U.S. patent application number 13/994320 was filed with the patent office on 2013-11-14 for polymer composite materials for building air conditioning or dehumidification and preparation method thereof.
The applicant listed for this patent is Young-soo Ahn, Churl-hee Cho, Kuck-tack Chue, Chang-kook Hong, Se-hee Kim, Hyeong-seon Oh, Sang-youn Oh, Jae-sik Ryu, Seung-hyun Shin, Jeong-gu Yeo. Invention is credited to Young-soo Ahn, Churl-hee Cho, Kuck-tack Chue, Chang-kook Hong, Se-hee Kim, Hyeong-seon Oh, Sang-youn Oh, Jae-sik Ryu, Seung-hyun Shin, Jeong-gu Yeo.
Application Number | 20130299121 13/994320 |
Document ID | / |
Family ID | 46244833 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130299121 |
Kind Code |
A1 |
Ahn; Young-soo ; et
al. |
November 14, 2013 |
POLYMER COMPOSITE MATERIALS FOR BUILDING AIR CONDITIONING OR
DEHUMIDIFICATION AND PREPARATION METHOD THEREOF
Abstract
The present disclosure relates to the preparation of a polymer
composite material for building air conditioning or
dehumidification having superior water-adsorbing ability,
durability and antibacterial properties by electro spinning.
Specifically, the disclosed method for preparing a polymer
composite material for building air conditioning or
dehumidification includes: (S1) adding a crosslinking agent or a
crosslinking agent and a porous filler for conferring durability
and antibacterial properties into a hydrophilic polymer solution
antibacterial properties to prepare a polymer composite material
solution; (S2) electrospinning the polymer composite material
solution to prepare a nanofiber sheet; and (S3) crosslinking the
nanofiber sheet by heat-treatment. Since the disclosed polymer
composite material for building air conditioning or
dehumidification has superior antibacterial properties and
excellent water-adsorbing ability and durability, the polymer
composite material can perform dehumidification when used for air
conditioning of a building, thereby reducing air conditioning load
and improving energy efficiency. Further, through dehumidifying
cooling, the high-efficiency polymer composite material can remove
moisture from the hot and humid air in the summer, thus reducing
air conditioning load by decreasing latent heat load and saving
energy. In addition, the polymer composite material can be used in
moisture-sensitive production processes, industrial applications
requiring moisture control or protection from damage or corrosion
by moisture to reduce moisture and provide dry air.
Inventors: |
Ahn; Young-soo; (Daejeon,
KR) ; Yeo; Jeong-gu; (Daejeon, KR) ; Chue;
Kuck-tack; (Daejeon, KR) ; Cho; Churl-hee;
(Daejeon, KR) ; Hong; Chang-kook; (Gwangju,
KR) ; Oh; Sang-youn; (Gwangju, KR) ; Kim;
Se-hee; (Gyeonggi-do, KR) ; Oh; Hyeong-seon;
(Gwangju, KR) ; Ryu; Jae-sik; (Jeonbuk, KR)
; Shin; Seung-hyun; (Jeonbuk, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ahn; Young-soo
Yeo; Jeong-gu
Chue; Kuck-tack
Cho; Churl-hee
Hong; Chang-kook
Oh; Sang-youn
Kim; Se-hee
Oh; Hyeong-seon
Ryu; Jae-sik
Shin; Seung-hyun |
Daejeon
Daejeon
Daejeon
Daejeon
Gwangju
Gwangju
Gyeonggi-do
Gwangju
Jeonbuk
Jeonbuk |
|
KR
KR
KR
KR
KR
KR
KR
KR
KR
KR |
|
|
Family ID: |
46244833 |
Appl. No.: |
13/994320 |
Filed: |
December 15, 2010 |
PCT Filed: |
December 15, 2010 |
PCT NO: |
PCT/KR2010/008982 |
371 Date: |
July 31, 2013 |
Current U.S.
