Note: Descriptions are shown in the official language in which they were submitted.
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THERMOINSULATIVE PROTECTIVE GA ENTS
FIELD OF THE INVENTION
The present invention relates to thermoinsulative
~ protective garments such as wet suits and cold or sea
survival suits.
PRIOR ART
British Patent No. 1,132,535 describes a thermoinsulative
protective suit including a water-tight and air-tight
overall having an inner "lining" of a thermoinsulative
voluminous synthetic thermoplastic fabric. The inner
"lining" appears to constitute a separate suit worn
below, but not connected to, the overall, although in the
paragraph bridging the two columns of page 3 of the
patent it is indicated that the fabrics of the overall
and the "lining" may alternatively be firmly united
together by sticking. The wearer's sweat is dissipated
into the voluminous fabric of the inner lining and the
suit provides insulation via a layer of air trapped
between the overall and the inner lining, as well as air
trapped within the voluminous fabric of the inner lining
and between the inner lining and the wearer's skin.
Such suit systems are bulky and unsuitable for wear in
non-emergency situations; even the lining on its own is
too bulky for ordinary wear. The use of such suits is
limited, therefore, to situations where there is
sufficient time during the emergency for a wearer to gain
access to, and don, both the inner "lining" sub-suit and
the outer overall.
British Patent No. 2,242,860 describes a thermoinsulative
protective fabric including a sheet of a substantially
impermeable closed-cell elastomeric material having
perforations provided therethrough, each perforation of
the sheet (or at least of a portion thereof) having at
least one relatively wide region snd at least one
relatively narrow region along its length to define an
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internal chamber open to a first side of the sheet (i.e.
the side towards the wearer's skin) and sufficiently
closed to the other side of the sheet -( i.e. the side away
from the wearer's skin) to permit moisture-laden air
passing from the first to the other side of the sheet to
accumulate in the chamber under increased pressure prior
to passing out to the other side of the sheet. Such a
fabric actively assists in removing moisture-laden air
from the vicinity of the wearer's skin and is wearable in
normal situations.
BRIEF DESCRIPTIpN OF THE INVENTION
We have now discovered that if an inner lining
constructed from a fabric in accordance with GB-2, 242, 860
is provided in a garment having a waterproof but vapour
permeable outer layer, the outer layer and lining being
sealed together at least at the apertures of the garment
so as to contain a layer of air between the outer layer
and the inner lining, an extremely advantageous
thermoinsulative clothing system is obtained, whereby the
outer layer and lining components positively interact to
enhance the advantages of the fabric of GB-2,242,860.
According to the present invention, there is therefore
provided a thermoinsulative protective garment-comprising
a first, outer, waterproof but vapour permeable, garment
part for covering at least a part of the body of a wearer
and a second, inner, thermoinsulative garment part
constituting a lining for the first garment part and
sealingly bonded to the first garment part at least at
the apertures) of the garment so as to contain a layer
of air between the said garment parts, wherein the second
garment part includes a thermoinsulative fabric sheet .
comprising a substantially impermeable closed-cell
elastomeric sheet having perforations provided
therethrough, each perforation of the sheet, or at least
of a portion thereof, having at least one relatively wide
region and at least one relatively narrow region along
its length to define an internal chamber open to the
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inner side of the sheet (i.e. the side of the sheet
directed towards the wearer's body) and sufficiently
closed to the outer side of the sheet (i.e. the side of
the sheet directed towards the outer garment part) to
~ 5 permit moisture-laden air passing from the inner to the
outer side of the sheet to accumulate in the chamber
under increased pressure prior to passing out to the
outer side of the sheet.
The expressions "relatively wide" and "relatively narrow"
mean that the respective regions of a perforation are
wide and narrow relative to each other. The expression
"fabric" includes a fabric portion, and the expression
"sheet" includes a sheet portion.
It should be noted that the layer of air described above
exists between the garment parts during normal use. In
conditions of which external pressure (e. g. hydrostatic
pressure when the garment is worn underwater ) the garment
parts may be pressed together so that no layer of air
exists between the garment parts.
