Purification method for crude polycarbonate diol containing titanate catalyst

Abstract

The present invention is applicable to the technical field of organic synthesis, and provides a method for purifying crude polycarbonate diol containing a titanate catalyst, comprising the following steps: Selecting a solvent such as dichloromethane, chloroform, tetrahydrofuran or ethyl acetate, and dissolving the crude product according to a mass ratio of crude PCDL: organic solvent: pure water = 1: 1-10: 1-10 under the condition of heating with hot water in a jacket. Pressurized filtration is carried out with high-purity nitrogen, the filtrate and the filter residue are separated, and after the filtrate is allowed to stand and layer, the organic phase and the aqueous phase are collected separately. Secondly, the organic phase is transferred to a concentration kettle, the temperature and the vacuum degree are adjusted, the organic solvent is recovered and recycled, and finally a qualified polycarbonate diol product is obtained. The present invention effectively removes the residual titanate catalyst in the polycarbonate diol product through an innovative purification process, and realizes the production of high-purity products.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a method for purifying crude polycarbonate diol containing a titanate catalyst. Background Art

[0002] Polycarbonate diol (PCDL) is a key polymer material that is widely used in the production of high-performance materials such as polycarbonate (PC). Its synthesis pathway mainly includes two methods: one-step method and two-step method. In the one-step method, PCDL is synthesized by directly reacting carbonate compounds with low molecular weight diols; while in the two-step method, low molecular weight PCDL is first prepared, and then its molecular weight is increased by polycondensation to obtain the final product. Titanate catalysts are often used to catalyze such reactions, especially in the preparation of PCDL from dimethyl carbonate and 1,6-hexanediol.

[0003] However, current technology faces a challenge when using titanate catalysts: a small amount of catalyst will remain in the resulting PCDL product. This unpurified PCDL will lead to further polycondensation reactions in subsequent applications, especially during heating and melting, which will affect the molecular weight and distribution of PCDL and adversely affect the performance of downstream products. Therefore, how to effectively remove residual catalysts in PCDL products is one of the current problems that need to be solved urgently. Optimizing this process is of great significance to improving the quality of PCDL products and broadening their application areas. Summary of the invention

[0004] The object of the present invention is to provide a method for purifying crude polycarbonate diol containing a titanate catalyst, aiming to solve the problems mentioned in the above background technology.

[0005] The present invention is achieved by a method for purifying a crude polycarbonate diol containing a titanate catalyst, comprising the following steps:

[0006] Step 1, select dichloromethane (DCM), chloroform, tetrahydrofuran (THF) or ethyl acetate as an organic solvent, and fully stir and dissolve the crude polycarbonate diol in a dissolving kettle at a mass ratio of crude polycarbonate diol: organic solvent: pure water = 1:1-10:1-10 under jacket hot water heating conditions; then, pass the mixed solution through a filter by means of high-purity nitrogen pressurization, collect the filtrate in a filtrate tank, and collect the filter residue in a dedicated storage tank; after the filtrate is allowed to stand for stratification, the separated organic phase and aqueous phase enter their respective storage tanks;

[0007] Step 2: The polycarbonate diol solution transferred from the organic phase storage tank enters the concentration kettle. By controlling the temperature and vacuum degree of the concentration kettle, the organic solvents such as dichloromethane, chloroform, tetrahydrofuran or ethyl acetate are condensed and recovered, and then returned to the dissolution kettle for reuse. Finally, the qualified polycarbonate diol product remaining in the concentration kettle enters the polycarbonate diol product tank for storage.

[0008] Further technical solution: In Step 1, the temperature of the jacket hot water heating is 25 - 39 °C.

[0009] Further technical solution: In Step 1, the dissolution kettle is pressurized with high-purity nitrogen to maintain the pressure in the dissolution kettle at 0.5 Mpa.

[0010] Further technical solution: In Step 1, the filter residue mainly includes titanium dioxide.

[0011] Further technical solution: In Step 1, the separated aqueous phase is returned to the polycarbonate diol dissolution kettle for recycling through the aqueous phase reflux pump.

[0012] Further technical solution: In Step 1, the organic solvents distilled out from the concentration kettle enter the crude product tank through the concentration kettle cooler, and then are returned to the polycarbonate diol dissolution kettle for recycling through the organic phase reflux pump.

