WO2023090761A1 - Method for electrospinning of high-efficiency nanofiber air filter by using pvdf-g-poem double comb copolymer - Google Patents

Abstract

The present invention relates to a method for electrospinning of a high-efficiency nanofiber air filter by using a PVDF-G-POEM double comb copolymer. According to the present invention, provided is a nanofiber air filter which: can adsorb both hydrophobic dust and hydrophilic dust; exhibits a uniform diameter distribution of nanofibers, thus compensating for the disadvantages of the prior art of the large diameter and non-uniform distribution of a filter; can exhibit excellent separation efficiency through the manufacture of nanofibers with a diameter similar to the mean free path of oxygen molecules; and has a slip effect due to a narrow fiber diameter, thus having high filter efficiency.

Description

Electrospinning method of high-efficiency nanofiber air filter using PVDF-G-POEM double comb copolymer

The present invention relates to an electrospinning method of a high-efficiency nanofiber air filter using a PVDF-g-POEM double comb copolymer.

Recently, due to various problems such as corona virus infection and fine dust, interest in and importance of air filters are increasing worldwide. Various solutions have been proposed, but one of the most basic and stable methods is to wear a mask. In the case of pollutants, when inhaled, they cause serious health problems such as having a fatal effect on the respiratory system, but as the size of fine dust to be blocked gradually decreases, the need for the development of air filters with excellent performance is required.

Existing air filters were manufactured by the melt-blown method, but had the disadvantage of low stability and decomposition in organic solvents when used for a long time. In the case of the electrospinning method, it has the advantage of being able to easily and simply manufacture a filter while compensating for these disadvantages, and has recently been in the limelight. However, when electrospinning is used, the distribution ratio of the diameter of the nanofibers is not uniform, so the filter efficiency is low. In particular, in the case of electrospinning using PVDF, there is a problem in that hydrophilic contaminants cannot be filtered.

Therefore, in the present invention, it is a technical task to solve the above problems of the PVDF nanofiber air filter and to provide a method for manufacturing a nanofiber air filter having high filter efficiency.

Accordingly, when the present inventor manufactures an air filter by electrospinning method using PVDF-g-POEM polymer synthesized by utilizing atomic transfer radical polymerization method, it is possible to obtain hydrophobicity and hydrophilicity by using the electrostatic attraction and amphiphilic property of the polymer itself. It can adsorb dust of both characteristics, and shows a uniform diameter distribution of nanofibers, making up for the disadvantages of the prior art in which the diameter of the filter is thick and non-uniform, and the diameter of the nanofibers is similar to the mean free path of oxygen molecules. The present invention was completed by confirming that excellent separation efficiency could be shown by manufacturing, and high filter efficiency was affected by the slip effect due to the narrow fiber diameter.

Therefore, according to the present invention, after dissolving PVDF (poly (vinylidene fluoride)) in a solvent, POEM (poly (oxyethylene methacrylate)), a catalyst, and a polymerization initiator are added and mixed with nitrogen gas to obtain internal oxygen After purging to completely replace with nitrogen, atom transfer radical polymerization is performed at 90 to 100 ° C to polymerize and replace POEM with fluorine in the PVDF structure, and then proceed with methanol PVDF-g-POEM double comb copolymer synthesis step to obtain PVDF-g-POEM double comb copolymer by precipitating and drying in a vacuum oven;

Electrospinning was performed by mixing 10 to 30% by weight of the synthesized PVDF- g -POEM double comb copolymer and 70 to 90% by weight of a cosolvent of DMAc and MEK and continuously stirring at 58 to 95 ° C. for 12 hours. Preparing a spinning solution for preparing a spinning solution, and

Electrospinning of a high-efficiency nanofiber air filter using PVDF-g-POEM double comb copolymer, characterized in that it consists of an electrospinning step of electrospinning on a membrane substrate with a high DC voltage of 28 to 50 kV while slowly injecting the spinning solution A method is provided.

In addition, in the electrospinning method of a high-efficiency nanofiber air filter using the PVDF-g-POEM double comb copolymer of the present invention, when the PVDF-g-POEM double comb copolymer is polymerized, the reaction solution is

3 to 5 parts by weight of PVDF having a molecular weight of 300K to 330K;

46-48 parts by weight of POEM having a molecular weight of 500 to 950;

0.01 to 0.5 parts by weight of at least one catalyst from the group consisting of Copper(I)chloride(CuCl), Copper(II)chloride(CuCl ₂ ), Copper(I)bromide(CuBr) or Copper(II)bromide(CuBr ₂ );

HMTETA (1,1,4,7,10,10-Hexamethyltriethylenetetramine), PMDETA (N,N,N',N',N''-pentamethyl diethylenetriamine), DMDP (4,4'-dimethyl-2,2 0.1 to 0.5 parts by weight of any one or more polymerization initiators of '-dipyridyl), TREN (tris(2-aminoethyl)amine), TMEDA (N,N,N',NTetramethylethylenediamine) and NMP (N-methyl-2-pyrrollidinone) or It is characterized in that it is a reaction solution containing 43.11 to 45 parts by weight of DMSO solvent.

