U.S. patent application number 12/530466 was filed with the patent office on 2010-02-04 for laminated fabric.
This patent application is currently assigned to KURARAY CO., LTD.. Invention is credited to Shinya Inada, Junichi Sugino, Masatoshi Takenoiri, Keisuke Takishima.
Application Number | 20100024136 12/530466 |
Document ID | / |
Family ID | 39759238 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100024136 |
Kind Code |
A1 |
Takenoiri; Masatoshi ; et
al. |
February 4, 2010 |
LAMINATED FABRIC
Abstract
To provide a laminated fabric having an air permeability and a
filtering capability, the laminated fabric includes a supporting
layer and a protective layer bonded together. The protective layer
includes a stretchable nonwoven fabric comprises an ultra-fine
fiber. This laminated fabric has an air permeability of 2
cc/cm.sup.2/sec. or higher and a 1 .mu.m quartz dust collecting
efficiency of 90% or higher. The laminated fabric may also have a
water resistant layer which is positioned on the protective layer
so that the protective layer is employed as an intermediate layer
between the water resistant layer and the supporting layer.
Inventors: |
Takenoiri; Masatoshi;
(Okayama, JP) ; Takishima; Keisuke; (Osaka,
JP) ; Sugino; Junichi; (Osaka, JP) ; Inada;
Shinya; (Okayama, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
KURARAY CO., LTD.
Kurashiki-shi, Okayama
JP
|
Family ID: |
39759238 |
Appl. No.: |
12/530466 |
Filed: |
March 6, 2008 |
PCT Filed: |
March 6, 2008 |
PCT NO: |
PCT/JP2008/000465 |
371 Date: |
September 9, 2009 |
Current U.S.
Class: |
8/147 ; 442/327;
442/329; 442/340 |
Current CPC
Class: |
B32B 2307/54 20130101;
B32B 2307/724 20130101; B32B 2571/00 20130101; B32B 5/022 20130101;
B32B 5/04 20130101; B32B 5/026 20130101; B32B 2307/7265 20130101;
B32B 5/08 20130101; B32B 2262/0276 20130101; B32B 2262/0215
20130101; Y10T 442/60 20150401; B32B 2307/306 20130101; Y10T
442/614 20150401; B32B 5/26 20130101; B32B 2437/00 20130101; Y10T
442/602 20150401; B32B 2262/0261 20130101; B32B 2262/0292 20130101;
A62D 5/00 20130101; B32B 2307/51 20130101; B32B 2307/718 20130101;
B32B 2262/023 20130101 |
Class at
Publication: |
8/147 ; 442/327;
442/340; 442/329 |
International
Class: |
D04H 1/00 20060101
D04H001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 15, 2007 |
JP |
2007-066496 |
Claims
1. A laminated fabric which comprises: a supporting layer; and a
protective layer comprising a stretchable nonwoven fabric formed
from an ultra-fine fiber, the protective layer bonded to the
supporting layer; whereby the laminated fabric having an air
permeability of 2 cc/cm.sup.2/sec or higher and also having an
efficiency of 90% or higher when collecting quartz particles 1
.mu.m in size.
2. The laminated fabric as claimed in claim 1, in which the
ultra-fine fiber comprises a thermoplastic elastomer.
3. The laminated fabric as claimed in claim 2, in which the
thermoplastic elastomer comprises at least one thermoplastic
elastomer selected from the group consisting of SEPS, SEBS, a
polyurethane series thermoplastic elastomer, a polyester series
thermoplastic elastomer and a polyamide series thermoplastic
elastomer.
4. The laminated fabric as claimed in claim 1, in which the
stretchable nonwoven fabric has a stretch of 30% or higher at
break.
5. The laminated fabric as claimed in claim 1, in which the
stretchable nonwoven fabric comprises an ultra-fine fiber being a
nanofiber of 10 to 1,000 nm in fiber diameter and also have a
weight within the range of 0.01 to 10 g/m.sup.2.
6. The laminated fabric as claimed in claim 1, in which at least a
part of the fibers forming the supporting layer is a volume
reducible fiber.
7. The laminated fabric as claimed in claim 6, in which the volume
reducible fiber comprises a polyvinyl alcohol fiber.
8. The laminated fabric as claimed in claim 1, further comprising a
water resistant layer, the water resistant layer being positioned
on the protective layer so that the protective layer is employed as
an intermediate layer between the water resistant layer and the
supporting layer.
9. The laminated fabric as claimed in claim 8, which has a
withstanding pressure within the range of 300 to 1,500
mmH.sub.2O.
10. The laminated fabric as claimed in claim 1, in which 5 to 90%
shrinkage takes place when immersed in a hot water of 60.degree. C.
or higher.
11. A protective material, in which at least a part thereof
comprises a laminated fabric as defined in claim 1.
12. A volume reducing method which comprises placing a laminated
fabric as defined in claim 1 into a sealable vessel and supplying a
hot water of 60.degree. C. or higher to the laminated fabric.
Description
CROSS REFERENCE TO THE RELATED APPLICATIONS
[0001] This application is based on and claims Convention priority
to Japanese application No. 2007-066496, filed Mar. 15, 2007, the
entire disclosure of which is herein incorporated by reference as a
part of this application.
FIELD OF THE INVENTION
[0002] The present invention relates to a laminated fabric (or a
multi-layered fabric) having a sufficient strength, an air
permeability and a filtering capability, and more particularly, to
the laminated fabric of a kind capable of being easily reduced in
volume at a low cost.
BACKGROUND ART
[0003] In order to protect human bodies from harmful and/or
hazardous substances such as dust harmful to human bodies,
contagions and viruses, and/or in order to avoid secondary
infection resulting from infected mediums having one or some of the
hazardous substances adhering thereto, various protective materials
are utilized. Such protective materials are required to have not
only a filtering capability for effectively removing the harmful
and/or hazardous substances, but also an air permeability to
minimize the discomfort which the user may feel when the protective
material is brought into direct contact with the user's body.
However, since the filtering capability and the air permeability
are properties incompatible with each other, and therefore, it is
difficult to fulfill both the filtering capability and the air
permeability at the same time.
[0004] By way of example, Patent Document 1 listed below discloses
a composite nonwoven fabric as a protective clothing material,
which comprises a nonwoven fabric having a water vapor permeability
and a water proofing property, a porous fabric, and a thermally
bondable nonwoven fabric. In the composite nonwoven fabric, the
thermally bondable nonwoven fabric is interposed between the water
vapor permeable and water resistant nonwoven fabric and the porous
fabric, and three of them are laminated together. However, this
conventional composite nonwoven fabric is incapable of being
increased in air permeability as a composite nonwoven fabric in its
entirety because the nonwoven fabric and the porous fabric are
bonded to the thermally bondable nonwoven fabric which is distorted
in a flexible film shape.
[0005] In addition, disposal of the protective materials
contaminated with those substances being harmful to human bodies
has now come to be a controversial issue. By way of example, the
protective materials of the kind referred to above are generally
utilized as a disposable material and are heaped up as hazardous
wastes in a plastic bag after one-time use. Then, the used
protective materials are to be disposed of by waste disposers.
However, if the protective materials are bulky, such a problem
arises that increase in transportation cost as well as disposal
cost of those protective materials, and therefore, demands have
been made to reduce the costs by reducing the volume of those
protective materials.
[0006] One way to reduce the volume of the protective materials may
include a method of reducing the pressure inside the bags or
compressing those bags, a method of reducing the volume of the bags
by means of heating such as dry heating or wet heating, and the
like. But the method to reduce the volume by way of reduction of
the pressure inside the bags is considered undesirable because it
may emit contaminants to air being exhausted.
[0007] Further, as one of the volume reduction methods by way of
compression of the bags, there has been suggested an equipment
designed to heat the contaminated wastes so that the wastes can be
caked in a block form to thereby reduce the volume, or an equipment
designed to pulverize the wastes to thereby reduce the volume. Both
of them are currently available in the commercial market, such
equipments, however, are undesirable because of being extremely
expensive and large in scale. Also, the reduction of the volume by
means of the dry heat treatment requires heat resistant bags and is
therefore costly to perform.
[0008] A method of and an apparatus for reducing the volume of
infectious medical wastes by means of, for example, hot water has
been suggested (See, for example, Patent Document 2 listed below.).
Patent Document 2 pertains to a method of and an apparatus for
treating infectious medical wastes, characterized in that a mixture
of infectious medical wastes (A) which are made of a hydrophilic
resin insoluble in a water having a temperature of not higher than
50.degree. C., and water (B), which mixture has a mixing ratio
(A)/(B) of 70/30 to 20/80, is treated at a temperature within the
range of 70 to 150.degree. C. so that the infectious medical wastes
(A) can be solidified with their volume reduced. Although the
apparatus disclosed in Patent Document 2 appears to be compact in
size, but has required a special device to achieve the volume
reduction.
[0009] [Patent Document 1] JP Laid-open Patent Publication No.
2003-336155
[0010] [Patent Document 2] JP Laid-open Patent Publication No.
2003-073498
DISCLOSURE OF THE INVENTION
[0011] An object of the present invention is to provide a laminated
fabric having both of incompatible properties of air permeability
and filtering capability (collecting capability).
[0012] Another object of the present invention is to provide a
laminated fabric which can be integrated without the air
permeability being degraded.
[0013] A further object of the present invention is to provide a
laminated fabric which is effective to maintain the filtering
capability even after it has been loaded.
[0014] A still further object of the present invention is to
provide a laminated fabric, the volume of which can be reduced at a
reduced cost and without requiring the use of any special
equipment.
[0015] As a result of intensive studies conducted by the inventors
of the present invention in an attempt to accomplish those and
other objects of the present invention, it has been found that if a
laminated or layered fabric is prepared by bonding a stretchable
nonwoven fabric as a protective layer to a supporting layer (or
holding layer), the laminated fabric can have both of the air
permeability and the filtering capability, which have hitherto been
incompatible with each other, and can hold the filtering capability
even when some burden is placed on the laminated fabric.
