KR20160119887A

KR20160119887A - Method for preparing nanofiber and nonwoven including a phase change materials

Info

Publication number: KR20160119887A
Application number: KR1020150048130A
Authority: KR
Inventors: 박준서
Original assignee: 한경대학교 산학협력단
Priority date: 2015-04-06
Filing date: 2015-04-06
Publication date: 2016-10-17
Also published as: KR101680356B1

Abstract

The present invention relates to a method for preparing a nano fiber and a nonwoven fabric including a phase change material, which is efficient and environmentally friendly as the phase change material is used, wherein the phase change material is capable of energy accumulation based on a melt electrospinning process and latent heat. The method for preparing a nano fiber including a phase change material includes: a step of supplying a polymer solution to a polymer supplier of an electrospinning device and supplying at least one phase change material supplier with at least two types of phase change materials formed from different types of compounds or the same type of compounds with different molecular weights; and a step of preparing a composite nano fiber having a core-shell structure surrounding the phase change material by melting the phase change material and electrospinning the phase change material and the polymer solution through a multi-nozzle such that the phase change material is positioned at the central part and the phase change material does not leak from the polymer.

Description

FIELD OF THE INVENTION [0001] The present invention relates to nanofibers and methods for preparing nanofibers and nonwoven fabrics containing phase transition materials,

The present invention relates to a method for producing a nanofiber and a nonwoven fabric containing a phase transition material, and more particularly, to a method for producing a nanofiber and a nonwoven fabric using a phase transition material capable of accumulating energy by a melt electrospinning process and latent heat, And a method for producing the nanofibers and the nonwoven fabric.

As global energy sources such as petroleum and coal become depleted, efforts are being made to solve energy problems around the world, and research on new energy sources is underway. On the other hand, research to improve the energy efficiency is also urgently required. In order to increase the energy efficiency, it is necessary to develop energy conversion device efficiency, energy storage and energy transfer methods. Particularly, it is important to develop a method of storing energy in order to solve the temporal and local inconsistency of supply and consumption of energy. The energy storage methods include mechanical storage methods using kinetic energy and position energy, Chemical storage methods for storing energy, and thermal energy storage methods using sensible heat and latent heat without changing the shape of energy.

In addition, as an effective method for maximizing energy efficiency, there is a method of adding a heat transfer medium having a high heat capacity. Studies on this heat transfer medium have been carried out steadily since then. Recently, much research has been focused on the latent heat storage method using phase change material (or phase change material, PCM). Here, the phase transition material is a substance that absorbs or emits a large amount of heat while changing only the state of the substance without changing the temperature at a specific temperature (in other words, when it is converted from a liquid state to a solid state, And absorbs heat from the surroundings when it is converted from a solid state to a liquid state), and the heat absorbed or emitted is called latent heat. The latent heat storage method, which is a method of storing heat energy by using the latent heat, can store a larger amount of heat per unit volume or unit weight than a method of storing heat energy using sensible heat.

However, in the latent heat storage method, the phase transition material usually has a melting temperature of -10 to 60 DEG C, and the phase transition material flows out due to liquefaction in accordance with the temperature change. That is, when the phase transition material undergo phase transition from a temperature below 100 ° C to a liquid state, the phase transition material in the liquid phase flows out to generate a loss, which leads to a decrease in thermal insulation effect or a thermal storage loss due to long- Therefore, it is required to develop a technique in which a phase transition material is not lost in a fiber or a fabric containing a phase transition material even when the ambient temperature changes.

In order to solve such a problem, Korean Patent Publication No. 2014-0145674 (polymer fiber in which a composite capsule containing a phase-change substance is dispersed and a manufacturing method thereof), Korean Patent Registration No. 10-1160156 (a phase change material is a conductive polymer And a method for producing the same) and 10-0943419 (a method for producing a polymer fiber containing a phase-change substance and uses thereof), a composite made of a phase transition material and a polymer is prepared to prevent the outflow of the phase transition material The contents are disclosed. However, the problem of environmental pollution caused by the organic solvent used in supplying the phase transition material is a problem to be solved.