In addition, the molecular weight of the PVDF-g-POEM double comb copolymer is characterized in that 350K ~ 400K.

In addition, the DMAc-MEK cosolvent in the spinning solution preparation step is characterized in that the weight ratio DMAc: MEK = 1: 1 cosolvent.

The present invention relates to an electrospinning method of a high-efficiency nanofiber air filter using PVDF-g-POEM double comb copolymer, which uses atom transfer radical polymerization to obtain a hydrophilic PVDF backbone and a hydrophobic backbone. By grafting POEM, a PVDF-g-POEM double comb copolymer is synthesized and a high-efficiency nanofiber air filter is provided through electrospinning.

First, the polymerization step of the PVDF-g-POEM double comb copolymer used as the main component of the spinning solution for electrospinning of the high-efficiency nanofiber air filter of the present invention will be described. PVDF-g-POEM double-comb copolymer is an atom transfer radical polymerization for a reaction solution in which PVDF (poly (vinylidene fluoride)), POEM (poly (oxyethylene methacrylate)), catalyst, polymerization initiator, and solvent are mixed. ) was carried out to synthesize fluorine in the PVDF structure by substituting it while polymerizing POEM.

A schematic diagram of the polymerization process of the PVDF-g-POEM double comb copolymer is shown in Scheme 1 below:

[Scheme 1]

PVDF is a hydrophobic polymer that is a polymer of vinylidene fluoride monomers and has a halogen element such as F in the back bone, so it is preferable to use atom transfer radical polymerization (ATRP) in the present invention. The molecular weight is preferably 300,000 to 330,000, which allows the copolymer to have a low molecular weight after synthesis, thereby providing nanofibers with a low diameter. PVDF is preferably contained in 3 to 5 parts by weight.

Poly(oxyethylene methacrylate) (POEM) is a hydrophilic polymer that is frequently used as a branch polymer for atom transfer radical reactions due to the presence of double bonds. The molecular weight is preferably 500 to 950, which allows the copolymer to have a low molecular weight after synthesis. It is possible to provide nanofibers of low diameter, and POEM is preferably contained in an amount of 46-48 parts by weight.

As the catalyst, at least one from the group consisting of Copper(I)chloride(CuCl), Copper(II)chloride(CuCl ₂ ), Copper(I)bromide(CuBr) or Copper(II)bromide(CuBr ₂ ) may be used. , It is not particularly limited thereto. The content of the catalyst may be 0.01 to 0.5 parts by weight, and a graft copolymer having a grafting ratio of 15 to 35% by weight can be made in the above range.

Polymerization initiators include HMTETA (1,1,4,7,10,10-Hexamethyltriethylenetetramine), PMDETA (N,N,N',N',N''-pentamethyl diethylenetriamine), DMDP (4,4'-dimethyl -2,2'-dipyridyl), TREN (tris (2-aminoethyl)amine), TMEDA (N, N, N', NTetramethylethylenediamine), any one or more may be used. It may contain 0.1 to 0.5 parts by weight, and a graft copolymer having a grafting ratio of 15 to 35% by weight within the above range can be made.

As a solvent, 43.11 to 45 parts by weight of a solvent such as NMP (N-methyl-2-pyrrollidinone) or DMSO is used.

After dissolving the PVDF (poly (vinylidene fluoride)) in a solvent, a reaction solution is prepared by adding POEM (poly (oxyethylene methacrylate)), a catalyst, and a polymerization initiator. As described above, if PVDF is not dissolved in a solvent first This is because PVDF is not uniformly dissolved by catalysts or other initiators, which hinders the synthesis of double comb copolymers.

The prepared reaction solution is purged using nitrogen gas to replace all internal oxygen with nitrogen, and then atom transfer radical polymerization is performed at 90 to 100 ° C to obtain fluorine in the PVDF structure. After carrying out a substitution reaction while polymerizing POEM, it is precipitated in methanol and dried in a vacuum oven to obtain a PVDF-g-POEM double comb copolymer.

The PVDF-g-POEM double-comb copolymer thus obtained is capable of collecting both hydrophobic and hydrophilic contaminants by grafting the hydrophilic POEM to the hydrophobic PVDF backbone. The PVDF-g-POEM double comb copolymer has a molecular weight of 350,000 to 400,000, which is preferable because it can provide nanofibers with a low diameter and can show excellent filter efficiency.

