Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02521626 2005-10-05
WO 2004/089143 PCT/IT2004/000208
PUNCTURE RESISTANT TEXTILE STRUCTURE, ESPECIALLY FOR SHOE
SOLES
DESCRIPTION
Technical Field
This invention concerns a textile structure suitable for use in footwear,
particularly
safety footwear, which is required to have a high level of resistance to
penetration by
sharp objects such as nails and the like, especially through the sole.
Background Art
There are known systems of composite structures used for shoe soles in safety
footwear
1o designed to protect the feet from sharp or pointed objects. Some of these
systems use
metal plates which, however, add weight and reduce the flexibility of the
shoe. The high
thermal conductivity of the metal plate also makes the shoes uncomfortable to
wear
under conditions of high temperature. In addition, there are further problems
when they
are worn in places subject to the surveillance of metal detectors.
Other systems male use of layers of fabrics made of aramidic fibers bonded
together by
a film of thermoplastic, polymers (see, for example, patent US63~8959). The
difficulty
with protective panels of this kind is that they are very expensive, due to
the use of
aramidic fibers a~nly.
Disclosure of Invention
2o The main object of this invention, therefore, is to provide a protective
textile structure to
be used in footwear, particularly shoe soles, which structure offers high
resistance to
piercing and penetration by sharp and pointed objects, while having limited
thickness
and weight, adequate flexibility and reduced cost.
A further object of this invention is to provide a perforation-resistant
textile structure
that is also antistatic and/or resistant to high temperatures.
These objects axe achieved with a perforation-resistant textile structure in
conformity
with enclosed claim 1. Advantageous forms of implementation of the invention
are
defined in the dependent claims.
The advantages and technical characteristics of the invention will appear
clear from the
3o following detailed description of two non-limiting examples of its
implementation.
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Brief Description of Drawings
In the drawings:
- Fig. 1 is a schematic illustration of a first textile structure in
conformity with the
invention;
- Fig. 2 shows the polyester fabric used in the structure of Fig. 1;
- Fig. 3 and 4 illustrate, respectively, the profile of the warp and weft of
the fabric in
Fig. 2;
- Fig. 5 is a schematic illustration of a second textile structure in
conformity with the
invention.
1o Modes of Implementation of the Invention
With reference to Fig. 1 and 5, a textile structure 10,10' resistant to
perforation in
conformity with the invention basically consists of a number of layers
12,14,12',14' of
woven fabrics bonded together by means of a thermoplastic elm. In particular,
the
structure consists of one or more layers 12,12' of woven aramidic fibers and
one or more
layers of high tenacity non-aramidic fibers (for example, polyamide,
polyester,
polyolefin, liquid crystal fibers) woven into a fabric structure. Each
separate layer of
fabric has, preferably on the right side, a treated surface 16 coated with a
polyurethane
andlor acrylic resin reinforced v~~ith poerJders of hard, abrasive substances,
preferably
microni~ed ceramic materials in the form ~f silicates, e.g. of aluminum.
2o In the structure, the layers of aramidic fibers can be individually
alternated with layers of
fabric in non-aramidic fibers.
Two textile structures, as described more in detail hereafter, have been found
to be
particularly effective as well as practical to produce.
With reference to Figures 1 to 4, a first textile structure resistant to
perforation consists
2s of a multilayer structure 10 including a layer 12 of a woven fabric in
aramidic fibers and,
stacked on this layer 12, three layers 14 of a woven fabric in high tenacity
polyester
fiber. The layers are bonded together by means of a thermoplastic film. At
least one side
of each layer has been provided with a surface ceramic treatment 16.
Advantageously, the layers of fabric 12,14 are treated on the right side of
the surface, the
30 layer of aramidic fabric 12 and the adjacent layer 14 of polyester fabric
with the treated
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surface 16 being in contact, the remaining layers of polyester fabric having
the treated
surface in contact with the untreated surface of the adjacent layer. In this
way, both outer
surfaces of the multilayer structure 10 are untreated. It is also advantageous
to use the
structure described above inside the soles of footwear with the layer in
aramidic fibers
s on the tread side.
