U.S. patent application number 14/182545 was filed with the patent office on 2014-08-21 for flame protective fabric structure.
This patent application is currently assigned to W. L. Gore & Associates, GmbH. The applicant listed for this patent is W. L. Gore & Associates, GmbH. Invention is credited to Heiko Knoerrer, John Ruediger, Reiner Schneider, Bernd Zischka.
Application Number | 20140234592 14/182545 |
Document ID | / |
Family ID | 47757342 |
Filed Date | 2014-08-21 |
United States Patent
Application |
20140234592 |
Kind Code |
A1 |
Ruediger; John ; et
al. |
August 21, 2014 |
Flame Protective Fabric Structure
Abstract
A flame protective fabric structure (1) comprises a fabric (10)
being formed with multiple yarns (20), each yarn (20) made of a
fiber blend of at least a first fiber component and a second fiber
component. The first fiber component comprises flame resistant
viscose fibers (22) in an amount of at least 50% of the fiber blend
weight and the second fiber component comprises meltable fibers
(24) in an amount of at least 10% of the fiber blend weight. The
fabric (10) is formed as a woven fabric with a total fractional
cover factor of greater than 60% having a capability to withstand a
horizontal flame exposure of 10 seconds without hole formation
according to ISO 15025/14116_Index III.
Inventors: |
Ruediger; John; (Bruckmuehl,
DE) ; Zischka; Bernd; (Tuntenhausen, DE) ;
Knoerrer; Heiko; (Kulmbach, DE) ; Schneider;
Reiner; (Schauenstein, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
W. L. Gore & Associates, GmbH |
Putzbrunn |
|
DE |
|
|
Assignee: |
W. L. Gore & Associates,
GmbH
Putzbrunn
DE
|
Family ID: |
47757342 |
Appl. No.: |
14/182545 |
Filed: |
February 18, 2014 |
Current U.S.
Class: |
428/196 ;
442/289; 442/301; 442/302 |
Current CPC
Class: |
B32B 2571/00 20130101;
B32B 2307/718 20130101; D03D 1/0035 20130101; B32B 2307/7265
20130101; D02G 3/443 20130101; B32B 5/30 20130101; Y10T 428/2481
20150115; Y10T 442/3976 20150401; B32B 2262/14 20130101; B32B
2262/106 20130101; A41D 31/08 20190201; B32B 2262/103 20130101;
B32B 5/22 20130101; D03D 13/008 20130101; B32B 2262/0261 20130101;
B32B 2262/0253 20130101; B32B 27/322 20130101; B32B 5/024 20130101;
B32B 5/08 20130101; B32B 5/16 20130101; B32B 27/12 20130101; B32B
2307/306 20130101; B32B 2307/402 20130101; D03D 15/12 20130101;
B32B 2307/3065 20130101; D10B 2401/041 20130101; B32B 2307/21
20130101; B32B 2307/554 20130101; B32B 2262/04 20130101; B32B
2262/062 20130101; D10B 2331/02 20130101; B32B 2437/00 20130101;
D10B 2201/24 20130101; Y10T 442/3878 20150401; B32B 2264/0257
20130101; B32B 2307/724 20130101; Y10T 442/3984 20150401 |
Class at
Publication: |
428/196 ;
442/301; 442/289; 442/302 |
International
Class: |
D03D 15/12 20060101
D03D015/12; D03D 1/00 20060101 D03D001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 18, 2013 |
EP |
13155646.6 |
Claims
1. A flame protective fabric structure comprising: a fabric being
formed with multiple yarns, wherein each of the yarns is made of a
fiber blend of at least a first fiber component and a second fiber
component, the first fiber component comprising flame resistant
viscose fibers in an amount of at least 50% of the fiber blend
weight and the second fiber component comprising meltable fibers in
an amount of at least 10% of the fiber blend weight; wherein the
fabric is formed as a woven fabric with a total fractional cover
factor of greater than 60% having a capability to withstand a
horizontal flame exposure of 10 seconds without hole formation
according to ISO 15025/14116 Index III.
2. The flame protective fabric structure according to claim 1,
wherein the meltable fibers are made of polyamide.
3. The flame protective fabric structure according to claim 1,
wherein the flame resistant viscose fibers are man-made cellulosic
fibers comprising flame resistant additives incorporated in the
viscose matrix.
4. The flame protective fabric structure according to claim 1,
wherein the fiber blend comprises the flame resistant viscose
fibers and the meltable fibers in a weight ratio of 80:20.
5. The flame protective fabric structure according to claim 1,
wherein the fabric has a weight in the range of 50 g/m.sup.2 to 550
g/m.sup.2.
6. The flame protective fabric structure according to claim 1,
wherein the fabric is formed in a plain weave construction.
7. The flame protective fabric structure according to claim 1,
further comprising at least one barrier layer adjacent to one side
of the fabric.
8. The flame protective fabric structure according to claim 7,
wherein the barrier layer comprises a porous membrane layer made of
expanded polytetrafluoroethylene.
9. The flame protective fabric structure according to claim 1,
wherein the first fiber component and the second fiber component
are homogenously distributed in the yarns.
10. The flame protective fabric structure according to claim 1,
wherein the fiber blend comprises at least one third or more
additional fiber components, the third and more additional fiber
components being provided in the fiber blend in an amount of not
more than 3% of the fiber blend weight.
11. The flame protective fabric structure according to claim 1,
wherein at least one surface of the fabric is dyed such that it has
a color fastness greater than 4.
12. The flame protective fabric structure according to claim 1,
wherein at least one surface of the fabric is dyed with a
carrier-free dye such that it has a color fastness of greater than
4.
13. The flame protective fabric structure according to claim 12,
wherein the carrier-free dye is directly integrated into the fabric
on at least one surface of the fabric.
