A polyketone filtration membrane containing a composite pore structure and a method of making the same

Abstract

The application discloses a polyketone filter membrane containing a composite pore structure and a preparation method thereof, and belongs to the technical field of organic filter membranes. Aliphatic polyketone is used as a main body resin, is uniformly mixed with an additive and a diluent dimethyl sulfoxide at 130-160 DEG C, and a filter membrane is prepared through a composite thermally induced phase separation method. The preparation method is simple, safe and environmentally friendly. The prepared membrane has the membrane structure characteristics of a non-solvent induced phase separation method and a thermally induced phase separation method, has a finger-shaped pore and a double-continuous net-shaped composite structure, and has a low price, good hydrophilicity and good solvent resistance. The aliphatic polyketone has a good application prospect in the field of membrane separation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic separation membrane, and particularly relates to a polyketone filter membrane containing a composite pore structure and a preparation method thereof. BACKGROUND

[0002] Aliphatic polyketone is a crystalline and thermoplastic engineering material with linear structure, which is polymerized from carbon monoxide and olefins (ethylene and propylene). Due to its high crystallinity, aliphatic polyketone has high mechanical properties, good hydrophilicity, good chemical resistance and high temperature resistance, and can fully meet the requirements of film preparation as an engineering plastic.

[0003] At present, two methods are commonly used to prepare polymer membranes, which are described as follows:

[0004] Non-solvent induced phase separation (NIPS): In the process of preparing the membrane, there are many parameters to be controlled in the preparation process, and many additives need to be added. The membrane structure obtained by this method is prone to have many finger-like pore structures, which affects the strength of the membrane.

[0005] (2) Thermal induced phase separation (TIPS): This method has simple film preparation conditions and fewer parameters to be controlled. The prepared membrane usually has a double continuous structure and fewer defects. However, the diluent selected is usually non-water-soluble, and another extraction agent is needed to remove it after film formation. This method has high energy consumption and pollutes the environment.

[0006] In addition, the composite thermal induced phase separation (NTIPS) is a process in which a homogeneous solution of a high polymer and a diluent is formed at high temperature, and non-solvent induced phase separation (NIPS) and thermal induced phase separation (TIPS) are simultaneously performed to form a membrane when the temperature is lowered. If a suitable diluent is found, the structure of the membrane can be conveniently and accurately controlled.

[0007] In Chinese Patent CN104415671B and Chinese Patent CN103252172B, composite thermal induced phase separation is used to prepare PVDF membranes with different structures. The prepared polyvinylidene fluoride membranes have excellent chemical stability and high mechanical strength, and are resistant to pollution. However, the price of PVDF is relatively high, resulting in high production cost and difficulty in popularization and use. SUMMARY

[0008] The technical problem to be solved by the present application is to provide a composite thermal induced phase separation method with simple process, safety and environmental protection, and low cost, for preparing an aliphatic polyketone filter membrane containing finger-like pores and a double continuous network structure. Specifically, the present application can be realized by the following technical scheme:

[0009] A polyketone filter membrane containing a composite pore structure, wherein the upper layer of the filter membrane is finger-like pores, and the lower layer is a double continuous network structure.

[0010] Further, the filter membrane comprises the following raw materials: aliphatic polyketone resin, additive and diluent.

[0011] Further, the weight ratio of the aliphatic polyketone resin, the additive and the diluent is 15-30:1-10:60-80.

[0012] Further, the additive is one or a mixture of F-127, F-108, nano-TiO2, nano-SiO2 and LiCl.

[0013] Further, the diluent is dimethyl sulfoxide.

[0014] The application also provides a preparation method of the aliphatic polyketone filter membrane with the composite pore structure, which comprises the following steps:

[0015] S1: heating and mixing the aliphatic polyketone resin, the additive and the diluent in proportion, heating to 130-160 DEG C, fully mixing to a uniform solution, vacuumizing and defoaming to obtain a casting solution;

[0016] S2: preparing a nascent membrane from the casting solution on different forming equipment;

[0017] S3: cooling the nascent membrane in a pure water cooling bath, controlling the water temperature of the cooling bath to be 30-50 DEG C, and solidifying the casting solution into a membrane for more than 0.5 h to obtain a membrane;

[0018] S4: soaking the membrane in S3 in pure water at 60-80 DEG C for 1-4 h, then soaking in a 20% glycerol aqueous solution for 20-28 h, and drying to obtain the aliphatic polyketone filter membrane with the finger-like pore structure and the bicontinuous network structure.