[0016] It has further been found that in the case where a volume
reducible supporting layer (A layer) is used as the supporting
layer and the volume reducible supporting layer is prepared from
fibers capable of shrinking 5 to 90% when at least one layer is
immersed in a hot water of not lower than 60.degree. C.; the
laminated fabric and a protective material prepared therefrom can
be obtained that can be readily reduced in volume at a reduced cost
without requiring the use of any special equipment.
[0017] In other words, the present invention provides a laminated
fabric which comprises: a supporting layer; and a protective layer
comprising a stretchable nonwoven fabric formed from an ultra-fine
fiber, the protective layer bonded to the supporting layer; whereby
the laminated fabric having an air permeability of 2
cc/cm.sup.2/sec or higher and also having an efficiency of 90% or
higher when collecting quartz particles 1 .mu.m in size.
[0018] The ultra-fine fibers referred to above may comprise a
thermoplastic elastomer, for example, a heat resistant
thermoplastic elastomer. The thermoplastic elastomer that can be
employed in the practice of the present invention may comprise a
thermoplastic elastomer selected from the group consisting of, for
example, SEPS, SEBS, a polyurethane series thermoplastic elastomer,
a polyester series thermoplastic elastomer and a polyamide series
thermoplastic elastomer. The stretchable nonwoven fabric forming
the protective layer may be of a kind having, for example, a
stretch of 30% or higher at break. This stretchable nonwoven fabric
preferably comprises an ultra-fine fiber in the form of,
particularly, a nanofiber having a fiber diameter within the range
of 10 to 1000 nm and also having a weight within the range of 0.01
to 10 g/m.sup.2.
[0019] On the other hand, a part of the fibers forming the
supporting layer may be a volume reducible fiber. By way of
example, the volume reducible fibers may comprise a polyvinyl
alcohol fiber. In other words, the present invention may encompass
a laminated fabric having its volume capable of being reduced with
a hot water. Such a volume reducible laminated fabric may be of a
kind capable of shrinking 5 to 90% when immersed in a hot water of
60.degree. C. or higher.
[0020] Also, the laminated fabric of the present invention may
include a water resistant layer which is positioned on the
protective layer so that the protective layer is employed as an
intermediate layer between the water resistant layer and the
supporting layer. In such case, the laminated fabric may have a
withstanding pressure within the range of about 300 to 1500
mmH.sub.2O.
[0021] Furthermore, the present invention also encompasses a
protective material, particularly, a protective clothing. The
protective material may comprise the laminated fabric referred to
above. Where the laminated fabric has a volume reducing capability,
the present invention also includes a method of reducing the volume
of the laminated fabric by placing the laminated fabric into a
sealable vessel and supplying a hot water of 60.degree. C. or
higher to the laminated fabric.
[0022] As hereinabove discussed, the laminated fabric of the
present invention can have the filtering capability and the air
permeability simultaneously when the laminated fabric comprises the
supporting layer and the unique protective layer. In particular,
since the protective layer has a stretchability, it can exhibit an
excellent follow-up characteristic to any other layers.
Accordingly, without the air permeability being degraded, not only
can the integrity of the laminated fabric be improved, but the
filtering capability of the laminated fabric can be maintained even
after a predetermined burden has been applied thereto.
[0023] Specifically, where the nanofiber nonwoven fabric is used as
the protective layer, both a high air permeability and a high
filtering capability can be realized.
[0024] Also, where a volume reducible material is used as the
supporting layer, the laminated fabric of the present invention
can, after its volume has been reduced with the use of hot water,
be transported and/or disposed of easily and, therefore, the cost
incurred in transportation and/or disposal can be reduced
advantageously.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In any event, the present invention will become more clearly
understood from the following description of preferred embodiments
thereof, when taken in conjunction with the accompanying drawings.
However, the embodiments and the drawings are given only for the
purpose of illustration and explanation, and are not to be taken as
limiting the scope of the present invention in any way whatsoever,
which scope is to be determined by the appended claims. The
drawings are not necessarily to scale, and emphasis has instead
been placed upon illustrating the principles of the invention. In
the accompanying drawings, like reference numerals are used to
denote like parts throughout the several views, and:
[0026] FIG. 1 is a schematic diagram of an apparatus for
manufacturing a protective layer which is a nanofiber layer
containing tangled and deposited nanofibers, showing an example of
a laminated fabric according to a preferred embodiment of the
present invention; and
[0027] FIG. 2 is a schematic sectional view showing an example of
the structure of the laminated fabric (a laminate) according to a
preferred embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0028] The laminated fabric of the present invention is a laminated
fabric (layered fabric) of a structure having a protective layer
and a supporting layer bonded together, in which the protective
layer includes a stretchable nonwoven fabric prepared from
ultra-fine fibers. The laminated fabric of the present invention
has an air permeability of 2 cc/cm.sup.2/sec. or higher and also
has an efficiency of 90% or higher when collecting quartz particles
1 .mu.m in size.
[Supporting Layer]
[0029] The supporting layer employed in the laminated fabric of the
present invention is provided for the purpose of retaining the
protective layer. The supporting layer may not be specifically
limited to a particular one, as long as the laminated fabric as a
whole can exhibit a specific air permeability. The supporting layer
may be employed in the form of a woven fabric, a knitted fabric, or
a nonwoven fabric.
[0030] The supporting layer referred to above may be prepared from
either natural fibers such as, for example, animal or vegetable
fibers, or various synthetic fibers, depending on the purpose of
use of the laminated fabric. Those fibers may be employed singly or
in combination.
[0031] The synthetic fibers used to form the supporting layer may
be polyvinyl alcohol fibers; ethylene-vinyl alcohol fibers;
polyamide fibers (including, for example, aliphatic polyamide
fibers comprising, for example, nylon 6, nylon 66, nylon 46, nylon
610, nylon 11 and/or nylon 12, alicyclic polyamide fibers, aromatic
polyamide fibers such as aramid fibers, and semi-aromatic polyamide
fibers consisting of an aromatic dicarboxylic acid and an aliphatic
alkylenediamine); polyolefinic fibers (including, for example,
polyethylene fibers, polypropylene fibers and composite fibers of
polypropylene and polyethylene); polyester fibers (including, for
example, polyethylene terephthalate fibers); acrylic fibers
(including, for example, polyacrylonitrile fibers and polymethyl
methacrylate fibers); polyurethane fibers; cellulose fibers
(including, for example, rayon fibers and acetate fibers);
halogen-containing fibers (including, for example, vinyl chloride
fibers, vinylidene chloride fibers, polyvinyl fluoride fibers,
polyvinylidene fluoride fibers and fibers made of a copolymer of
polyvinylidene fluoride and hexafluoropropylene); polyimide fibers;
polybenzimidazole fibers; polyarylate fibers; or polyphenylene
sulfide fibers.
[0032] Of those fibers enumerated above, the polyvinyl alcohol
fibers, the ethylene vinyl alcohol fibers, the polyamide fibers or
the polyester fibers are preferred as a material for the synthetic
fibers employed in the supporting layer.
[0033] The fineness of the fibers forming the supporting layer may
be of any value that can be chosen as desired depending on the
texture or feeling which is required to the laminated fabric, but
may be within the range of, for example, about 0.1 to 1000 dtex,
and preferably within the range of about 1 to 400 dtex. Also, where
the supporting layer is a woven fabric, warps and wefts of the
woven fabric may have respective finenesses, which may be either
the same or different from each other, but the ratio of the
fineness of the wefts relative to the fineness of the wasp (i.e.,
the warp fineness/weft fineness) may be within the range of about
10/1 to 1/10, and preferably within the range of about 5/1 to
1/5.
[0034] The weight of the supporting layer per unit area may be of
any value that can be chosen as desired depending on the form of
the supporting layer, and not specifically limited to a particular
value so long as the air permeability and the collecting capability
both required in the practice of the present invention are
satisfied. The weight of the supporting layer per square meter may
be within the range of about 5 to 100 g/m.sup.2 and, preferably,
within the range of about 10 to 90 g/m.sup.2.
[0035] The supporting layer may be in the form of a woven fabric, a
knitted fabric, a nonwoven fabric or a synthetic paper, and may not
be specifically limited to a particular form as long as the
eventually formed laminated fabric can have a predetermined or
required air permeability and collecting capability. In any event,
the woven fabric, the knitted fabric, the nonwoven fabric or the
synthetic resin referred to above may be prepared in any known or
customarily practiced method.
[0036] Of the various forms of the supporting layer, the nonwoven
fabric is preferred for the supporting layer in terms of the
collecting capability and the air permeability.
[0037] The method of making the supporting layer using the nonwoven
fabric is not specifically limited to a particular method, and any
of a spun bonding method, a meltblown method, a spun lacing method,
a thermal bonding method, a chemical bonding method, an airlaid
method and a needle punching method can be employed therefor.
(Volume Reducible Supporting Layer)
[0038] Further, in terms of the volume reducing capability, the
supporting layer of the present invention, may be a volume
reducible supporting layer (A layer) prepared from fibers capable
of shrinking 5 to 90% after immersion of the fibers in a hot water
of 60.degree. C. or higher. In other words, when the laminated
fabric of the present invention is used under the working
environment of 50.degree. C. or lower, the laminated fabric can
exhibit a satisfactory protective function against dust, contagions
and/or viruses without shrinking due to moisture such as sweat. On
the contrary, at the time it is desired to be disposed of, the
laminated fabric is immersed in a hot water of 60.degree. C. or
higher, and the shrinkage of a portion of the fibers forming the
laminated fabric results in reduction of the laminated fabric
entirely in volume.
[0039] Where such a feature as discussed above is possessed in the
laminated fabric of the present invention, even if a layer (B
layer) incapable of undergoing shrinkage in a water of 50.degree.