14. The flame protective fabric structure according to claim 1,
wherein the fabric is printed with a dye having a color fastness of
greater than 4.
15. The flame protective fabric structure according to claim 1,
wherein the flame resistant viscose fibers and meltable fibers are
made by staple fiber spinning and twisting.
16. A clothing article comprising a flame protective fabric
structure according to claim 1.
Description
[0001] The invention relates to a flame protective fabric structure
comprising a fabric being formed with yarns, the yarns made of a
fiber blend of at least a first fiber component and a second fiber
component, the first fiber component comprising flame resistant
viscose fibers and the second fiber component comprising meltable
fibers. The invention also relates to a clothing article comprising
such flame protective fabric structure.
[0002] Fabrics, particularly for clothing, with flame protective
properties are desired. They are typically used in so-called
Personal Protective Equipment (PPE) for protection in working
environment like for firefighting. It is often essential that work
clothing fulfill a protective function, such as flame resistance,
in order to protect the wearer of the work clothing from dangerous
environmental conditions, such as fire and heat. Disadvantageously,
material structures for heat- and flame-resistant clothing produced
from specific fibers or yarns, such as aramide, which are
particularly suited for fire-protective clothing, often provide
reduced wearing comfort and often can only be dyed with
considerable difficulty or not at all with common dying methods. In
addition there is a strong need for environmental preferable
fibers, e.g. with preferable LCA (life cycle analysis).
[0003] Up to now, the only fabrics with full flame retardant (FR)
protection (Index III according to ISO 15015) used in PPE are (a)
blends of inert FR fiber blends, e.g. aramides, Polybenzimidazol
(PBI), Modacryl and FR Viscose, examples: Nomex III, Defender M
(Lenzing (viscose FR) 65%, para aramide 25%, Nylon 10%),
aramide/viscose blends, and (b) post FR treated cellulosic fiber
blends with low percentage of meltable fibers, examples: Westex
INDURA (R) Ultra Soft (R).
[0004] In WO 2009/012266 there is disclosed a thermal protective
knit fabric. It has been discovered therein that a knit fabric
exhibiting effective thermal protective characteristics, including
the absence of melting or dripping, may be achieved when the fabric
is comprised of an intimate blend of cellulosic and nylon staple
fibers. Such a fabric may be used to particular advantage to offer
protection against severe thermal events to the wearer of a garment
made from that fabric. The fabric may comprise blended cellulosic
and nylon staple yarn characterized by a weight ratio of cellulosic
to nylon within said yarn ranging from about 55:45 to about 85:15.
One embodiment of the fabric may contain yarn having a ratio of
cellulose to nylon within the yarn of from about 60:40 to about
70:30. Certain yarns made from intimate blends of nylon and
cellulosic staple fibers can be knit to provide fabrics
particularly suitable for the manufacture of garments. Cellulosic
fibers are derived from linear long-chain polymer polysaccharide
consisting of linked, beta glucose units. Cellulosic fibers include
naturally occurring fibers, such as cotton, flax, hemp, jute, ramie
and synthetically manufactured fibers, such as rayon (regenerated
cellulose), FR (fire resistant) rayon, acetate (cellulose acetate),
triacetate (cellulose triacetate), etc. In certain yarn and fabric
embodiments, the weight percentage of the cellulosic fiber exceeds
the weight percentage of nylon fiber.
[0005] Fabric structures with full flame retardant (FR) protection
(Index III according to ISO 15015) used in PPE are known.
Typically, such fabric structures are made of fiber or fiber blends
comprising aramides, PBI, or modacrylics which are difficult to dye
and expensive. Especially the dying of such fibers/fiber blends
involves a more complex process to ensure that all fiber components
are covered with dyestuff and that the dyestuff is durably and
permanently bonded to the fibers.
[0006] US 2012/0270456 A1 discloses a flame retardant fabric for
use in personal protective clothing which provides a high level of
protection from flames or other sources of heat characterized in
that it is made from a mixture of a primary yarn which is a blend
of FR cellulosic fibers with high temperature resistant polymer
fibers and a secondary yarn which is a twisted yarn containing a
continuous synthetic filament yarn. Particularly, the high
temperature resistant polymer fibers are chosen from para-aramide,
meta-aramide, PBI and blends of these fibers which are difficult to
dye and expensive. The fabric is constructed so that the secondary
yarn occurs in the warp and the weft at a predetermined frequency,
resulting in a rough mesh structure formed by the secondary
yarn.
[0007] Besides the requirement of protection there are as well
requirements for optical aspects as uniform colors, disruptive
patterns, corporate colors and easy to care requirements,
particularly regarding the fabric. Today, the flexibility in dying
of available fabric solutions is a big concern. The currently
existing solutions have the following disadvantages: For a broad
flexibility in dye ability and color performance (particularly safe
and solid dye process), up to now the typical compromise was to use
Modacryl as "easy to dye" fiber in the blend, but Modacryl cannot
stand high thermal exposures and has low mechanical properties.
Alternatively, in prior available FR viscose blends Aramide fibers
have been used for mechanically and flame resistancy reasons. As
there is no thermoplastic fiber involved, the blend cannot be
heatsetted and therefore shows disadvantages in the care process,
and the dimensional stability is limited. For dyeing of Aramide
blends, a carrier is unavoidable. Another way of designing easy to
dye fabrics is double face technology, whereby an easy to dye fiber
component is mainly on the surface of the fabric and the
reinforcement and FR components are in a second layer, e.g. "full
option" Kermel blend. Such disadvantages are overcome according to
the concept of the present invention, as set out in more detail
below.
[0008] One object of the invention is to provide a flame protective
fabric structure with improved protection properties such to
achieve an improved non-melt performance and preferably good dye
ability and color quality.