DETAILE DESCRIPTION OF TRF INVENTION
The garment may take the form of a whole-body suit, a
top-body or bottom-body garment, a garment for the
extremities or any other garment providing for any
desired extent of body cover. A whole-body suit is
preferred in which gloves, shoes and/or balaclava
portions may optionally be incorporated. The garment is
relatively lightweight and tight-fitting, in comparison
with prior garments having similar uses. The garment has
the unique property of combining comfort in normal
working use with an ability to provide thermal insulation
and protection in the case of accidental cold water
immersion. The garment has the advantage of buoyancy, in
addition to thermal insulation, when used as a water-
immersion suit.
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The garment is suitably provided with resilient (e. g.
rubber) aperture seals, preferably of the type
conventionally used as cuff seals in dry-suit systems, to
prevent entry of water between the lining part and the
wearer's skin.
The outer garment part is preferably constructed from a
conventional fabric having the required properties of
being waterproof but vapour-permeable. Such fabrics may
comprise microporous membranes and/or coatings, e.g. of
a hydrophilic polymer (e.g. a polyurethane) to confer the
required properties. Depending on the intended
conditions of wear of the garment, the fabric of the
outer garment part may be further treated to confer
heatproofness, fireproofness, chemical-proofness and/or
resistance to biological or radiation degradation or
damage on the garment part. Any coating or similar
special surface of the fabric may suitably be on the
inner side of the first garment part (i.e. the side
directed towards the second garment part ) , to protect the
surface from external damage. The fabric of the outer
garment part will also normally have sufficient
durability, launderability and machinability so as to
make manufacture, cleaning and maintenance of the garment
acceptably simple and convenient.
The second garment part is preferably relatively close-
fitting to the wearer. The elastomeric sheet of the
second garment part is suitably formed of a closed-cell
neoprene or other suitable closed-cell elastomeric
polymer foam. The elastomeric sheet may suitably have a
thickness in the range approximately 0.5 mm to 10 mm ( for
example about 5.0 mm). The sheet may be a unitary sheet
or a laminate. In the case of a laminate, different
materials may if desired be used for different lamina so
as to provide a sheet having the desired properties.
Each perforation defines at least one chamber within the
elastomeric sheet at the relatively wide region( s ) of the
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perforation. A chamber is typically formed by a
depression in that side of the sheet which is closer to
the body of the user (the "inner" side), to partially
enclose a volume of air directly above the user's skin.
The walls of each relatively narrow region of the
perforations are suitably capable of resiliently
expanding and contracting in use between a relatively
closed condition, in which the perforation is practically
closed off to permit air to accumulate in the chamber
under increased pressure, and a relatively open
condition, in which the air accumulated in the chamber
can pass through the relatively narrow region to the
outer side of the sheet.
Closure of the perforations to the outer side of the
elastomeric sheet by a relatively narrow region of the
perforation, in the resting condition of the sheet, may
be complete or partial, and the materials and/or shape of
the perforations are suitably chosen so that on
stretching and/or bending of the sheet or one or more
particular lamina thereof the relatively narrow region
opens wider than Sts resting condition to allow exchange
of air between the two sides of the sheet. Stretching/
bending so as to cause the relatively narrow region of
the perforation to open typically results from the
desired build-up of pressure in the chamber and/or by
movement of the fabric in use.
The arrangement may also suitably be capable of creating
a pumping effect in the chambers) by the periodic
stretching and/or bending of the fabric in use, to assist
the exchange of afr between the inner and the outer sides
of the sheet.
In general, it is preferred that even at its widest
stretch the relatively narrow region of the perforation
is no more than about 65% of the widest width of the
relatively wide region, and less (most preferably
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substantially less) in the resting condition of the
sheet,-e. g. less than about 50%, more preferably lass
than about 35%, for example less than about 15%, of the ,
width of the relatively wide region in the resting
condition of the sheet. Where the sheet is a laminate,
different lamina may optionally be of different
flexibility, and suitably the lamina including the
relatively narrow region of the perforation may be of
greater flexibility than the lamina including the
relatively wide region, for example through being thinner
and/or of a material of greater elasticity.