C. or lower is used, when the B layer is bonded to the volume
reducible supporting layer (A layer) prepared from the fibers
capable of undergo 5 to 90% shrinkage when immersed in the hot
water of 60.degree. C. or higher, the resultant protective
laminated fabric as well as a protective clothing prepared
therefrom will have an excellent volume reducing capability as will
be discussed in detail later.
[0040] In the practice of the present invention, in order to reduce
the volume of the laminated fabric for a protective clothing on the
whole, at least a part of the fibers forming the supporting layer
may be a volume reducible fiber capable of undergoing shrinkage
when immersed in a hot water.
[0041] The volume reducible fibers referred to above are preferably
hydrophilic fibers, more specifically, fibers of a water soluble
synthetic polymer, and particularly PVA (polyvinyl alcohol) fibers
comprising a vinyl alcohol polymer. The PVA fiber has a
biodegradability and is, therefore, excellent in terms of low
impacts on the environments during underground disposal.
[0042] The kind of vinyl alcohol polymers used for the PVA fibers
that can be suitably employed in the A layer in accordance with the
present invention may not be specifically limited to a particular
type, and the preferred vinyl alcohol polymers may be the one
having a viscosity-average degree of polymerization of 1,000 or
higher, and particularly 1,500 or higher in terms of the practical
mechanical performance; or 5,000 or lower in terms of the spinning
capability and cost. Also, by the same reason, the preferred vinyl
alcohol polymers may be the one having a degree of saponification
of 50 mole % or higher, preferably 65 mole % or higher and, more
preferably 80 mole % or higher.
[0043] The vinyl alcohol polymer may be copolymerized with any
other monomer, and the examples of a copolymerizing component
include ethylene, vinyl acetate, itaconic acid, vinyl amine,
acrylamide, vinyl pivalate, maleic anhydride, a sulfonic
acid-containing vinyl compound, and the like.
[0044] In terms of the practice mechanical performance, the vinyl
alcohol polymer preferably contains a vinyl alcohol unit in a
quantity of 70 mole % or higher of the total constituent unit.
Also, so long as the effects of the present invention are not lost,
the fibers may contain one or more polymers, other than the vinyl
alcohol polymer, and any additive(s). In terms of the fiber
performance, the content of the vinyl alcohol polymer preferably
exceeds 30 mass % per fibers and, more preferably 50 mass % per
fibers.
[0045] There will now be described a method of making the PVA
fibers, which can be suitably employed in the A layer in accordance
with the present invention. When the fibers are prepared with a
spinning liquid in which a water soluble PVA polymer is dissolved
in water or an organic solvent by a method as will be described
later, the fiber excellent in mechanical characteristics can be
efficiently manufactured. Nevertheless, so long as the effects of
the present invention are not lost, the spinning liquid may contain
one or more additives and any other polymer. The solvent forming a
part of the spinning liquid includes, for example, water; a polar
solvent such as dimethylsulfoxide (DMSO), dimethylacetamide,
dimethylformamide or N-methylpyrrolidone; a polyvalent alcohol such
as glycerin or ethylene glycol; a mixture of one of those solvents
with a swellable metal salt such as rhodan salt, lithium chloride,
calcium chloride or zinc chloride; a mixture of those solvents; or
a mixture of one of those solvents with water. Among those
solvents, water or DMSO is most preferred in terms of the
solubility at a low temperature, low toxicity and low corrosive
properties.
[0046] The concentration of the polymer contained in the spinning
liquid may vary depending on the liquid components, the degree of
polymerization or the solvent to be used, and is preferably within
the range of 8 to 40 weight percent. The liquid temperature of the
spinning liquid at the time of extrusion is within a range enough
to avoid gelling, decomposing and coloring of the spinning liquid,
and is specifically preferably within the range of 50 to
150.degree. C.
[0047] The above-mentioned spinning liquid can be suitably allowed
to subject to a wet spinning, a dry spinning or a dry-jet wet
spinning after extruding of the spinning liquid from a nozzle, and
the spinning liquid may be extruded into a coagulating bath capable
of solidifying the PVA polymer. In particular, where the spinning
liquid is extruded through multiple holes, the use of the wet
spinning process is preferred rather than the dry-jet wet spinning
process because conglutination of the fibers can be avoided during
the extrusion of the spinning liquid. It is to be noted that the
wet spinning process referred to above is a process, in which the
spinning liquid can be extruded from a nozzle directly into a
coagulating bath (solidifying bath), whereas the dry-jet wet
spinning process is a process, in which the spinning liquid is
first extruded from a nozzle into the atmosphere full of air or
inert gas and then introduced into a coagulating bath.
[0048] The coagulating liquid used in the practice of the present
invention varies depending on whether the solvent in the spinning
liquid is an organic solvent or whether it is water. In the case of
the spinning liquid utilizing the organic solvent, the use is
preferred of a mixed liquid containing the coagulating liquid and
the spinning liquid solvent in order to improve the eventually
obtained fiber strength or the like. The coagulating liquid used in
the mixed solution may be an organic solvent such as an alcohol
(including, for example, methanol and ethanol), or a ketone
(including, for example, acetone and methyl ethyl ketone), which
solvent is of a kind having a solidifying capability to the PVA
polymer. In particular, an organic solvent containing methanol and
DMSO is preferred, which are preferably mixed in a mixing ratio
(methanol)/(DMSO) of 55/45 to 80/20 in terms of the productivity
and the solvent recovery. Also, the temperature of the coagulating
liquid is preferably 30.degree. C. or lower, and particularly for
achieving a uniform gelatinization upon cooling, it is preferably
20.degree. C. or lower, and more preferably 15.degree. C. or lower.
On the other hand, in the case where the spinning liquid is used in
the form of an aqueous solution, the coagulating bath includes an
aqueous solution of mineral salts having a solidifying capability
to the PVA polymer. For example, mirabilite, sodium chloride or
carbon hydrate can be suitably employed for the solidifying solvent
forming a part of the coagulating liquid. As a matter of course,
the coagulating liquid referred to above may be either acidic or
alkaline.
[0049] Thereafter, the solvent in the spinning liquid is removed by
extraction from extruded filaments to solidify the filaments. It is
preferred that the filaments can be stretched in the bath during
the extraction step, not only because conglutination of the fibers
during drying can be suppressed, but also because the eventually
obtained fibers can have an increased strength. The degree of
stretching is preferably within the range of 1.5 to 6 times. The
extraction of the solvent is carried out generally by passing the
extruded filaments through a plurality of extraction baths. For the
extraction baths, the coagulating liquid singly or a mixture of the
coagulating liquid with the solvent for the spinning liquid can be
employed, and the extraction baths may have a temperature within
the range of 0 to 80.degree. C.
[0050] Then, the filaments are dried to obtain PVA fibers. At this
time, an oiling agent may be applied as required during the drying
process. The drying temperature is preferably 210.degree. C. or
lower. In particular, the use of a multi-stage drying is preferred,
which may be carried out in such a manner that the drying is
performed at a temperature equal to or lower than 160.degree. C. at
the initial stage of drying, and at the later stage of drying, the
drying is performed at a higher temperature. Further, a dry heat
stretching and, if required a dry heat shrinking, are preferably
carried out to orient and crystallize PVA molecular chains to
thereby increase the tenacity of the fibers. When the fibers are
used to form structures such as nonwoven fabrics, if the tenacity
of the fibers is too low, reduction in in-process transportability
may be readily expected. In order to increase the mechanical
performance of the fibers, the dry heat stretching is preferably
carried out under a temperature condition within the range of 120
to 280.degree. C.
[0051] The fineness of the PVA fibers that can be obtained by the
manufacturing method described hereinabove is not specifically
limited to a particular value, and the PVA fibers may have a
fineness selected from a large range, for example, within the range
of 0.1 to 1,000 dtex, and preferably 1 to 400 dtex. The fineness of
the fibers may be suitably adjusted depending on the diameter of
the nozzle and/or the stretching ratio. Also, the fibers may have a
length which is not specifically limited to a particular value, and
may be suitably selected in consideration of the purpose of
use.
[0052] It is to be noted that the fibers that can undergo 5 to 90%
shrinkage when immersed in a hot water of a temperature equal to or
higher than 60.degree. C. may be employed as a part of the A layer,
not necessarily employed in the entirety of the A layer. Where a
part of the A layer comprises those shrinkable fibers capable of
undergoing 5 to 90% shrinkage when immersed in the hot water of
60.degree. C. or higher, the shrinkage percentage may be lowered as
compared with the case, in which the A layer in its entirety is
prepared from the shrinkable fibers. However, even if only a part
of the A layer comprises those shrinkable fibers; the laminated
fabric in its entirety can be shrunken 5 to 90% when the material
and the composition ratio are suitably selected.
[Protective Layer]
[0053] The protective layer employed in the laminated fabric of the
present invention includes a stretchable nonwoven fabric prepared
from ultra-fine fibers in terms of the capability of collecting
microparticles. The stretchable nonwoven fabric substantially
retains a fibrous shape as a nonwoven fabric, without being
transformed into a film in the laminated fabric, for the purpose of
securing the air permeability. For this reason, while the laminated
fabric of the present invention has a high filtering performance
enough to have an efficiency of 90% or higher when collecting
quarts particles of 1 .mu.m in size, it also ensures an air
permeability as high as 2 cc/cm.sup.2/sec concurrently. Also, since
the protective layer has a stretchability, it can exhibit a good
follow-up characteristic with both the supporting layer and a water
resistant layer as will be described later. Accordingly, when the
laminate fabric is used for wearing as a protective clothing, the
protective layer will hardly break. Accordingly, reduction in
filtering capability of the laminated fabric as a whole can be
suppressed advantageously, even when a predetermined loading such
as stretching is imposed on the laminated fabric.
[0054] The ultra-fine fibers employed in the practice of the
present invention may not be specifically limited to a particular
type as long as it provides stretchability to the non-woven fabric.