[0009] The present invention provides a flame protective fabric
structure according to claim 1 and a clothing article comprising
such flame protective fabric structure according to claim 16. The
dependent claims refer to embodiments of said fabric structure and
clothing article.
[0010] In a first aspect, there is provided a flame protective
fabric structure comprising a fabric being formed with multiple
yarns, wherein each of the yarns is made of a fiber blend of at
least a first fiber component and a second fiber component, the
first fiber component comprising flame resistant (FR) viscose
fibers in an amount of at least 50% of the fiber blend weight and
the second fiber component comprising meltable fibers in an amount
of at least 10% of the fiber blend weight. The fabric is formed as
a woven fabric with a total fractional cover factor of greater than
60% having a capability to withstand a horizontal flame exposure of
10 seconds without hole formation according to ISO
15025/14116_Index III.
[0011] The invention provides the advantage that a woven fabric
structure based on a fiber blend of FR viscose fibers and meltable
fibers can withstand high temperatures, thus providing flame
protection. The melting component, particularly the melting polymer
component reinforces the fiber structure of the viscose fibers,
thus strengthening the fabric structure itself until the flame and
heat exposure stops. The woven fabric structure with a total
fractional cover factor of greater than 60% ensures the required
tightness and density of the fabric structure to hinder a break
open in the flame exposure. Therefore, it provides, as a result of
the particular combination of its constitutional and constructional
features, a capability to withstand a horizontal flame exposure of
10 seconds without hole formation according to ISO
15025/14116-Index III.
[0012] According to existing art, fabrics are typically assessed
with respect to flame retardancy according to their specific
weight, i.e. flame retardancy is typically assessed to be higher
with fabrics having a higher specific weight compared to light
weight fabrics, On the other hand, with this invention it has been
found that the cover factor, particularly the total fractional
cover factor, is an appropriate means for achieving and improving
flame resistance. Increasing the cover factor, however, may also
increase material and manufacturing costs. A cover factor in that
amount has been found to be advantageous for fulfilling the
requirements of ISO 15025, since it has been found that such
closely woven structure ensures that flames cannot break
through.
[0013] A woven fabric refers to a fabric formed by weaving. Weaving
is a process of fabric forming by the interlacement of warp and
weft yarns. Both warp and weft yarns run essentially straight and
parallel to each other, either lengthwise (warp) or crosswise
(weft). Woven fabric only stretches diagonally on the bias
directions (between the warp and weft directions), unless the
threads are elastic.
[0014] According to an embodiment the total fractional cover factor
is .gtoreq.60%, preferably greater than 65%. It has been found that
such cover factor results in obtaining a reproduceable flame
resistancy over a high number of fabrics.
[0015] With providing a fiber blend having a defined ratio of FR
viscose fibers and meltable fibers in each of the yarns, an
effective mixture can be achieved to prevent the typical
fusion/melting behaviour of the meltable fibers, such as polyamide.
The fabric with such blend of fiber components in the yarns does
not show the typical melting behaviour, since the molten component
of the yarn is taken up by the viscose fibers of the yarn, and does
not show dripping and a sticky behaviour after cooling. In
particular, the FR viscose fiber component of the fiber blend is
able in case of heat exposure to hold/store the molten fiber
component within its fiber structure. The flame protection by the
FR component in the FR viscose fiber is sufficient to stop the
afterflame and afterglow. Particularly, the FR viscose fibers and
the meltable fibers are homogeneously distributed within the blend
of the yarns of the fabric.
[0016] Using an amount of at least 10% meltable fibers like
polyamide has the advantage of providing sufficient reinforcement
of the viscose fibers, good dyeability and color quality.
Especially when the meltable fibers melt upon flame exposure, they
contribute to stabilizing the viscose fibers so that these may
maintain their flame protection properties upon flame exposure over
a longer time.
[0017] Using an amount of at least 50% FR viscose fibers has the
advantage of providing sufficient amount to take up the molten
component, a good flame protection and the use of the moisture
management capabilities of viscose fibers.
[0018] Particularly, textile structures based on FR viscose can
withstand high temperatures until the meltable fibers, such as PA
polymer, start decomposition, wherein the melting polymer is used
to reinforce the grid structure of the FR viscose fibers and
strengthening the package until the flame and heat exposure
stops.
[0019] Therefore, a thermally stable, dyeable flame protective
fabric structure for Personal Protective Equipment use can be
provided.
[0020] The meltable fiber component or fibers can be provided with
flame retardant additives for increasing the flame resistance.
However, it is not required to add flame retardant additives into
the meltable fiber component, but it is possible to do so.
[0021] Meltable fibers are fiber materials that are meltable when
tested according to the Melting and Thermal Stability test.
According to an embodiment, in accordance with the Melting and
Thermal Stability Test such meltable fibers have a melting
temperature of less than 268.degree. C.
[0022] According to an embodiment of the invention, the meltable
fibers are made of polyamide (optionally including inert FR
additive), preferably of polyamide 6.6, Alternatively PP
(polypropylen), and/or PE (polyethylen) may be used. Polyamide 6.6
has a melting temperature in the range of 255-260.degree. C.,
polyamide 6 has a melting temperature in the range of
215-220.degree. C., polypropylen has a melting temperature in the
range of 160-175.degree. C. and polyethylen has a melting
temperature in the range of 105-135.degree. C.
[0023] Polyamide fibers are popular in fabrics applications because
they are easy to dye, have a high abrasion resistance, are easy to
manufacture and cheap in comparison to other fibers. Typically,
polyamide fibers are not used in flame protective applications as
the LOI of polyamide is with 22 too low for flame retardant
performance on its own and the fibers show melting, dripping;
afterglow; afterburn and hole formation in flame tests. There is a
broad range of other known additional or continuative textile
manufacturing processes which are easy to adopt (e.g. sanfor,
brushing, calendring, etc.).
