and obtain the upper benzene solution.

[0121] S43. Under the protection of high-purity nitrogen, the upper benzene solution obtained in step S33 is treated, and the temperature is controlled at 105℃ to remove toluene and obtain an intermediate product.

[0122] S53. Dissolve the intermediate product obtained in step S43 with methyl isobutyl ketone, with a mass ratio of methyl isobutyl ketone to intermediate product of 5.5:1; after dissolution, add a core-shell structured adsorbent, with the amount of core-shell structured adsorbent being 0.5% of the total mass of intermediate product and methyl isobutyl ketone, and perform adsorption treatment at a temperature of 55°C for 28 min; after adsorption treatment, allow the mixture to stand and separate into layers, remove the lower solid phase, and obtain the upper clear liquid.

[0123] The preparation method of the core-shell structured adsorbent includes the following steps:

[0124] S501, Preparation of core layer material: 15nm macroporous silica gel (purchased from Xi'an Qiyue Biotechnology, model Q-0301680) was activated under vacuum at 120℃, and then placed under nitrogen atmosphere and reflux conditions to undergo a modification reaction with octadecyltrichlorosilane at a reaction temperature of 80℃ for 13 hours to obtain octadecyl-modified macroporous silica gel (core layer material).

[0125] S502, Shell Material Construction: The core material from S501 was dispersed in a mixed solution of ethanol and water (volume ratio of ethanol to water: 5:1), followed by the addition of tetraethyl orthosilicate and 3-aminopropyltriethoxysilane, with a molar ratio of tetraethyl orthosilicate to 3-aminopropyltriethoxysilane of 5.5:1. A co-condensation reaction was carried out under alkaline catalytic conditions (ammonia as catalyst, concentration 0.4 mol / L) at 35°C for 26 h, forming an amino-modified mesoporous silica gel (shell material) with a pore size of 5 nm on the surface of the core material, thus obtaining a core-shell structured adsorbent.

[0126] S63. Under the protection of high-purity nitrogen, the supernatant obtained in step S53 is treated, and the temperature is controlled at 95°C to remove methyl isobutyl ketone, finally obtaining a colorless, transparent, viscous liquid, which is propoxylated bisphenol A.

[0127] Example 4

[0128] This embodiment provides a method for preparing propoxylated bisphenol A, which may specifically include the following steps:

[0129] S14. Add 100.0g of bisphenol A and 220mL of 5% sodium hydroxide aqueous solution to a dry reaction vessel, and stir for 30min at 20℃ to form a milky white prestructured system.

[0130] S24. Maintaining the system temperature at 23°C, under reflux conditions, add 262.8 g of propylene oxide dropwise to the prestructured system obtained in step S14. The molar ratio of bisphenol A to propylene oxide is 1:4.4. After the addition is complete, continue the reaction at this temperature for 4 hours to obtain the reaction mixture.

[0131] S34. Add 140 mL of water-saturated toluene to the reaction mixture obtained in step S24. The volume ratio of the reaction mixture to water-saturated toluene is 1:1.4, and the mass fraction of water in the water-saturated toluene is 0.05%. After mixing, stir for 22 min, then let stand to separate the layers, remove the lower aqueous phase, and obtain the upper benzene solution.

[0132] S44. Under the protection of high-purity nitrogen, the upper benzene solution obtained in step S34 is treated, and the temperature is controlled at 90°C to remove toluene and obtain an intermediate product.

[0133] S54. Dissolve the intermediate product obtained in step S44 using methyl isobutyl ketone, with a mass ratio of methyl isobutyl ketone to intermediate product of 3:1; after dissolution, add a core-shell structured adsorbent, with the amount of core-shell structured adsorbent being 0.4% of the total mass of intermediate product and methyl isobutyl ketone, and perform adsorption treatment at a temperature of 40°C for 30 min; after adsorption treatment, allow the mixture to stand and separate into layers, remove the lower solid phase, and obtain the upper clear liquid.