The frequently employed ultra-fine fibers are formed from a
thermoplastic elastomer in view of the elasticity and fiber forming
properties.
[0055] Examples of the thermoplastic elastomer includes a styrene
series thermoplastic elastomer, a urethane series thermoplastic
elastomer, an olefinic thermoplastic elastomer, a vinyl chloride
series thermoplastic elastomer, a polyester series thermoplastic
elastomer, a polyamide series thermoplastic elastomer, and the
like. Those thermoplastic elastomers may be employed singly or in
combination. Also, the thermoplastic elastomer referred to above
may be a polymer blend of thermoplastic elastomer, in which the
thermoplastic elastomer is combined with a polymer material for the
synthetic fibers (for example, olefinic polymers) discussed
previously under the heading of the supporting layer. In addition,
if required, one or more kind of organic or inorganic powders may
be mixed in the thermoplastic elastomer referred to above.
[0056] The urethane series thermoplastic elastomer comprises a hard
segment comprising a low molecular weight glycol and a
diisocyanate, and a soft segment comprising a high molecular weight
diol and diisocyanate.
[0057] The low molecular weight glycol includes, for example, C1-10
diols such as ethylene glycol, 1,4-butane diol and 1,6-hexane diol,
whereas the high molecular weight diol includes, for example,
poly(1,4-butylene adipate, poly(1,6-hexane adipate),
polycaprolactone, polyethylene glycol, polypropylene glycol and
polyoxytetramethylene glycol. The diisocyanate referred to above
includes, for example, tolylene diisocyanate, 4,4-diphenylmethane
diisocyanate, hexamethylene diisocyanate and isophorone
diisocyanate.
[0058] The styrene series thermoplastic elastomer includes, for
example, SBS (styrene/butadiene/styrene block copolymer), SIS
(styrene/isoprene/styrene block copolymer), SEBS
(styrene/ethylene/butadiene/styrene block copolymer) and SEPS
(styrene/ethylene/propylene/styrene block copolymer).
[0059] The olefinic thermoplastic elastomer comprises a
polyethylene or a polypropylene as a hard segment and SEBS or an
ethylene/propylene copolymer as a soft segment.
[0060] The vinyl chloride series thermoplastic elastomer comprises
a crystalline polyvinyl chloride as a hard segment and a
non-crystalline polyvinyl chloride or acrylonitrile as a soft
segment.
[0061] The polyester series thermoplastic elastomer comprises a
saturated polyester as a hard segment and an aliphatic polyether or
aliphatic polyester as a soft segment.
[0062] The polyamide series thermoplastic elastomer comprises a
polyamide as a hard segment and, as a soft segment, a polyester or
a polyether that is non-crystalline and has a low glass transition
temperature.
[0063] Of those thermoplastic elastomers referred to above, SEPS,
SEBS, the urethane series thermoplastic elastomer, the polyester
series thermoplastic elastomer or the polyamide series
thermoplastic elastomer can be advantageously employed in terms of
the heat resistance.
[0064] This kind of the heat resistant and stretchable nonwoven
fabric does not transform into a film even when the protective
layer and the supporting layer are integrated together by means of
a thermo compression bonding to form the laminated fabric, and,
therefore, a predetermined air permeability can be secured in the
laminated fabric.
[0065] It is to be noted that if the supporting layer is a volume
reducible supporting layer (A layer) capable of undergoing
shrinkage when immersed in a hot water, such a supporting layer may
be bonded to a layer (B layer) of a kind, which does not undergo
shrinkage in a water having a temperature of not higher than
50.degree. C., to provide a laminated fabric, and the resultant
laminated fabric will be a volume reducible laminated fabric
capable of undergoing shrinkage in a hot water of a temperature
equal to or higher than 60.degree. C.
[0066] In such case, the fabric material, the weight and the
thickness of the B layer may not be specifically limited to a
particular one or particular values and may be arbitrarily chosen
in consideration of an object to be protected, but the B layer
preferably has a water resistance sufficient to substantially avoid
shrinkage in contact with a moisture component such as, for
example, sweats when it is used under the working environment of
50.degree. C. or lower.
[0067] The ultra-fine fibers forming the stretchable nonwoven
fabric referred to above has an average fiber diameter preferably
not greater than, for example, 10 .mu.m (for example, within the
range of about 10 nm to about 8 .mu.m), and more preferably not
greater than 5 .mu.m because the eventually formed laminated fabric
has both the air permeability and the filtering capability. The
ultra-fine fibers of this kind can be prepared in any known manner
such as a meltblown process.
[0068] Specifically, in view of the necessity to increase the air
permeability and the protecting capability, the ultra-fine fibers
employed in the practice of the present invention may be nanofibers
having an average fiber diameter within the range of 10 to 1,000 nm
(preferably within the range of about 15 to 800 nm and, more
preferably, within the range of about 25 to 600 nm).
[0069] In order to strike a delicate balance between the protecting
capability and the air permeability of the laminate fabric, the
important point should be how the pressure loss of the fabric is
minimized and how harmful microparticles can be collected by the
fabric. In view of the above point, the nanofibers are considered
to be suitable from the viewpoint of striking a balance between the
protecting capability and the air permeability partly because they
can exhibit the Slip Flow effect enough to reduce the pressure loss
during the filtration and partly because they have a high air
permeability. (Takeyuki Kawaguchi, "Kodo Sangyo Hakkutsu Senryaku
(Strategy of Advanced Industrial Structure Development Using
Nanofiber Technology)" (Supervising Editor: Tatsuya Motomiya),
Chapter 10, pp. 373)
[0070] It is to be noted that the fiber diameter herein referred to
in connection with the present invention means a diameter of the
transverse section of fibers that can be measured from an electron
micrograph taken of a fiber aggregation at a magnification of
.times.5,000, and is an average value obtained by measuring the
fiber diameters of randomly chosen 50 fibers.
[0071] The weight of the stretchable nonwoven fabric per unit area
employed in the practice of the present invention is not
specifically limited to a particular value as long as the laminated
fabric of the present invention satisfies the air permeability and
the collecting ability both defined in the present invention, but
may be chosen in consideration of the average fiber diameter of the
ultra-fine fibers.
[0072] By way of example, in the case where the average fiber
diameter of the ultra-fine fibers exceeds 1 .mu.m, the weight of
the stretchable nonwoven fabric is preferably within the range of
about 1 to 20 g/m.sup.2, and more preferably within the range of
about 5 to 15 g/m.sup.2.
[0073] Also, by way of example, if the average fiber diameter of
the ultra-fine fibers is not greater than 1 .mu.m, the weight of
the stretchable nonwoven fabric is preferably within the range of
about 0.01 to 10 g/m.sup.2, more preferably within the range of
about 0.03 to 8 g/m.sup.2, and further preferably within the range
of about 0.05 to 6 g/m.sup.2.
[0074] If the weight of the non-woven fabric is too large for the
average fiber diameter, it may occur that the air permeability
discussed previously will be lowered below 2 cc/cm.sup.2/sec.
although the laminate fabric has an improved protecting capability
from passage of microparticles such as, for example, asbestos
hazardous to the human body. In particular, in the case of the
nanofibers, increase in cost will occur with an increased
proportion to the nanofibers in the fabric, and therefore, it is
not preferable. On the other hand, if the weight of the non-woven
fabric is too small, the air permeability will improve, but it is
not preferable because it would be difficult to uniformly
distribute over the entire supporting layer, and as a result, the
efficiency of collecting the 1 .mu.m quartz particles will be
lowered below 90%.
[0075] Since the protective layer comprises the stretchable
nonwoven fabric as hereinabove described, it is possible to
increase the stretch at break (%) as compared with the
non-stretchable nonwoven fabric. By way of example, the stretch (%)
of the stretchable nonwoven fabric at break may be of a value equal
to or higher than, for example, 30% (for example, within the range
of about 30 to 200%) and, preferably, within the range of about 35
to 180%, when an oblong test piece thereof having a width of 15 mm
is measured in accordance with JIS P8113.
[0076] The stretchable nonwoven fabric can be prepared by the
method of making the nonwoven fabric, described hereinbefore under
the heading of the supporting layer, using ultra-fine fibers. Also,
in the case of the ultra-fine fibers being nanofibers, the nonwoven
fabric prepared from the nanofibers may be manufactured by the use
of the following process.
[0077] In the first place, the nanofibers referred to above may be
prepared by the use of, for example, the following method. As a
polymer spinning liquid (or spinning liquid), either a dissolved
polymer solution in which a polymer is dissolved in a solvent
capable of dissolving such polymer, or a melted polymer solution in
which the polymer is melted by heating, can be suitably employed.
Then, nanofibers are laminated or conjugated as the previously
described B layer by means of an electrostatic spinning process
using the spinning liquid. For the electrostatic spinning process,
a method can be employed, in which while a high voltage is applied
to an electroconductive member capable of dispensing the spinning
liquid, nanofibers can be deposited on a counter electroconductive
member (or electrode) that is grounded to the earth. By this
method, the spinning liquid that is extruded from a spinning liquid
supply unit can be electrified (or charged) to split the droplets
from the spinning liquid; fibers are then continuously drawn from
one point of the liquid droplets under the influence of an electric
field; and the split and divided fibers are diffused, and finally
being deposited on a collecting belt or sheet disposed at a
location spaced a few to tens centimeters from the spinning liquid
supply unit. The fibers are slightly conglutinated simultaneously
with deposition to inhibit movement of those fibers and a dense
sheet can be obtained when ultra-fine fibers are successively
deposited on the moving collecting belt or sheet.