Class: |
165/8 ; 156/167;
264/465; 424/684 |
Current CPC
Class: |
D01F 1/10 20130101; D01F
6/50 20130101; D01F 6/14 20130101; D01D 5/0015 20130101; D04H 1/728
20130101; F24F 3/147 20130101; F28D 19/04 20130101; D01D 5/0084
20130101; D01F 1/103 20130101 |
Class at
Publication: |
165/8 ; 424/684;
264/465; 156/167 |
International
Class: |
F28D 19/04 20060101
F28D019/04 |
Claims
1. A method for preparing a polymer composite material for building
air conditioning or dehumidification, comprising: (S1) adding a
crosslinking agent or a crosslinking agent and a porous filler for
conferring durability and antibacterial properties into a
hydrophilic polymer solution to prepare a polymer composite
material solution; (S2) electrospinning the polymer composite
material solution to prepare a nanofiber sheet; and (S3)
crosslinking the nanofiber sheet by heat-treatment.
2. The method according to claim 1, further comprising: adhering
the nanofiber sheet to a metal sheet, a ceramic fiber sheet or a
conductive polymer film before or after heat treatment.
3. The method according to claim 1, comprising: (S1) adding a
crosslinking agent or a crosslinking agent and a porous filler for
conferring durability and antibacterial properties into a
hydrophilic polymer solution to prepare a polymer composite
material solution; (S2') electrospinning the polymer composite
material solution directly onto a metal sheet, a ceramic fiber
sheet or a conductive polymer film to prepare a nanofiber sheet;
and (S3) crosslinking the nanofiber sheet by heat-treatment.
4. The method according to claim 1, wherein, in step S1, the
hydrophilic polymer solution is prepared by dissolving a
hydrophilic polymer in a solvent.
5. The method according to claim 1, wherein, in step S1, the
hydrophilic polymer solution is prepared by the steps of
comprising: dissolving a hydrophilic polymer in a solvent to
prepare a first solution; dissolving another hydrophilic polymer
different from the hydrophilic polymer in a solvent to prepare a
second solution; and mixing the first solution and the second
solution to prepare the hydrophilic polymer solution.
6. The method according to claim 4, wherein the solvent is at least
one selected from the group consisting of water, alcohol, DMF, NMP
and DMAc.
7. The method according to claim 4, wherein the hydrophilic polymer
is selected from the group consisting of polyvinyl alcohol (PVA),
polystyrene sulfonic acid, polystyrene sulfonic acid/maleic acid
copolymer, sodium polystyrene sulfonate, polyacrylate, polyethylene
glycol, polyethylene oxide, cellulose derivatives, and ion exchange
resins.
8. The method according to claim 4, wherein the hydrophilic polymer
is present in an amount of 0.5 to 50 wt % based on a weight of the
hydrophilic polymer solution.
9. The method according to claim 1, wherein the hydrophilic polymer
is polyvinyl alcohol.
10. The method according to claim 1, wherein the crosslinking agent
is at least one selected from the group consisting of: peroxides,
inorganic precursors and silane coupling agents, aldehydes,
polyacrylic acids, diisocyanates, diacids and derivatives thereof,
and organic acids containing a sulfonic acid group.
11. The method according to claim 10, wherein the organic acid
containing the sulfonic acid group is selected from the group
consisting of sulfosuccinic acid (SSA), polystyrene sulfonic acid
and poly(4-styrenesulfonic acid-co-maleic acid) sodium salt.
12. The method according to claim 10, wherein the crosslinking
agent is present in an amount of 20 wt % or less based on a weight
of the hydrophilic polymer.
13. The method according to claim 1, wherein the porous filler is
zeolite, SBA-15, MCM-41, silica gel, carbon, carbon nanotube, or a
porous filler substituted with Cu or Ag.
14. The method according to claim 1, wherein the porous filler is
present in an amount of 50 wt % or less based on a weight of the
hydrophilic polymer.