[0134] The preparation method of the core-shell structured adsorbent includes the following steps:

[0135] S501, Preparation of core layer material: 12nm macroporous silica gel (purchased from Zhengzhou Huiju Chemical, model SBA-15) was activated under vacuum at 120℃, and then placed under nitrogen atmosphere and reflux conditions to undergo a modification reaction with octadecyltrichlorosilane. The reaction temperature was 70℃ and the reaction time was 10h to obtain octadecyl-modified macroporous silica gel (core layer material).

[0136] S502, Shell Material Construction: The core material from S501 was dispersed in a mixed solution of ethanol and water (volume ratio of ethanol to water was 4.5:1), followed by the addition of tetraethyl orthosilicate and 3-aminopropyltriethoxysilane, with a molar ratio of tetraethyl orthosilicate to 3-aminopropyltriethoxysilane of 4.5:1. A co-condensation reaction was carried out under alkaline catalytic conditions (ammonia water as catalyst, concentration of 0.1 mol / L) at a reaction temperature of 20℃ for 28 h, forming an amino-modified mesoporous silica gel (shell material) with a pore size of 3.5 nm on the surface of the core material, thus obtaining a core-shell structured adsorbent.

[0137] S64. Under the protection of high-purity nitrogen, the supernatant obtained in step S54 is treated, and the temperature is controlled at 80°C to remove methyl isobutyl ketone, finally obtaining a colorless, transparent, viscous liquid, which is propoxylated bisphenol A.

[0138] Comparative Example 1

[0139] This comparative example is modified from the one disclosed in Example 1 as follows:

[0140] The steps S11 and S21 were adjusted as follows: 100.0 g of bisphenol A, 200 mL of 8% sodium hydroxide aqueous solution and 244.0 g of propylene oxide (molar ratio of bisphenol A to propylene oxide 1:4) were added to a dry reaction vessel and stirred directly at 25 °C without first stirring for 22 min to form a prestructured system; then, the reaction was directly kept at 25 °C under reflux conditions for 5 h to obtain the reaction mixture.

[0141] Steps S31 to S61 are completely identical to those in Example 1, without any modifications.

[0142] Comparative Example 2

[0143] This comparative example is modified from the one disclosed in Example 1 as follows:

[0144] The adjustment step S31 is as follows: 115 mL of ordinary toluene (excluding 0.04-0.06% water) is added to the reaction mixture obtained in step S21. The volume ratio of the reaction mixture to ordinary toluene is still 1:1.2. After mixing, the mixture is stirred for 18 min, and the lower aqueous phase is removed by standing to obtain the upper benzene solution.

[0145] Steps S11 to S21 and S41 to S61 are completely consistent with those in Example 1 and have not been modified.

[0146] Comparative Example 3

[0147] This comparative example is modified from the one disclosed in Example 1 as follows:

[0148] The adjusted step S51 is as follows: Dissolve the intermediate product obtained in step S41 with methyl isobutyl ketone (mass ratio of 4.5:1 to the intermediate product), without adding a core-shell structure adsorbent, stir directly at 50°C for 25 min, let stand to separate the layers and remove the small amount of precipitate in the lower layer (solid phase without adsorbent) to obtain the upper clear liquid.

[0149] Steps S11 to S41 and S61 are completely consistent with those in Example 1 and have not been modified.

[0150] Comparative Example 4

[0151] This comparative example is modified from the one disclosed in Example 1 as follows:

[0152] The core-shell structure adsorbent was adjusted to a pure shell material (amino-modified mesoporous silica gel), specifically as follows:

[0153] The adjusted step S51 is as follows: after dissolving the intermediate product with methyl isobutyl ketone, add an equal amount of pure shell adsorbent (0.3% of the total mass) as in Example 1, adsorb at 50°C for 25 min, allow to stand and separate into layers to remove the lower solid phase, and obtain the upper clear liquid.

[0154] Steps S11 to S41 and S61 are completely consistent with those in Example 1 and have not been modified.