[0024] According to the invention, after a direct horizontal flame
exposure for 10 seconds according to ISO 15025/14116_Index III, an
afterburn, melting and hole formation of the fabric structure
according to the invention can be prevented.
[0025] In one embodiment the inventive fabric structure comprises
at least on barrier layer adjacent to one side of the fabric. It
was found that a combination of the fabric structure and at least
one barrier layer can deliver a multilayer arrangement which
protects against open flame according to ISO 15025 A for 10 seconds
(Full FR Protection).
[0026] According to an embodiment of the invention, the fiber blend
comprises the flame resistant viscose fibers and the meltable
fibers in a weight ratio of 80:20.
[0027] According to an embodiment, the above advantages are
particularly well observable with a fabric having blended fibers
containing 80% viscose FR fibers and 20% polyamide fibers.
[0028] The fabric is formed as a woven fabric or textile with a
total fractional cover factor of greater than 60%. It provides, as
a result of the particular combination of its constitutional and
constructional features, a capability to withstand a horizontal
flame exposure of 10 seconds without hole formation according to
ISO 15025/14116_Index III.
[0029] The fabric structure performs as full FR protective layer
and remains its non melt performance, and shows no visible molten
droplets after FR exposure or convective heat exposure.
[0030] According to an embodiment of the invention, the inventive
fabric structure achieves an LOT of greater than 25, in the
combination with a microporous PTFE containing membrane the LOI can
be increased far more than 27 (>>27), most likely greater
than 30, depending on the weight of the PFTE component.
[0031] According to an embodiment of the invention, at least one
third fiber component or more additional fiber components can be
used in the fiber blend in combination (e.g., antistatic fibers) in
an amount of not more than 3% of the fiber blend weight. Additional
fiber components may include carbon fiber, steel fiber, anti micro
bacterial fibers (like silver fibers or metal ion containing
fibers), PTFE fibers.
[0032] Particularly, the yarns of the fabric according to the
invention do not include fibers or fiber blends comprising
Aramides, PBI, or Modacryl, particularly do not include aramides,
paraaramid, meta-aramid, PBI, Modacryl or blends thereof.
[0033] According to an embodiment, the flame resistant (FR) viscose
fibers are man-made cellulosic fibers comprising flame resistant
additives which have been incorporated in the viscose matrix during
fiber production.
[0034] In a particular embodiment, the fabric according to the
invention has a weight in the range of 50 g/m.sup.2 to 550
g/m.sup.2, preferably 90 g/m.sup.2-300 g/m.sup.2, more preferably
140 g/m.sup.2+/-10 g/m.sup.2.
[0035] According to a further embodiment of the invention, the
fabric structure comprises at least one barrier layer adjacent to
one side of the fabric. For example, the barrier layer comprises a
porous membrane layer made of expanded polytetrafluoroethylene
(ePTFE).
[0036] Preferably, the first fiber component and the second fiber
component are homogenously distributed in the yarns.
[0037] Regarding the dyeing, in an embodiment of the invention, at
least one surface of the fabric is dyed such that it has a color
fastness of greater than 4. According to another embodiment, at
least one surface of the fabric is dyed with a carrier-free dye and
such that it has a color fastness of greater than 4. Preferably,
the carrier-free dye is directly integrated into the fabric on at
least one surface of the fabric having a color fastness of greater
than 4. According to a further embodiment, the fabric is printed
with a dye having a color fastness of greater than 4, particularly
for camouflage applications.
[0038] Further advantageous features and aspects of the invention
are evident from the dependent claims.
[0039] The invention will now be described by way of example
according to embodiments with reference to the following Figures,
in which:
[0040] FIG. 1 shows a schematic cross-sectional view of a yarn of a
fabric structure according to an embodiment of the invention,
[0041] FIG. 2 shows a schematic top view of a part of a flame
protective fabric structure according to an embodiment of the
invention,
[0042] FIG. 3 shows a schematic cross-sectional view of a flame
protective fabric structure which comprises a laminate of a flame
protective fabric and a barrier layer according to an embodiment of
the invention,
[0043] FIG. 4 shows an exemplary clothing article with comprises a
flame protective fabric structure according to the invention,
[0044] FIG. 5 shows a schematic sectional view of a woven fabric
structure for illustrating the fractional cover as used herein,
[0045] FIG. 6 shows a schematic view of a unit cell of plain fabric
for illustrating the total fractional cover factor as used
herein.
[0046] In the following, embodiments of the invention will be
explained with reference to FIGS. 1-4, wherein FIG. 2 shows a
schematic top view of a part of a woven flame protective fabric 10
in a flame protective fabric structure 1, and FIG. 1 shows a
schematic cross-sectional view of a yarn 20 of the fabric 10
according to an embodiment of the invention.
[0047] The fabric 10 is formed as a woven fabric with warp and weft
yarns 20 each made of a fiber blend of at least a first fiber
component and a second fiber component, as shown in FIG. 1.
Particularly, the first fiber component comprises flame resistant
viscose fibers 22 and the second fiber component comprises meltable
fibers 24. More specifically, the flame resistant viscose fibers 22
are provided in an amount of at least 50% of the fiber blend weight
and the meltable fibers 24 are provided in an amount of at least
10% of the fiber blend weight. Said ratio ensures the required
flame protection due to a sufficient high amount of flame resistant
fibers and the required stability due to a defined range of a
minimum amount of meltable fibers.
[0048] The fabric 10 is a woven textile construction, especially
formed in a plain weave construction, as shown schematically in
FIG. 2.
[0049] In one embodiment the fiber blend comprises the flame
resistant viscose fibers 22 and the meltable fibers 24 in a weight
ratio of 80:20. According to an embodiment, the meltable fibers 24
are made of polyamide (PA), preferably of polyamide 6.6.
