Method for controlling the acid value of polycaprolactone polyols and method for preparing

Abstract

The present application relates to a kind of acid value control method of polycaprolactone polyol and preparation method, belong to high molecular compound purification technical field, the acid value control method of polycaprolactone polyol is to the crude product of polycaprolactone polyol with acid value is added solvent, then it is handled by the adsorption column of loading basic anion exchange resin, according to characteristic formula, by controlling viscosity, liquid phase air speed and adsorption temperature, the polycaprolactone polyol with acid value is obtained,;Wherein, the parameter in characteristic formula, the value of the molecular weight of polycaprolactone polyol and functionality is influenced.The acid value control method of the present application can ensure that the acid value of different batches of polycaprolactone polyol has good consistency.

Description

Technical Field

[0001] This invention relates to the field of polymer purification technology, and in particular to a method for controlling the acid value of polycaprolactone polyol and a preparation method thereof. Background Technology

[0002] Polycaprolactone polyols are key raw materials in high-end materials fields such as polyurethane, coatings, and adhesives. Their acid value directly affects the stability of downstream polymerization reactions, the mechanical properties of products, and long-term durability.

[0003] Currently, traditional methods for reducing the acid value of polycaprolactone polyols mainly include high-temperature vacuum devolatilization and adsorption. High-temperature vacuum devolatilization typically requires heating the material to above 170°C, a process with significant drawbacks: First, the high-temperature environment easily triggers ester bond hydrolysis and thermal oxidative breakage in polycaprolactone, leading to a shift in hydroxyl value, increased color, and a wider molecular weight distribution, resulting in significant deterioration of core performance. Second, this method has limited ability to remove non-volatile carboxyl oligomers, making it difficult to achieve deep deacidification and failing to meet the low acid value requirements of high-end products. Furthermore, high-temperature treatment also results in significant material volatilization losses, low product yields, and is accompanied by high energy consumption and significant safety and environmental pressures, making it particularly unsuitable for the purification of low molecular weight and heat-sensitive polycaprolactone polyols.

[0004] In contrast, the adsorption method can achieve acid value control under milder conditions, but in practical applications, it often faces the problem of difficulty in accurately controlling the acid value when scaling up the process, resulting in significant fluctuations in acid value between production batches and making it difficult to guarantee the consistency of polycaprolactone polyol products. Summary of the Invention

[0005] Therefore, it is necessary to provide a method for controlling the acid value of polycaprolactone polyol and a preparation method to address the above problems. The acid value control method can ensure that the acid value of different batches of polycaprolactone polyol products has good consistency.

[0006] A method for controlling the acid value of polycaprolactone polyols, adjusting the acid value to a specific value. Crude polycaprolactone polyol was added to a solvent to obtain a crude product solution, which was then subjected to adsorption treatment through an adsorption column packed with basic anion exchange resin. The viscosity of the crude product solution was controlled according to a characteristic formula. Liquid space velocity and adsorption temperature The acid value was obtained. Polycaprolactone polyol, ;

[0007] Among them, the number-average molecular weight M of polycaprolactone polyol n 350Da≤M n At ≤500Da, airspeed index The viscosity index is 0.82. When the functionality of polycaprolactone polyol is 2, the kinetic constant is 0.70. The kinetic constant is 0.124 when the functionality of polycaprolactone polyol is 3. It is 0.130;

[0008] Number average molecular weight M of polycaprolactone polyol n 500Da < M n At ≤1000Da, airspeed index The viscosity index is 0.86. The kinetic constant is 0.67 when the functionality of polycaprolactone polyol is 2. The kinetic constant is 0.121 when the functionality of polycaprolactone polyol is 3. It is 0.127;

[0009] Number-average molecular weight M of polycaprolactone polyols n 1000Da < M n At ≤2000Da, airspeed index The viscosity index is 0.89. The kinetic constant is 0.64 when the functionality of polycaprolactone polyol is 2. The kinetic constant is 0.108 when the functionality of polycaprolactone polyol is 3. It is 0.113;

[0010] Number-average molecular weight M of polycaprolactone polyols n 2000Da < M n At ≤3000Da, airspeed index The viscosity index is 0.92. The kinetic constant is 0.61 when the functionality of polycaprolactone polyol is 2. The kinetic constant is 0.099 when the functionality of polycaprolactone polyol is 3. It is 0.099.

[0011] In one embodiment, the backbone of the basic anion exchange resin is selected from styrene-divinylbenzene;

[0012] And or, the functional group of the basic anion exchange resin is selected from at least one of tertiary amine group or secondary amine group;

[0013] And or, the degree of crosslinking of the alkaline anion exchange resin is 6% to 12%.