[0019] The application has the following advantages and beneficial effects:

[0020] 1. The composite structure membrane prepared by the composite thermally induced phase separation method has the characteristics of the finger-like pore structure prepared by the non-solvent induced phase separation method and the bicontinuous network structure prepared by the thermally induced phase separation method, has large membrane flux, high retention rate and good mechanical strength.

[0021] 2. The diluent dimethyl sulfoxide used in the application is water-soluble, and when water is selected as the coolant, water also serves as the extractant, thereby avoiding the step of further removing the diluent by using an extractant in the traditional and conventional preparation, simplifying the preparation process, easily recycling the solvent, reducing the membrane preparation cost, and making the production process safe and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0023] Figure 1 Scanning electron microscope image of the cross section of the aliphatic polyketone filter membrane of Example 1 of the present application.

[0024] Figure 2 Scanning electron microscope image of the cross section of the aliphatic polyketone filter membrane of Example 2 of the present application.

[0025] Figure 3 Scanning electron microscope image of the cross section of the aliphatic polyketone filter membrane of Example 3 of the present application.

[0026] Figure 4 Scanning electron microscope image of the cross section of the aliphatic polyketone filter membrane of Example 4 of the present application.

[0027] Figure 5 Scanning electron microscope image of the cross section of the aliphatic polyketone filter membrane of Example 5 of the present application.

[0028] Figure 6 Scanning electron microscope image of the cross section of the aliphatic polyketone filter membrane of Example 6 of the present application.

[0029] Figure 7 Scanning electron microscope image of the cross section of the aliphatic polyketone filter membrane of Example 7 of the present application.

[0030] Figure 8 Scanning electron microscope image of the cross section of the aliphatic polyketone filter membrane of Example 8 of the present application. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

[0032] Specifically, the main purpose of the present embodiment is to prepare an aliphatic polyketone filter membrane containing finger-like pores and a bicontinuous network structure, and the specific scheme of the filter membrane is as follows:

[0033] The aliphatic polyketone filter membrane contains a composite pore structure, the upper layer of the filter membrane is finger-like pores, and the lower layer is a bicontinuous network structure; the filter membrane comprises the following raw materials: aliphatic polyketone resin (POK), additives, and diluents.

[0034] The weight ratio of the aliphatic polyketone resin, the additives, and the diluents is 15-30:1-10:60-80.

[0035] The additives are one or more mixtures of F-127, F-108, nano-TiO2, nano-SiO2, and LiCl.

[0036] wherein the diluent is dimethyl sulfoxide (DMSO).

[0037] (II) It should be noted that in the following examples, a method for preparing a polyketone filter membrane having a composite pore structure is specifically provided, wherein the representative formula of dimethyl sulfoxide is DMSO, and the representative formula of the aliphatic polyketone resin is POK.

[0038] Example 1:

[0039] S1, first disperse 0.5 parts of nano-TiO2 in 74.5 parts of DMSO, mechanically stir rapidly for 10 min, then add the remaining 20 parts of POK, 3 parts of F-127, 2 parts of LiCl into the container and mix, heat to 145°C, fully disperse and uniform, then vacuum degassing to obtain a casting solution;

[0040] S2, prepare a flat membrane on an automatic film coater with the casting solution;

[0041] S3, immediately immerse the nascent flat membrane in a pure water cooling bath, control the water temperature of the cooling bath at 40°C, and the solidification time is 1 h;

[0042] S4, immerse the solidified membrane in 80°C pure water for 2 h, then immerse it in a 20% glycerol aqueous solution for 24 h, and dry it in an oven at 50°C, see Figure 1 , to obtain an aliphatic polyketone flat filter membrane containing finger-shaped pores and a bicontinuous network structure.