Preferably, the first fiber component, i.e. the viscose fibers 22,
and the second fiber component, i.e. the meltable fibers 24, are
homogenously distributed in the yarns 20.
[0050] As explained in more detail below, the fabric 10 is formed
as a woven fabric or textile with a total fractional cover factor
of greater than 60%. A dense and tight fabric structure is
necessary for a flame resistant fabric in order to prevent the
formation of holes in case of flame exposure. Especially with a
woven fabric, highly dense and tight fabric structures can be
provided which stabilize each other within the fabric
structure.
[0051] The cover factor quantifies the grade of density and
tightness of the woven fabric structure with regard to ratio, yarn
fineness, woven fabric and density. In general the cover factor
indicates the extent to which the area of a fabric is covered by
one set of threads. FIG. 6 shows a principle aspect of the total
cover factor, a top view of a woven fabric with the combination of
fractional cover factor warp and weft.
[0052] The inventive fabric structure provides, as a result of the
particular combination of its constitutional and constructional
features, a capability to withstand a horizontal flame exposure of
10 seconds without hole formation according to ISO
15025/14116_index III.
[0053] According to an embodiment, the fabric 10 has a weight in
the range of 50 g/m.sup.2 to 550 g/m.sup.2, preferably 140
g/m.sup.2.+-.10%.
[0054] As shown in FIG. 3, the flame protective fabric structure 1
further comprises an additional barrier layer 30 adjacent to one
side of the fabric 10, for example, laminated to the fabric 10 by
adhesive 40 discontinuously distributed over one surface of the
fabric 10 so as to not compromise breathability of the fabric
structure 1. According to an embodiment, the barrier layer 30 is
formed from a membrane layer and may be waterproof and/or
windproof, and it may be breathable, i.e. permeable to water vapor.
In one embodiment the harrier layer 30 is formed from a porous
membrane made of expanded polytetrafluoroethylene (ePTFE). With the
combination of the fabric 10 with a functional barrier layer 30,
particularly an ePTFE comprising membrane, the thermal protection
level can be improved further. Particularly, using a microporous
ePTFE barrier improves flame retardancy performance
considerably.
[0055] In this context, all known types of such functional barrier
layers can be used. By providing a waterproof, water vapor
permeable barrier layer 30, an additional protective function can
be achieved, so that, in addition to the above-mentioned protective
properties, waterproof protective clothing can also be achieved
that has high wearing comfort, because of the
water-vapor-permeability.
[0056] Appropriate materials for a waterproof,
water-vapor-permeable barrier layer are especially polyurethane,
polypropylene, and polyester, including polyether ester and
laminates thereof, as described in the documents U.S. Pat. No.
4,725,418 and U.S. Pat. No. 4,493,870. However, expanded
microporous polytetrafluoroethylene (ePTFE) is particularly
preferred, as described, for example, in documents U.S. Pat. No.
3,953,566, as well as U.S. Pat. No. 4,187,390, and expanded
polytetrafluoroethylene provided with hydrophilic impregnation
agents and/or hydrophilic layers; see, for example, document U.S.
Pat. No. 4,194,041. "Microporous functional layer" or "microporous
barrier layer" is understood to mean a functional layer whose
average pore size is between about 0.2 .mu.m and about 0.3 .mu.m.
The pore size can be measured with a Coulter Porometer.TM.,
produced by Coulter Electronics, Inc., Hialeah, Fla., USA.
[0057] A functional or barrier layer and the respective laminates
are considered "waterproof" optionally including the seams provided
on the barrier layer, if it guarantees a water-entry pressure of at
least 1.times.10.sup.4 Pa. The barrier layer material preferably
guarantees a water-entry pressure of more than 1.times.10.sup.5 Pa.
The water-entry pressure is then measured according to a test
method in which distilled water, at 20.+-.2.degree. C., is applied
to a sample of 100 cm.sup.2 of the barrier layer with increasing
pressure. The pressure increase of the water is 60.+-.3 cm H.sub.2O
per minute. The water-entry pressure then corresponds to the
pressure at which water first appears on the other side of the
sample. Details of the procedure are stipulated in ISO standard
0811 from the year 1981.
[0058] A functional or barrier layer is then considered
"water-vapor-permeable" if it has a water-vapor transmission
resistance Ret of less than 150 m.sup.2 Pa/W. Water vapor
permeability may be expressed by water vapor transmission
resistance (RET) The water vapor transmission resistance (RET) is a
specific material property of sheet-like structures or composites
which determines the latent evaporation heat flux through a given
area of the sheet-like structure or composite, under a constant
partial pressure gradient. The RET is measured by the Hohenstein
skin model, of the Bekleidungsphysiologisches Institut (Apparel
Physiology Institute] e.V. Hohenstein. The Hohenstein skin model is
described in ISO 11092:1993.
[0059] For instance, the barrier layer 30 is waterproof in that it
bears a water pressure of at least 8 kPa (according to ISO
811-1981). It may have a water vapor transmission resistance
Ret<20 m.sup.2 Pa/W (ISO 11092).
[0060] The barrier layer may be air impermeable according to an air
permeability of <1 l/m.sup.2/s (ISO 9237-1995; 100 cm.sup.2, 2.5
kPa). The barrier layer may be windproof according to an air
permeability of <50 l/m.sup.2/s (ISO 9237-1995; 100 cm.sup.2,
2.5 kPa). For example, the barrier layer has an air permeability of
not more than 6 l/m.sup.2/s (according to ISO 9237).
[0061] According to an embodiment, the fabric 10 is formed in a
plain weave construction. It was found that, advantageously, a
blend of 20% polyamide (PA) (particularly, PA 6.6 high tenacity)
and 80% Lenzing FR fiber is a fiber blend with a good combination
of advantageous properties as outlined herein, particularly for a
plain weave fabric, such as having a weight of 140 g/m.sup.2. In
other weight categories the ratio can be adjusted but should
maintain a minimum percentage of 50% viscose FR fibers.