It is an object of the present invention to provide a method of manufacturing nanofibers and nonwoven fabrics containing a phase transition material capable of reducing environmental pollution by reducing or eliminating the use of an organic solvent by spinning a phase transition material in a molten state, .

Another object of the present invention is to provide a method for producing nanofibers and nonwoven fabrics containing a phase transition material capable of more efficiently storing thermal energy by using two or more phase transition materials having different molecular weights.

In order to achieve the above object, the present invention provides a method for producing a polymer electrolyte fuel cell, which comprises supplying a polymer solution to a polymer feeder of an electrospinning apparatus and feeding two or more phase transition materials composed of different kinds of compounds or of the same kinds of compounds having different molecular weights , To the one or more phase change material suppliers; And melting the phase change material and electrospun through the multiple nozzles together with the polymer solution to place the phase change material at the center and the polymer to form a composite of a core cell structure that surrounds the phase change material to prevent the phase change material from leaking A method for producing a nanofiber comprising a phase transition material comprising the step of producing a nanofiber.

The method for manufacturing a nanofiber and a nonwoven fabric including a phase change material according to the present invention can reduce environmental pollution by reducing or eliminating the use of an organic solvent by spinning the phase change material in a molten state instead of a solution during electrospinning, The process is efficient, and the manufacturing cost can be reduced. In addition, according to the method for producing a nanofiber and a nonwoven fabric including a phase change material according to the present invention, two or more phase transition materials having different molecular weights can be used to more efficiently store thermal energy.

1 is a view of an electrospinning device for explaining a method of manufacturing a nanofiber and a nonwoven fabric including a phase change material according to an embodiment of the present invention.
2 is a view for comparing DSC curves of nanofibers containing two or more phase transition materials and nanofibers containing a single phase transition material according to an embodiment of the present invention.
FIG. 3 is a water contact angle (WCA) measurement chart for confirming leakage of a phase transition material included in the nanofibers according to the present invention. FIG.
4 is a schematic view (A) showing a cross section of a nanofiber including a phase change material according to an embodiment of the present invention and an image (B) observed with a transmission electron microscope (TEM).
FIG. 5 is a graph showing the mechanical strengths of nanofibers including a phase change material and nanofibers added with silica according to an embodiment of the present invention. FIG.
6 is a view showing a state (A) in which two kinds of phase transition materials are included in a nanofiber according to an embodiment of the present invention and a state (B) in which three kinds of phase transition materials are included.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a view of an electrospinning apparatus for explaining a method of manufacturing a nanofiber and a nonwoven fabric including a phase change material according to an embodiment of the present invention, wherein an enlarged view of a dotted line in FIG. And FIG. 1B is an enlarged view of the state in which two kinds of phase transition materials are supplied to different nozzles. 1, a method of manufacturing a nanofiber and a nonwoven fabric including a phase change material according to the present invention will be described. First, a polymer solution 10 and two or more phase change materials (PCM) To the polymer feeder 19 of the electro spinning apparatus and to the one or more phase change material feeder 20, respectively.

The two or more phase change materials 12, 35, and 36 may be mixed and supplied to one phase change material supply unit 20 or may be separately supplied to two or more different phase change material supply units. A in Fig. 1 is a diagram showing the case of the former case (two or more phase transition materials 12 are mixed and supplied to one phase transition material supply device 20) , 36) are separately supplied to two or more different phase change material supply units, respectively (note that each phase change material supply unit connected to the nozzle is not shown), and in the latter case, In addition to the phase change material supply device, at least one phase change material supply device must be additionally provided. In addition, a method in which two or more phase change materials are not mixed in one phase change material supply device Be in a hurry.