[0014] In one embodiment, the total exchange capacity of the basic anion exchange resin is greater than or equal to 2.5 meq / g;

[0015] And or, the alkaline anion exchange resin has a pore size of 20nm~100nm, a particle size of 0.4mm~1.25mm, and a pore volume of 0.3mL / g~0.6mL / g;

[0016] And or, the tertiary amine group is selected from at least one of N,N-dimethyl tertiary amine or N,N-diethyl tertiary amine.

[0017] In one embodiment, the liquid space velocity is 0.2 BV / h to 10.0 BV / h.

[0018] In one embodiment, the adsorption temperature is 20°C to 80°C.

[0019] In one embodiment, the viscosity of the crude solution is less than 20 cP.

[0020] In one embodiment, the solvent has a boiling point of 30°C to 150°C.

[0021] In one embodiment, the solvent is selected from at least one of ethyl acetate, butyl acetate, toluene, xylene, acetone, methyl isobutyl ketone, tetrahydrofuran, or dichloromethane.

[0022] In one embodiment, after the adsorption treatment, vacuum distillation is performed, with the gauge pressure of the vacuum distillation being -0.06MPa to -0.1MPa and the temperature being 15℃ to 100℃.

[0023] A method for preparing polycaprolactone polyol includes the following steps:

[0024] Preparation of crude polycaprolactone polyol;

[0025] Polycaprolactone polyols were prepared using the acid value control method described above.

[0026] In this invention, an adsorption method using alkaline anion exchange resin is employed, coupled with fixed-bed fluid dynamics, pseudo-first-order adsorption kinetics, and liquid-phase mass transfer mechanism, to establish a predictive model for the acid value of polycaprolactone polyols, namely a characteristic formula. Based on this formula, by controlling the viscosity of the crude product solution, the liquid hourly space velocity, and the adsorption temperature, crude polycaprolactone polyols with a number-average molecular weight of 350 Da to 3000 Da and a functionality of 2 or 3 can be precisely controlled within the target acid value range. This achieves the low acid value target in the production process and ensures good consistency in the acid value of different batches of polycaprolactone polyol products. Detailed Implementation

[0027] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0029] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0030] This invention provides a method for controlling the acid value of polycaprolactone polyols, thereby controlling the acid value of polycaprolactone polyols. Crude polycaprolactone polyol was added to a solvent to obtain a crude product solution, which was then subjected to adsorption treatment through an adsorption column packed with basic anion exchange resin. The viscosity of the crude product solution was controlled according to a characteristic formula. Liquid space velocity and adsorption temperature The acid value was obtained. Polycaprolactone polyol, Among them, the acid value of crude polycaprolactone polyol and the acid value of polycaprolactone polyol after adsorption treatment All units are mg KOH / g, viscosity The unit is cP, liquid space velocity. The unit is BV / h, and the adsorption temperature is... The unit is Kelvin (K).

[0031] This invention employs an alkaline anion exchange resin adsorption method, coupling fixed-bed fluid dynamics, pseudo-first-order adsorption kinetics, and liquid-phase mass transfer mechanisms to establish a predictive model for the acid value of polycaprolactone polyols, namely, a characteristic formula. Specifically, the derivation of the characteristic formula is as follows: The flow of alkaline anion exchange resin within the resin bed conforms to the flow laws of a fixed bed, and the flow resistance is described by the Ergun equation: In engineering, liquid space velocity is used. Characterizing the treatment intensity, the empty bed contact time satisfies: It can be seen that the higher the liquid hourly space velocity, the shorter the contact time between the crude solution and the basic anion exchange resin, and the lower the deacidification efficiency. The degree of performance degradation of the system is directly related to the actual contact time of the crude solution in the reaction zone. Closely related, the decay rate increases with increasing contact time. Combining the reciprocal relationship between liquid space velocity and contact time, the influence of contact time is introduced into the rate constant correlation in power law form, which better reflects practical engineering laws. The adsorption of carboxyl impurities follows pseudo-first-order kinetics, and the acid value decay relationship is obtained by integration. ; while observing the rate constant Determined by both adsorption temperature and viscosity, i.e. It can be seen that increasing the adsorption temperature increases the diffusion rate, while increasing the viscosity exacerbates the mass transfer resistance; by combining the above formulas, the characteristic formula of this invention is obtained: .