Thanks to the coating of ceramic material on the individual layers of fabric,
a structure
produced in conformity with this invention has high mechanical resistance to
perforation
by pointed metal objects and impedes their progress through the layers of
fabric.
In addition, this structure is advantageously characterized by the fact of
being composed
1o in a proportion that does not exceed about 15 % by weight - of the total
weight of the
textile fibers used - of aramidic fibers, with the remaining part in high
tenacity polyester
fibers. This greatly reduces the production costs with respect to structures
consisting
entirely of aramidic fibers, maintaining it on the order of the production
costs of
structures consisting of mettall plates, over which it has the advantage of
being highly
15 flexible.
In the practical implementation of a protective structure in conformity with
the
invention, it has been found to be particularly advantageous to select fabrics
12,14
forming the multil~yer structure 10 described above in the following way.
Fabric in aramidic fibers:
20 - plain weave;
- warp yarns in aramidic fibers, specifically Kevlar~ 730 dtex, density 19 ~
2% per
cm;
- weft yarns in aramidic fibers, specifically Kevlar~ 730 dtex, density 1 S ~
2% per
cm;
2s - ceramic surface layer applied by coating with 90 = 120 gr/sq.mt. of a
compound
consisting of 50% polyurethane resin, 25% acrylic resin, and 25% aluminum
silicate.
The fabric produced in this way has a finished weight of 340 = 350 ~ 5%
gr/sq.mt. with
a composition by weight of approximately 80% Kevlar ~, 10% polyurethane, 5%
acrylic, 5% aluminum silicate.
3o Fabric in polyester fibers:
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- compound weave (illustrated in Figures 2 to 4), made up of two simple weaves
3X3;
- warp yarns in high tenacity (H.T.) polyester fiber 1100 dtex, density 22 ~
2% per
cm;
- weft yarns in high tenacity polyester fiber 1100 dtex, density 29 ~ 2% per
cm;
- ceramic surface layer applied by coating with 90 = 120 gr/sq.mt.
The fabric produced in this way has a finished weight of 690 = 720 ~ 5%
gr/sq.mt. with
a composition by weight of approximately 86% polyester fibers, 7%
polyurethane, 3.5%
acrylic, 3.5% aluminum silicate.
The weaves used make it possible to produce fabrics with very tightly woven
yarns,
to making their structure highly cohesive to provide by their very
construction a good
resistance to penetration, while maintaining a high degree of flexibility.
In particular, the compound weave used for the fabric in polyester fiber has
been found
to be particularly effective in the production of the multilayer sixucture 10.
The bonding between the layers of fabric is obtained by hot calandering with
the
insertion of a thermoplastic film (polyolefin and/or polyurethane and/or
polyester)
between the layers of the structure; processing the combination with heat
causes the
bonding by merger of the ceramic material both with the thermoplastic film and
with the
surface layer of the adjacent fabric layer so as to obtain a single unit ~~ith
a total
thiclgness of not more than 3 mm and limited weight.
2o f~dvantageously, using thermoplastic film made of polyester that is
resistant to high
temperatures, a structure can be obtained that is particularly suitable for
footwear
designed to be used in the presence of high heat sources.
The textile structure described above has a general composition of
- aramidic fibers by weight in a percentage of approximately 12%.;
- high tenacity polyester fibers by weight in a percentage of approximately
73%.;
- surface treatment in ceramic by weight in a percentage of approximately 15%.
- total weight 2435 = 2555 ~ 5% gr/sq.mt..
Tests carried out on the structure have proven its effective resistance to a
force of at least
1100N exerted by a nail, as foreseen by standards pr EN ISO 20344, EN 344/92
and EN
12568/98.
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By inserting electrically conductive wires in the fabric of the aramidic
fibers and in the
fabrics in non-aramidic fibers composing the multilayer structure, an
antistatic structure
is obtained which can be used in footwear for which this feature is required.