The polymer solution is obtained by dissolving a polymer in a solvent, and examples of the polymer include nylon-6, polystyrene, polyvinyl pyrrolidone, polyurethane, polyester, polymethyl methacrylate, polyvinyl alcohol, Nitrile, and mixtures thereof. The polymer is preferably contained in an amount of 5 to 100 parts by weight based on 100 parts by weight of the polymer solution. When the content of the polymer is less than 5 parts by weight based on 100 parts by weight of the polymer solution, the final polymer layer (that is, a shell layer to be described later) does not have a uniform fiber form, When the amount of the polymer solution is more than 100 parts by weight, the viscosity of the polymer solution excessively increases, and the flow of the polymer solution in the connection pipe and the solution injecting device of the electrospinning device is blocked, There is a possibility that it will not be. Therefore, when the content of the polymer is within the above range, it is more preferable that the phase transition material is formed in the core and the coating layer of the organic polymer is formed on the outside. As the solvent contained in the polymer solution, a typical solvent can be used without any particular limitation. Examples of the solvent include water, chloroform, tetrahydrofuran, acetic acid, methanol, ethanol, dimethylformamide, dimethylsulfoxide , Dichloromethane, dichloroethane, and mixtures thereof.

The phase change material (PCM) has a melting point at a specific temperature (preferably at room temperature), and an organic material that absorbs or emits a large amount of heat while changing only the state of the material without changing the temperature (LHTES) method using latent heat (latent heat), which is an efficient method of energy storage, as a method of storing heat energy Is a much higher amount per unit volume or per unit weight since the temperature difference between heat storage and release is lower than the sensible heat storage method of storing heat energy using sensible heat Can store the thermal energy of. In other words, selecting the phase transition material as a thermal energy storage material is very important from the viewpoint of maximizing energy efficiency and economical feasibility, and the phase is changed from the solid phase to the liquid phase during heating to store the energy and the phase is changed from the liquid phase to the solid phase upon cooling, .

Examples of such phase transition materials are polyethylene, polyethylene glycol (PEG), acetamide, propyl amide, naphthalene, stearic acid, cyanamide, glycerol, acetic acid, n-octanoic acid, n- n-octadecane, n-heptadecane, n-hexadecane, n-hexadecane, n-hexadecane, n-hexadecane, , n-pentadecane, n-tetradecane, n-tridecane, ketones, aldehydes, ethers and mixtures thereof can be exemplified. Examples of the environmentally friendly organic compounds include polyethylene glycol PEG). In particular, polyethylene glycol (PEG) is useful and superior among organic phase transition materials because it has a relatively high latent heat, a constant behavior of melting and freezing, and a wide melting temperature range depending on the molecular weight. Substances.

The 'two or more kinds of phase transition materials' supplied to the phase change material supply unit 20 may be a mixture of two or more different kinds of compounds as illustrated above, or a compound of the same kind having a different molecular weight Two or more species. Examples of the above-mentioned homogeneous compounds having different molecular weights include PEG (polyethylene glycol) -200, PEG-800 and PEG-5000 having different molecular weights (the numbers after each compound are polymerized ethylene oxide As described above, since the melting points of different phase transition materials or phase transition materials having different molecular weights are different from each other, the storage of heat energy can be made more efficient.

2 is a diagram for comparing DSC (Differential Scanning Calorimetry) curves of a nanofiber including two or more phase change materials and a single phase transition material according to a comparative example according to an embodiment of the present invention , Nanofibers (20%, 40%, 60% PEGs) containing a single phase transition material as shown in FIG. 2, nanofibers containing two or more phase transition materials according to the present invention (That is, less peak and less fluctuation) than a 50% PEG-600 + 50% PEG-1000, from which a single phase transition material , It is understood that the use of different kinds of phase transition materials or phase transition materials having different molecular weights together enables efficient storage of heat energy.

Next, the phase change materials (PCM, 12, 35, 36) are melted and electrospun through the multiple spinnerets 30 together with the polymer solution 10 to form the phase transition material The composite nanofiber having a core-shell structure is wrapped around the phase change material 12, 35, 36 so that the phase change material 12, 35, 36 does not leak .