The walls of each chamber are suitably shaped so that the
inner surface has a domed or conical configuration
closing towards the relatively narrow region of the
perforation at the apex, creating a structure whereby a
back pressure from outside the sheet may tend to collapse
the dome or cone to close the relatively narrow region at
the apex, whereas a forward pressure from the inner
towards the outer side of the sheet tends to open the
relatively narrow region of the perforation.
The perforations and associated chambers are suitably of
sufficient size and spacing apart to permit the natural
biological functions of the user's skin to continue
substantially unhindered over a desired period of time,
while permitting a controlled (but not excessive)
retention of the user's body heat. The perforations are
suitably provided in the elastomeric sheet at a density
of between about 500 and about 5,000 per square metre,
e.g. about 2,500 per square metre.
The perforations are preferably provided in the
elastomeric sheet by pressing the sheet in.a suitable
mould at a temperature of between about 100°C and about
200°C, e.g. about 150°C, and a pressure of between about
50 psi (345 kPa) and about 150 psi (1034 kPa), e.g. about
100 psi (690 kPa). The pressed sheet typically has
perforations which comprise hollow dome-like depressions
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in the inner surface of the sheet, forming the chambers
or relatively wide region of the perforations, closing
towards a relatively narrow region, at the apex of the
dome, which passes through the sheet as a straight sided
~ 5 pore to the outer surface. Dome-like depressions in the
inner surface of the sheet are suitably in the range from
about i.0 mm to about 18.0 mm, e.g. about 12.0 mm, in
diameter and in the range from about 1 mm to about 10.0
mm, e.g. about 6.0 mm, in depth.
The internal diameter of the relatively narrow region of
the perforation in its resting condition is suitably in
the range from about 0.01 mm to about 5.0 mm, e.g. about
1.0 mm. As viewed from the outer side of the sheet, the
tops of the domes project a short distance (suitably
between about 0.5 mm and 5 mm, e.g. about 2.5 mm) above
the surface and define dome-like projections from about
3.0 mm to about 20.0 mm, e.g. about 15.0 mm in diameter.
The elastomeric sheet may also include perforations of
different configuration to those described in GB-
2,242,860, e.g. conventional straight-sided fully open
perforations. The sheet may also include unperforated
regions.
The components of the second garment part should be non-
toxic, non-irritant and comfortable to wear (in the sense
of lightweight, flexible and soft to the touch), as well
as being resistant to attack and degradation from all
natural by-products of the user's body (e. g. sweat,
blood, tissue fluid, urine, pus, and gases such as carbon
dioxide). An internal layer of a skin-compatible fabric
such as woven material, e.g. cotton, is preferably
permanently bonded to the inner side of the second
garment part.
In the case of fabrics in which the elastomeric sheet is
a laminate, the lamina including the relatively marrow
region of the perforation may suitably be of greater
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flexibility than the lamina including the relatively wide
region.
The thermoinsulative fabric sheet of the second garment
part is preferably arranged to regulate .the wearer' s skin
temperature to normal body temperature (37°C). This
requires that the fabric functions as an insulator below
body temperature and as a cooling medium above body
temperature.
The capacity of the perforations to open above a
threshold chamber pressure and/or temperature can be
exploited to permit increased evaporative loss due to
sweating from the skin surface as the body temperature
exceeds 37°C, resulting in a skin temperature reduction
through loss of latent heat of vaporisation from the
skin. Thus, the fabric acts to cool the skin surface- an~3
maintain normal body temperature.
As the body temperature drops to 37°C the production of
sweat ceases and hence the cooling effect diminishes.
This is seen as a continuous process resulting in the
maintenance of homoiothermic biological conditions under
varying environmental temperatures.
Hy selecting particular elastomeric materials, particular
lamina thicknesses, particular sizes of relatively
wide regions of perforations, different concentrations of
perforations over the fabric area and/or different
arrangements of perforation types over the area of the
fabric, the fabric's properties can be adjusted to suit
the intended use. Moreover, by careful selection of
materials and configuration, the fabric can be made to
respond in its "breathability" to variations in external
conditions and/or in the user's biological functions, so
that to some extent such fabrics can self-regulate their
"breathability" and hence automatically control the
environment next to the wearer's skin within a pre-set
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temperature range. In one particular form, the
perforations open when the vapour pressure of moisture in
' the chambers) reaches saturated vapour pressure.