15. A polymer composite material for building air conditioning or
dehumidification having superior durability and antibacterial
properties prepared in the method according to claim 1 from a
solution comprising a hydrophilic polymer and a crosslinking agent,
or a crosslinking agent and a porous filler by electrospinning and
crosslinking.
16. The polymer composite material according to claim 15, wherein
the polymer composite material for building air conditioning or
dehumidification is used for an air conditioning system selected
from the group consisting of a total heat exchanger for a
ventilation unit and a rotor-type total heat exchanger.
17. The polymer composite material according to claim 15, wherein
the polymer composite material for building air conditioning or
dehumidification is used for a dehumidification/cooling system
selected from the group consisting of a dehumidification rotor for
dehumidification and a dehumidification rotor for dehumidification
type cooling.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to polymer composite
materials for building air conditioning or dehumidification and a
method for preparing the same. More particularly, the present
disclosure relates to the preparation of high-efficiency composite
materials for building air conditioning or dehumidification having
superior antibacterial properties and durability as well as
excellent water adsorption/desorption ability due to a large
surface area by electrospinning of a polymer composite material
solution with a crosslinking agent or a crosslinking agent and a
porous filler added to a hydrophilic polymer solution to prepare a
fiber sheet composed of fibers having a nano or a submicron scale
diameter followed by crosslinking.
BACKGROUND ART
[0002] Recently, government regulations have been instituted which
require air conditioning systems to perform decontamination
functions in addition to basic air conditioning functions. Air
conditioning of a building includes heating, cooling, ventilation
and heat exchange. Quality air conditioning provides a healthy and
comfortable environment, improves satisfaction with the indoor
environment and enhances productivity. Two heat loads--sensible
heat and latent heat--determine the capacity of an air conditioning
system. The latent heat load accounts for 30.about.50% of the total
heat load. The sensible heat means the heat exchanged during a
change of temperature, whereas the latent heat refers to the heat
that cannot be, observed as a change of temperature, e.g. heat
absorbed during the phase change of water. A phase change of water
without change of temperature results in an air conditioning load.
If water is removed from the air using an air conditioning
material, the size and energy consumption of an air conditioner may
be reduced since the dehumidification/cooling system needs only to
address the sensible heat load.
[0003] The air conditioning system includes a total heat exchanger
for a ventilation unit a dehumidification rotor for
dehumidification/cooling, a rotor-type total heat exchanger, or the
like. FIG. 1 shows a rotor-type total heat exchanger, illustrating
a process whereby air is supplied from outside and indoor air is
exhausted outside. After water is absorbed from the indoor air to
be exhausted in order to reduce the latent heat load, a
water-absorbent polymer composite material exchanges heat with
water in the air supplied from outside and supplies the air indoors
while the rotor-type total heat exchanger rotates, thus providing
cool air and ventilation with reduced energy consumption.
[0004] Current studies on building air conditioning materials focus
only upon general water absorbents using super-dense paper,
inorganic materials, metal silicates, silica gel, zeolite, or the
like. For example, Japan's Seibu Giken has developed
water-absorbent polymer powder and is marketing a total heat
exchanger with the water-absorbent polymer powder impregnated in or
coated on a metal sheet. However, since the water-absorbent polymer
powder adsorbs water through hydration by ions, not by pores,
pollutant molecules are discharged into the air without being
adsorbed.
[0005] Recently, demand for high-efficiency composite materials for
building air conditioning or dehumidification having antibacterial
properties as well as excellent water absorbing ability and being
easily applicable to various designs is increasing.
DISCLOSURE
Technical Problem
[0006] Aspects of the present disclosure are directed to
high-efficiency composite materials for building air conditioning
or dehumidification having antibacterial properties as well as
excellent water absorbing ability and being easily applicable to
various designs.