[0078] In other words, referring to FIG. 1, the spinning liquid in
which the polymer is dissolved is measured and transmitted by a
metering pump 1, and is distributed under a uniform pressure and
flow by a distributing and rectifying block 2. Then the distributed
spinning liquid is supplied to a nozzle unit 3. The nozzle unit 3
has spinnerets 4 each fitted thereto so as to protrude the
spinnerets 4 having a respective hole of a hollow needle
configuration, and leakage of electricity over the nozzle unit 3 is
prevented by electrically insulating members 5. The protruding
spinnerets 4, each made of an electroconductive material, are
fitted to the nozzle unit 3 so as to be vertically downwardly
oriented and juxtaposed relative to each other in a direction
perpendicular to the direction of travel of a sheet take-up
apparatus 7, which may be in the form of an endless conveyor. An
output terminal of a high voltage DC generating unit is fitted to
each of the projecting spinnerets 4 so that application to those
spinnerets 4 can be made possible through a conducting wire. The
endless conveyor in the sheet take-up apparatus 7 has a grounded
electroconductive member 8 fitted thereto so that the applied
potential can be neutralized. The spinning liquid supplied under
pressure from the nozzle unit 3 to the projecting spinnerets 4 is
electrified to split, fibers are then continuously drawn from one
point of liquid droplets under the influence of an electric field,
and then the nanofiber scaffolds deposited on the electroconductive
member fitted to the sheet take-up apparatus 7. The deposited
nanofibers, in which slight conglutination proceeds, are moved with
the movement of the sheet take-up apparatus 7, and simultaneously
with the movement of the endless conveyor, another deposition
ejected from the spinnerets 4 is placed onto the next to the former
deposition in the endless conveyor. As a result, a dense and
uniform sheeting can be formed by repeating deposition of
ultra-fine fibers.
[Laminated Fabric]
[0079] The laminated fabric comprises the protective layer and the
supporting layer which are bonded together. The method of bonding
the supporting layer and the protective layer together to provide
the laminated fabric may not be specifically limited to a
particular one. By way of example, where the nonwoven fabric is
used, thermal bonding, chemical bonding, needle punching,
hydroentangling or any other method can be suitably employed. Also,
coating of the protective layer to the supporting layer by means of
a method such as, for example, spun bonding, meltblowing, and
electro-spinning may be suitably employed with no problem.
[0080] Also, where no affinity exists between the supporting layer
and the protective layer, a bonding layer (for example, a layer to
be used for bonding with a binder or for bonding resulting from
thermal fusion) having an affinity to respective compositions of
those layers may be inserted in between those layers. For example,
where a thermally fusible bonding layer is employed therebetween,
the relationship between the softening point (TB) of the fibers
forming the stretchable nonwoven fabric (the protective layer) and
the softening point (TH) of the thermally fusible bonding layer may
be TH<TB, preferably about TH+5.ltoreq.TB and more preferably
about TH+10.ltoreq.TB.
[0081] Also, in the practice of the present invention, in order to
increase the water resistance of the laminated fabric, a water
resistant layer may be further positioned or laminated on the
protective layer so that the protective layer is employed as an
intermediate layer between the water resistant layer and the
supporting layer. The use of the water resistant layer so laminated
is effective to inhibit the reduction of the collecting capability
and the air permeability of the protective layer resulting from
deposition of water components, even when the laminated fabric is
used under high humidity or under the environment susceptible to
deposition of the water components.
[0082] For example, as the water resistant layer, a moisture
permeable and water resistant nonwoven fabric may be employed. The
moisture permeable and water resistant nonwoven fabric referred to
above can be formed by applying a water repellent or water
resistant coating to the nonwoven fabric formed by the use of the
various fibers previously discussed under the heading of the
supporting layer, but in terms of securement of the air
permeability of the supporting layer, the water resistant layer is
preferably formed with hydrophobic fibers. The hydrophobic fibers
may be exemplified with polyolefinic fibers or polyester series
fibers, both of which have been discussed previously under the
heading of the supporting layer, and two of them, the polyolefinic
fibers are preferred therefor. As a process of laminating the water
resistant layer, any of the method discussed under the method of
laminating the supporting layer and the protective layer together
can be employed. The water resistant layer has a weight, which may
be so chosen as to be within the range of, for example, about 5 to
50 g/m.sup.2 and, preferably, within the range of about 10 to 45
g/m.sup.2 in order to impart water resistant property.
[0083] Also, in the laminated fabric, the total of the respective
weights of the supporting and protective layers (plus that of the
water resistant layer that is employed if desired) may be
arbitrarily chosen depending on the characteristics of the
supporting layer and/or those of the protective layer and may be
within the range of, for example, about 30 to 100 g/m.sup.2 and,
preferably within the range of about 40 to 90 g/m.sup.2.
[0084] Specifically, in the case where the supporting layer has a
volume reducing capability in view of reducing the volume of
laminate fabric in its entirety, the thickness of the protective
layer (plus the thickness of the water resistant layer that is
employed if desired) relative to the thickness of the supporting
layer may be not larger than about twice of the thickness of the
supporting layer, and preferably not larger than about 1.5 times
the thickness of the supporting layer.
[0085] It is to be noted that if required, a film may be bonded to
a part of the supporting layer. Even in such case, a method of
bonding the film to the fibers may not specifically limited, but
such bonding may be accomplished by means of the use of a binder or
a thermal fusion.
[0086] Also, if required, in order for the resultant sheeting
comprising the film to be utilizable in any of various
applications, any post-treatment may be performed. By way of
example, a calendering treatment for densification, a treatment to
impart a hydrophilic property, a water repellent treatment, and/or
a surfactant depositing treatment may be performed.
[0087] The laminated fabric for a protective clothing according to
the present invention is preferably subjected to an electret
treatment. The electret treatment referred to above means a
material capable of semipermanently retaining electric polarization
even in the absence of any external electric field and forming an
electric field in the surrounding, and the electret treatment can
be performed with an easily chargeable material such as, for
example, a polypropylene.
[0088] That is because since when the electret treatment is
performed, a collecting function by means of the electrostatic
force can be added, the efficiency of collecting the microparticles
can be drastically increased without altering the air permeability.
With respect to the electret treatment, various systems such as,
for example, a thermal electret, an electroelectret, a
photoelectret, a radioelectret, a magnetelectret, a mechanoelectret
are available, and any of them can be suitably employed.
[0089] In terms of the protecting capability, the laminated fabric
manufactured in the manner described hereinabove has an efficiency
of 90% or higher, preferably 93% or higher, and more preferably 96%
or higher, when collecting quartz particles 1 .mu.m in size.
[0090] Dust particles, contagions and viruses, all harmful to human
bodies, have varying particle sizes. Asbestos, which are an
exemplary harmful dust, are made up of an aggregation of fibrous
matters of a length within the range of a few .mu.m to some tens
.mu.m. The sizes of bacteria and fungi, which are a kind of
contagions, are 2 to 3 .mu.m in most cases. Although viruses
themselves have sizes of 0.01 to 0.1 .mu.m, the route of infection
is in most cases by way of a droplet infection caused by patients'
coughing, and the sizes of the droplets are 2 .mu.m or greater in
most cases. Considering the above mentioned sizes, it can be
expected that if the efficiency of collecting the 1 .mu.m quarts
particles is 90% or higher, those dusts, contagions and viruses can
be substantially almost completely protected.
[0091] On the other hand, if the efficiency of collecting the 1
.mu.m quartz particles is lower than 90%, it is indeed undesirable
in terms of the protecting capability discussed above.
[0092] The laminated fabric of the present invention has an air
permeability of 2 cc/cm.sup.2/sec. or higher in order to secure an
amenity to the human body. If the air permeability is lower than 2
cc/cm.sup.2/sec., one will feel uncomfortable with humid and,
therefore, it is not desirable. The air permeability of the
laminated fabric is preferably not lower than 3 cc/cm.sup.2/sec.
and more preferably within the range of 3.5 cc/cm.sup.2/sec. to 10
cc/cm.sup.2/sec. As for the relationship between the air
permeability and the 1 .mu.m quartz particle collecting efficiency
discussed previously, increase of the protecting capability lowers
the air permeability, accompanied by increase of the humidity. As a
result, the usage characteristics, for example, the amenity of
wearing will be lowered. In order to prevent such an undesirable
result, the protecting capability and the air permeability are
desired to fall within the respective ranges of performance
discussed hereinbefore.
[0093] In the present invention, since the stretchable nonwoven
fabric is used for the protective layer, the follow-up
characteristic of the protective layer with any other layers, that
is, the supporting layer or the protective layer is excellent.
Accordingly, even after a predetermined loading has been imposed,
it is possible to keep the integrity of the laminated fabric as a
whole, and any undesirable reduction in filtering capability can
also be avoided. The laminated fabric of the present invention,
even when being washed five times and dried in a manner according
to, for example, the JIS L1096 B.23.1 A method, may have a 1 .mu.m
quarts particle collecting efficiency of 90% or higher (preferably
93% or higher and, more preferably, 95% or higher).
[0094] If the laminated fabric has a water resistance, the
withstanding pressure of the laminated fabric, when measured
according to a low water pressure method stipulated in JIS L1092
may be within the range of about 300 to 1,500 mmH.sub.2O, and
preferably within the range of 400 to 1,000 mmH.sub.2O. If the
withstanding pressure is too low, it will not play a role of
protecting the protective layer from water, but if the withstanding
pressure is too high, there is a possibility that the laminated
fabric as a whole will have an air permeability departing from the
predetermined value.
[0095] Also, where the laminated fabric has a volume reducing
capability, the volume reducible laminated fabric may undergo about
5 to 90% shrinkage in a hot water of 60.degree. C. or higher (for
example, 60.degree. C. or higher, but lower than 70.degree. C.),
and when a disposal space is considered, it may undergo about 10 to
92% shrinkage, and preferably about 20 to 94% shrinkage. In
particular, in terms of increase in the rate of shrinkage, the
laminated fabric may undergo 30 to 95% shrinkage and, preferably 40
to 90% shrinkage when held in a hot water of 70.degree. C. or
higher (for example, 70.degree. C. or higher, but lower than
80.degree. C.).