There is also a method for producing a fiber composite composed of a phase transition material and a polymer using a phase transition material and a polymer solution. However, in the conventional methods, the phase transition material is supplied from the beginning to the electrospinning device in the state of a solution. In order to supply the phase transition material in a state of a solution, an organic solvent should be used. Can cause problems that arise in using organic solvents of < RTI ID = 0.0 >

However, the method of manufacturing the nanofibers and the nonwoven fabric according to the present invention does not supply the phase change materials 12, 35, and 36 to the phase change material supply unit 20 in a solution state, 35 and 36 are supplied to the phase change material supply device 20 in a solid state and then melted and radiated to the outside in the phase change material supply device 20. In this case, It is possible to lower or eliminate the concern of environmental pollution and to reduce the cost, and it is also possible to radiate only the pure phase transition material 12, 35, 36 without the organic solvent , The content of the phase transition material in the produced nanofiber can be increased. The amount of the phase transition material contained in the nanofiber is 5 to 100 parts by weight, preferably 10 to 80 parts by weight, based on 100 parts by weight of the polymer contained in the nanofiber, When the content of the substance is less than 5 parts by weight based on 100 parts by weight of the polymer contained in the nanofibers, the phase transition material may not efficiently store thermal energy. When the amount exceeds 100 parts by weight, There may be no special advantages.

When two or more kinds of the above-mentioned different kinds of compounds are used in the phase transition material in the nanofiber, or when two or more kinds of the same kinds of compounds having different molecular weights are used, May be contained in the same ratio in the fibers, or may be included in different ratios in consideration of the efficiency of heat energy storage and the like, which can be adjusted through the one or more phase change material suppliers 20. For example, when two phase change materials are used, the content of each phase change material with respect to the total phase change material is 20 to 80% by weight, preferably 30 to 70% by weight, for example, 50% have.

As shown in FIG. 1, the method of melting the phase change material 12, 35, 36 in the phase change material supply device 20 includes the steps of: The phase change material melt 18 is supplied to the formed phase transition material melt inlet port 14 so that the phase change material 12, 35 and 36 flows around the phase transition material melt inlet port 14, The phase transition material melt 18 is continuously supplied to the phase change material melt inlet port 14 to continuously melt the phase change materials 12, 35 and 36, The material melt 18 is discharged to the melt outlet 16 of the phase transition material formed at the other end of the outer surface of the phase change material feeder 20.

As the phase change material melt 18, a liquid material having a temperature of 5 to 100 ° C, preferably 10 to 80 ° C, and more preferably 20 to 70 ° C, may be used. The phase change material 12, 35, And can be used without any particular limitations, for example, hot silicone oil and the like.

Since the present invention uses a multiple electro spinning method, the multiple nozzles 30 in which the polymer solution 10 and the phase change materials (PCM, 12, 35, 36) are radiated and the fibers are manufactured A positive voltage and a negative charge must be respectively immersed in the collected fiber collectors 40 to make a potential difference between the multiple nozzles 30 and the fiber aggregate 40. For this purpose, ) Should be supplied with a voltage of 1 to 50 KV, preferably 10 to 30 KV, more preferably 15 to 20 KV. That is, when such an electrospinning method is used, an electrical repulsive force is generated in the material to cause a bonding phenomenon between molecules, and ultimately, an ultrafine fiber having a diameter of several tens of nanometers to several hundreds of nanometers is formed. The electro spinning method is advantageous in that it is possible to manufacture various types of nanofibers such as a core-cell structure, a hollow structure, and a porous structure as well as a simple process, easy diameter control of the fibers, and the like.

1, the molten phase transfer material (PCM, 12, 35, 36) flows into the central portion 32 of the multiple nozzle 30, The polymer solution 10 fills the peripheral portion 34 by surrounding the central portion 32 of the multiple nozzles 30 through which the molten phase transition material 12, 35 and 36 flows. At this time, the feed flow rate of the polymer solution 10 is controlled to be about 5 to 20 times faster than the supply flow rate of the phase change materials 12, 35, and 36, so that the phase change material is dispersed inside, (For example, the supply flow rate of the polymer solution 10 is 1.5 mL / h and the supply flow rate of the phase change materials 12, 35 and 36 is 0.09 to 0.24 mL / h).