Technical Solution
[0007] One aspect of the present disclosure provides a method for
preparing a polymer composite material for building air
conditioning or dehumidification, including: (S1) adding a
crosslinking agent or a crosslinking agent and a porous filler for
conferring durability and antibacterial properties into a
hydrophilic polymer solution to prepare a polymer composite
material solution; (S2) electrospinning the polymer composite
material solution to prepare a nanofiber sheet; and (S3)
crosslinking the nanofiber sheet by heat-treatment. Before or after
step S3, the nanofiber sheet may be adhered to a metal sheet, a
ceramic fiber sheet or a conductive polymer film.
[0008] Another aspect of the present disclosure provides a method
for preparing a polymer composite material for building air
conditioning or dehumidification, including: (S1) adding a
crosslinking agent or a crosslinking agent and a porous filler for
conferring durability and antibacterial properties into a
hydrophilic polymer solution to prepare a polymer composite
material solution; (S2) electrospinning the polymer composite
material solution directly onto a metal sheet, a ceramic fiber
sheet or a conductive polymer film to prepare a nanofiber sheet;
and (S3) crosslinking the nanofiber sheet by heat-treatment.
[0009] A further aspect of the present disclosure provides a
polymer composite material for building air conditioning or
dehumidification having superior durability and antibacterial
properties prepared from a solution including a hydrophilic polymer
and a crosslinking agent, or a crosslinking agent and a porous
filler by electrospinning and crosslinking.
Advantageous Effects
[0010] According to the present disclosure, the polymer composite
material for building air conditioning or dehumidification has
superior antibacterial properties and excellent water-adsorbing
ability and durability. As a result, the polymer composite material
may control humidity when used for air conditioning of a building,
thereby reducing air conditioning load and improving energy
efficiency. In addition, the polymer composite material may prevent
various diseases and allows supply of pleasant indoor air. Further,
through dehumidifying/cooling, the polymer composite material may
remove moisture from hot and humid air in the summer, thus reducing
air conditioning load by decreasing latent heat load and saving
energy. Furthermore, the high-efficiency polymer composite material
may be used in moisture-sensitive production processes or
industrial applications requiring moisture control or protection
from damage or corrosion by moisture in order to dehumidify and
provide dry air.
[0011] The polymer composite material according to the present
disclosure may be utilized for water adsorption and
dehumidification in various fields, for example, in building air
conditioning and dehumidification/cooling, including a total heat
exchanger of a ventilation unit, a dehumidification rotor for
dehumidification/cooling, a rotor-type total heat exchanger, or the
like.
DESCRIPTION OF DRAWINGS
[0012] The above and other aspects, features and advantages of the
present disclosure will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0013] FIG. 1 shows a total heat-exchange rotor according to an
embodiment of the present disclosure;
[0014] FIG. 2 illustrates a crosslinking mechanism of a PVA polymer
in Example 1;
[0015] FIG. 3 shows scanning electron micrographs of a PVA
nanofiber sheet, a crosslinked sheet and a zeolite-introduced
nanofiber sheet in Example 1;
[0016] FIG. 4 shows water adsorption by a nanofiber sheet in
Example 2;
[0017] FIG. 5 shows the amount of polymer remaining after washing
as compared to the initial polymer amount in Examples 2-4, as a
measure of durability;
[0018] FIG. 6 shows a result of culturing E. coli at 35.degree. C.
for 24 hours in Examples 5-7, in order to evaluate antibacterial
properties; and
[0019] FIG. 7 shows a result of culturing salmonella at 35.degree.
C. for 24 hours in Examples 5-7, in order to evaluate antibacterial
properties.
BEST MODE
[0020] Exemplary embodiments of the present disclosure will now be
described.
[0021] In one embodiment, a method for preparing a polymer
composite material for building air conditioning or
dehumidification according to the present disclosure includes: (S1)
adding a crosslinking agent or a crosslinking agent and a porous
filler for conferring durability and antibacterial properties into
a hydrophilic polymer solution to prepare a polymer composite
material solution; (S2) electrospinning the polymer composite
material solution to prepare a nanofiber sheet; and (S3)
crosslinking the nanofiber sheet by heat-treatment.