[0013] Further technical solution: In Step 2, the temperature of the concentration kettle is controlled at 39 - 100 °C, and the vacuum degree is 3 - 30 KPa.

[0014] A method for purifying crude polycarbonate diol containing a titanate catalyst provided by the present invention has the following beneficial effects:

[0015] The present invention uses a titanate catalyst to catalyze the reaction of a carbonate compound with a low molecular weight diol to prepare polycarbonate diol, and effectively removes the residual titanate catalyst in the product through an innovative purification process, thereby obtaining high-purity polycarbonate diol. This process not only realizes the recycling of solvents and water, reduces environmental pollution and resource waste, but also realizes efficient purification from laboratory scale to industrial scale by optimizing the dosage of organic solvents and pure water and adjusting reaction parameters, significantly improving the product quality and production efficiency, and at the same time increasing the commercial value of by-products, having broad application prospects and higher industrial application value. Description of the Drawings

[0016] Figure 1 It is a purification flow chart of crude polycarbonate diol containing a titanate catalyst provided by an embodiment of the present invention. Detailed Embodiments

[0017] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0019] like Figure 1 As shown, the given process flow chart includes a crude product tank for polycarbonate diol, a polycarbonate diol dissolving kettle, organic solvent storage tanks such as dichloromethane / chloroform / tetrahydrofuran / ethyl acetate, a pure water storage tank, a dissolving kettle filter, a filtrate tank, a titanium dioxide storage tank, an organic phase storage tank, an aqueous phase storage tank, a concentration kettle, a concentration kettle condenser, a vacuum pump unit, a crude product tank for organic solvents such as dichloromethane / chloroform / tetrahydrofuran / ethyl acetate, an organic phase reflux pump, an aqueous phase reflux pump, a PCDL product tank, etc.

[0020] Example 1

[0021] An embodiment of the present invention provides a method for purifying a crude polycarbonate diol containing a titanate catalyst, wherein the mass ratio of crude PCDL:DCM:pure water is 1:1:1; the catalyst is then removed by dissolving, pressure filtering, standing and stratifying, and concentrating to obtain a pure PCDL without a catalyst. The specific operation is as follows:

[0022] 1) Dissolution of crude product: Under heating conditions of jacket hot water (temperature 25°C), the materials are put into a dissolution kettle according to the mass ratio of crude PCDL:DCM:pure water = 1:1:1, and are fully stirred and dissolved to obtain a mixed solution containing titanium dioxide solid.

[0023] 2) Crude product filtration and stratification: High-purity nitrogen is introduced into the dissolving kettle to maintain the pressure in the dissolving kettle at 0.5MPa. The dissolving kettle discharge valve and the filter feed valve are opened to allow the mixed solution to pass through the filter. Titanium dioxide solids remain in the filter and are then collected in a titanium dioxide storage tank. The filtrate enters the filtrate tank for storage. The filtrate in the filtrate tank is left to stand for 12 hours to obtain a stratified organic phase and an aqueous phase.

[0024] 3) Concentration and purification: Open the organic phase discharge valve of the filtrate tank and the feed valve of the organic phase storage tank, and the organic phase enters the organic phase storage tank for storage; open the discharge valve of the organic phase storage tank and the feed valve of the concentration kettle, use a pump to pump the material into the concentration kettle, and then turn on the vacuum unit to evacuate the vacuum to maintain the pressure of the concentration kettle at 3KPa; gradually heat the concentration kettle with low-pressure steam to evaporate the DCM in the material, and the final temperature of the concentration kettle is maintained at 39°C. Continue the concentration reaction for 5 hours to obtain a high-purity PCDL product.

[0025] 4) Solvent recovery and reuse: The aqueous phase in the filtrate tank enters the aqueous phase storage tank, and then is pumped back to the dissolution kettle through the aqueous phase reflux pump to achieve the recycling of the aqueous phase. The solvent DMC distilled out from the concentration kettle enters the crude DMC tank through the concentration kettle cooler, and then DCM is pumped back to the dissolution kettle through the organic phase reflux pump to achieve the recovery and reuse of the solvent DMC.

[0026] Example 2

[0027] The difference from Example 1 is as follows:

[0028] The mass ratio of crude PCDL:DCM:pure water is 1:10:10; the temperature of the jacket hot water heating is 39°C; the temperature of the concentration kettle is controlled at 100°C and the vacuum degree is 30 KPa.

