阅读说明：本技术 一种亲水性聚丙烯中空纤维膜及其制备方法 (Hydrophilic polypropylene hollow fiber membrane and preparation method thereof ) 是由 李法亮 于 2019-09-18 设计创作，主要内容包括：本发明提供一种亲水性聚丙烯中空纤维膜及其制备方法,涉及膜材料技术领域。该制备方法包括铸膜液配置、热致相分离法纺丝和后处理,将亲水性聚合物、引发剂、聚合物、稀释剂和非稀释剂加入到铸膜液中,通过原位聚合接枝的方法在铸膜液制备过程中将亲水性聚合物接枝到聚丙烯分子链上,形成均一铸膜液后再经过挤出机和纺丝机、热牵伸、凝固浴分相、热处理和溶剂萃取等方法制备亲水性聚丙烯中空纤维膜。该方法通过原位反应的方法非常便捷地将亲水性聚合物接枝到聚丙烯上,制备的亲水性聚丙烯中空纤维膜的亲水性能够明显提高并具有极好的稳定性,水通量大,且不易发生污染。(the invention provides a hydrophilic polypropylene hollow fiber membrane and a preparation method thereof, and relates to the technical field of membrane materials. The preparation method comprises the steps of preparing a casting solution, spinning by a thermally induced phase separation method and post-processing, adding a hydrophilic polymer, an initiator, a polymer, a diluent and a non-diluent into the casting solution, grafting the hydrophilic polymer onto a polypropylene molecular chain in the preparation process of the casting solution by an in-situ polymerization grafting method to form a uniform casting solution, and then preparing the hydrophilic polypropylene hollow fiber membrane by an extruder and a spinning machine, thermal drafting, coagulating bath phase separation, heat treatment, solvent extraction and other methods. The method grafts the hydrophilic polymer to the polypropylene very conveniently by an in-situ reaction method, and the prepared hydrophilic polypropylene hollow fiber membrane has the advantages of obviously improved hydrophilicity, excellent stability, large water flux and difficult pollution.)

1. A preparation method of a hydrophilic polypropylene hollow fiber membrane is characterized by comprising the following steps:

S1, preparing a casting solution:

Dissolving 1-5 parts by weight of a polymerization monomer in 5-20 parts by weight of a lipid non-diluent to prepare a lipid non-diluent, and dissolving 0.001-0.01 part by weight of an oily initiator in 5-10 parts by weight of the lipid diluent to prepare a lipid diluent; then stirring 5-20 parts of lipid non-diluent, 20-50 parts of polypropylene, 35-60 parts of lipid diluent and 0.1-1 part of nucleating agent at 150-210 ℃ for 2-3 hours, adding the lipid diluent, and continuously stirring at 150-210 ℃ for 2-4 hours to form a uniform solution; finally, defoaming in vacuum to form a membrane casting solution;

S2, spinning by thermally induced phase separation method

extruding the membrane casting solution prepared in the step S1, spinning the membrane casting solution into hollow fibers through a spinneret plate, performing phase splitting forming at 10-30 ℃ through a coagulating bath, and performing hot drawing and heat treatment to obtain hollow fiber primary yarns;

S3, post-treatment

And (4) adding the hollow fiber primary filament prepared in the step (S2) into the extraction liquid for extraction for 6-24 h, and then carrying out heat setting at 80-140 ℃ for 30-90 min to obtain the hydrophilic polypropylene hollow fiber membrane.

2. The hydrophilic polypropylene hollow fiber membrane and the preparation method thereof according to claim 1, wherein in step S1, the polymerized monomer is one or more of methacrylic acid, acrylic acid, methacrylamide, acrylamide and 2-acrylamido-2-methylpropanesulfonic acid.

3. The method for preparing a hydrophilic polypropylene hollow fiber membrane according to claim 1, wherein in step S1, the lipid non-diluent is one or more of dibutyl phthalate, triacetin, dimethylacetamide and dimethylformamide.

4. The method of claim 1, wherein in step S1, the oily initiator is one or more of azobisisobutyronitrile, azobispimelic cyanide, benzophenone, dibenzoyl peroxide, dicumyl peroxide, and di-t-butyl peroxide.

5. The method for preparing a hydrophilic polypropylene hollow fiber membrane according to claim 1, wherein the lipid diluent is dioctyl phthalate, dioctyl sebacate or isononyl cyclohexane-1, 2-dicarboxylate in step S1.

6. The method for preparing a hydrophilic polypropylene hollow fiber membrane according to claim 1, wherein in step S1, the polypropylene is homo-polypropylene or high melt strength homo-polypropylene containing branched chains, and the melt index is 0.3-4 g/10 min; the nucleating agent is a beta-type polypropylene nucleating agent.