[0022] In step S1, a crosslinking agent or a crosslinking agent and
a porous filler are added to a hydrophilic polymer solution in
order to confer durability and antibacterial properties, thereby
preparing a polymer composite material solution. The hydrophilic
polymer solution may be prepared by dissolving at least one
hydrophilic polymer selected from the group consisting of polyvinyl
alcohol (PVA), polystyrene sulfonic acid, polystyrene sulfonic
acid/maleic acid copolymer, sodium polystyrene sulfonate,
polyacrylate, polyethylene glycol, polyethylene oxide, cellulose
derivatives, and ion exchange resins in at least one solvent
selected from the group consisting of water, alcohol, DMF, NMP and
DMAc. The content of the hydrophilic polymer may be 0.5 to 50 wt %
based on the weight of the hydrophilic polymer solution. If the
hydrophilic polymer content exceeds 50 wt %, the resulting high
viscosity may prevent effective electrospinning. Conversely, if the
hydrophilic polymer content is below 0.5 wt %, nanofiber may not be
produced because of low viscosity.
[0023] This step may include: dissolving a hydrophilic polymer in a
solvent to prepare a first solution; dissolving another hydrophilic
polymer different from the first hydrophilic polymer in a solvent
to prepare a second solution; and mixing the first solution and the
second solution to prepare the hydrophilic polymer solution.
[0024] The proportion of the contents of the hydrophilic polymers
in the hydrophilic polymer solution is not particularly limited and
may be appropriately adjusted considering required physical
properties.
[0025] The crosslinking agent added to improve durability and
antibacterial properties may include at least one selected from the
group consisting of peroxides such as dibenzoyl peroxide, inorganic
precursors such as tetraethyl orthosilicate, silane coupling agents
such as 3,3-diethoxypropyltriethoxysilane, aldehydes such as
glutaraldehyde; polyacrylic acids, diisocyanates, diacids and
derivatives thereof, and organic acids containing a sulfonic acid
group. Particularly, an organic acid containing a sulfonic acid
group selected from the group consisting of sulfosuccinic acid
(SSA), polystyrene sulfonic acid and poly(4-styrenesulfonic
acid-co-maleic acid) sodium salt may be used.
[0026] The porous filler added to improve durability and
antibacterial properties may be zeolite, SBA-15, MCM-41, silica
gel, carbon, carbon nanotube, or the like. Further, a porous filler
substituted with metal ions such as Cu or Ag may also be used.
[0027] The content of the crosslinking agent in the polymer
composite material solution may be 20 wt % or less based on the
weight of the hydrophilic polymer. If the content of the
crosslinking agent exceeds 20 wt %, the resulting polymer composite
material may be too hard or brittle.
[0028] In addition, the content of the porous filler in the polymer
composite material solution may be 50 wt % or less based on the
weight of the hydrophilic polymer. If the content of the porous
filler exceeds 50 wt %, the filler may not be dispersed well but
coagulate. Further, the amount or rate of water adsorption may
decrease.
[0029] In step S2, electrospinning is carried out. By
electrospinning the polymer composite material solution using an
electric field after injecting the solution into a syringe or
capillary tube, a nanofiber sheet with increased surface area may
be prepared. By applying a high-voltage electric field during
electrospinning, a nanofiber structure may be more effectively
formed. In addition, by controlling the viscosity of the polymer
composite material solution, the applied voltage, spinning
distance, or the like, the diameter of the nanofiber may be
adjusted. The nanofiber may have a diameter ranging from tens of
nanometers to tens of micrometers. Thus, the surface area of the
composite material sheet may be controlled to confer a very large
water adsorbing capacity.
[0030] In step S3, the nanofiber sheet prepared in step S2 is
crosslinked by heat treatment. The crosslinking is initiated by
heating and performed while maintaining the elevated temperature.