[0096] It is to be noted that the rate of shrinkage herein referred
to means a value calculated according to the method described later
under the heading of the rate of shrinkage (%) of the fabric in a
hot water.
[Method of Reducing the Volume of Volume Reducible Laminated
Fabric]
[0097] Where the laminated fabric of the present invention has a
volume reducing capability, the volume of the laminated fabric can
easily be reduced with no use to any special equipment and at a
reduced cost.
[0098] By way of example, reduction in volume of the laminated
fabric can be accomplished by putting the volume reducible
laminated fabric (and the protective material prepared form such
fabric) into a suitable vessel (for example, a plastic container or
a plastic bag) and supplying a hot water of 60.degree. C. or higher
to the laminated fabric. A method of supplying the hot water is not
particularly limited to a specific method, and the hot water may be
filled in the vessel before the laminated fabric is put therein; or
after water is filled in a sealable vessel, such water may be
heated to a predetermined temperature in the vessel.
[0099] For example, for heating, any suitable method may be
employed, as long as the water within the vessel can be heated to a
temperature equal to or higher than 60.degree. C. There may be
suitably employed for this purpose, for example, a method of
applying a hot air from the outside of the vessel, a method of
immersing the vessel itself into a hot water, or a method of
heating water in the vessel by the means of an induction heating
apparatus such as, for example, an electronic oven.
[0100] The proportion of the hot water relative to the laminated
fabric is not specifically limited to a particular value as long as
the volume of the laminated fabric can be reduced, and relative to
100 parts by weight of the laminated fabric, 200 parts by weight or
larger (for example, within the range of about 250 to 500 parts by
weight), and preferably 300 parts by weight or larger (for example,
within the range of about 350 to 450 parts by weight) of the hot
water may be employed.
[0101] Where the vessel used to achieve the volume reduction is
employed in the form of a plastic bag, reduction of the volume of
the protective clothing can be achieved by putting 200 parts by
weight or larger of water relative to 100 parts by weight of the
laminated fabric constituting the protective clothing into the
plastic bag; sealing the plastic bag; and then heating the plastic
bag from the outside of the bag with a heater or heating the inside
of the bag by means of an induction heating apparatus such as, for
example, an electronic oven, to thereby reduce the volume of the
protective clothing. The plastic bag referred to herein may not be
particularly limited to a specific one as long as it will be
neither melted or decomposed at a temperature of use thereof, and
may be of a kind having a moisture resistance and a water
resistance effective to avoid leakage of water.
[0102] It is to be noted that a method of sealing the plastic bag
may also not be specifically limited to a particular method, and
any of a method of tightly tying itself, a method of closing the
mouth of the bag with the use of a fastening tool and a method of
heat sealing the bag may be employed.
[0103] The protective clothing utilizing the volume reducible
laminated fabric can be transported or disposed of after the volume
thereof has been reduced subsequent after use. As a result, the
cost, which will be incurred in transportation and disposal, can be
reduced advantageously.
[0104] Hereinafter, the present invention will be demonstrated by
way of examples and comparative examples, which are not intended to
limit the scope of the present invention, but are only for
illustrative purpose.
[Shrinkage Rate of Fabric in Hot Water (%)]
[0105] The fabric is cut into a sample of 10.times.10 cm in size,
which sample is then immersed for 2 minutes in a hot water in a
free state. After the immersion, the fabric is removed from the hot
water and the removed fabric is drained off lightly. Then
respective dimensions (cm) of the fabric in a longitudinal
direction (X) and a transverse direction (Y) are measured so that
the rate of shrinkage can be calculated by the following
equation:
Shrinkage Rate(%)={[(10-X)/10]+[(10-Y)/10]}/2.times.100
[Dust Collecting Efficiency (%)]
[0106] In accordance with the testing for particulate respirators
stipulated in JIS T8151, the dust collecting efficiency was
measured using a "Mask Tester: Model AP-6310FP" manufactured by and
available from Shibata Scientific Technology Ltd. For the dust,
quartz particles of 1 .mu.m in particle size were used and the
measurement was carried out under a condition of the wind velocity
of 8.6 cm/min at measurement.
[0107] Further, after 5 times washing in accordance with the method
stipulated in JIS L1096 B.23.1A, the dust collecting efficiency of
the dried sample fabric was measured in a manner similar to that
described above.
[Air Permeability (cc/cm.sup.2/sec.)]
[0108] The air permeability was measured with the use of the
FRAZIER TYPE AIR PERMEABILITY TESTER (manufactured by and available
from Toyo Seiki Seisaku-sho, Ltd.).
[Stretch of Protective Layer at Break (%)]
[0109] The stretch of protective layer at break was measured
according to the method stipulated in JIS P8113, with the use of an
oblong test piece of 1.5 cm in width.
[Tensile Strength (N/5 cm)]
[0110] The tensile strength was measured according to the method
stipulated in JIS L1906, with the use of an oblong test piece of 5
cm in width.
Example 1
[0111] (1) Using crimped PVA fibers, which has a polymerization
degree of 1,750, saponification degree of 98.5 mole %, 2.2 dtex in
single fiber fineness, 51 mm in fiber length and 5 cN/dtex in
strength (tradenamed "WN7" manufactured by and available from
Kuraray Co., Ltd.: 6% in shrinkage rate in 60.degree. C. hot water,
65% shrinkage rate in 70.degree. C. hot water and dissolvable at
75.degree. C.), a random web comprised of 100 parts by mass of the
crimped PVA fibers and having a weight of 35 g/m.sup.2 was
prepared.
[0112] (2) Then, a nonwoven fabric was produced with the web
obtained under (1) above in the following manner, a so-called foam
bonding process. More specifically, onto the web obtained under (1)
above, was applied a foam prepared by beating a 10% aqueous
solution of PVA which has a polymerization degree of 1,750 and a
saponification degree of 98.5 mole % by a commercially available
bubble machine. Then, the resultant web was squeezed to spread the
PVA resin foam uniformly over the web by means of a mangle, and the
resultant was dried to obtain the nonwoven fabric. Thus obtained
nonwoven fabric was used as a supporting layer. It is to be noted
that the rate of shrinkage of this supporting layer was 15% in a
hot water of 60.degree. C. and 70% in a hot water of 70.degree.
C.
[0113] (3) On the other hand, the protective layer and the water
resistant layer were prepared in the following manner.
[0114] SEPTON (tradenamed under "SEPTON 2002" manufactured by and
available from Kuraray Co., Ltd.) and polypropylene (tradenamed
under "NOVATEC PP" manufactured by and available from Japan
Polychem Corporation) were melted and kneaded together in a mixing
ratio of 60/40 (mass ratio), and subsequently a layer was formed by
means of a meltblowing process to provide a SEPTON/polypropylene
blended nonwoven fabric having a weight of 10 g/m.sup.2, which
fabric was used as the protective layer.
[0115] Also, as the water resistant layer, a nonwoven fabric having
a weight of 20 g/m.sup.2 was prepared by the meltblowing process,
using polypropylene (tradenamed under "NOVATEC PP" manufactured by
and available from Japan Polychem Corporation).
[0116] (4) Thereafter, the supporting layer, the protective layer
and the water resistant layer were overlapped one above the other
in this specific order, followed by bonding together by means of a
calendering process (carried out under calendering conditions of
130.degree. C. in temperature, 0.1 MPa in contact pressure, and 5
m/min. in processing velocity) to thereby provide a layered body
having such a sectional structure as shown in FIG. 2. It is to be
noted that in FIG. 2, A represents the supporting layer, B
represents the protective layer and C represents the water
resistant layer.
[0117] (5) The performance of the fabric consisting of the layered
body, which has been manufactured in the manner described in (4),
is shown in Table 1. The fabric so obtained was found to have a
weight of 65 g/m.sup.2, a tensile strength of 120 N/5 cm.times.100
N/5 cm (MD direction.times.CD direction), an air permeability of
2.1 cc/cm.sup.2/sec., a 1 .mu.m quartz dust collecting efficiency
of 97.3%, and a 1 .mu.m quartz dust collecting efficiency after 5
times washing of 97.1%. The fabric was also found to have both of
an air permeability and a filtering capability as the laminated
fabric and to be excellent in integrity enough to exhibit the
required filtering capability even after it has been loaded by
means of, for example, washing. Therefore, the laminated fabric has
a performance sufficient to allow it to be used as a fabric for a
protective clothing. Also, when the laminated fabric was immersed
in a hot water of 60.degree. C., 12% shrinkage occurred, and when
it was immersed in a hot water of 70.degree. C., 61% shrinkage
occurred.
Example 2
[0118] (1) Using crimped PVA fibers of a kind, which has a
polymerization degree of 1,750, a saponification degree of 98.5
mole %, 2.2 dtex in single fiber fineness, 51 mm in fiber length
and 5 cN/dtex in strength (tradenamed "WN7" manufactured by and
available from Kuraray Co., Ltd.), a random web comprised of 100
parts by mass of the crimped PVA fibers and having a weight of 35
g/m.sup.2 was prepared and was subsequently subjected to an
embossing process to provide an embossed nonwoven fabric. The
embossing process was carried out under conditions of 12% in the
ratio of embossing area, 180.degree. C. in temperature, 40 kgf/cm
in line pressure and 15 m/min. in processing velocity. This
nonwoven fabric was used as the supporting layer.
[0119] (2) On the other hand, the protective layer and the water
resistant layer were prepared in the following manner:
[0120] After placing polyurethane (tradenamed under "KURAMIRON
1190-000" manufactured by and available from Kuraray Co., Ltd.) in
a vessel containing dimethylformamide (DMF) so that the
concentration of polyurethane was 10 mass %, the mixture was
agitated at 90.degree. C. to dissolve the polyurethane, and the
completely dissolved solution was then cooled down to ambient
temperatures to thereby provide a spinning liquid. Using the
spinning liquid so prepared in the manner described above, an
electrostatic spinning was carried out with the spinning apparatus
shown in FIG. 1. For the spinnerets 4, needles each 0.9 mm in
diameter were used. Also, the spinnerets 4 and the sheet take-up
apparatus 7 were spaced at a distance of 12 cm from each other. It
is to be noted that in the sheet take-up apparatus 7, a
polypropylene nonwoven fabric (the water resistant layer) having a
weight of 20 g/m.sup.2, which was prepared from the polypropylene
(tradenamed under "NOVATEC PP" manufactured by and available from
Japan Polychem Corporation) in the same way as in Example 1 by
means of the meltblowing process, was wound beforehand.
