阅读说明：本技术 一种石墨烯复合pp过滤膜的制备方法 (Preparation method of graphene composite PP filtering membrane ) 是由 沙嫣 沙晓林 于 2020-04-15 设计创作，主要内容包括：本发明公开了一种石墨烯复合PP过滤膜的制备方法；先将石墨烯与聚丙烯的接枝复合制备石墨烯复合PP母粒,再将该母粒与添加剂加入到聚丙烯熔融挤出机制备石墨烯复合PP单层膜片,膜片叠加热压成型制得石墨烯复合PP过滤膜。与普通的膜片相比,石墨烯复合PP膜具有较细的孔径,而且吸附性能刚好,可以有效的阻挡水中的杂质,达到良好的过滤效果。(The invention discloses a preparation method of a graphene composite PP filtering membrane; the preparation method comprises the steps of preparing graphene composite PP master batches by graft compounding of graphene and polypropylene, adding the master batches and additives into a polypropylene melt extrusion machine to prepare the graphene composite PP single-layer membrane, and performing superposition and hot-press molding on the membrane to obtain the graphene composite PP filtering membrane. Compared with the common membrane, the graphene composite PP membrane has a fine pore size, has the adsorption performance which is just good, can effectively block impurities in water, and achieves a good filtering effect.)

1. The preparation method of the graphene composite PP filtering membrane is characterized by comprising the following steps:

s1, uniformly mixing the graphene powder and the polypropylene white slices, and extruding and granulating to obtain graphene composite PP master batches;

s2, uniformly mixing the graphene composite PP master batches, the additive and the polypropylene white chips, and performing melt extrusion to obtain a graphene composite PP membrane;

s3, overlapping the graphene composite PP membranes and then carrying out hot press forming to obtain the graphene composite PP filtration membrane.

2. The preparation method of the graphene composite PP filtering membrane according to claim 1, wherein in the step S1, the weight ratio of the graphene powder to the polypropylene white chips is 5-10: 100.

3. The preparation method of the graphene composite PP filtering membrane according to claim 1, wherein in step S1, the graphene powder has a graphene single layer rate of more than 95%, a single layer thickness of 0.335nm, and a lamella thickness of 0.1-10 nm.

4. The method for preparing the graphene composite PP filtering membrane according to claim 1, wherein in the step S1, the extrusion granulation is performed in a twin-screw extruder, the temperature of the twin-screw extruder is 140-180 ℃, and the rotation speed is 60-100 r/min.

5. The preparation method of the graphene composite PP filtering membrane according to claim 1, wherein in the step S2, the weight ratio of the graphene composite PP master batch, the additive and the polypropylene white slice is 20-40:2-10: 100.

6. The preparation method of the graphene composite PP filtering membrane according to claim 1, wherein in the step S2, the additive is one or more of polystyrene, polyvinyl chloride, polyethylene, polyacrylonitrile, polytetrafluoroethylene, polysulfone and cellulose.

7. The method for preparing the graphene composite PP filtering membrane according to claim 1, wherein the melt extrusion is performed in a melt extruder at a temperature of 150 ℃ to 200 ℃ and a rotation speed of 80 to 120r/min in step S2.

8. The method for preparing the graphene composite PP filtration membrane according to claim 1, wherein in the step S2, the thickness of the graphene composite PP membrane sheet is 0.04-0.08 mm.

9. The method for preparing the graphene composite PP filtering membrane according to claim 1, wherein in the step S3, the temperature of the hot press forming is 180-200 ℃, and the pressure is 0.3-0.8 MPa.

10. The method for preparing the graphene composite PP filtration membrane according to claim 1, wherein in the step S3, the thickness of the graphene composite PP filtration membrane is 0.15-0.32 mm.

Technical Field

The invention relates to the field of water purification filter materials, in particular to a preparation method of a graphene composite PP (polypropylene) filter membrane.

Background

The filtration membrane is a material for performing solid-liquid separation, and is classified into a PP filtration membrane, a PVC filtration membrane, a pvdf filtration membrane, a PAN filtration membrane, a PES filtration membrane, and the like, depending on the raw material. The principle of membrane filtration is that many uniform micropores on the surface of the membrane are utilized to intercept impurities in water, so that filtration is realized, and the process generally has no chemical change. And is divided into a nanofiltration membrane, an ultrafiltration membrane, a reverse osmosis membrane and the like according to the size of micropores on the surface of the membrane.

Polypropylene (PP) is a semi-crystalline thermoplastic. Has high impact resistance, high mechanical property and high resistance to corrosion of various organic solvents and acid and alkali. Has wide application in industry, and is one of the most common polymer materials. The polypropylene is melted and then is sprayed to be spun, so that the PP cotton filter element can be prepared. As a primary or pre-filter material.

Graphene is the most subversive new material in this century, two scientists successfully separating single-layer graphene, and thus the 2010 Nobel prize is obtained. Since the theoretical production of graphene to the actual application, a series of breakthroughs have been made on batteries, carpets, yarns, fabrics and the like based on the characteristics of high conductivity, heat generation, antibiosis, mite resistance and the like of graphene.