[0029] Example 3

[0030] The difference from Example 1 is as follows:

[0031] The mass ratio of crude PCDL:DCM:pure water is 1:5:2; the temperature of the jacket hot water heating is 31°C; the temperature of the concentration kettle is controlled at 80°C and the vacuum degree is 10 KPa.

[0032] Example 4

[0033] A method for purifying crude polycarbonate diol containing a titanate catalyst provided by an embodiment of the present invention uses a mass ratio of crude PCDL:THF:pure water = 1:1:1; then the catalyst is removed by means of dissolution, pressure filtration, static stratification, and concentration to obtain pure PCDL without catalyst. The specific operations are as follows:

[0034] 1) Crude product dissolution: Under the heating condition of jacket hot water (temperature 25°C), the materials are put into the dissolution kettle according to the mass ratio of crude PCDL:THF:pure water = 1:1:1 and stirred sufficiently to dissolve to obtain a mixed solution containing titanium dioxide solid.

[0035] 2) Crude product filtration and stratification: High-purity nitrogen is introduced into the dissolution kettle to maintain the pressure in the dissolution kettle at 0.5 MPa. The discharge valve of the dissolution kettle and the feed valve of the filter are opened, and the mixed solution passes through the filter. The titanium dioxide solid remains in the filter and is then collected into the titanium dioxide storage tank uniformly; the filtrate enters the filtrate tank for storage. The filtrate in the filtrate tank is allowed to stand for 12 h to obtain a stratified organic phase and aqueous phase.

[0036] 3) Concentration and purification: Open the organic phase discharge valve of the filtrate tank and the feed valve of the organic phase storage tank, and the organic phase enters the organic phase storage tank for storage; open the discharge valve of the organic phase storage tank and the feed valve of the concentration kettle, use a pump to pump the material into the concentration kettle, and then turn on the vacuum unit to evacuate the vacuum to maintain the pressure of the concentration kettle at 3KPa; gradually heat the concentration kettle with low-pressure steam to evaporate the THF in the material, and the final temperature of the concentration kettle is maintained at 39°C. Continue the concentration reaction for 5 hours to obtain a high-purity PCDL product.

[0037] 4) Solvent recycling: The water phase in the filtrate tank enters the water phase storage tank, and then is pumped back to the dissolving kettle through the water phase reflux pump to achieve the recycling of the water phase. The solvent THF evaporated from the concentration kettle enters the THF crude product tank through the concentration kettle cooler, and then is pumped back to the dissolving kettle through the organic phase reflux pump to achieve the recycling of the solvent THF.

[0038] Example 5

[0039] The difference from Example 4 is that:

[0040] The mass ratio of crude PCDL:THF:pure water is 1:10:10; the temperature of the jacket hot water heating is 39°C; the temperature of the concentration kettle is controlled to be 100°C and the vacuum degree is 30KPa.

[0041] Example 6

[0042] The difference from Example 4 is that:

[0043] The mass ratio of crude PCDL:THF:pure water is 1:7:2; the temperature of the jacket hot water heating is 31°C; the temperature of the concentration kettle is controlled at 90°C and the vacuum degree is 10KPa.

[0044] Example 7

[0045] An embodiment of the present invention provides a method for purifying a crude polycarbonate diol containing a titanate catalyst, wherein the mass ratio of crude PCDL: ethyl acetate: pure water is 1:1:1; the catalyst is then removed by dissolving, pressure filtering, standing and stratifying, and concentrating to obtain a pure PCDL without a catalyst. The specific operation is as follows:

[0046] 1) Dissolution of crude product: Under heating conditions of jacket hot water (temperature 25°C), the materials are put into a dissolution kettle according to the mass ratio of crude PCDL: ethyl acetate: pure water = 1:1:1, and are fully stirred and dissolved to obtain a mixed solution containing titanium dioxide solid.

[0047] 2) Filtration and layering of crude product: Introduce high-purity nitrogen into the dissolution kettle to maintain the pressure in the dissolution kettle at 0.5 MPa. Open the discharge valve of the dissolution kettle and the feed valve of the filter, and let the mixed solution pass through the filter. The titanium dioxide solid remains in the filter and is then uniformly collected in the titanium dioxide storage tank; the filtrate enters the filtrate tank for storage. The filtrate in the filtrate tank is allowed to stand for 12 h to obtain a layered organic phase and aqueous phase.