7. The method for preparing a hydrophilic polypropylene hollow fiber membrane according to claim 1, wherein in step S2, the spinning dope is dioctyl phthalate, dioctyl sebacate, cyclohexane-1, 2-dicarboxylic acid isononyl ester, and the temperature is 40-140 ℃; the coagulating bath is dioctyl phthalate, dioctyl sebacate, cyclohexane-1, 2-dicarboxylic acid isononyl ester or water.

8. The method for preparing a hydrophilic polypropylene hollow fiber membrane according to claim 1, wherein in step S2, the hot stretching temperature is 90 to 130 ℃, the draw ratio is 1/1.5 to 1/4; the heat treatment is carried out at 90-130 ℃ for 30-60 min.

9. The method of claim 1, wherein the extraction liquid is an aqueous solution of ethanol with a concentration of greater than 80% in step S3.

10. A hydrophilic polypropylene hollow fiber membrane manufactured by the method for manufacturing a hydrophilic polypropylene hollow fiber membrane according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of membrane materials, in particular to a hydrophilic polypropylene hollow fiber membrane and a preparation method thereof.

Background

The membrane separation technology is a new and high technology of emerging multidisciplinary intersection in recent decades. The high molecular separating membrane is a membrane prepared from polymer or high molecular composite material and having the function of separating fluid mixture, the membrane separation process is to use the high molecular separating membrane as a separating medium, under the action of one or more driving forces such as pressure difference, concentration difference, potential difference or temperature difference on two sides of the membrane, a certain component on the raw material side selectively permeates through the membrane, and other components are intercepted on the raw material side, so that the purposes of separation, purification and concentration are realized. Membranes are the key to membrane separation processes. The hollow fiber membrane has the advantages of large surface area, no need of a support body for components, equipment miniaturization, simple structure and the like, and is widely applied to the fields of water treatment, food processing and medicine product separation. The polypropylene hollow fiber membrane has the characteristics of good mechanical strength, low cost, easy film formation and the like, and is very widely applied.

But because the polypropylene has lower surface energy and shows strong hydrophobicity, the polypropylene is easy to pollute in the using process, the actual membrane separation process is influenced, the cleaning frequency is increased, and the service life of the membrane is shortened. Therefore, the separation membrane needs to be modified for hydrophilization. Common hydrophilic modification means include both physical blending and chemical modification. Physical blending, that is, a method for obtaining a hydrophilic hollow fiber membrane by melt blending a hydrophilic polymer and polypropylene and performing thermally induced phase separation or melt spinning, for example, in chinese patent CN104689726A, polypropylene, an ethylene-vinyl alcohol copolymer, and polypropylene grafted with maleic anhydride are blended, and are extruded and pelletized by an extruder, and then melt spinning is performed. Physical blending is a simple hydrophilization method, but the hydrophilic agent is dissolved and consumed during the use of the component, and the long-term hydrophilic stability of the component is poor. In order to be able to enhance the bonding strength of the hydrophilic substance and the polypropylene material, a chemical modification is introduced thereto. In chinese patent CN105727769A, acrylic acid is grafted onto the surface of a fiber membrane in polypropylene by means of ultraviolet irradiation to achieve hydrophilization. The polypropylene hollow fiber membrane prepared by the hydrophilization mode has strong hydrophilic stability, but the process is complicated, organic solvent is involved in the modification process, the environment-friendly requirement of industrial production is not facilitated, and meanwhile, the uniformity is relatively poor. In chinese patent CN101966430A, a polyethylene glycol-polypropylene graft polymer is prepared by a chemical reaction and a polymer synthesis process, and then the prepared polypropylene-polyethylene glycol and polypropylene are blended, and melt-drawn and spun to obtain a polyethylene glycol-containing polypropylene separation membrane. Although the hydrophilicity is improved, there are disadvantages that the synthesis reaction is complicated and the industrial implementation is not facilitated. Therefore, it is necessary to develop an efficient, stable and economical method for modifying the hydrophilization of a polypropylene hollow fiber membrane.