[0121] Thereafter, while the conveyor was driven at a velocity of
0.1 m/min., the spinning liquid was extruded from the spinnerets in
a predetermined supply rate, and a 25 kV voltage was applied to the
spinnerets to form a laminate comprising a polyurethane nanofiber
layer which had a weight of 1.0 g/m.sup.2 laminated over the water
resistant layer which was pre-wound around the sheet take-up
apparatus 7.
[0122] (3) The supporting layer, prepared in the manner described
in (1) above, and the protective layer and the water resistant
layer, both prepared in the manner described in (2) above, were
overlapped with the protective layer forming an interlayer, and
were then calendered in a manner similar to that described under
Example 1 to thereby provide a layered body.
[0123] (4) The fabric prepared from this layered body was found to
have a weight of 56 g/m.sup.2, a tensile strength of 64 N/5
cm.times.54 N/5 cm (MD direction.times.CD direction), an air
permeability of 5.7 cc/cm.sup.2/sec., a 1 .mu.m quartz dust
collecting efficiency of 99.9%, and a 1 .mu.m quartz dust
collecting efficiency after 5 times washing of 99.8%, as shown in
Table 1. The fabric was also found to have both of an air
permeability and a filtering capability as the laminated fabric and
to be excellent in integrity enough to exhibit the required
filtering capability even after it has been loaded by means of, for
example, washing. For the reason discussed above, the laminated
fabric has a performance sufficient to allow it to be used as a
fabric for a protective clothing. Also, when the laminated fabric
was immersed in a hot water of 60.degree. C., 11% shrinkage
occurred, and when it was immersed in a hot water of 70.degree. C.,
58% shrinkage occurred.
Example 3
[0124] (1) Using crimped PVA fibers of a kind, which has a
polymerization degree of 1,750, a saponification degree of 98.5
mole %, 2.2 dtex in single fiber fineness, 51 mm in fiber length
and 5 cN/dtex in strength (tradenamed "WN7" manufactured by and
available from Kuraray Co., Ltd.: 6% in shrinkage rate in
60.degree. C. hot water, 65% shrinkage rate in 70.degree. C. hot
water and dissolvable at 75.degree. C.), a random web comprised of
100 parts by mass of the crimped PVA fibers and having a weight of
35 g/m.sup.2 was prepared.
[0125] (2) Then, a nonwoven fabric was produced with the web
obtained under (1) above in the following manner, a so-called foam
bonding process. More specifically, onto the web obtained under (1)
above, was applied a foam prepared by beating a 10% aqueous
solution of PVA which has a polymerization degree of 1,750 and a
saponification degree of 98.5 mole % by a commercially available
bubble machine. Then, the resultant web was squeezed to spread the
PVA resin foam uniformly over the web by means of a mangle, and the
resultant was dried to obtain the nonwoven fabric. Thus obtained
nonwoven fabric was used as a supporting layer. It is to be noted
that the rate of shrinkage of this supporting layer was 15% in a
hot water of 60.degree. C. and 70% in a hot water of 70.degree.
C.
[0126] (3) For the water resistant layer, was prepared a
polypropylene nonwoven fabric (water resistant layer) having a
weight of 20 g/m.sup.2, which was prepared by the meltblowing
process using the same polypropylene as that used in Example 1
("NOVATEC PP" tradenamed polypropylene manufactured by and
available from Japan Polychem Corporation).
[0127] (4) Thereafter, while the supporting layer was moved at a
conveyor velocity of 50 m/min., a hot melt resin (tradenamed
"INSTANTLOCK MP801" available from Nippon NSC Ltd.; melting point:
about 140.degree. C.) was uniformly applied to the supporting layer
in a quantity of 2 g/m.sup.2 under conditions of 190.degree. C. in
nozzle temperature and 205.degree. C. in hot air temperature to
form a resin coating on the supporting layer, followed by cooling
the coating once and winding around a take-up roll. Also, in a
manner similar to the supporting layer, the hot melt resin referred
to above was also applied to the water resistant layer referred to
above in a quantity of 2 g/m.sup.2.
[0128] (5) On the other hand, the protective layer was prepared in
the following manner.
[0129] After placing SEPTON (tradenamed under "SEPTON 2002"
manufactured by and available from Kuraray Co., Ltd. and having a
softening point of about 150.degree. C.) in a vessel containing
dimethylformamide (DMF) so that the concentration of SEPTON was 10
mass %, the mixture was agitated at 90.degree. C. to dissolve the
SEPTON, and the completely dissolved solution was then cooled down
to ambient temperatures to thereby provide a spinning liquid. Using
the spinning liquid so prepared in the manner described above, an
electrostatic spinning was carried out with the spinning apparatus
shown in FIG. 1. For the spinnerets 4, needles each 0.9 mm in
diameter were used. Also, the spinnerets 4 and the sheet take-up
apparatus 7 were spaced at a distance of 10 cm from each other. It
is to be noted that the sheet take-up apparatus 7 was surrounded by
the supporting layer coated with the hot melt resin which was
obtained in (4) above, so that the surface of the hot melt resin
was deposited with nanofibers.
[0130] Thereafter, while the conveyor was driven at a velocity of
0.1 m/min., the spinning liquid was extruded from the spinnerets,
to the spinnerets a 20 kV voltage was applied, in a predetermined
supply rate to obtain deposit or scaffold of 1.0 g/m.sup.2 of
SEPTON nanofibers over the water resistant layer, and then the
composite layer was wound around the sheet take-up apparatus 7.
[0131] (6) Further, the supporting layer, deposited with the SEPTON
nanofiber layer, and the water resistant layer, coated with the hot
melt resin as in (4) above, were overlapped one above the other
with the hot melt resin coating on the water resistant layer held
in contact with the SEPTON nanofiber layer, and then were bonded
together by means of a calendering process (carried out under
calendering conditions of 140.degree. C. in temperature, 0.1 MPa in
contact pressure, and 5 m/sec. in processing velocity) to thereby
provide a layered body. The fabric prepared from this layered body
was found to have a weight of 60 g/m.sup.2, a tensile strength of
93 N/5 cm.times.49 N/5 cm (MD direction.times.CD direction), an air
permeability of 8.1 cc/cm.sup.2/sec., a 1 .mu.m quartz dust
collecting efficiency of 99.7%, and a 1 .mu.m quartz dust
collecting efficiency after 5 times washing of 99.7%, as shown in
Table 1. The fabric was also found to have both of an air
permeability and a filtering capability as the laminated fabric and
to be excellent in integrity enough to exhibit the required
filtering capability even after it has been loaded by means of, for
example, washing. Accordingly, the laminated fabric has a
performance sufficient to allow it to be used as a fabric for a
protective clothing. Also, when the laminated fabric was immersed
in a hot water of 60.degree. C., 12% shrinkage occurred, and when
it was immersed in a hot water of 70.degree. C., 64% shrinkage
occurred.
Example 4
[0132] (1) A nylon spun bonded nonwoven fabric having a weight of
30 g/m.sup.2 (tradenamed "ELTAS N01030" manufactured by and
available from Asahi Kasei Corporation) was used as the supporting
layer.
[0133] (2) A polypropylene nonwoven fabric having a weight of 20
g/m.sup.2 prepared from the same polypropylene (tradenamed "NOVATEC
PP" manufactured by and available from Japan Polychem Corporation)
as that used in Example 1 by means of the meltblowing process was
used as the water resistant layer.
[0134] (3) Then, while the supporting layer was moved at a conveyor
velocity of 50 m/min., a hot melt resin (tradenamed "INSTANTLOCK
MP801" available from Nippon NSC Ltd.) was uniformly applied to the
supporting layer in a quantity of 2 g/m.sup.2 under conditions of
190.degree. C. in nozzle temperature and 205.degree. C. in hot air
temperature to form a resin coating on the supporting layer,
followed by cooling the coating once and winding around a take-up
roll. Also, in a manner similar to the supporting layer, the hot
melt resin referred to above was also applied to the water
resistant layer referred to above in a quantity of 2 g/m.sup.2.
[0135] (4) On the other hand, the protective layer was prepared in
the following manner.
[0136] After placing polyurethane (tradenamed under "KURAMIRON
1190-000" manufactured by and available from Kuraray Co., Ltd.) in
a vessel containing dimethylformamide (DMF) so that the
concentration of polyurethane was 10 mass %, the mixture was
agitated at 90.degree. C. to dissolve the polyurethane and the
completely dissolved solution was then cooled down to ambient
temperatures to thereby provide a spinning liquid. Using the
spinning liquid so prepared in the manner described above, an
electrostatic spinning was carried out with the spinning apparatus
shown in FIG. 1. For the spinnerets 4, needles each 0.9 mm in
diameter were used. Also, the spinnerets 4 and the sheet take-up
apparatus 7 were spaced at a distance of 12 cm from each other. It
is to be noted that the sheet take-up apparatus 7 was surrounded by
the supporting layer coated with the hot melt resin which was
obtained in (3) above, so that the surface of the hot melt resin
was deposited with nanofibers.
[0137] Thereafter, while the conveyor was driven at a velocity of
0.1 m/min., the spinning liquid was extruded from the spinnerets in
a predetermined supply rate, and a 25 kV voltage was applied to the
spinnerets to laminate 1.0 g/m.sup.2 of polyurethane nanofibers
over the nonwoven layer.