[0048] 3) Concentration and purification: Open the organic phase discharge valve of the filtrate tank and the feed valve of the organic phase storage tank, and the organic phase enters the organic phase storage tank for storage; open the discharge valve of the organic phase storage tank and the feed valve of the concentration kettle, pump the material into the concentration kettle with a pump, and then turn on the vacuum unit to evacuate, so that the pressure in the concentration kettle is maintained at 3 KPa; gradually heat the concentration kettle with low-pressure steam to distill out the ethyl acetate in the material. The final temperature of the concentration kettle is maintained at 39 °C, and the continuous concentration reaction is carried out for 5 h to obtain a high-purity PCDL product.

[0049] 4) Solvent recovery and utilization: The aqueous phase in the filtrate tank enters the aqueous phase storage tank, and then is pumped back to the dissolution kettle through the aqueous phase reflux pump to achieve the recycling of the aqueous phase. The distilled solvent ethyl acetate in the concentration kettle enters the crude ethyl acetate tank through the concentration kettle cooler, and then the ethyl acetate is pumped back to the dissolution kettle through the organic phase reflux pump to achieve the recovery and utilization of the solvent ethyl acetate.

[0050] Example 8

[0051] The difference from Example 7 is as follows:

[0052] The mass ratio of crude PCDL: ethyl acetate: pure water is 1:10:10; the temperature of the jacket hot water heating is 39 °C; the temperature of the concentration kettle is controlled at 100 °C and the vacuum degree is 30 KPa.

[0053] Example 9

[0054] The difference from Example 7 is as follows:

[0055] The mass ratio of crude PCDL: ethyl acetate: pure water is 1:9:2; the temperature of the jacket hot water heating is 31 °C; the temperature of the concentration kettle is controlled at 80 °C and the vacuum degree is 10 KPa.

[0056] Example 10

[0057] A purification method for a crude polycarbonate diol containing a titanate catalyst provided by an embodiment of the present invention uses a mass ratio of crude PCDL: chloroform: pure water of 1:1:1; and then removes the catalyst by means of dissolution, pressure filtration, static layering, and concentration to obtain a catalyst-free pure PCDL. The specific operations are as follows:

[0058] 1) Dissolution of crude product: Under the heating condition of jacket hot water (temperature 25°C), the materials are put into the dissolution kettle according to the mass ratio of crude PCDL: chloroform: pure water = 1:1:1, and stirred sufficiently to dissolve to obtain a mixed solution containing titanium dioxide solid.

[0059] 2) Filtration and stratification of crude product: High-purity nitrogen is introduced into the dissolution kettle to maintain the pressure in the dissolution kettle at 0.5 MPa. The discharge valve of the dissolution kettle and the feed valve of the filter are opened, so that the mixed solution passes through the filter, and the titanium dioxide solid remains in the filter and is then uniformly collected into the titanium dioxide storage tank; the filtrate enters the filtrate tank for storage. The filtrate in the filtrate tank is allowed to stand for 12 h to obtain a stratified organic phase and aqueous phase.

[0060] 3) Concentration and purification: The organic phase discharge valve of the filtrate tank and the feed valve of the organic phase storage tank are opened, and the organic phase enters the organic phase storage tank for storage; the discharge valve of the organic phase storage tank and the feed valve of the concentration kettle are opened, and the materials are pumped into the concentration kettle by a pump, and then the vacuum unit is turned on to evacuate, so that the pressure in the concentration kettle is maintained at 3 kPa; the concentration kettle is gradually heated with low-pressure steam to distill out the chloroform in the materials, and the final temperature of the concentration kettle is maintained at 39°C, and the concentration reaction is continued for 5 h to obtain a high-purity PCDL product.

[0061] 4) Solvent recovery and reuse: The aqueous phase in the filtrate tank enters the aqueous phase storage tank, and then is pumped back to the dissolution kettle by the aqueous phase reflux pump to realize the recycling of the aqueous phase. The solvent chloroform distilled out from the concentration kettle enters the crude chloroform tank through the concentration kettle cooler, and then the chloroform is pumped back to the dissolution kettle by the organic phase reflux pump to realize the recovery and reuse of the solvent chloroform.