In particular, it is advantageous to produce the fabric in aramidic fibers
with:
s - the warp yarns consisting, every 74 threads, of a first yarn repeated 73
times in
Kevlar~ 730 dtex and a second yarn repeated once in high tenacity polyamide
180
dtex in two ply twisted with a filament in stainless steel measuring 60 micron
in
diameter (a composition thus consisting of 82% polyamide and 18% stainless
steel);.
- the weft yarns consisting, every 56 wefts, of a first weft repeated 55 times
in
1o Kevlar~ 730 dtex 730 and a second weft repeated once in polyamide and steel
as
described above.
The fabric in polyester fiber is in turn preferably produced with:
- 23 ~ 2°/~ warp threads per cm consisting, every 24 threads, of a
ftrst yarn repeated 23
times in polyester FLT. 1100 dtex and a second thread repeated once in
polyester
~5 I~.T. 1100 dtex plus a twisted filament of carbon (or steel) 24 dtex (final
composition 95 % polyester 5% carbon);
- 25.5 ~ 2% weft yarns per cm consisting, every 30 wefts, of a first weft
repeated 28
times in polyester I-LT. 1100 dte~~ and a second weir repyated t~~ice in
polyester I-LT.
and carbon as described shove.
2o A second example of a textile structure resistant to perforation in
conformity with the
invention is schematically illustrated in Fig. 5.
In this case the structure 10' includes two bonded multilayers 120,140,
consisting of a
first set of three stacked layers of a woven fabric 12' in aramidic fibers
provided with a
surface ceramic treatment 16 and a second set of three stacked layers of a
woven fabric
25 14' in high tenacity polyamide provided with a surface ceramic treatment.
Advantageously, at least two adjacent layers 12' of fabric in aramidic fibers
or two
adjacent layers of fabric 14' in polyamide fibers or the two adjacent layers
of the
multilayer structures 120,140 have the treated surfaces 16 in contact with
each other so
that both the outer surfaces (top and bottom) of the structure 10' are not
treated.
3o In practical implementation, it has been found to be particularly
advantageous to select
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the fabrics forming the multilayer structures 120,140 described above in the
following
way.
Fabric in aramidic fibers: as in the first example described above.
Fabric in polyamide fibers:
s - weft rep weave;
- warp yarns in polyamide 6:6 high tenacity fiber, 200 dtex, taslanized and
density 62
per cm;
- weft yarns in high tenacity nylon 6:6, 636 dtex, taslanized and density 16.5
per cm;
- surface layer of ceramic applied by coating of 60 gr/sq.mt. of the same
compound
to described above.
The fabric produced in this way has a finished weight of about 300 gr/sq.mt.
with a
composition by weight of 80% of polyamide fbers, 10% polyurethane, 5% acrylic,
5%
aluminum silicate.
A structure composed of three layers of fabric in aramidic fibers and three
layers of
1 s fabric in high tenacity polyamide as described above, has a general
composition of
- aramidic fibers by weight in a percentage of approximately 38%.;
- high tenacity polyamide fibers by weight in a percentage of approximately
34%.;
- ceramic surface treatment by weight in a percentage of appro~~imately
18°/~.;
- total weight approximately 2200 gr/sq.mt.
2o the thickness is under 3 mm (after bonding of the layers by hot calandering
and insertion
of thermoplastic film).
A textile structure capable of resisting penetration, as described in the
above examples,
is also thermally insulating and can be used, in the traditional way, as a
protective insert
into soles which are applied to footwear by means of sewing or gluing.
25 This structure can also be used advantageously in the production of
footwear the sole of
which is directly made on the upper by injection molding. For example, in
Strobel type
footwear, this structure can constitute the insole, which is first sewn onto
the upper after
which the sole is injected. It has been ascertained, in fact, that the
effective resistance to
perforation and penetration of a nail, according to the terms of standard EN
344/92, does
3o not prevent sewing the structure onto the upper, using needles of an
appropriate type.
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The invention thus conceived is susceptible to numerous alterations and
variations, all
coming within the sphere of the inventive concept. Also, all the details can
be replaced
with technically equivalent elements.
7_