Disclosure of Invention

The invention aims to solve the problems and provide a preparation method of a hydrophilic polypropylene hollow fiber membrane, which is characterized in that a hydrophilic polymer is grafted onto polypropylene very conveniently by an in-situ reaction method, and then after spinning and treatment, a hydrophilic substance is exposed on the surface of the membrane, so that hydrophilic modification of a hydrophobic polypropylene membrane is realized, the hydrophilicity of the membrane can be obviously improved, and the membrane has excellent stability, large water flux and is not easy to pollute.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

A preparation method of a hydrophilic polypropylene hollow fiber membrane comprises the following steps:

s1, preparing a casting solution:

dissolving 1-5 parts by weight of a polymerization monomer in 5-20 parts by weight of a lipid non-diluent to prepare a lipid non-diluent, and dissolving 0.001-0.01 part by weight of an oily initiator in 5-10 parts by weight of the lipid diluent to prepare a lipid diluent; then stirring 5-20 parts of lipid non-diluent, 20-50 parts of polypropylene, 35-60 parts of lipid diluent and 0.1-1 part of nucleating agent at 150-210 ℃ for 2-3 hours, adding the lipid diluent, and continuously stirring at 150-210 ℃ for 2-4 hours to form a uniform solution; finally, vacuum defoaming is carried out to form the casting solution.

s2, spinning by thermally induced phase separation method

And (4) extruding the casting solution prepared in the step (S1), spinning the casting solution into hollow fibers through a spinneret plate, performing phase splitting forming at 10-30 ℃ through a coagulating bath, and performing hot drawing and heat treatment to obtain hollow fiber primary yarns.

S3, post-treatment

And (4) adding the hollow fiber primary filament prepared in the step (S2) into the extraction liquid for extraction for 6-24 h, and then carrying out heat setting at 80-140 ℃ for 30-90 min to obtain the hydrophilic polypropylene hollow fiber membrane.

Preferably, in step S1, the polymerized monomer is one or more of methacrylic acid, acrylic acid, methacrylamide, acrylamide and 2-acrylamido-2-methylpropanesulfonic acid.

preferably, in step S1, the lipid non-diluent is one or more of dibutyl phthalate (DBP), triacetin (GTA), dimethylacetamide (DMAc), and Dimethylformamide (DMF).

Preferably, in step S1, the oily initiator is one or more of Azobisisobutyronitrile (AIBN), azobisisoheptonitrile (MSDS), Benzophenone (BP), dibenzoyl peroxide (BPO), dicumyl peroxide (DCP), and di-tert-butyl peroxide (dTBP) initiator.

Preferably, in step S1, the lipid diluent is dioctyl phthalate (DOP), dioctyl sebacate (DOS) or isononyl cyclohexane-1, 2-dicarboxylate (Dinch).

Preferably, in step S1, the polypropylene is homo-polypropylene or high melt strength homo-polypropylene containing branched chains, and the melt index is 0.3 to 4g/10 min; the nucleating agent is a beta-type polypropylene nucleating agent.

Preferably, in step S2, the spinning bore fluid is dioctyl phthalate (DOP), dioctyl sebacate (DOS), cyclohexane-1, 2-dicarboxylic acid isononyl ester (Dinch), and the temperature is 40-140 ℃; the coagulating bath is dioctyl phthalate (DOP), dioctyl sebacate (DOS), cyclohexane-1, 2-dicarboxylic acid isononyl ester (Dinch) or water.

Preferably, in step S2, the hot stretching temperature is 90 to 130 ℃, and the draw ratio is 1/1.5 to 1/4; the heat treatment is carried out at 90-130 ℃ for 30-60 min.

Preferably, in step S3, the extract is an aqueous solution of ethanol with a concentration greater than 80%.

another object of the present invention is to provide a hydrophilic polypropylene hollow fiber membrane, which is manufactured by the above method.

Due to the adoption of the technical scheme, the invention has the following beneficial effects:

1. According to the hydrophilic polypropylene hollow fiber membrane prepared by the invention, a hydrophilic polymer, an initiator, a polymer, a diluent and a non-diluent are added into a membrane casting solution, the hydrophilic polymer is grafted to a polypropylene molecular chain in the preparation process of the membrane casting solution by an in-situ polymerization grafting method to form a uniform membrane casting solution, and then the uniform membrane casting solution is subjected to methods such as a double-screw extruder and a spinning machine, hot drawing, coagulation bath phase splitting, heat treatment and solvent extraction to prepare the hydrophilic polypropylene hollow fiber membrane.

The hydrophilic polymer is grafted to the polypropylene very conveniently by an in-situ reaction method, and then after spinning and treatment, a hydrophilic substance is exposed on the surface of the membrane, so that hydrophilic modification of the hydrophobic polypropylene membrane is realized.

2. The preparation method of the hydrophilic polypropylene hollow fiber membrane has simple process, the hydrophilicity of the prepared polypropylene hollow fiber membrane can be obviously improved, the prepared polypropylene hollow fiber membrane has excellent stability, large water flux and difficult pollution, and can be used for membrane components for sewage treatment, membrane bioreactors and the like.

Drawings

FIG. 1 is an infrared analysis chart of a polypropylene hollow fiber membrane prepared in example 1.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the following embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.