As a result of a search of the prior patent documents, patent invention 201710840717.0 discloses a modified polypropylene film and a method for producing the same, in which vinyl acetate, allyl glycidyl ether and an initiator are subjected to a first polymerization reaction to obtain a vinyl acetate-allyl glycidyl ether copolymer; carrying out modification reaction on silicon dioxide by adopting a part of vinyl acetate-allyl glycidyl ether copolymer to obtain a silicon dioxide modifier; and sequentially carrying out melt blending and biaxial tension treatment on the first polypropylene resin and the silicon dioxide modifier to obtain the modified polypropylene film. The amorphous polypropylene is filled among the reticular fiber bundles, so that on one hand, the mechanical strength of the modified polypropylene film is improved, and the number and the length of cracks on the surface of the modified polypropylene film are reduced; on the other hand, the surface of the polypropylene is beneficial to form a compact structure. However, silica or a simple polypropylene resin hardly adsorbs impurities in water, and thus a good filtration effect cannot be obtained.

The invention patent 201711000724.6 discloses a preparation method of a graphene oxide/non-woven fabric composite membrane, which is characterized in that graphene oxide with a single layer is ultrasonically coated on a graphene oxide glass layer, then the single layer graphene oxide is used as a modifier, and the surface of a non-woven fabric membrane is modified by a direct immersion coating method, so that the graphene oxide is loaded on the non-woven fabric membrane, and the graphene oxide/non-woven fabric composite membrane is prepared. However, the painting method cannot completely combine the graphene and the polypropylene film, and particularly in the process of passing water, the impact of water flow can peel off the coating of the graphene, so that the graphene enters the water to cause pollution or reduce the filtering effect of the film.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a preparation method of a graphene composite PP filtering membrane.

The purpose of the invention is realized by the following technical scheme:

the invention relates to a preparation method of a graphene composite PP filtering membrane, which comprises the following steps:

s1, uniformly mixing the graphene powder and the polypropylene white slices, and extruding and granulating to obtain graphene composite PP master batches;

s2, uniformly mixing the graphene composite PP master batches, the additive and the polypropylene white chips, and performing melt extrusion to obtain a graphene composite PP membrane;

s3, overlapping the graphene composite PP membranes and then carrying out hot press forming to obtain the graphene composite PP filtration membrane.

In an embodiment of the present invention, in step S1, the weight ratio of the graphene powder to the polypropylene white chips is 5-10: 100.

In an embodiment of the present invention, in step S1, the graphene powder has a graphene monolayer rate of more than 95%, a monolayer thickness of 0.335nm, and a lamella thickness of 0.1 to 10 nm.

As an embodiment of the present invention, in step S1, the extrusion granulation is performed in a twin-screw extruder at a temperature of 140 ℃ and 180 ℃ and a rotation speed of 60-100 r/min.

In step S2, the weight ratio of the graphene composite PP masterbatch, the additive and the polypropylene white slice is 20-40:2-10: 100. The proportion is the key to achieve the aim of the invention.

In step S2, the additive is one or more selected from polystyrene, polyvinyl chloride, polyethylene, polyacrylonitrile, polytetrafluoroethylene, polysulfone, and cellulose. The invention adopts the specific additive to match and combine with PP, which is beneficial to the molding of the diaphragm, can also enhance the service life of the diaphragm and enhance the pollution resistance.

As an embodiment of the present invention, in step S2, the melt extrusion is performed in a melt extruder, the temperature of the melt extruder is 150 ℃ and 200 ℃, and the rotation speed is 80-120 r/min.

As an embodiment of the present invention, in step S2, the thickness of the graphene composite PP membrane sheet is 0.04 to 0.08 mm. The graphene PP film is too thin to prepare, strict in process requirement and high in cost. If the film is too thick, it is not easily formed in the subsequent hot press forming.

As an embodiment of the present invention, in step S3, the temperature of the hot press forming is 180-. The hot-press forming temperature is determined according to the material of the membrane, the temperature is too low to reach the melting point, and the membrane can be damaged if the temperature is too high.

As an embodiment of the present invention, in step S3, the graphene composite PP filtration membrane has a thickness of 0.15 to 0.32 mm. The graphite alkene compound PP filtration membrane cladding is in the carbon-point outside, and filtration membrane is too thick, and unit interval flux is too little, influences the use, if too thin, then can't reach corresponding volume and filter the effect of getting rid of.

Compared with the prior art, the invention has the beneficial effects that:

1) according to the invention, the specific additive is matched and combined with PP, so that the graphene composite PP membrane is favorably formed, the service life of the membrane can be prolonged, and the pollution resistance is enhanced;

2) compared with the common PP membrane, the graphene composite PP filtering membrane has more excellent adsorption function, can reduce the TDS value and achieves the effects of antibiosis and bacteriostasis;

3) compared with the common membrane, the graphene composite PP membrane has a fine pore size, has the adsorption performance which is just good, can effectively block impurities in water, and achieves a good filtering effect.

Detailed Description

The present invention will be described in detail with reference to examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be apparent to those skilled in the art that several modifications and improvements can be made without departing from the inventive concept. All falling within the scope of the present invention.

The TDS referred to in the examples below is collectively referred to as total dissolved solids, measured in milligrams per liter (mg/L), and indicates how many milligrams of dissolved solids are dissolved in 1 liter of water. Higher TDS values indicate more solutes in the water. Total dissolved solids refers to the total amount of total solutes in the water, including both inorganic and organic content. Generally, the salt content of the solution is known approximately by the conductivity value, and generally, the higher the conductivity, the higher the salt content, and the higher the TDS. Among inorganic substances, there may be inorganic substances in molecular form in addition to components dissolved in ionic form. Since organic matter and inorganic matter in molecular form contained in natural water are not generally considered, the salt content is generally referred to as total dissolved solids.