Particularly preferred for constructing the second
garment part is the material marketed under the brand
name STOMATEX (TM) by St. Albans Rubber Limited, Stanley,
County Durham, England.
As stated above, the first garment part overlies the
thermoinsulative fabric sheet and the two enclose in
normal use an intermediate layer of air. This itself
acts as a heat regulator in that it can provide an
insulating "blanket" effect within the garment while
enabling cooling through permeation of water vapour
through the first garment part, from whence the water
vapour is lost to the surroundings. However in extreme
external conditions of hydrostatic pressure underwater,
the first garment part is pressed firmly against the
second part, tending to close the perforations and cover
them so that the wearer's body fluids are conserved.
The improved self-adjustability of the system to extreme
conditions and combinations of circumstances is described
in more detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in greater detail,
but without limitation, with reference to the
accompanying drawings, in which:
Figure 1 shows in cross-section a portion of a
garment;
Figure 2 shows in cross-section detail of an outer
garment part;
Figure 3 shows in perspective and partial cross-
section a portion of an inner garment part;
Figure 4 shows in cross-section the garment portion
of Figure 1 when present in conditions of high external
pressure; and
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Figure 5 shows a partial cut-away perspective detail
of cuff (or other aperture) seals, and relationship of
parts of the garment.
',TAILED DESCRIPTION OF THE DRAWINGS , _ '
Referring to the drawings, there is shown generally a
thermoinsulative protective garment 1 comprising a first,
outer, waterproof but vapour permeable, garment part 2
and a second, inner, thermoinsulative, garment part 3
constituting a lining for the first garment part 2.
As shown in detail in Fig. 2, the first garment part 2 is
formed of a conventional fabric 4 coated on one surface
(preferably the inner surface in the made-up garment,
i.e. the surface directed towards the second garment part
3) with a polymer layer 5, e.g. a polyurethane.
The fabric 4 of -the first garment part 2 is vapour
permeable and waterproof and preferably has one or more
of the following additional properties: durability,
heatproofness, flreproofness, chemicalproofness,
resistance to biological and radiation dehydration or
damage, launderability and machinability. Such
properties can be conferred and/or enhanced by
conventional treatments applied to the fabric, as w311 be
readily understood by a worker of ordinary skill in this
art.
The garment parts 2 and 3 are sealingly bonded to each
other at least at the aperture( s ) of the garment ( as
discussed in more detail below, with reference to Fig. 5)
so as to contain a layer of air 6 between the garment
parts.
r
The second garment part 3 comprises a thermoinsulative
fabric sheet 7 and a porous woven fabric (e. g. cotton)
layer 8 bonded to the sheet 7 to provide a soft surface
in contact with the wearer's skin. Bonding is achieved
via conventional adhesives.
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The preferred thermoinsulative fabric sheet 7 is the
commercially available STOMATEX (TM) fabric (St. Albans
Rubber Limited, Stanley, County Durham, England). It
comprises a substantially impermeable closed-cell
~ 5 neoprene sheet of thickness about 5 mm, having
perforations 10 provided therethrough, each perforation
of the sheet 9 having a relatively wide region 11 and a
relatively narrow region 12 along Sts length to define an
internal chamber 13 open to the inner side of the sheet
9 and sufficiently closed to the outer side of the sheet
9 to permit moisture-laden air passing from the inner to
the outer side of the sheet be accumulated in the chamber
13 under increased pressure prior to passing to the outer
side of the sheet 9.
The chamber 13 is configured in the general form of a
hollow dome, through the apex of which passes the
relatively narrow region 12 of the perforation. The dome
projects above the outer surface of the sheet 9 by a
distance of about 2.5 mm and the diameter of the dome as
apparent from the outer surface of the sheet is about 15
mm.
The internal dimensions of the chamber 13 are as follows:
maximum internal diameter at the inner surface of sheet
9 approximately 12 mm; internal height approximately 6
mm.