In the present invention, a nanofiber air filter is prepared using the electrospinning method of the PVDF-g-POEM double comb copolymer synthesized as described above. The manufacturing steps of the spinning solution are as follows.

Electrospinning was performed by mixing 10 to 30% by weight of the synthesized PVDF- g -POEM double comb copolymer and 70 to 90% by weight of a cosolvent of DMAc and MEK and continuously stirring at 58 to 95 ° C. for 12 hours. Prepare the spinning solution for

The DMAc-MEK cosolvent is preferably a cosolvent having a weight ratio of DMAc:MEK = 1:1 because the double comb copolymer can be dissolved at a high concentration.

In the electrospinning step, the nanofiber air filter is provided by electrospinning the membrane substrate at a high DC voltage of 28 to 50 kV while slowly injecting the spinning solution in the same manner as in a known technique.

In this way, the present invention can provide an air filter capable of capturing both hydrophilic and hydrophobic pollutants using the PVDF-g-POEM double comb copolymer grafted by atom transfer radical polymerization as a raw material.

Therefore, according to the present invention, by providing an air filter by electrospinning using PVDF-g-POEM polymer synthesized using atom transfer radical polymerization, hydrophobicity and hydrophilic properties are obtained by using the electrostatic attraction and amphiphilic property of the polymer itself. It can adsorb dust of both characteristics, and shows a uniform diameter distribution of nanofibers, making up for the disadvantages of the prior art in which the diameter of the filter is thick and non-uniform, and the diameter of the nanofibers is similar to the mean free path of oxygen molecules. By manufacturing, it is possible to show excellent separation efficiency, and to provide a nanofiber air filter having high filter efficiency due to the slip effect due to the narrow fiber diameter.

1 is a schematic diagram explaining the electrospinning method of a high-efficiency nanofiber air filter using the PVDF-g-POEM double comb copolymer of the present invention,

Figure 2 is a graph of the results of analyzing the molecular reactive groups of Example 1 and Comparative Example 1 using FT-IR,

3 is an XRD graph of Example 1 and Comparative Example 1,

Figure 4 is the contact angle measurement test results of Example 1 and Comparative Example 1,

5 is a molecular structure analysis graph,

6 is a graph of thermogravimetric analysis in which composition ratio analysis of Example 1 and Comparative Example 1 was performed;

7 is a distribution chart showing the diameter distribution of air filters of Example 1 and Comparative Example 1;

8 is a performance measurement value of the filter of Example 1 and Comparative Example 1,

9 is a performance measurement value of the filter of Comparative Example 1,

10 is a performance measurement value of the filter of Example 1,

11 is a performance measurement value of the filter of Example 1 and Comparative Example 1.

In the following examples, a non-limiting example of the electrospinning method of a high-efficiency nanofiber air filter using the PVDF-g-POEM double comb copolymer of the present invention is shown.

[Example 1]

5 g of PVDF (molecular weight 300K) and 50 ml of NMP were put in a 250 ml round flask and sufficiently dissolved for 12 hours. After PVDF is completely dissolved, 50 ml of POEM (molecular weight: 500), 0.04 g of CuCl, and 0.23 g of DMDP are added, and all internal oxygen is substituted with nitrogen using nitrogen gas. After purging for more than an hour and a half, the reaction was carried out at 90-100 ° C for 24 hours, and the polymer obtained by precipitating in methanol (PVDF-g-POEM double comb copolymer, molecular weight 400K)) was placed in a vacuum oven for 24 hours dried in

10% by weight of the synthesized PVDF- g -POEM double comb copolymer and 90% by weight of a cosolvent in a DMAc:MEK = 1:1 ratio were mixed and continuously stirred at 58°C for 12 hours to obtain electrospinning. After preparing the spinning solution, while slowly injecting the spinning solution into the electrospinning device at a supply rate of 1 ml / h, electrospinning was performed on a membrane substrate spaced 16 cm apart at a high DC voltage of 28 kV to obtain a nanofiber web.

[Comparative Example 1]

After preparing a spinning solution for electrospinning by mixing 10% by weight of PVDF polymer and 90% by weight of a DMAc solvent and continuously stirring at 58 ° C for 12 hours, the spinning solution was slowly supplied to the electrospinning device at a supply rate of 1 ml / h. Electrospinning was performed on a membrane substrate 16 cm apart at a high DC voltage of 28 kV while injecting to obtain a nanofiber web.