[0032] To accommodate the differences in viscosity and mass transfer resistance gradients of polycaprolactone polyols with different number-average molecular weights, the materials were divided into categories with a number-average molecular weight of 350 Da ≤ M. n ≤500Da, 500Da<M n ≤1000Da, 1000Da<M n ≤2000Da, 2000Da<M n Differentiated assignment of kinetic constants in four intervals ≤3000Da Airspeed index Viscosity index Among them, the adsorption temperature Take a linear relationship, i.e., the power exponent is 1.

[0033] In 350Da≤M n ≤500Da, 500Da<M n ≤1000Da, 1000Da<M n In the low to medium number-average molecular weight range (≤2000 Da), the kinetic constant for polycaprolactone polyols with a functionality of 3 is obtained by multiplying the kinetic constant for a functionality of 2 in the same range by a fixed correction factor of 1.05; in the range of 2000 Da < M... nIn the high number-average molecular weight range of ≤3000 Da, due to the severe chain entanglement of polycaprolactone polyol molecules and the high viscosity of the system, liquid film diffusion and intraparticle mass transfer resistance become the absolute controlling steps of the adsorption process. The influence of functionality differences on the kinetic constant can be ignored. Therefore, in the high number-average molecular weight range, the same kinetic constant is used for both functionality 2 and functionality 3 without a 1.05-fold correction, which is in line with the basic law of mass transfer control of high-viscosity fluids.

[0034] Specifically, when the number-average molecular weight M of polycaprolactone polyol n 350Da≤M n At ≤500Da, airspeed index The viscosity index is 0.82. When the functionality of polycaprolactone polyol is 2, the kinetic constant is 0.70. The kinetic constant is 0.124 when the functionality of polycaprolactone polyol is 3. It is 0.130.

[0035] Specifically, when the number-average molecular weight M of polycaprolactone polyol n 500Da < M n At ≤1000Da, airspeed index The viscosity index is 0.86. The kinetic constant is 0.67 when the functionality of polycaprolactone polyol is 2. The kinetic constant is 0.121 when the functionality of polycaprolactone polyol is 3. It is 0.127.

[0036] Specifically, when the number-average molecular weight M of polycaprolactone polyol n 1000Da < M n At ≤2000Da, airspeed index The viscosity index is 0.89. The kinetic constant is 0.64 when the functionality of polycaprolactone polyol is 2. The kinetic constant is 0.108 when the functionality of polycaprolactone polyol is 3. It is 0.113.

[0037] Specifically, when the number-average molecular weight M of polycaprolactone polyol n 2000Da < M n At ≤3000Da, airspeed index The viscosity index is 0.92. The kinetic constant is 0.61 when the functionality of polycaprolactone polyol is 2. The kinetic constant is 0.099 when the functionality of polycaprolactone polyol is 3. It is 0.099.

[0038] Based on the characteristic formula, by controlling the viscosity, liquid hourly space velocity, and adsorption temperature of the crude product solution, crude polycaprolactone polyol with a number average molecular weight of 350 Da to 3000 Da and a functionality of 2 or 3 can be precisely deacidified to the target acid value range. Furthermore, this deacidification process has minimal impact on the original properties of the polycaprolactone polyol and yields a high product. Specifically, after deacidification, the change in hydroxyl value is within the range of -0.50 mg KOH / g to 0.50 mg KOH / g, the increase in color is within 5 Hazen, the increase in molecular weight distribution (PDI) is within 0.02, and the yield of polycaprolactone polyol is above 98%.

[0039] Therefore, while achieving the goal of low acid value, the present invention can maintain the original indicators of polycaprolactone polyol products and achieve high yield, and ensure that the acid values ​​of different batches of polycaprolactone polyol products have good consistency.

[0040] Optionally, the skeleton of the alkaline anion exchange resin is selected from styrene-divinylbenzene. This is because the styrene-divinylbenzene skeleton has stable chemical properties, is resistant to organic solvent erosion and swelling in the polycaprolactone polyol organic system, and has excellent skeleton rigidity, which can effectively resist fluid erosion and pressure, avoid resin particle breakage and internal pore collapse, and is suitable for fixed bed continuous production conditions.

[0041] Optionally, the degree of crosslinking of the basic anion exchange resin is preferably 6% to 12%, and can be selected as any value or a range between 6%, 7%, 8%, 9%, 10%, 11% or 12%. This range of crosslinking degree allows the basic anion exchange resin to have both good mechanical strength and pore structure stability, thereby extending its service life while ensuring adsorption treatment efficiency.