In the case where a metal peroxide is used as the crosslinking
agent, the solution is left at room temperature for predetermined
time and then the crosslinking is performed in the same manner.
[0031] Before or after step S3, the nanofiber sheet may be adhered
to a metal sheet, a ceramic fiber sheet or a conductive polymer
film. A metal sheet such as aluminum sheet or stainless steel
sheet, a ceramic fiber sheet, or a conductive polymer film such as
polyvinyl chloride may be adhered to the crosslinked polymer
composite material sheet or to the nanofiber sheet prior to
crosslinking. Further, an adhesive may be applied on the surface of
the metal sheet and the nanofiber sheet may be adhered to either or
both sides of the metal sheet.
[0032] In another embodiment, a method for preparing a polymer
composite material for building air conditioning or
dehumidification according to the present disclosure comprises:
(S1) adding a crosslinking agent or a crosslinking agent and a
porous filler for conferring durability and antibacterial
properties into a hydrophilic polymer solution to prepare a polymer
composite material solution; (S2) electrospinning the polymer
composite material solution directly onto a metal sheet, a ceramic
fiber sheet or a conductive polymer film to prepare a nanofiber
sheet; and (S3) crosslinking the nanofiber sheet by heat-treatment.
This embodiment is the same as the above embodiment, except that
the nanofiber sheet is prepared by directly electrospinning the
polymer composite material solution onto the metal sheet, the
ceramic fiber sheet or the conductive polymer film.
[0033] The polymer composite material for building air conditioning
or dehumidification according to the present disclosure may be used
for various applications, including a total heat exchanger for a
ventilation unit, a dehumidification rotor for
dehumidification/cooling, a rotor-type total heat exchanger, and
the like. The total heat exchanger for a ventilation unit is a
rectangular-shaped heat exchanger fabricated using an insulating
exchange membrane with superior water permeability. An insulating
exchange membrane that transmits water but blocks polluted air is
prepared in the form of a honeycomb. The total heat exchanger
transmits latent heat of water included in the air through the
paper insulating membrane to the introduced air during ventilation,
thereby lowering indoor temperature and humidity, removes fine dust
such as pollen, thereby preventing various diseases, is installed
in the ceiling, thereby minimizing noise and providing a quiet
environment, provides excellent ventilation through forced
ventilation in both directions using separate exhaust and inlet
vents, and supplies cleanly filtered fresh outside air, rather than
recirculated the indoor air, thereby maintaining a pleasant indoor
environment.
[0034] The dehumidification rotor for dehumidification/cooling is a
key component of a dehumidification/cooling system, which is used
to dehumidify the hot and humid summer air through low-energy
cooling by separating the latent heat load and the sensible heat
load. Further, it is used to dehumidify the air for the purpose of
cooling and drying of products, quality improvement and
maintenance, humidity control of a production process, or the like.
Specific applications include moisture-sensitive production
processes such as pharmaceutical, electronic or food production
processes or fields requiring prevention of damage or corrosion by
moisture, to remove moisture in the air and provide a dry
environment.
[0035] The rotor-type total heat exchanger is a high-efficiency,
energy-saving device capable of controlling thermal balance
associated with introduction and exhaust of indoor and outdoor air,
effectively purifying indoor air, and reducing cooling/heating
load. The rotor-type total heat exchanger may be utilized as a heat
recovery ventilator for forced air supply/discharge by reducing the
latent heat of water in the exhausted air during ventilation and
exchanging heat with the water, in the air supplied from outside,
without requiring an additional heating or cooling source. The
absorbent of the rotor-type total heat exchanger, which serves as a
latent heat exchange medium, is impregnated in, coated on or
adhered to a cylindrical honeycomb structure. The polymer composite
material for building air conditioning of the present disclosure
may be used as the latent heat exchange medium employed in the
honeycomb structure.