FIG. 3 is a water contact angle (WCA) measurement chart for confirming whether the phase transition material contained in the nanofiber according to the present invention is leaked. For example, assuming that the supply flow rate of the polymer solution 10 is 1.5 mL / h The nanofibers (or nonwoven fabrics) prepared by performing the feed rates of the phase transition materials at 0.09, 0.108, 0.126, and 0.15 mL / h, respectively, during the electrospinning, as shown in FIG. 3, ; WCA). As a result, it can be seen that the order of 108 °, 107 °, 102 ° and 28 ° is shown in order. (The nanofiber made of a polymer solution only has a water contact angle of 109 °). Particularly, when the feeding rate of the phase change material is 0.15 mL / h, the contact angle of water is drastically reduced to 28 °, indicating that the phase transition material contained in the nanofiber can easily flow out to the outside, that is, If the supply flow rate of the phase transition material is too high, the formation of the nanofibers becomes insufficient, and the possibility that the phase transition material flows out to the outside becomes high. Therefore, when the supply flow rate of the polymer solution 10 at the time of electrospinning is 1.5 mL / h, it is required to adjust the feed rate of the phase change material to about 0.09 to 0.130 mL / h.

4 is a schematic view (A) showing a cross section of a nanofiber including a phase change material according to an embodiment of the present invention and an image (B) observed with a transmission electron microscope (TEM). Therefore, when the polymer solution 10 and the phase change material 12 are emitted through the multiple nozzles 30, the phase transition material 12 is located at the center of the polymer solution 10 The polymer 11 in which the solvent is removed in the step (1) of the present invention has a core-shell structure of the composite nanofiber wrapping the phase-transition material 12. At this time, the diameter of the produced nanofiber is 0.1 to 1 탆 (micrometer), preferably 0.2 to 0.9 탆, more preferably 0.3 to 0.8 탆.

As described above, when the polymer solution 10 surrounds the phase change material 12, it is possible to eliminate or minimize the possibility that the phase change material 12 leaks to the outside when the phase change material 12 of the core layer transitions to the liquid phase can do. That is, the polymer layer 11 protects the phase transition material 12 from leaking. When the phase transition material is transformed from a solid state to a liquid state through phase transition, form stable packing in which the liquid phase transition material does not leak in the packaging is very important, so that the polymer layer (11) The method of surrounding the material 12 can be said to be very significant.

On the other hand, in order to minimize the possibility that the phase transition material 12 leaks to the outside in the nanofiber (that is, to keep the shape of the nanofiber more thoroughly) or to increase the mechanical strength of the nanofiber, , SiO ₂ ), preferably dry silica, may be used. The polymer solution may be supplied to the polymer feeder 19 so as to be mixed with the polymer solution 10, or may be separately supplied to cover the phase transition material located in the nanofiber Can be supplied to the feeder of the apparatus for electrospinning.

FIG. 5 is a graph showing the mechanical strengths of nanofibers containing phase change materials and nanofibers added with silica according to an embodiment of the present invention, wherein FIG. 5 (a) is a nanofiber produced only from a polymer solution , FIG. 5 (b) is a nanofiber prepared from a polymer solution and a phase transition material, and FIG. 5 (c) is a nanofiber made from a polymer solution, a phase transition material and silica. 5 (a) and 5 (b), mechanical strength such as tensile stress and elongation of the nanofiber (b) containing a phase transition material is And the mechanical strength of the nanofiber (b) containing such a phase transition material can be further improved by further including silica as shown in FIG. 5 (c).

The fiber aggregate 40 in which the nanofibers are gathered may be in the form of a flat plate as shown in FIG. 1 to collect the nanofibers. Alternatively, the nanofibers may be rotated as in a thread, There is no particular limitation on the method of collecting the nanofibers, and when the fiber aggregate portion 40 is rotated, the rotation can be controlled by an rpm regulator (not shown).

FIG. 6 is a view showing a state (A) in which two kinds of phase transition materials are included in a nanofiber according to an embodiment of the present invention and a state (B) in which three kinds of phase transition materials are included, 6, the two or more phase transition materials 52, 53, or 54 to 56 are respectively located inside the polymer 51, and the polymer 51 is disposed in the interior of the polymer 51. In the case where the material is supplied separately to two or more mutually different phase transfer material feeders, The composite nanofibers are formed so as to surround the phase change materials 52, 53 or 54 to 56 so that the phase change materials 52, 53 or 54 to 56 do not leak.