[0043] Example 2:

[0044] S1, first disperse 0.5 parts of nano-TiO2 in 74.5 parts of DMSO, mechanically stir rapidly for 15 min, then add the remaining 20 parts of POK, 3 parts of F-108, 2 parts of LiCl into the container and mix, heat to 145°C, fully disperse and uniform, then vacuum degassing to obtain a casting solution;

[0045] S2, prepare a flat membrane on an automatic film coater with the casting solution;

[0046] S3, immediately immerse the nascent flat membrane in a pure water cooling bath, control the water temperature of the cooling bath at 40°C, and the solidification time is 1 h;

[0047] S4, immerse the solidified membrane in 70°C pure water for 1.5 h, then immerse it in a 20% glycerol aqueous solution for 24 h, and dry it naturally, see Figure 2 , to obtain an aliphatic polyketone flat filter membrane containing finger-shaped pores and a bicontinuous network structure.

[0048] Example 3:

[0049] S1, first 0.5 parts of nano TiO2 dispersed in 79.5 parts of DMSO, mechanical fast stirring 10 min, then the remaining 15 parts of POK, 3 parts of F-127, 2 parts of LiCl into the container mixed, heated to 145℃, fully dispersed uniform, vacuum degassing, get casting solution;

[0050] S2, the casting solution on the automatic film machine to prepare flat film;

[0051] S3, the nascent flat film immediately immersed in pure water cooling bath, cooling bath water temperature control for 40℃, solidification time 1h;

[0052] S4, the solidification after the film soaking in 80℃ pure water 3h, then soaked in 20% glycerol solution 24h, oven drying, see Figure 3 , get the aliphatic polyketone flat filter membrane containing finger-like pores and bicontinuous network structure.

[0053] Example 4:

[0054] S1, first 0.5 parts of nano TiO2 dispersed in 79.5 parts of DMSO, mechanical fast stirring 15 min, then the remaining 17 parts of POK, 3 parts of F-127 into the container mixed, heated to 145℃, fully dispersed uniform, vacuum degassing, get casting solution;

[0055] S2, the casting solution on the automatic film machine to prepare flat film;

[0056] S3, the nascent flat film immediately immersed in pure water cooling bath, cooling bath water temperature control for 40℃, solidification time 1h;

[0057] S4, the solidification after the film soaking in 75℃ pure water 2h, then soaked in 20% glycerol solution 24h, natural drying, see Figure 4 , get the aliphatic polyketone flat filter membrane containing finger-like pores and bicontinuous network structure.

[0058] Example 5:

[0059] S1, 20 parts of POK, 3 parts of F-127, 2 parts of LiCl, 75 parts of DMSO into the container mixed, heated to 150℃, fully dispersed uniform, vacuum degassing, get casting solution;

[0060] S2, the casting solution on the automatic film machine to prepare flat film;

[0061] S3, the nascent flat film immediately immersed in pure water cooling bath, cooling bath water temperature control for 40℃, solidification time 1h;

[0062] S4, soak the solidified membrane in 70℃ pure water for 2h, then soak in 20% glycerol aqueous solution for 24h, dry in oven at 40℃, see Figure 5 , to obtain the aliphatic polyketone flat filter membrane containing finger-like pores and bicontinuous reticular structure.

[0063] Example 6:

[0064] S1, first disperse 0.5 parts of nano-TiO2 in 79.5 parts of DMSO, mechanically fast stir for 10 min, then add the remaining 20 parts of POK, 2 parts of LiCl into the container and mix, heat to 140℃, fully disperse and uniform, then vacuum degassing, to obtain the casting solution;

[0065] S2, prepare flat membrane on the automatic film casting machine;

[0066] S3, immediately immerse the nascent flat membrane into the pure water cooling bath, control the water temperature of the cooling bath to be 40℃, and the solidification time is 1h;

[0067] S4, soak the solidified membrane in 80℃ pure water for 2h, then soak in 20% glycerol aqueous solution for 24h, dry in oven at 35℃, see Figure 6 , to obtain the aliphatic polyketone flat filter membrane containing finger-like pores and bicontinuous reticular structure.

[0068] Example 7:

[0069] S1, first disperse 1 part of nano-SiO2 in 74 parts of DMSO, mechanically fast stir for 30 min, then add the remaining 20 parts of POK, 3 parts of hydrophilic modifier F-127, 2 parts of LiCl into the container and mix, heat to 140℃, fully disperse and uniform, then vacuum degassing, to obtain the casting solution;

[0070] S2, prepare flat membrane on the automatic film casting machine;

[0071] S3, immediately immerse the nascent flat membrane into the pure water cooling bath, control the water temperature of the cooling bath to be 40℃, and the solidification time is 1h;

[0072] S4, soak the solidified membrane in 80℃ pure water for 2h, then soak in 20% glycerol aqueous solution for 24h, dry in oven at 45℃, see Figure 7 , to obtain the aliphatic polyketone flat filter membrane containing finger-like pores and bicontinuous reticular structure.