[0036] The polymer composite material for building air conditioning
or dehumidification according to the present disclosure has
superior water-adsorbing ability because of the increased surface
area and the hydration by ions, and has excellent durability and
antibacterial properties. Thus, when used to air condition a
building, it may reduce the latent heat load of water included in
the indoor air, thereby saving energy by reducing air conditioning
load and supplying pleasant indoor air. Further, when used for
dehumidification/cooling, it can remove moisture from hot and humid
air, thus reducing air conditioning load by decreasing the latent
heat load and saving energy. In addition, it may be used in
moisture-sensitive production processes or industrial applications
requiring moisture control or protection from damage or corrosion
by moisture in order to dehumidify and provide dry air.
Accordingly, the present disclosure is applicable to various fields
for water adsorption and dehumidification.
MODE FOR INVENTION
[0037] Hereinafter, Examples of the present disclosure will be
described in detail. However, it will be apparent to those skilled
in the art that the present disclosure is not limited to these
examples disclosed below but can be implemented in various
ways.
Example 1
[0038] A polyvinyl alcohol (PVA) solution was prepared by
dissolving PVA (87.about.89% hydrolyzed, Sigma-Aldrich) in
distilled water to 10 wt % at 60.degree. C. After adding
sulfosuccinic acid (SSA, Aldrich) to the PVA solution as a
crosslinking agent in an amount of 20 wt % based on the weight of
PVA, the mixture was stirred for over 1 hour. Then, zeolite A was
added in an amount of 1 wt % based on the weight of PVA to prepare
a polymer composite material solution.
[0039] The prepared polymer composite material solution was
electrospun using an electrospinning apparatus (NT-PS-35K, NTSEE
Co., Korea) to prepare a polymer nanofiber sheet. The voltage used
for the electrospinning was 20 kV, and the distance between the
positively charged syringe needle and the negatively charged
collector was 18 cm. The syringe used to hold the spinning solution
was a 10 mL glass syringe, and the diameter of the syringe needle
was 0.5 mm. The feed rate of the solution was 0.7 mL/hr, and the
collector rotation speed was 300 rpm. The thickness of the
nanofiber sheet was controlled by adjusting spinning time. The
nanofiber sheet prepared in this example had a thickness of 30
.mu.m.
[0040] The prepared nanofiber sheet was subjected to crosslinking
by heating at 120.degree. C. for 1 hour. The associated
crosslinking mechanism is illustrated in FIG. 2. Also, the
nanofiber sheet was observed using a scanning electron microscope
(SEM, Hitachi S-4700). Scanning electron micrographs of the PVA
nanofiber sheet, the crosslinked sheet and the zeolite-introduced
nanofiber sheet are shown in FIG. 3.
[0041] The water adsorption rate of the nanofiber sheet was
measured. Experiments were performed according to the KS standard
for heat exchange efficiency measurement. The diffusion coefficient
was calculated from Fick's law. Under the condition of 30.degree.
C. and relative humidity 60%, the water adsorption rate was
2.48.times.10.sup.-11 cm.sup.2/s for the PVA nanofiber sheet and
2.96.times.10.sup.-11 cm.sup.2/s for the 1% zeolite-introduced
nanofiber sheet.
Examples 2 to 4
[0042] A PVA solution was prepared by dissolving PVA (87.about.89%
hydrolyzed, Sigma-Aldrich) in distilled water to 10 wt % at
60.degree. C. A 10 wt % polystyrene sulfonic acid-maleic acid
copolymer (PSSA-MA, Sigma-Aldrich) solution was prepared separately
using distilled water. Thus prepared 10 wt % PVA solution and 10 wt
% PSSA-MA solution were mixed at 9:1 (Example 2), 8:2 (Example 3)
or 7:3 (Example 4), based on PVA:PSSA-MA, and then stirred to
prepare a PVA/PSSA-MA solution. After adding SSA (Aldrich) to the
resultant mixture solution as a crosslinking agent in an amount of
20 wt % based on the weight of PVA, the mixture was stirred for
over 1 hour.