[0155] The preparation method of amino-modified mesoporous silica gel is as follows: ordinary mesoporous silica gel (initial pore size of about 3-5 nm, purchased from Bailingwei, model 100742, type MCM-41) is activated in vacuum at 120℃ for 2 h, dispersed in a mixed solution of ethanol and water (volume ratio of ethanol to water is 4:1), tetraethyl orthosilicate and 3-aminopropyltriethoxysilane (molar ratio 5:1) are added, and under alkaline catalytic conditions (ammonia concentration 0.3 mol / L), a co-condensation reaction is carried out at 30℃ for 24 h. After filtration and drying, amino-modified mesoporous silica gel (pure shell material) with a pore size of 4 nm is obtained.

[0156] Comparative Example 5

[0157] This comparative example is modified from the one disclosed in Example 1 as follows:

[0158] The core-shell structure adsorbent was adjusted to a pure core-layer material (shellless octadecyl-modified macroporous silica gel), specifically:

[0159] The adjusted step S51 is as follows: after dissolving the intermediate product with methyl isobutyl ketone, add an equal amount of pure core layer adsorbent (0.3% of the total mass) as in Example 1, adsorb at 50°C for 25 min, allow to stand and separate into layers to remove the lower solid phase, and obtain the upper clear liquid.

[0160] Steps S11 to S41 and S61 are completely consistent with those in Example 1 and have not been modified.

[0161] The preparation method of octadecyl-modified macroporous mesoporous silica gel is as follows: macroporous mesoporous silica gel with a pore size of 10 nm (purchased from Beijing Huideyi Technology, product model DIOLMB100-75 / 200) is activated under vacuum at 120℃ for 2 h, and then placed under nitrogen atmosphere and reflux conditions to carry out a modification reaction with octadecyltrichlorosilane (CAS No. 112-04-9). The reaction temperature is 77℃ and the reaction time is 12 h to obtain octadecyl-modified macroporous mesoporous silica gel (core layer material).

[0162] Comparative Example 6

[0163] This comparative example is modified from the one disclosed in Example 1 as follows:

[0164] The steps S41 and S61 are adjusted as follows: the upper benzene solution obtained in step S31 is directly detoxified at 100℃ (without passing high-purity nitrogen gas) to obtain the intermediate product.

[0165] The supernatant obtained in step S51 is directly demethylated at 90°C to remove methyl isobutyl ketone (without passing high-purity nitrogen gas) to obtain propoxylated bisphenol A.

[0166] Steps S11 to S31 and S51 are completely consistent with those in Example 1 and have not been modified.

[0167] The propoxylated bisphenol A obtained from Examples 1-4 and Comparative Examples 1-6 was subjected to performance testing, and the results are shown in Table 1. The performance testing method is as follows:

[0168] Hydroxyl value: determined using the phthalic anhydride method specified in GB / T7383-2020 standard;

[0169] Free phenols: Refer to HJ1192-2021 standard and use solid phase extraction / high performance liquid chromatography;

[0170] Aldehyde impurities: The content of specific aldehyde compounds such as propionaldehyde in the sample was determined by high performance liquid chromatography in accordance with the HJ997-2018 standard.

[0171] Colorimetric: Comparison was performed using the APHA platinum-cobalt color standard;

[0172] Molecular weight distribution: Gel permeation chromatography was used, equipped with a highly sensitive light scattering detector.

[0173] Table 1. Performance of propoxylated bisphenol A in Examples and Comparative Examples

[0174] Group Hydroxyl value (mg KOH / g) Free phenol (%) Aldehyde impurities (ppm) Color (APHA) Molecular weight distribution (PDI) Example 1 217 0.03% 28 15 1.18 Example 2 220 0.05% 35 18 1.22 Example 3 214 0.04% 32 20 1.25 Example 4 222 0.06% 38 22 1.28 Comparative Example 1 235 0.25% 55 45 1.65 Comparative Example 2 219 0.20% 85 50 1.21 Comparative Example 3 225 0.30% 90 60 1.30 Comparative Example 4 218 0.08% 50 25 1.20 Comparative Example 5 221 0.25% 88 55 1.23 Comparative Example 6 230 0.07% 45 70 1.19

[0175] As shown in Table 1, the propoxylated bisphenol A prepared in Examples 1-4 exhibits excellent and stable performance indicators: hydroxyl value of 214-222 mg KOH / g, free phenol content of only 0.03%-0.06%, aldehyde impurity concentration controlled at 28-38 ppm, color (APHA) of 15-22, and molecular weight distribution (PDI) of 1.18-1.28. This fully demonstrates that the core process of this application effectively guarantees the structural regularity and purity of the product.