The relatively narrow region 12 of the perforation
connects the apex of the chamber 13 to the outer side of
the sheet 9. The relatively narrow region 12 is in the
form of a straight-sided pore of diameter approximately
1 mm.
The chambers 13 are provided in the fabric at a density
of about 2,500 per square metre.
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The sheet 9 is suitably formed by pressing a 5 mm thick
sheet of closed-cell neoprene at a temperature of about
150°C and a pressure of about 100 psi (690 kPa). ,
Fig. 1 illustrates the garment in normal use on dry land. ,
The air space 6 keeps the garment parts 2 and 3 separate
and allows exchange of air through the perforations and
the permeable outer part 2 into and out of the air space
6. If the wearer becomes immersed in water, however, the
situation shown in Fig. 4 Would prevail. In that event,
the external hydrostatic pressure forces the garment
parts 2 and 3 together and additionally forces the dome
to collapse slightly, closing off the relatively narrow
region 12 of the perforation 10, thus preserving the
wearer's body fluids and transforming the chambers 13
into air pockets which enhance the insulating and
buoyancy effect of the neoprene sheet 9.
Referring now to Fig. 5, the seal between the garment
parts 2 and 3 at a cuff or other aperture of the garment
(e.g. ankle, wrist or neck) is shown. The parts 2 and 3
are bonded together by conventional adhesives and the
whole aperture is elasticated at the extremity 14, in a
manner well known in dry-suit construction so as to form
a watertight seal around the wearer's body, e.g. at the
wrists, ankles and/or neck.
The garment is suitably a whole-body garment, with or
without glove, shoe and/or balaclava parts. The garment
is suitably machined in two parts in conventional manner
from the materials of the garment parts 2 and 3 and the
inner lining part is then positioned within the outer
part and the parts sealed together at the garment
apertures with adhesive. Waterproof slide fasteners are
provided to allow the garment to be put on and taken off.
The inner garment is intended to be relatively tight
fitting, but allowance should be made for use of
undergarments. The outer garment part is generally less
closely tailored, so as to leave the desired layer of air
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between the parts, and to accommodate pockets and other
normal details.
J
It is preferred that the only points of seal between the
garment parts are at the apertures, with free movement
and an air space between the garment parts at all other
points.
All seams are constructed in conventional manner so as to
render them impermeable to liquid water.
INDUSTRTA~, APPLICAThN
There now follows a description of the function of the
system as a means for protection from unfavourable
environmental conditions. The system is intended to
provide user comfort and protection in a wide variation
of environmental conditions.
Under conditions of dry usage the elastomeric sheet
provides protection from variance in environmental
temperature (e.g. extreme heat or cold) by virtue of its
poor thermal conductivity. At the same time the external
fabric component provides durability and protection
against rain, wind, fire, chemicals, radiation etc.
The chambers and pores of the elastomeric sheet provide
a means of allowing vapour transfer from the user into
the air space between the two components. This maintains
a relatively dry and comfortable environment at skin
surface for the user. The exhausted water vapour can
then leave the system by passing through the vapour
permeable coating of the external fabric.
During cold water immersion the pressure of the water
compresses the domes and causes closure of the
communicating pores. With the closure of the
communicating pores, the thermal integrity of the
insulative elastomeric sheet component is re-established.
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The system is waterproof by virtue of the hydrophilic
polymer coating and therefore no water can enter the
space between the two components of the system. If
accidental water entry occurs the elastomeric lining
sheet will act as a semi-dry suit and therefore its
thermal efficiency will not be compromised. Air trapped
between the garment parts, within the closed-off
perforations of the second garment part, and within the
closed-cell structure of the second garment part, creates
buoyancy to maintain the wearer afloat.
The suit is intended for use in dry conditions for
extended periods of time, having the ability to transform
into a semi-dry suit upon immersion in Water.
Ideally this system is intended tocover the whole
surface of the body except the face, with a single
integral suit. However the system can be utilised in the
construction of particular items of clothing, i.e.
jacket, trousers, gloves, shoes, balaclavas.