[0042] Optionally, the total exchange capacity of the dry basic anion exchange resin is preferably greater than or equal to 2.5 meq / g, and can be any value among 2.5 meq / g, 2.9 meq / g, 3.2 meq / g, or 3.5 meq / g, or any range between the two. The pore volume of the basic anion exchange resin is preferably 0.3 mL / g to 0.6 mL / g, and can be 0.3 mL / g, 0.4 mL / g, 0.5 mL / g, or 0.6 mL / g. Within this range of total exchange capacity and pore volume, sufficient adsorption capacity for acidic impurities can be provided, and the acid value can be reduced to a specific range more effectively according to the characteristic formula.

[0043] Optionally, the pore size of the basic anion exchange resin is preferably 20nm~100nm, and can be any value among 20nm, 40nm, 60nm, 80nm or 100nm or any range between two. Within this pore size range, it can accommodate the diffusion of polycaprolactone polyol molecules with a wide molecular weight range, promote the full contact of acidic impurities with adsorption sites, and improve adsorption efficiency while fully reducing acidity.

[0044] Optionally, the particle size of the basic anion exchange resin is preferably 0.4 mm to 1.25 mm, and can be any value among 0.4 mm, 0.8 mm, 1.0 mm or 1.25 mm or any range between two of them. This can take into account both the fluid permeability of the fixed bed and the solid-liquid adsorption contact area, avoid excessive bed pressure or insufficient adsorption, and thus better reduce the acid value to a specific range according to the characteristic formula.

[0045] To achieve highly selective adsorption of carboxyl acidic impurities and suppress the ester bond hydrolysis problem that may be caused by strong basic resins, thereby better avoiding problems such as degradation, discoloration and yield reduction of polycaprolactone polyols, the basic anion exchange resin is preferably a weakly basic anion exchange resin. More preferably, the functional group of the basic anion exchange resin is preferably at least one of tertiary amine group or secondary amine group. For example, the functional group of the basic anion exchange resin is mainly mild aliphatic tertiary amine group, supplemented by a small amount of weakly basic secondary amine group. The tertiary amine group can be selected from at least one of N,N-dimethyl tertiary amine group or N,N-diethyl tertiary amine group. For example, the basic anion exchange resin can be selected from Dowex® Marathon WBA, Purolite® A170, D301, Amberlyst® A-21, Lewatit® MP68 industrial macroporous weakly basic anion exchange resin.

[0046] It is understandable that when preparing the crude product solution, the crude polycaprolactone polyol can be cooled to 40℃~70℃ to keep the material molten and in a low viscosity state, and then the solvent is added and stirred for 30min~60min. The amount of solvent added is 10wt%~500wt% of the crude polycaprolactone polyol.

[0047] To achieve better deacidification, the viscosity of the crude product solution is preferably below 20 cP, and can be any value among 3 cP, 5 cP, 10 cP, 15 cP or 20 cP or any range between two of them.

[0048] The hydroxyl value of the crude polycaprolactone polyol used in this invention is not specifically limited and can be from 30 mg KOH / g to 450 mg KOH / g.

[0049] Optionally, the liquid space velocity is preferably 0.2 BV / h to 10.0 BV / h, and can be any value or a range between 0.2 BV / h, 0.5 BV / h, 1.0 BV / h, 2.0 BV / h, 4.0 BV / h, 6.0 BV / h, 8.0 BV / h or 10.0 BV / h. Within this low viscosity range, the mass transfer resistance of the adsorption process can be reduced and the adsorption efficiency can be improved.

[0050] To better suppress the thermal degradation and ester bond breakage of polycaprolactone polyol, thereby maintaining the stability of key indicators such as hydroxyl value, color, and molecular weight distribution, the adsorption temperature can be selected to be less than 100℃. Further, the adsorption temperature is preferably 20℃~80℃ (i.e., 293.15K~353.15K), and can be any value among 20℃, 30℃, 40℃, 50℃, 60℃, 70℃ or 80℃ or any range between two.

[0051] After adsorption treatment, distillation can be performed to remove the solvent. It is understood that the distillation temperature should be higher than the boiling point of the solvent under the corresponding vacuum degree and lower than the thermal decomposition temperature of the polycaprolactone polyol. This avoids thermal degradation of the polycaprolactone polyol and ensures product quality. Specifically, the boiling point of the solvent is preferably 30℃~150℃, and can be any value or a range between 50℃, 60℃, 80℃, 100℃, 120℃, or 140℃. For example, the solvent can be selected from at least one of ethyl acetate, butyl acetate, toluene, xylene, acetone, methyl isobutyl ketone, tetrahydrofuran, or dichloromethane.