[0138] (5) Further, the supporting layer, deposited with the
polyurethane nanofiber layer, and the water resistant layer, coated
with the hot melt resin as in (3) above, were overlapped one above
the other with the hot melt resin coating on the water resistant
layer held in contact with the polyurethane nanofiber layer, and
then were bonded together by means of a calendering process
(carried out under calendering conditions of 140.degree. C. in
temperature, 0.1 MPa in contact pressure, and 5 m/sec. in
processing velocity) to thereby provide a layered body. The fabric
prepared from this layered body was found to have a weight of 55
g/m.sup.2, a tensile strength of 105 N/5 cm.times.71 N/5 cm (MD
direction.times.CD direction), an air permeability of 8.4
cc/cm.sup.2/sec., a 1 .mu.m quartz dust collecting efficiency of
99.9%, and a 1 .mu.m quartz dust collecting efficiency after 5
times washing of 99.8%, as shown in Table 1. The fabric was also
found to have both of an air permeability and a filtering
capability as the laminated fabric and to be excellent in integrity
enough to exhibit the required filtering capability even after it
has been loaded by means of, for example, washing. Accordingly, the
laminated fabric has a performance sufficient to allow it to be
used as a fabric for a protective clothing.
Example 5
[0139] Except for using a polyethylene terephthalate spun bonded
nonwoven fabric (tradenamed "ELTAS E01030" manufactured by and
available from Asahi Kasei Corporation) having a weight of 30
g/m.sup.2 as the supporting layer instead of the foam bonded PVA
nonwoven fabric employed on the supporting layer in Example 3, a
fabric was prepared in a manner similar to that in Example 3. As
shown in Table 1, the fabric so prepared was found to have a weight
of 55 g/m.sup.2, a tensile strength of 124 N/5 cm.times.77 N/5 cm
(MD direction.times.CD direction), an air permeability of 9.1
cc/cm.sup.2/sec., a 1 .mu.m quartz dust collecting efficiency of
99.6%, and a 1 .mu.m quartz dust collecting efficiency after 5
times washing of 99.5% and was also found to have both of an air
permeability and a filtering capability as the laminated fabric and
to be excellent in integrity enough to exhibit the required
filtering capability even after it has been loaded by means of, for
example, washing.
Comparative Example 1
[0140] The polypropylene nonwoven fabric (the water resistant
layer) and the nylon nonwoven fabric (the supporting layer) both
obtained in (3) of Example 4 and applied with the hot melt resin
were directly overlapped one above the other with the hot melt
resin adhering thereto, with no protective layer intervening
therebetween, and were subsequently subjected to a calendaring
process in a manner similar to that in Example 4 to form a fabric.
As shown in Table 1, this fabric was found to have a weight of 54
g/m.sup.2, a tensile strength of 101 N/5 cm.times.70 N/5 cm (MD
direction.times.CD direction), an air permeability of 21
cc/cm.sup.2/sec., a 1 .mu.m quartz dust collecting efficiency of
33.1%, and a 1 .mu.m quartz dust collecting efficiency after 5
times washing of 32.8% and was also found to have an unacceptable
filtering capability.
Comparative Example 2
[0141] (1) A nylon spun bonded nonwoven fabric having a weight of
30 g/m.sup.2 (tradenamed "ELTAS N01030" manufactured by and
available from Asahi Kasei Corporation) was used as the supporting
layer.
[0142] (2) A polypropylene nonwoven fabric having a weight of 20
g/m.sup.2 prepared from the same polypropylene (tradenamed "NOVATEC
PP" manufactured by and available from Japan Polychem Corporation)
as that used in Example 1 by means of the meltblowing process was
used as the water resistant layer.
[0143] (3) Then, while the supporting layer was moved at a conveyor
velocity of 50 m/min., a hot melt resin (tradenamed "INSTANTLOCK
MP801" available from Nippon NSC Ltd.) was uniformly applied to the
supporting layer in a quantity of 2 g/m.sup.2 under conditions of
190.degree. C. in nozzle temperature and 205.degree. C. in hot air
temperature to form a resin coating on the supporting layer,
followed by cooling the coating once and winding around a take-up
roll. Also, in a manner similar to the supporting layer, the hot
melt resin referred to above was also applied to the water
resistant layer referred to above.
[0144] (4) On the other hand, the protective layer was prepared in
the following manner.
[0145] After placing polyacrylonitrile (manufactured by and
available from Sigma Aldrich Co.; weight average molecular weight:
150,000) in a vessel containing dimethylformamide (DMF) so that the
concentration of polyacrylonitrile is 11 mass %, the mixture was
agitated at 90.degree. C. to dissolve the polyacrylonitrile and the
completely dissolved solution was then cooled down to ambient
temperatures to thereby provide a spinning liquid. Using the
spinning liquid so prepared in the manner described above, an
electrostatic spinning was carried out with the spinning apparatus
shown in FIG. 1. For the spinnerets 4, needles each 0.9 mm in
diameter were used. Also, the spinnerets 4 and the sheet take-up
apparatus 7 were spaced at a distance of 10 cm from each other. It
is to be noted that the sheet take-up apparatus 7 was surrounded by
the supporting layer coated with the hot melt resin which was
obtained in (3) above, so that the surface of the hot melt resin
was deposited with nanofibers.
[0146] Thereafter, while the conveyor was driven at a velocity of
0.1 m/min., the spinning liquid was extruded from the spinnerets in
a predetermined supply rate, and a 18 kV voltage was applied to the
spinnerets to laminate 1.0 g/m.sup.2 of polyacrylonitrile
nanofibers over the nonwoven layer.
[0147] (5) Also, the supporting layer, laminated with the
polyacrylonitrile nanofiber layer, and the water resistant layer,
coated with the hot melt resin as in (3) above, were overlapped one
above the other with the hot melt resin coating on the water
resistant layer held in contact with the polyacrylonitrile
nanofiber layer and were bonded together by means of a calendering
process (carried out under calendering conditions of 140.degree. C.
in temperature, 0.1 MPa in contact pressure, and 5 m/sec. in
processing velocity) to thereby provide a layered body. The fabric
prepared from this layered body was found to have a weight of 55
g/m.sup.2, a tensile strength of 104 N/5 cm.times.70 N/5 cm (MD
direction.times.CD direction), an air permeability of 7.5
cc/cm.sup.2/sec., a 1 .mu.m quartz dust collecting efficiency of
99.6%, and a 1 .mu.m quartz dust collecting efficiency after 5
times washing of 84.1%, as shown in Table 1. The fabric was also
found to have lost an integrity for the nonwoven fabric enough to
fail to maintain the required filtering capability.
Comparative Example 3
[0148] As a comparison, when the performance of a commercially
available fabric tradenamed "TYVEK SOFT" (having a weight of 41
g/m.sup.2) and manufactured by and available from E. I. du Pont de
Nemours and Company, which is currently used as the standard
protective base material, was evaluated, the tensile strength
thereof was found to be 80 N/5 cm.times.94 N/5 cm (MD
direction.times.CD direction) and the 1 .mu.m quartz dust
collecting efficiency was found to be so high as 98.5% as shown in
Table 1. However, the air permeability of the commercially
available fabric referred to above was found to be very low of 0.4
cc/cm.sup.2/sec. and no shrinkage was found occurring in a hot
water of either 60.degree. C. and 70.degree. C.
TABLE-US-00001 TABLE 1 Com. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Com. Ex.
1 Com. Ex. 2 Ex. 3 Supporting Material PVA PVA PVA Nylon PET Nylon
Nylon "TYVEK Layer Form Foambond Emboss Foambond Spunbond Spunbond
Spunbond Spunbond SOFT" Weight(g/m.sup.2) 35 35 35 30 30 30 30
Protective Material SEPTON/PP Polyurethane SEPTON Polyurethane
SEPTON -- PAN Layer Form Meltblowing Nanofiber Nanofiber Nanofiber
Nanofiber -- Nanofiber Weight(g/m.sup.2) 10 1 1 1 1 -- 1 Stretch at
205 51 38 51 38 -- 24 break (%) Water Material PP PP PP PP PP PP PP
Resistant Form MB MB MB MB MB MB MB Layer Weight(g/m.sup.2) 20 20
20 20 20 20 20 Adhering Method Calender Calender Hot melt Hot melt
Hot melt Hot melt Hot melt Total Weight 65 56 60 55 55 54 55 41
Tensile MD 120 64 93 105 124 101 104 80 Strength CD 100 54 49 71 77
70 70 94 (N/5 cm) Air Permeability 2.1 5.7 8.1 8.4 9.1 21 7.5 0.4
(cc/cm.sup.2/sec) Collecting Before 97.3 99.9 99.7 99.7 99.6 33.1
99.6 98.5 Efficiency Washing After 5 times 97.1 99.8 99.7 99.8 99.5
32.8 84.1 98.3 Washing Withstanding 1132 850 753 811 781 751 831
1005 Pressure (mmH.sub.2O) Shrinkage 60.degree. C. water 12 11 12 0
0 0 0 0 Rate (%) 70.degree. C. water 61 58 64 0 0 0 0 0
[0149] The laminated fabric of the present invention is
advantageously used as a protective material for protecting human
bodies from harmful and/or hazardous substances such as, for
example, dust harmful to human bodies, contagions and viruses,
and/or harmful and/or hazardous substances afloat in the
atmospheric air. Such protective material is used not only as a
protective clothing (such as, for example, protective clothes,
masks, gloves and/or hats), but also sheeting, protectors and/or
filters of a kind used under the environment, where the harmful
and/or hazardous substances tend to stick thereto, to protect human
bodies from the secondary infection of those harmful and/or
hazardous substances.
[0150] Also, where the laminated fabric has a volume reducing
capability, since the laminated fabric (or the protective material)
can be reduced in volume and be then transported or disposed of
after use, the cost incurred in transportation or disposal can be
reduced advantageously.
* * * * *