[0062] According to an embodiment, the woven fabric comprises a
total fractional cover factor of greater than 66%. Particularly, it
comprises a fractional cover factor weft of greater than 33%,
and/or a fractional cover factor warp of greater than 50%,
preferably adding up to a total fractional cover factor of greater
than 66%.
[0063] Additional blended fiber components in small quantities,
e.g. for antistatic properties, can be added as long as they do not
change the performance as considered in the concept.
[0064] The blend of meltable, e.g. polyamide, and viscose FR fibers
can be processed in conventional staple fiber spinning processes,
e.g. ring spinning, open end, and/or compact spinning. For example,
the flame resistant viscose fibers and meltable fibers are made by
staple fiber spinning and twisting.
[0065] The coloring process may be very flexible for the fiber
blend or the fabric structure, the choice of the fiber components
allows the dying of the fiber blend or the fabric structure with
reactive dye stuff. As well, high quality printing is possible
delivering a clear, high-contrast print with high color fastness
with reactive dye stuff, which may be required for multiple uniform
applications.
[0066] The inventive fabric structure itself shows a Limited Oxigen
Index (LOI) of greater than 25, together with a microporous ePTFE
containing membrane the level can be increased above 30.
[0067] The invention provides the advantage that all fibers in the
blend may be chosen such that they are dyeable in high quality. The
components of the blend are easy to process, therefore providing
good repeatability. Thermosetting is possible, therefore providing
a durable easycare performance, and all components together deliver
high thermal stability and a very high LOI.
[0068] In the following, possible fiber components according to
embodiments of the invention are described in more detail:
Flame Retardant or Resistant Viscose Fiber (in the Following: FR
Viscose Fiber):
[0069] According to embodiments of the invention, a variety of
flame resistant viscose fibers can be used. In the following,
examples of various embodiments of appropriate flame resistant
viscose fibers are described:
[0070] According to an embodiment of the invention, the FR Viscose
fiber is a man-made cellulosic fiber which is flame retardant by
incorporating "phosphorous" in the viscose matrix. The phosphorous
flame retardant (or any other appropriate flame retardant) is
incorporated at the fiber spinning stage. FR Viscose has been
extensively used in fabric blends where it provides increased
moisture absorption and comfort without compromising protection.
The dyeability of the FR Viscose fiber is possible in a wide range
of colors; however, color fastness to laundering is variable and
similar to normal viscose fiber. FR Viscose is stable when exposed
to a wide variety of acids and alkalis. FR Viscose is stable when
exposed to a wide variety of bleaching agents and organic solvents.
It has typically a LOI of 29.
[0071] Particularly, flame resistant viscose fibers as may be used
herein are cellulosic man-made fibers containing viscose. An
overview of methods used to render cellulosic textiles
flame-retardant (or flame-resistant) and the mechanisms used for
this is supplied by the publication: Horrocks, A. R.; Kandola, B.
K. "Flame Retardant Cellulosic Textiles" Spec. Publ.-Royal Society
of Chemistry, volume 224, year 1998, pages 343-362. The methods
described differ in the element responsible for the
flame-retardation (mainly phosphorus, however, nitrogen, boron and
sulphur as well), the place of the application (surface treatment
mainly with cotton, additive in fiber production with man-made
fibers) and the permanency (degree of resistance of flame-retardant
properties after laundering treatments).
[0072] Among the cellulosic man-made fibers, a large number of
substances were suggested as flame-retardant additives for viscose
fibers in fiber production.
[0073] In U.S. Pat. No. 3,266,918 Tris(2,3-bromopropyl)phosphate is
suggested as the flame-retardant agent. A fiber of this kind was
produced for some time on an industrial scale.
[0074] A class of substances used as a flame-retardant agent is
that of substituted phosphazenes, A flame-retardant viscose fiber
was produced at industrial level on the basis of these substances
(U.S. Pat. No. 3,455,713). The flame-retardant agent is however in
liquid form and can only be spun into viscose fibers with a lower
yield (approx. 75 weight percent) and it tends to migrate out of
the fiber thus giving the fiber an undesirable stickiness.
[0075] Apart from the above named Tris(2,3-bromopropyl)phosphate, a
series of other organo-phosphates respectively phosphonic acid
amides and esters were described as flame-retardant agents for
viscose fibers (DE 2,451,802; DE 2,622,569; U.S. Pat. No.
4,193,805; U.S. Pat. No. 4,242,138; JP 51-136914; DE
4,128,638).
[0076] Of this class of substances, until now only the compound
2,2'-oxybis[5,5-dimethyl-1,3,2-dioxaphosphorinane]2,2 fulfils the
requirements with regard to the effectiveness (the necessary amount
of incorporation in order to fulfill EN ISO 15025:2002),
quantitative yield in the spinning process and not containing
halogen.
[0077] As a possible FR Viskose fiber, Lenzing FR Viskose fibers
may be used.
[0078] Possible meltable fibers are PA (polyamide), PP
(polypropylen), and/or PE (polyethylen), which may be used
herein.
[0079] Polyamide Fiber, Particularly Polyamide Staple Fiber:
[0080] Most technically important polyamide (PA) types are
part-crystalline thermoplastic polymers and are characterized by a
high firmness, rigidity and tenacity, possess a good chemical
resistance and workability. PA Fiber up to now is typically not
used in FR applications as the LOI is with 22 too low for FR
performance on its own and the fibers show melting and hole
formation in flame tests. In blends it has been used only with
cotton with additional FR post treatment (probanisation).