[0052] Optionally, the distillation can be vacuum distillation, and the gauge pressure of vacuum distillation is preferably -0.08MPa to -0.1MPa, which can be any value among -0.08MPa, -0.09MPa, or -0.1MPa, or any range between the two; the temperature of vacuum distillation is preferably 15℃ to 100℃, which can be any value among 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃, or any range between the two; after vacuum distillation, the purity of the low-acid-value polycaprolactone polyol obtained is above 99%, and the solvent recovery rate is above 96%.

[0053] The present invention also provides a method for preparing polycaprolactone polyol, comprising the following steps: preparing crude polycaprolactone polyol; and preparing polycaprolactone polyol using the acid value control method described above.

[0054] The technical solution of the present invention will be further described below through specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without specified manufacturers are all commercially available conventional products.

[0055] Example 1

[0056] A crude polycaprolactone polyol with a number average molecular weight of 500, a functionality of 3, and an initial acid value of 0.18 mg KOH / g was used to prepare a refined polycaprolactone polyol with an acid value of 0.006 mg KOH / g. =0.130、 =0.70、 Substituting 0.82 into the characteristic formula, we can design the following process parameters: viscosity of 5 cP, liquid space velocity of 5 BV / h, and adsorption temperature of 30℃ (i.e., 303.15 K).

[0057] 50g of crude polycaprolactone polyol was cooled to 40℃, and then 50g of toluene was added. The mixture was stirred for 40min to obtain a crude solution with a viscosity of 5cP. The crude solution was then packed into an adsorption column of an alkaline anion exchange resin for adsorption treatment. The alkaline anion exchange resin was a styrene-divinylbenzene framework resin containing N,N-dimethyl tertiary amine groups. The adsorption treatment temperature was controlled at 30℃ and the liquid hourly space velocity was 5 BV / h.

[0058] After deacidification, the product was subjected to vacuum distillation at 65℃ and -0.09MPa(G) for 1 hour to remove toluene, yielding purified polycaprolactone polyol.

[0059] Example 2

[0060] The only difference between Example 2 and Example 1 is that Example 2 aims to prepare purified polycaprolactone polyol with an acid value of 0.022 mg KOH / g. =0.130、 =0.70、 Substituting 0.82 into the characteristic formula, the process parameters were designed and executed: viscosity of 5 cP, liquid hourly space velocity of 9 BV / h, and adsorption temperature of 30℃, to obtain refined polycaprolactone polyol.

[0061] Example 3

[0062] The only difference between Example 3 and Example 1 is that the goal is to prepare purified polycaprolactone polyol with an acid value of 0.022 mg KOH / g. =0.130、 =0.70、 Substituting 0.82 into the characteristic formula, the process parameters were designed and executed: 30g of toluene was added until the viscosity was 10cP, the liquid hourly space velocity was 5BV / h, and the adsorption temperature was 30℃, to obtain refined polycaprolactone polyol.

[0063] Example 4

[0064] A crude polycaprolactone polyol with a number average molecular weight of 1000, a functionality of 2, and an initial acid value of 0.17 mg KOH / g was used to prepare a refined polycaprolactone polyol with an acid value of 0.011 mg KOH / g. =0.121、 =0.67、 Substituting 0.86 into the characteristic formula, we can design process parameters: viscosity of 8 cP, liquid space velocity of 4 BV / h, and adsorption temperature of 30℃.

[0065] 50g of crude polycaprolactone polyol was cooled to 50℃, and then 65g of ethyl acetate was added. The mixture was stirred for 40min to obtain a crude solution with a viscosity of 8cP. The crude solution was then packed into an adsorption column of an alkaline anion exchange resin for adsorption treatment. The alkaline anion exchange resin was a styrene-divinylbenzene framework resin containing N,N-dimethyl tertiary amine groups. The adsorption treatment temperature was controlled at 30℃ and the liquid hourly space velocity was 4 BV / h.

[0066] After deacidification, the product was distilled under reduced pressure at 45℃ and -0.09MPa (G) for 1 hour to remove ethyl acetate, yielding purified polycaprolactone polyol.

[0067] Example 5

[0068] The only difference between Example 5 and Example 4 is that the goal is to prepare purified polycaprolactone polyol with an acid value of 0.004 mg KOH / g. =0.121、 =0.67、 Substituting 0.86 into the characteristic formula, the process parameters were designed and executed: 87g of ethyl acetate was added until the viscosity was 5cP, the liquid hourly space velocity was 4BV / h, and the adsorption temperature was 30℃, to obtain refined polycaprolactone polyol.