[0062] Example 11

[0063] The difference from Example 10 is that:

[0064] The mass ratio of crude PCDL: chloroform: pure water = 1:10:10 is adopted; the temperature of jacket hot water heating is 39°C; the temperature of the concentration kettle is controlled at 100°C and the vacuum degree is 30 kPa.

[0065] Example 12

[0066] The difference from Example 10 is that:

[0067] The mass ratio of crude PCDL: chloroform: pure water = 1:6:2 is adopted; the temperature of jacket hot water heating is 31°C; the temperature of the concentration kettle is controlled at 80°C and the vacuum degree is 10 kPa.

[0068] In the above embodiments of the present invention, a method for purifying a crude polycarbonate diol containing a titanate catalyst is provided, and the main advantages are:

[0069] 1) By adopting the method that the mass ratio of crude PCDL, organic solvents (such as DCM, THF, chloroform or ethyl acetate) and pure water is 1:1 to 10:1 to 10, through the steps of dissolution, pressure filtration, static layering and concentration, the catalyst is effectively removed, and pure PCDL without catalyst is obtained. This method not only realizes the recycling of solvents and water, simplifies the operation process, reduces environmental pollution and resource waste, but also promotes the purification application of polycarbonate diol in industrial production.

[0070] 2) The main component of the filter residue collected in the dissolution kettle filter is titanium dioxide solid formed by the reaction of titanate catalyst with water. When accumulated to a certain amount, these titanium dioxides can be sold as products, bringing additional benefits to the enterprise.

[0071] 3) By optimizing the dosage of organic solvents such as DCM, THF, chloroform, ethyl acetate and pure water, and combining with the adjustment of parameters such as the temperature and pressure of the dissolution kettle, the temperature of the concentration kettle and the reaction time, the large-scale production purification of polycarbonate diol is realized. It solves the limitation that the existing technology is only applicable to small-scale laboratory production, and significantly improves the purification efficiency and output.

[0072] 4) The present invention relates to multiple fields such as "organic chemical synthesis", "catalyst research and development" and "polymer materials", showing broad application prospects. Compared with the existing technology, the present invention provides a more general method, which is applicable to the production purification of different types of polycarbonate diols, greatly enhancing its practical value.

[0073] 5) The technology of the present invention can not only be applied to the purification of small-scale laboratory production, but also meet the needs of large-scale industrial production. Its flexibility enables it to be adjusted according to the requirements of different production scales, has higher industrial application value, and is more superior compared with the existing technology.

[0074] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0075] The above-described embodiments only express several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. A method for purifying a crude polycarbonate diol containing a titanate catalyst, characterized in that: The following steps are involved: Step 1, select dichloromethane, chloroform, tetrahydrofuran or ethyl acetate as an organic solvent, and fully stir and dissolve the crude polycarbonate diol in a dissolving kettle at a mass ratio of crude polycarbonate diol: organic solvent: pure water = 1:1-10:1-10 under jacket hot water heating conditions; then, pass the mixed solution through a filter by means of high-purity nitrogen pressurization, collect the filtrate in a filtrate tank, and collect the filter residue in a dedicated storage tank; after the filtrate is allowed to stand for stratification, the separated organic phase and aqueous phase enter their respective storage tanks; Step 2: The polycarbonate diol solution transferred from the organic phase storage tank enters a concentration kettle, and the dichloromethane, chloroform, tetrahydrofuran or ethyl acetate organic solvent is condensed and recovered by controlling the temperature and vacuum degree of the concentration kettle, and returned to the dissolution kettle for reuse; finally, the remaining polycarbonate diol product that has passed the test in the concentration kettle enters a polycarbonate diol product tank for storage; Wherein, in step 1, the dissolving kettle is pressurized by high-purity nitrogen gas so that the pressure in the dissolving kettle is maintained at 0.5Mpa; In step 1, the filter residue mainly includes titanium dioxide; In step 1, the separated water phase is returned to the polycarbonate diol dissolving kettle through a water phase reflux pump for recycling; In step 1, the organic solvent evaporated from the concentration kettle enters the crude product tank through the concentration kettle cooler, and then returns to the polycarbonate diol dissolving kettle through the organic phase reflux pump for recycling; In step 1, the jacket is heated to a temperature of 25 to 39°C with hot water; In step 2, the temperature of the concentration kettle is controlled to be 39-100° C. and the vacuum degree is controlled to be 3-30 KPa.

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