The nanofiber webs of Example 1 and Comparative Example 1 were analyzed and shown in FIGS. 2 to 11. Figure 2 is a molecular reactive analysis using FTIR for Example 1 and Comparative Example 1, and after polymerization, 2872.2 (methyl group, CH ₃ ), 1727 (carbonyl group, C=O) and 1100.2 ( It was confirmed that a strong absorption band of ester group COC)cm ^-1 appeared, confirming that the PVDF- g -POEM double comb copolymer was successfully synthesized in Example 1.

3 shows Example 1 and Comparative Example 1 using XRD to confirm that the d-spacing was reduced as the reactive copolymer of the molecule was polymerized, and the amorphous polymer characteristics were confirmed.

4 shows the contact angle measurement test results of Example 1 and Comparative Example 1. In the case of PVDF, it is confirmed that POEM, which is hydrophobic but hydrophilic after polymerization, has amphiphilic properties as it is polymerized. Comparative Example 1 has a contact angle with water 54 ° (a), but Example 1 showed a contact angle of less than 1 °. (b)

5 is a molecular structure analysis graph showing ¹ H NMR of PVDF-g-POEM. Molecular structures and corresponding peaks are indicated in the graph. When the polymerization ratio was calculated using NMR, it was calculated as synthesized in a 4:1 ratio in mass%.

6 is a thermogravimetric analysis graph in which composition ratio analysis was performed, and it was confirmed that POEM was decomposed at around 250 ° C.

7 is a distribution chart showing the distribution of diameters of air filters of Example 1 and Comparative Example 1 calculated through SEM. Despite the filter manufactured by the electrospinning method, Example 1 showed an even diameter distribution as in (b), and it was confirmed that the diameter was greatly reduced compared to PVDF (a) of Comparative Example 1.

8 to 11 are performance measurement values of the filters of Example 1 and Comparative Example 1. It showed excellent filter performance compared to PVDF and confirmed its use as an excellent air filter.

The present invention relates to an electrospinning method of a high-efficiency nanofiber air filter using a PVDF-g-POEM double comb copolymer.

Claims (4)

1. After dissolving PVDF (poly (vinylidene fluoride)) in a solvent, POEM (poly (oxyethylene methacrylate)), a catalyst, and a polymerization initiator are added and mixed with nitrogen gas to replace all internal oxygen with nitrogen. After purging, atom transfer radical polymerization is performed at 90 to 100 ° C to polymerize and replace POEM with fluorine in the PVDF structure, and then precipitate in methanol and in a vacuum oven. PVDF-g-POEM double comb copolymer synthesis step to obtain PVDF-g-POEM double comb copolymer by drying;

   Electrospinning was performed by mixing 10 to 30% by weight of the synthesized PVDF- g -POEM double comb copolymer and 70 to 90% by weight of a cosolvent of DMAc and MEK and continuously stirring at 58 to 95 ° C. for 12 hours. Preparing a spinning solution for preparing a spinning solution, and

   Electrospinning of a high-efficiency nanofiber air filter using PVDF-g-POEM double comb copolymer, characterized in that it consists of an electrospinning step of electrospinning on a membrane substrate with a high DC voltage of 28 to 50 kV while slowly injecting the spinning solution method.
2. According to claim 1,

   When the PVDF-g-POEM double comb copolymer is polymerized, the reaction solution is

   3 to 5 parts by weight of PVDF having a molecular weight of 300K to 330K;

   46-48 parts by weight of POEM having a molecular weight of 500 to 950;

   0.01 to 0.5 parts by weight of at least one catalyst from the group consisting of Copper(I)chloride(CuCl), Copper(II)chloride(CuCl ₂ ), Copper(I)bromide(CuBr) or Copper(II)bromide(CuBr ₂ ); HMTETA (1,1,4,7,10,10-Hexamethyltriethylenetetramine);

   PMDETA (N,N,N',N',N''-pentamethyl diethylenetriamine), DMDP (4,4'-dimethyl-2,2'-dipyridyl), TREN (tris(2-aminoethyl)amine), TMEDA (N, N, N', NTetramethylethylenediamine) of any one or more polymerization initiators 0.1 to 0.5 parts by weight and

   Electrospinning method of high-efficiency nanofiber air filter using PVDF-g-POEM double comb copolymer, characterized in that the reaction solution contains 43.11 to 45 parts by weight of NMP (N-methyl-2-pyrrollidinone) or DMSO solvent.
3. According to claim 1,

   The electrospinning method of a high-efficiency nanofiber air filter using the PVDF-g-POEM double comb copolymer, characterized in that the molecular weight of the PVDF-g-POEM double comb copolymer is 350K to 400K.
4. According to claim 1,

   The DMAc-MEK cosolvent in the spinning solution preparation step is a high-efficiency nanofiber air using PVDF-g-POEM double comb copolymer, characterized in that the weight ratio DMAc: MEK = 1: 1 cosolvent Electrospinning method of filter.

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