[0069] Example 6

[0070] A crude polycaprolactone polyol with a number average molecular weight of 2000, a functionality of 2, and an initial acid value of 0.20 mg KOH / g was used to prepare a refined polycaprolactone polyol with an acid value of 0.014 mg KOH / g. =0.108、 =0.64、 Substituting 0.89 into the characteristic formula, the following process parameters can be designed: viscosity of 12 cP, liquid space velocity of 3 BV / h, and adsorption temperature of 50℃ (323.15 K).

[0071] 50g of crude polycaprolactone polyol was cooled to 50℃, and then 60g of xylene was added. The mixture was stirred for 40min to obtain a crude solution with a viscosity of 12cP. The crude solution was then packed into an adsorption column of an alkaline anion exchange resin for adsorption treatment. The alkaline anion exchange resin was a styrene-divinylbenzene framework resin containing N,N-dimethyl tertiary amine groups. The adsorption treatment temperature was controlled at 50℃ and the liquid hourly space velocity was 3 BV / h.

[0072] After deacidification, the product was subjected to vacuum distillation at 70℃ and -0.09MPa (G) for 1 hour to remove xylene, yielding purified polycaprolactone polyol.

[0073] Example 7

[0074] The only difference between Example 7 and Example 6 is that Example 7 aims to prepare purified polycaprolactone polyol with an acid value of 0.006 mg KOH / g. =0.108、 =0.64、 Substituting 0.89 into the characteristic formula, the process parameters were designed and executed: 75g of xylene was added until the viscosity was 8cP, the liquid hourly space velocity was 3BV / h, and the adsorption temperature was 50℃, to obtain refined polycaprolactone polyol.

[0075] Example 8

[0076] A crude polycaprolactone polyol with a number average molecular weight of 3000, a functionality of 3, and an initial acid value of 0.26 mg KOH / g was used to prepare a refined polycaprolactone polyol with an acid value of 0.016 mg KOH / g. =0.099、 =0.61、 Substituting 0.92 into the characteristic formula, the following process parameters can be designed: viscosity of 18 cP, liquid space velocity of 2 BV / h, and adsorption temperature of 35℃ (308.15 K).

[0077] 50g of crude polycaprolactone polyol was cooled to 50℃, and then 50g of dichloromethane was added and refluxed to 35℃. The mixture was stirred for 40min to obtain a crude solution with a viscosity of 18cP. The crude solution was then packed into an adsorption column of an alkaline anion exchange resin for adsorption treatment. The alkaline anion exchange resin was a styrene-divinylbenzene framework resin containing N,N-dimethyl tertiary amine groups. The adsorption treatment temperature was controlled at 35℃ and the liquid hourly space velocity was 2 BV / h.

[0078] After deacidification, the product was subjected to vacuum distillation at 15℃ and -0.09MPa(G) for 1 hour to remove dichloromethane, yielding purified polycaprolactone polyol.

[0079] Example 9

[0080] The only difference between Example 9 and Example 8 is that the goal is to prepare purified polycaprolactone polyol with an acid value of 0.008 mg KOH / g. =0.099、 =0.61、 Substituting 0.92 into the characteristic formula, the process parameters were designed and executed: 65g of dichloromethane was added until the viscosity was 12cP, the liquid hourly space velocity was 2BV / h, and the adsorption temperature was 35℃, to obtain refined polycaprolactone polyol.

[0081] Comparative Example 1

[0082] The crude polycaprolactone polyol with a number average molecular weight of 1000, a functionality of 2, and an initial acid value of 0.17 mg KOH / g was used to prepare a refined polycaprolactone polyol with an acid value of 0.011 mg KOH / g.

[0083] 50g of crude polycaprolactone polyol was cooled to 50℃, and then 65g of ethyl acetate was added. The mixture was stirred for 40min to obtain a crude solution with a viscosity of 8cP. The crude solution was then packed into an adsorption column of an alkaline anion exchange resin for adsorption treatment. The alkaline anion exchange resin was a styrene-divinylbenzene framework resin containing N,N-dimethyl tertiary amine groups. The adsorption treatment temperature was controlled at 30℃ and the liquid hourly space velocity was 7 BV / h.

[0084] After deacidification, the product was distilled under reduced pressure at 45℃ and -0.09MPa (G) for 1 hour to remove ethyl acetate, yielding purified polycaprolactone polyol.