[0081] Possible polyamide fibers are made of polyamide (PA), such
as PA 6, PA 6.4, PA 6.12, and/or PA 6.6.
Dyeability:
[0082] Dying as used herein shall be understood as relating to a
process of adding color to the textile component. For example, it
may comprise processes like color printing, transfer film printing
and all known dye bath processes.
EXAMPLES
[0083] In an exemplary embodiment, a fabric structure according to
the invention comprises in a homogeneous distribution of fibers a
fiber blend of 20% Cordura.RTM. (PA 6.6) commercially available by
the company Invista and 80% Lenzing FR.RTM. viscose fibers,
commercially available by the company Lenzing made by ring spinning
and twisting, the fabric formed as a woven fabric (plain weave)
with a total cover factor of 66.6% and a weight of 140
g/m.sup.2.+-.10%, which passes the horizontal flame test. The
fabric can be provided with a flour carbon finish.
Example 1
Textile Components
TABLE-US-00001 [0084] Construction: Plain weave Fabric content: 80%
FR viscose/20% Polyamid 6.6 Fiber 1 FR Viscose, 40 mm (staple
length) Lenzing FR Type Fiber 2 Polyamid 6.6, 40 mm (staple length)
Invista 420 Yarn blend: Ring spin process Treatment: 4 g/m.sup.2
Flourcarbon Description unit standard Values weight g/m.sup.2 137.9
cover factor % warp 50% % weft 35% % total 66.60% face ignition
test initial test method ISO 15025 afterburn sec. warp/weft 0
afterglow sec. warp/weft 0 Hole formation mm according to ISO 14116
warp/weft 0 INDEX III face ignition test after test method ISO
15025 washing afterburn sec. after 5.times. ISO 6330 2A, E
warp/weft 0 afterglow sec. warp/weft 0 Hole formation mm according
to ISO 14116 warp/weft 0 INDEX III thermal stability initial %
according to ISO 11612 warp -1.2% oventest ISO 17493@185.degree.
C., 5 min weft -1.1% thermal stability after % according to ISO
11612 warp -1.3% washing ISO 17493@185.degree. C., 5 min weft -1.0%
oventest ISO 6330 2A, E dimension stability after % DIN EN ISO 5077
warp 0.0% washing ISO 6330 2A, E weft -1.0% after 5 times HLC
60.degree. C. dimension stability after % DIN EN ISO 5077 warp 1.0%
dry cleaning after 5 times dry cleaning weft -1.0% cycles tensile
strength N DIN EN ISO 13934-1 warp 565 weft 425 tear strength
(single) N DIN EN ISO 13937-2 warp 35 weft 33
Example 2
Laminate Components
TABLE-US-00002 [0085] Face Fabric: 80% FR viscose 20% Polyamid 6.6
Membrane: Bicomponent Membrane based on ePTFE Description unit
Standard Values weight g/m.sup.2 ISO 3801 160.2 face ignition test
initial test method ISO 15025 afterburn sec. warp/weft 0 afterglow
sec. warp/weft 0 holeformation mm according to ISO 14116 warp/weft
0 INDEX III face ignition test after washing test method ISO 15025
afterburn sec. after 5.times. ISO 6330 2A, E warp/weft 0 afterglow
sec. warp/weft 0 holeformation mm according to ISO 14116 warp/weft
0 INDEX III thermal stability initial % according to ISO 11612 warp
-1.3% oventest ISO 17493@185.degree. C., 5 min. weft -1.3% thermal
stability after washing % according to ISO 11612 warp -1.2%
oventest ISO 17493@185.degree. C., 5 min. weft -1.0% ISO 6330 2A, E
dimension stability after washing % EN ISO 5077 warp -2.4% after 5
times HLC 60.degree. C. after 5.times. ISO 6330 2A, E weft -1.9%
dimension stability after dry % EN ISO 5077 warp -0.5% cleaning
after 5 times dry cleaning cycles after 5.times. EN ISO 3175-2 weft
-0.4% tensile strength N DIN EN ISO 13934-1 warp .gtoreq.471 weft
.gtoreq.346 tear strength (single) N DIN EN ISO 13937-2 warp
.gtoreq.31 weft .gtoreq.30
[0086] FIG. 4 shows an example of a clothing article 70 in the form
of an outer covering, for example, a firefighting protective
jacket, constructed with a fabric structure 1 according to the
invention, as explained above. In particular, the fabric 10 is
arranged to form an outer material 71 of the clothing article 70
and the barrier layer 30 may be part of a two or three layer
laminate attached to the inner side of the fabric 10, as shown in
FIG. 3, the laminate forming an inner material 72 of the clothing
70.
[0087] Several advantages according to aspects of the invention are
in particular: [0088] Good dye ability, color quality, and piece
dye process (reactive dye), [0089] non melt performance, no visible
melting or brittling of the meltable fiber component (determined by
the oven test at a temperature of 260.degree. C.), [0090] good
protective fabric characteristics like abrasion resistance,
dimensional stability, no need for additional FR post treatment
[0091] In an embodiment of the fabric structure, in which the
fabric is combined with a thermally resistant film (such as PTFE)
in a laminate, a very high LOI>27 can be obtained.
[0092] According to embodiments of the invention, the following
improvements versus existing solutions can be obtained:
[0093] The inventive fabric structure shows a lower textile weight
than a fabric structure made with, e.g. Modacryl/Cotton blends or
Viscose Modacryl blends.
[0094] A sample of a fabric structure according to the invention
having a weight of 140 g/m.sup.2 can pass the ISO 15025 requirement
as set out above. In comparison, a Modacryl/Cotton blend requires a
minimum fabric weight of 230 g/m.sup.2 to pass said ISO 15025 test.
Plain colors can be obtained with high color fastness as compared
to Aramide fiber blends (achievable color fastness>4 for
ISO105-B02, -X12).