[0176] Comparative Example 1 (without pre-structuring step) showed significant performance degradation, with a hydroxyl value of 235 mg KOH / g, free phenol of 0.25%, PDI of 1.65, and color APHA of 45, all exceeding the range of the examples. Due to the lack of a pre-structuring step, the phenolic anions were unevenly dispersed when bisphenol A was mixed with the alkaline aqueous solution, resulting in localized over-polymerization of propylene oxide and localized under-polymerization, leading to incomplete reaction of bisphenol A. Ultimately, this resulted in disordered chain length distribution, increased free phenol residue, and side reactions that also caused deviations in the hydroxyl value and increased color.

[0177] Comparative Example 2 (using ordinary toluene) had aldehyde impurities of 85 ppm, color APHA 50, and free phenol of 0.20%, all higher than the Example, with only PDI of 1.21 approaching that of the Example. Because ordinary toluene does not contain 0.04–0.06% specific water, it cannot capture highly polar impurities such as aldehydes and unreacted bases through hydrogen bonding, resulting in a large amount of impurities remaining. Aldehydes are easily oxidized, leading to increased color, and the incomplete catalysis of bisphenol A by residual bases increases the level of free phenols.

[0178] Comparative Example 3 (without core-shell adsorbent) had the highest levels of free phenol (0.30%), aldehyde impurities (90 ppm), and color (APHA 60), with a hydroxyl value of 225 mg KOH / g, slightly exceeding the upper limit of the examples. Due to the lack of deep purification with a core-shell adsorbent, toluene layering alone was insufficient to remove free phenol, small molecule aldehydes, and alkane byproducts; impurity accumulation led to increased color and fluctuating hydroxyl values. Although the PDI of 1.30 was close to that of the examples, the purity did not meet high-end requirements.

[0179] Comparative Example 4 (using only the shell adsorbent): aldehyde impurities were 50 ppm, color APHA was 25, higher than the example; free phenol was 0.08%, and PDI was 1.20, close to the example. Because only the amino-modified shell was retained, although it could adsorb some free phenol, it lacked the adsorption capacity of the octadecyl-modified core layer for large-molecule hydrophobic impurities. Therefore, the aldehyde removal rate decreased, the color was slightly higher, and the purification effect was inferior to that of the intact core-shell adsorbent.

[0180] Comparative Example 5 (using only the core layer adsorbent) had 0.25% free phenol, 88 ppm aldehyde impurities, and an APHA color of 55, all higher than the Example, while its PDI was 1.23, close to that of the Example. Because only the octadecyl-modified core layer was retained, although it could adsorb large hydrophobic impurities, it lacked the shell amino layer's ability to capture free phenols and small aldehydes. The large amount of residual polar impurities led to increased color, and the performance degradation trend was similar to that of Comparative Example 2.

[0181] Comparative Example 6 (without inert gas protection) had the highest APHA70 color among all groups, with a hydroxyl value of 230 mgKOH / g slightly exceeding the upper limit of the example. Free phenol was 0.07%, aldehyde impurities were 45 ppm, and PDI was 1.19, which are close to the example. Because no inert gas was introduced during solvent removal, the phenolic hydroxyl groups in the product were oxidized at high temperature upon contact with air to form quinone color-producing substances, causing a sharp increase in color. The oxidation of some phenolic hydroxyl groups also caused a slight deviation in the hydroxyl value. Since the reaction and impurity removal processes were not affected, other indicators were close to the example.

[0182] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1 to 6" cover all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including" and "contains" as used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects.