[0085] Comparative Example 2

[0086] The crude polycaprolactone polyol with a number average molecular weight of 2000, a functionality of 2, and an initial acid value of 0.20 mg KOH / g was used to prepare a refined polycaprolactone polyol with an acid value of 0.014 mg KOH / g.

[0087] 50g of crude polycaprolactone polyol was cooled to 50℃, and then 60g of xylene was added. The mixture was stirred for 40min to obtain a crude solution with a viscosity of 12cP. The crude solution was then packed into an adsorption column of an alkaline anion exchange resin for adsorption treatment. The alkaline anion exchange resin was a styrene-divinylbenzene framework resin containing N,N-dimethyl tertiary amine groups. The adsorption treatment temperature was controlled at 50℃ and the liquid hourly space velocity was 5 BV / h.

[0088] After deacidification, the product was subjected to vacuum distillation at 70℃ and -0.09MPa (G) for 1 hour to remove xylene, yielding purified polycaprolactone polyol.

[0089] Comparative Example 3

[0090] The crude polycaprolactone polyol with a number average molecular weight of 3000, a functionality of 3, and an initial acid value of 0.26 mg KOH / g was used to prepare a refined polycaprolactone polyol with an acid value of 0.016 mg KOH / g.

[0091] 50g of crude polycaprolactone polyol was cooled to 50℃, and then 50g of dichloromethane was added and refluxed to 35℃. The mixture was stirred for 40min to obtain a crude solution with a viscosity of 18cP. The crude solution was then packed into an adsorption column of an alkaline anion exchange resin for adsorption treatment. The alkaline anion exchange resin was a styrene-divinylbenzene framework resin containing N,N-dimethyl tertiary amine groups. The adsorption treatment temperature was controlled at 35℃ and the liquid hourly space velocity was 3BV / h.

[0092] After deacidification, the product was subjected to vacuum distillation at 15℃ and -0.09MPa(G) for 1 hour to remove dichloromethane, yielding purified polycaprolactone polyol.

[0093] Comparative Example 4

[0094] 50g of crude polycaprolactone polyol with a number average molecular weight of 500, a functionality of 3, and an initial acid value of 0.18mg KOH / g was taken and purified by short-path molecular distillation. The purified polycaprolactone polyol was obtained by devolatilization treatment at a distillation temperature of 200℃ and a pressure of 50Pa(A) for 2h.

[0095] The acid values ​​of the refined polycaprolactone polyols prepared in the above examples and comparative examples were tested according to the standard HG / T2708-1995 "Determination of Acid Value in Polyester Polyols". The deacidification rate was calculated as (initial acid value - actual acid value after deacidification) / initial acid value. The results are shown in Table 1.

[0096] Table 1

[0097]

[0098] As shown in Table 1, the present invention limits the viscosity of the crude product solution to a low viscosity range by solvent adjustment, thus shielding the interference of viscosity variables. The space velocity index in each group of kinetic parameters is always greater than the viscosity index, and the influence of liquid phase space velocity on the product acid value is significantly higher than that of the system viscosity. Using the same crude polycaprolactone polyol and under the same viscosity conditions, increasing the space velocity alone will result in acid value exceeding the standard, while decreasing the space velocity can achieve deacidification to meet the standard.

[0099] As can be seen from the data in Examples 1-9, the acid value control method for polycaprolactone polyols of the present invention can control the acid value to within 0.02 mg KOH / g, with a deacidification rate ≥88%, demonstrating excellent deacidification effect. Examples 4, 6, and 8, and Comparative Examples 2-3 show that without process control according to the characteristic formula, the expected acid value of the polycaprolactone polyol product could not be obtained. The traditional high-vacuum high-temperature devolatilization process in Comparative Example 4 shows that high-temperature distillation easily causes thermal degradation of the polycaprolactone polyol, deteriorating the product's acid value. In contrast, the adsorption treatment of the present invention requires a low temperature and can be carried out at room temperature. Therefore, the adsorption treatment process does not involve thermal decomposition, and the deacidification precision is controllable, resulting in a higher product yield.

[0100] The hydroxyl value, color, and PDI of crude and refined polycaprolactone polyols in the above examples and comparative examples were tested using HG / T2709-2022 "Determination of Hydroxyl Value of Polyester Polyols for the Production of Polyurethane", GB / T6324.6-2014 "Test Methods for Organic Chemical Products Part 6: Determination of Color of Liquids by Tristimulation Value Colorimetric Method", and GB / T21863-2008 "Gel Permeation Chromatography (GPC) with Tetrahydrofuran as Eluent". The differences in hydroxyl value fluctuation, color increase, and PDI after deacidification treatment were calculated, and the yield of polycaprolactone polyol was calculated. The yield of polycaprolactone polyol was calculated as: (mass of refined polycaprolactone polyol / mass of crude polycaprolactone polyol). The results are shown in Table 2.