[0095] No post FR treatment is required as compared to
cotton/polyamide blends (such as INDURA.RTM. SOFT).
Terms/Test Methods:
[0096] The term "flame retardant" or "flame resistant", in the
context of this invention, means that the fabric structure has
limited flame propagation and works as flame barrier against break
open under flame exposure. European standard EN 533 (1997)
establishes performance requirements for limited flame propagation
of materials, based on the results of tests according to EN 532
(corresponds to EN ISO 15025 (2003)/14116).
Melting and Thermal Stability Test:
[0097] The test was used to determine the thermal stability of
textile materials. This test is based on thermal stability test as
described in section 8.3 of NFPA 1975, 2004 Edition. The test oven
was a hot air circulating oven as specified in ISO 17493. The test
was conducted according to ASTM D 751, Standard Test Methods for
Coated Fabrics, using the Procedures for Blocking Resistance at
Elevated Temperatures (Sections 89 to 93), with the following
modifications: [0098] Borosilicate glass plates measuring 100
mm.times.100 mm.times.3 mm (4 in..times.4 in..times.1/8 in.) were
used. [0099] A test temperature of 265.degree. C., +3/-0.degree. C.
(510.degree. F., +5/-0.degree. F.) was used.
[0100] The specimens were allowed to cool a minimum of 1 hour after
removal of the glass plates from the oven.
[0101] Any sample side sticking to glass plate, sticking to itself
when unfolded, or showing evidence of melting or dripping was
considered as meltable. Any sample side lacking evidence of
meltable side was considered as thermally stable.
[0102] For the purpose of this invention, a textile made of
meltable fibers according to an embodiment of the invention has
been manufactured and tested based on the test description
above.
Horizontal Flame Exposure Test:
[0103] Measurement of flame retardant was carried out in accordance
with International Standard ISO 15025 (2003) for 10 sec flame to
surface. Outer textile face of the sample was exposed to the flame
for 10 sec. After flame time was recorded. Samples with an after
flame time of greater than 10 sec were considered as flammable.
Samples with an after flame of 2 sec or less were considered as
non-flammable. Preferred samples have an after glow of 2 sec or
less. Most preferred samples have no after flame, no after glow and
no hole formation.
[0104] The performance is expressed by an index of limited flame
propagation defined in ISO 14116, Three performance stages are
established: [0105] In index-I materials, no flame propagation
occurs, hole formation can occur during flame contact. [0106] In
index-II materials, no flame propagation occurs, hole formation
does not occur on flame contact, [0107] In index-III materials, no
flame propagation occurs, hole formation does not occur on flame
contact, only limited afterburning occurs.
[0108] Clothing with Index III fulfills the requirements of
protective clothing for fire fighters and other Heat &Flame
protective clothing.
[0109] Regarding woven fabric calculation, and in particular
regarding cover factor, the following definitions are given:
Cover Factor:
[0110] The cover factor indicates the extent to which the area of a
fabric is covered by one set of threads.
[0111] For any fabric there are two cover factors: the warp cover
factor and the weft cover factor. The cloth cover factor is
obtained by adding the weft cover factor to the warp cover.
[0112] Calculation: The cover factor in SI units is calculated
as:
Cover Factor (SI): (threads/cm)/10.times. tex
[0113] The term "tex" is a standard unit of measure for the linear
mass density of fibers and is defined as the mass in grams per 1000
meters.
[0114] Example: Tex=20: threads/cm=28
Cover factor (SI)=(28.times. 20)/10=12.5
Cover Factor (Pierce)=n/ N where n=threads/inch and N is cotton
count
Fractional Cover Factor:
[0115] In fabrics constructed from yarns, cover may be considered
as the fraction of the total fabric area that is "covered" by the
component yarns. An over-simplification of the idea for woven
fabric is shown in FIG. 5.
[0116] The yarn has a circular cross-section of diameter, d, and
adjacent yarns are displaced by a distance s. The fractional cover
is then d/s.
[0117] In the ideal model, s will be equal to 1/n, where n is the
number of threads per unit length. The fractional cover could be
expressed in terms of d and n.
Fractional cover factor=d.times.n
Fractional Cover Factor:
[0118] C.sub.1=4.44 (tex/fiber
density).times.threads/cm.times.10.sup.-3
Total Cover Factor:
[0119] The total area covered by the fabric (Plain weave) is ABCD.
The shaded area in FIG. 6 is the part of the total area covered by
both yarns, and, because of this, it would not be strictly accurate
merely to add the warp and weft cover values together and quote
them as the total cover factor.
[0120] The shaded areas in FIG. 6 are each d.sub.1.times.d.sub.2
and the total area of the cell is s.sub.1.times.s.sub.2. By
definition, fractional cover factor, C=d/s. Hence
d.sub.1=C.sub.1s.sub.1
d.sub.2=C.sub.2s.sub.2
d.sub.1d.sub.2=C.sub.1s.sub.1C.sub.2s.sub.2
[0121] Expressed as a fraction of total area s.sub.1.times.s.sub.2,
the shaded area becomes:
d.sub.1d.sub.2=C.sub.1s.sub.1C.sub.2s.sub.2/s.sub.1.times.s.sub.2=C.sub.-
1C.sub.2
[0122] The term C.sub.1 C.sub.2 must be deducted from the sum of
C.sub.1 and C.sub.2, hence
Total fractional cover factor=C.sub.1+C.sub.2-C.sub.1C.sub.2
[0123] The fabric according to example 1 shows the following total
fractional cover factor:
TABLE-US-00003 Cover Factor (%) Fractional Cover factor warp C1 50
Fractional Cover factor weft C2 35 Total Fractional Cover factor:
66.6 C(tot) = (C1 + C2) - (C1 .times. C2)
* * * * *