[0183] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing propoxylated bisphenol A, characterized in that, The method includes the following steps: S1. Under the temperature conditions of 20-30℃, bisphenol A and alkaline aqueous solution are stirred and mixed for 15-30 min to obtain a prestructured system; S2. Under the conditions of temperature of 23-27℃ and reflux, propylene oxide is added dropwise to the prestructured system and the reaction is carried out at this temperature for 3-8 hours to obtain a reaction mixture; the molar ratio of bisphenol A to propylene oxide is 1:(4.0-4.4). S3. Add a water-saturated benzene solvent to the reaction mixture, mix, allow to stand and separate into layers, remove the lower aqueous phase to obtain the upper benzene solution; the water-saturated benzene solvent contains 0.04-0.06% by mass of water. S4. Under inert gas protection, remove the benzene solvent from the upper benzene solution to obtain an intermediate product; S5. Dissolve the intermediate product using a ketone solvent, then add a core-shell structured adsorbent for adsorption treatment, allow it to stand and separate into layers, remove the lower solid phase, and obtain the upper clear liquid; the core layer material of the core-shell structured adsorbent is octadecyl-modified macroporous silica gel, and the shell layer material is amino-modified mesoporous silica gel. S6. Under inert gas protection, remove the ketone solvent from the supernatant to obtain propoxylated bisphenol A.

2. The method for preparing propoxylated bisphenol A according to claim 1, characterized in that, In step S1, the ratio of the mass M of bisphenol A to the volume V of the alkaline aqueous solution, M:V, is 1:(1.5~3), where M is in g and V is in mL. The alkaline aqueous solution is a sodium hydroxide or potassium hydroxide aqueous solution with a mass fraction of 5-10%.

3. The method for preparing propoxylated bisphenol A according to claim 1, characterized in that, In step S3, the volume ratio of the reaction mixture to the water-saturated benzene solvent is 1:(0.8-1.5), and the water-saturated benzene solvent is water-saturated toluene.

4. The method for preparing propoxylated bisphenol A according to claim 1, characterized in that, In step S5, the mass ratio of the ketone solvent to the intermediate product is (3-6):1, and the ketone solvent is methyl isobutyl ketone.

5. The method for preparing propoxylated bisphenol A according to claim 1, characterized in that, In step S5, the amount of the core-shell structured adsorbent is 0.1 to 0.5% of the total mass of the intermediate product and the ketone solvent.

6. The method for preparing propoxylated bisphenol A according to claim 1, characterized in that, In step S5, the adsorption treatment is carried out at a temperature of 40–60°C for 20–30 minutes.

7. The method for preparing propoxylated bisphenol A according to claim 1, characterized in that, In step S5, the preparation method of the core-shell structured adsorbent includes: S501. Under inert atmosphere and reflux conditions, vacuum-activated large-pore mesoporous silica gel is modified with octadecylsilane reagent to obtain core layer material. S502. The core layer material is dispersed in a mixed solution of ethanol and water, and then tetraethyl orthosilicate and 3-aminopropyltriethoxysilane are added. A co-condensation reaction is carried out under alkaline catalytic conditions to form an amino-modified shell mesoporous silica gel on the surface of the core layer material, thereby obtaining the core-shell structure adsorbent.

8. The method for preparing propoxylated bisphenol A according to claim 7, characterized in that, The pore size of the macroporous silica gel is 8-15 nm; The octadecylsilane reagent is octadecyltrichlorosilane; The molar ratio of the tetraethyl orthosilicate to the 3-aminopropyltriethoxysilane is (4-6):1; The pore size of the shell mesoporous silica gel is 3-5 nm; The modification reaction is carried out at a temperature of 70℃~85℃ for a time of 10~14h. The co-condensation reaction is carried out at a temperature of 20℃ to 40℃ for a time of 20 to 28 hours.

9. The method for preparing propoxylated bisphenol A according to claim 1, characterized in that, In step S4, the temperature for removing benzene-based solvents is 90–110°C; In step S6, the temperature for removing ketone solvents is 80–100°C.

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