[0043] The prepared polymer composite material solution was
electrospun using an electrospinning apparatus (NT-PS-35K, NTSEE
Co., Korea) to prepare a polymer nanofiber sheet. The voltage used
for the electrospinning was 20 kV, and the distance between the
positively charged syringe needle and the negatively charged
collector was 18 cm. The syringe used to hold the spinning solution
was a 10 mL glass syringe, and the diameter of the syringe needle
was 0.5 mm. The feed rate of the solution was 0.7 mL/hr, and the
collector rotation speed was 300 rpm. The thickness of the
nanofiber sheet was controlled by adjusting spinning time. The
prepared nanofiber sheet was subjected to crosslinking by heating
at 120.degree. C. for 1 hour.
[0044] The water adsorption rate of the nanofiber sheet was
measured and the results are shown in FIG. 4. Experiments were
performed according to the KS standard for heat exchange efficiency
measurement. The diffusion coefficient was calculated from Fick's
law. The results show that the water adsorption rate was increased
above the anticipation through the crosslinking reaction by
addition of SSA. Under the condition of 30.degree. C. and relative
humidity 60%, the adsorption rate of the sample of Example 2 was
2.59.times.10.sup.-9 cm.sup.2/s before the crosslinking and
1.79.times.10.sup.-8 cm.sup.2/s after the crosslinking.
[0045] To evaluate durability of the nanofiber sheets prepared in
these examples, each of the nanofiber sheets was washed for 1 hour
using distilled water at 60.degree. C. After washing, the amount of
remaining polymer was calculated as a percentage of the initial
polymer amount. Results are shown in FIG. 5. The sample of Example
2 is denoted as "1", the sample of Example 3 is denoted as "2", and
the sample of Example 4 is denoted as "3". It can be seen that use
of the crosslinking agent resulted in a remarkable, improvement in
durability.
Examples 5 to 7
[0046] A PVA solution was prepared by dissolving PVA (87.about.89%
hydrolyzed, Sigma-Aldrich) in distilled water to 10 wt % at
60.degree. C. A 10 wt % PSSA-MA (Sigma-Aldrich) solution was
prepared separately using distilled water. The prepared 10 wt % PVA
solution and 10 wt % PSSA-MA solution were mixed 9:1 (Example 5),
based on PVA:PSSA-MA, and then stirred to prepare a PVA/PSSA-MA
solution. Further, after adding SSA (Aldrich) to the resultant
solution as a crosslinking agent in an amount of 20 wt % based on
the weight of PVA, the mixture was stirred for over 1 hour to
prepare a polymer solution (Example 6). Then, zeolite A was added
thereto in an amount of 1 wt % based on the polymer weight to
prepare a polymer composite material solution (Example 7).
[0047] In order to evaluate antibacterial properties, E. coli and
salmonella bacteria were cultured in the prepared polymer composite
material solutions. After culturing at 35.degree. C. for 24 hours,
photographs were taken to evaluate the antibacterial properties.
For measurement of the antibacterial properties against E. coli, E.
coli samples were cultured separately. Results are shown in FIG. 6.
The sample of Example 5 is denoted as "1", the sample of Example 6
is denoted as "3", and the sample of Example 7 is denoted as "4".
Some E. coli was observed in the sample of Example 5, but none was
observed in Example 6 or Example 7. When the experiment was
performed repeatedly, very slight E. coli was found from the sample
of Example 6. FIG. 7 shows the result of culturing salmonella
bacteria. In the figure, the right side shows the result when only
the bacteria were cultured, and the left side shows the result when
the polymer solution was used. Some salmonella bacteria were
observed in Example 5, but none was observed in Example 6 or
Example 7. Even when the experiment was performed repeatedly, no
salmonella bacteria was observed in Example 6 or Example 7. Thus,
it was confirmed that the addition of the crosslinking agent and
the porous filler results in far superior antibacterial
properties.
* * * * *