[0101] Table 2

[0102]

[0103] As can be seen from Table 2, the purified polycaprolactone polyols prepared in the above examples showed no significant deterioration in hydroxyl value, color, and PDI, and the yield of polycaprolactone polyols was relatively high.

[0104] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0105] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for controlling the acid value of polycaprolactone polyols, characterized in that, acid value Crude polycaprolactone polyol was added to a solvent to obtain a crude product solution, which was then subjected to adsorption treatment through an adsorption column packed with basic anion exchange resin. The viscosity of the crude product solution was controlled according to a characteristic formula. Liquid space velocity and adsorption temperature The acid value was obtained. Polycaprolactone polyol, ; Among them, the number-average molecular weight M of polycaprolactone polyol n 350Da≤M n At ≤500Da, airspeed index The viscosity index is 0.

82. When the functionality of polycaprolactone polyol is 2, the kinetic constant is 0.

70. The kinetic constant is 0.124 when the functionality of polycaprolactone polyol is 3. It is 0.130; Number average molecular weight M of polycaprolactone polyol n 500Da < M n At ≤1000Da, airspeed index The viscosity index is 0.

86. The kinetic constant is 0.67 when the functionality of polycaprolactone polyol is 2. The kinetic constant is 0.121 when the functionality of polycaprolactone polyol is 3. It is 0.127; Number average molecular weight M of polycaprolactone polyol n 1000Da < M n At ≤2000Da, airspeed index The viscosity index is 0.

89. The kinetic constant is 0.64 when the functionality of polycaprolactone polyol is 2. The kinetic constant is 0.108 when the functionality of polycaprolactone polyol is 3. It is 0.113; Number average molecular weight M of polycaprolactone polyol n 2000Da < M n At ≤3000Da, airspeed index The viscosity index is 0.

92. The kinetic constant is 0.61 when the functionality of polycaprolactone polyol is 2. The kinetic constant is 0.099 when the functionality of polycaprolactone polyol is 3. It is 0.

099.

2. The method for controlling the acid value of polycaprolactone polyol according to claim 1, characterized in that, The backbone of the basic anion exchange resin is selected from styrene-divinylbenzene; And or, the functional group of the basic anion exchange resin is selected from at least one of tertiary amine group or secondary amine group; And or, the degree of crosslinking of the basic anion exchange resin is 6% to 12%.

3. The method for controlling the acid value of polycaprolactone polyol according to claim 2, characterized in that, The total exchange capacity of the basic anion exchange resin is greater than or equal to 2.5 meq / g; And or, the alkaline anion exchange resin has a pore size of 20nm~100nm, a particle size of 0.4mm~1.25mm, and a pore volume of 0.3mL / g~0.6mL / g; And or, the tertiary amine group is selected from at least one of N,N-dimethyl tertiary amine or N,N-diethyl tertiary amine.

4. The method for controlling the acid value of polycaprolactone polyol according to claim 1, characterized in that, The liquid space velocity is 0.2 BV / h to 10.0 BV / h.

5. The method for controlling the acid value of polycaprolactone polyol according to claim 1 or claim 4, characterized in that, The adsorption temperature is 20℃~80℃.

6. The method for controlling the acid value of polycaprolactone polyol according to claim 5, characterized in that, The viscosity of the crude product solution is less than 20 cP.

7. The method for controlling the acid value of polycaprolactone polyol according to claim 1, characterized in that, The solvent has a boiling point of 30℃ to 150℃.

8. The method for controlling the acid value of polycaprolactone polyol according to claim 7, characterized in that, The solvent is selected from at least one of ethyl acetate, butyl acetate, toluene, xylene, acetone, methyl isobutyl ketone, tetrahydrofuran, or dichloromethane.

9. The method for controlling the acid value of polycaprolactone polyol according to claim 1, characterized in that, After the adsorption treatment, vacuum distillation is performed. The gauge pressure of the vacuum distillation is -0.06MPa to -0.1MPa, and the temperature is 15℃ to 100℃.

10. A method for preparing polycaprolactone polyol, characterized in that, Includes the following steps: Preparation of crude polycaprolactone polyol; Polycaprolactone polyols are prepared using the acid value control method for polycaprolactone polyols according to any one of claims 1 to 9.

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