[0073] Example 8:

[0074] S1, first 1 part of nano TiO2 is dispersed in 63 parts of DMSO, and is mechanically stirred rapidly for 20 min, then 30 parts of remaining POK, 2 parts of F-127, 4 parts of LiCl are added into the container for mixing, and heating to 160 DEG C, after being dispersed uniformly, vacuum degassing is carried out, and casting solution is obtained;

[0075] S2, the casting solution is prepared into a flat film on an automatic film scraper;

[0076] S3, the nascent flat film is immediately immersed in a pure water cooling bath, the water temperature of the cooling bath is controlled to be 40 DEG C, and the curing time is 0.5 h;

[0077] S4, the film after curing is soaked in 65 DEG C pure water for 2 h, then is soaked in 20% glycerol aqueous solution for 24 h, and is naturally dried, and see Figure 8 , the aliphatic polyketone flat filter membrane with finger-shaped pores and double-continuous network structure is obtained.

[0078] (Three) the filter membranes prepared in the above examples are tested and analyzed:

[0079] The filter membranes prepared in the above examples are all tested under the conditions of temperature 25 DEG C and operating pressure 0.1 MPa, the pure water flux of the membrane is tested, anhydrous ethanol is used as the infiltrating liquid, and the average pore size is tested by a bubble point method pore size analyzer, and the results are shown in the following table.

[0080]

[0081] Comprehensive analysis shows that:

[0082] The composite structure membrane prepared by the composite thermally induced phase separation method has the characteristics of the finger-shaped pore structure prepared by the non-solvent induced phase separation method and the double-continuous network structure prepared by the thermally induced phase separation method, the prepared membrane has large flux, high retention rate and good mechanical strength.

[0083] The diluent dimethyl sulfoxide used in the application has water solubility, when water is selected as the coolant, water also acts as the extractant, so that the step of removing the diluent by further using an extractant in the traditional conventional preparation is avoided, the preparation process is simplified, the solvent is easy to recycle and reuse, the aliphatic polyketone has low price, good hydrophilicity and good solvent resistance, the aliphatic polyketone is used as the resin for preparing the membrane, the cost is reduced, and the production process is safe and environmentally friendly.

[0084] The technical solutions and beneficial effects of the application are described in detail in the above examples, and it should be understood that the above description is only a specific embodiment of the application, and is not used to limit the application, and any modification, supplement and equivalent replacement made within the principle range of the application should be included in the protection range of the application.

Claims

1. A method for preparing a polyketone filter membrane containing a composite pore structure, characterized in that, The method includes the following steps: S1: Heat and mix aliphatic polyketide resin, additives and diluent in proportion, heat to 130-160℃, mix thoroughly until a homogeneous solution is obtained, then degas under vacuum to obtain casting solution. The casting solution additive must contain one or more of the following: nano TiO2, nano SiO2, and LiCl; S2: The casting solution is used to prepare a primary film on different molding equipment; S3: The nascent membrane is introduced into a pure water cooling bath, the water temperature of which is controlled at 30-50℃, and the curing time of the casting solution is greater than 0.5h to obtain the film. S4: Immerse the film formed in S3 in pure water at 60-80℃ for 1-4 hours, then immerse it in a 20% glycerol aqueous solution for 20-28 hours, and air dry or dry at 30-50℃ to obtain an aliphatic polyketide filter membrane containing finger pores and a bicontinuous network structure. The diluent is dimethyl sulfoxide.

2. A polyketone filter membrane with a composite pore structure prepared by the method for preparing a polyketone filter membrane with a composite pore structure according to claim 1.

3. The polyketone filter membrane with a composite pore structure according to claim 2, characterized in that: The upper layer of the filter membrane has finger-shaped pores, and the lower layer has a double continuous mesh structure; The weight ratio of the aliphatic polyketone resin, additives, and diluent is 15-30:1-10:60-80; The casting solution additive also contains one or more of F-127 and F-108.

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