Since the composite nanofibers prepared as described above have a very large surface area compared with their volume, they have an excellent filtration effect when used for a filter, and when the polymer used in the production of nanofibers has electrical conductivity, Etc., its use is very wide. On the other hand, when the phase change material is used in a mixture of two or more types, or not independently, as in the present invention, it is possible to more efficiently store thermal energy and cope with changes in external temperature appropriately.

In addition, the composite nanofibers can be made into a nonwoven fabric by mechanical or chemical treatment such as adhesion and fusing requiring heat and pressure, and the nonwoven fabric using the nanofibers containing the phase transition material has excellent mechanical strength and weight Porous fabric having a wide surface area can be used in various fields such as space suit, sports apparel, patient suit and bedding where heat preservation and heat insulation are required. In addition, such a nonwoven fabric may be used to produce a fabric for a thermal energy storage function and a temperature control function.

Claims

Supplying a polymer solution to a polymer feeder of an electrospinning device and supplying two or more phase transition materials composed of different kinds of compounds or compounds of the same kind having different molecular weights to at least one phase change material feeder; And
The phase transition material is melted and electrospun through a plurality of nozzles together with the polymer solution to place the phase transition material in the center portion and the polymer has a core-shell structure nano-particle structure in which the phase transition material is wrapped so that the phase transition material does not leak A method for producing a nanofiber comprising a phase transition material comprising the steps of: preparing a fiber.

The method of claim 1, wherein, when the two or more phase change materials are supplied to two or more mutually different phase change material supply units, two or more phase change materials are respectively located inside the composite nanofiber, and the polymer prevents the phase change materials from leaking Wherein the phase transition material is surrounded by the phase transition material.

The method of manufacturing a nanofiber according to claim 1, wherein the phase change material is melted by a hot phase transition material melt flowing around the phase change material.

The method of manufacturing a nanofiber according to claim 1, wherein the phase change material melt is a hot silicone oil at 5 to 100 ° C.

The method of claim 1, wherein the phase change material is selected from the group consisting of polyethylene, polyethylene glycol (PEG), acetamide, propylamide, naphthalene, stearic acid, cyanamide, glycerol, acetic acid, N-hexadecanoic acid, n-octadecane, n-heptadecane, n-hexadecane, n-hexadecanoic acid, n-pentadecane, n-tetradecane, n-tridecane, ketones, aldehydes, ethers, and mixtures thereof.

The method according to claim 1, wherein the polymer solution is selected from the group consisting of nylon-6, polystyrene, polyvinylpyrrolidone, polyurethane, polyester, polymethylmethacrylate, polyvinyl alcohol, polyacrylonitrile, And a solvent selected from the group consisting of water, chloroform, tetrahydrofuran, acetic acid, methanol, ethanol, dimethylformamide, dimethylsulfoxide, dichloromethane, dichloroethane and mixtures thereof. &Lt; / RTI > wherein the nanofibers comprise a material.

[Claim 6] The method according to claim 5, wherein the polymer is used in an amount of 5 to 100 parts by weight based on 100 parts by weight of the polymer solution.

The method according to claim 1, wherein the amount of the phase change material contained in the nanofibers is 5 to 100 parts by weight based on 100 parts by weight of the polymer contained in the nanofibers.

The method according to claim 1, wherein the diameter of the nanofibers is 0.1 to 1 占 퐉.

Supplying a polymer solution to a polymer feeder of an electrospinning device and supplying two or more phase transition materials composed of different kinds of compounds or compounds of the same kind having different molecular weights to at least one phase change material feeder;
The phase transition material is melted and electrospun through a plurality of nozzles together with the polymer solution to place the phase transition material in the center portion and the polymer has a core-shell structure nano-particle structure in which the phase transition material is wrapped so that the phase transition material does not leak Producing a fiber; And
And subjecting the nanofibers to mechanical or chemical treatment.

The method of claim 10, wherein, when the two or more phase change materials are supplied to two or more mutually different phase change material supply units, two or more phase change materials are respectively disposed in the composite nanofibers, and the polymer prevents the phase change materials from leaking Wherein the phase transition material is wrapped around the phase transition material.