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Description  |
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The present invention relates to a lining material and more particularly,
but not exclusively, to a lining material for footwear.
A large number of products include a lining material for a variety of
reasons. For example, a lining material is used within footwear to improve
wearer comfort, abrasion resistance and for presentational reasons.
Alternatively, linings are applied to clothing and other products in order
to achieve a similar wear abrasion, moisture control and simply to
facilitate more efficient product construction or operation.
Of particular concern with some lining materials is the ability to wick
away moisture from damp areas and this is a particular requirement in
footwear linings. Absorbent fibres can be used in linings to facilitate
this moisture wick ability. However, the abrasion resistance of linings
using such fibres has been limited. More recently, improved wicking
synthetic fibres have been developed which have a grooved cross-section to
promote capillary transport of moisture along the fibre and thus disperse
moisture more rapidly about the lining material made from such fibres.
One type of lining material is a non-woven felt comprising appropriately
needle entangled fibres to form a felt of suitable weight and gauge for
the product in which the lining is to be applied. One such lining is
marketed by British United Shoe Machinery Limited, Leicester, England
under the trademark Aquiline. In order to incorporate such grooved cross
section fibres for their wicking efficiency within a non-woven fabric, the
grooved cross-section fibres it will generally be needle entangled as with
previous felts. However, it has been found with typically available
grooved cross section fibres, such as fibre 4DG supplied by the Eastman
Chemical Company of Tennessee, USA or multi-lobed cross-section such as
fibres-sold as Dacron, in simple fibre entangled felts have had too high
an abrasion rate for acceptable performance in such products as footwear
or clothing. Furthermore, the felts have had too high a stretch rate
during product manufacture.
It will be appreciated that generally non-woven felts depend upon fibre
entanglement and fibre friction slip resistance to ensure consolidation.
Thus, with grooved or multi-lobed cross section fibres it may be that
there is less surface contact between fibres to provide such entanglement
and friction resistance i.e. only the tops of the grooves or channels are
available as compared to a generally round cross section fibre. The
valleys of the channels are not available even though they do provide the
facility of capillary wicking as indicated above and are available for
application of a suitable coating for hydrophobic or hydrophobic
attraction of moisture or other desired performance criteria e.g.
electrical/thermal conductivity, ph resistance etc. With regard to
stretching, it will be appreciated that the felt may become distorted
after a manufacturing stage due to fibre slippage passed one another and
there will be no `bounce back` to its original shape.
It is an object of the present invention to provide a lining material based
upon non-woven felts that incorporates grooved or multi-lobed cross
sectioned fibres for improved wicking whilst maintaining acceptable
abrasion levels and properties adequate for shoe manufacture and for
durability in use.
In accordance with the present invention there is provided a lining
material for footwear, the material comprising a non-woven felt made of up
to 80% by weight of grooved or multi-lobed cross section transport fibres
and the remainder thermally bondable fibres arranged to secure said
transport fibres against abrasion and excessive mechanical stretch present
during incorporation of such lining material into a product during that
product's manufacture.
Preferably the transport fibres are 4DG fibre supplied by the Eastman
Chemical Company of Tennessee, USA or Dacron.
Preferably the thermally bondable fibres may be polypropylene fibres,
bicomponent fibres or low melting polyester fibres, all of the appropriate
decitex.
In replacement of a certain proportion of the transport fibres,
anti-bacterial fibres or other special performance fibres may be included
in the non woven felt.
Preferably, the lining material has a density in the range 150-160 kg per
cubic meter and preferably about 156 kg per cubic meter. The material
preferably has a weight of 250 gsm and a gauge of 1.6 mm but may have a
weight in the range 100-400 gsm.
Preferably the thermally bondable fibres have a decitex in the range
1.7-5.0 decitex but in any event sufficient to allow upon heating the
transport fibres to be resiliently bonded or embedded within the thermally
bondable fibres without the thermally bondable fibres melting completely.
The preferred decitex of the thermally bondable fibres is 2.5 whilst the
transport fibres may have a decitex in the range 2.5 to 4.0 decitex but
most advantageously, with 4DG fibre, of 3.3 decitex.
The preferred composition of the lining material is 70% 4DG fibre, 3.3
decitex blended with 30% polypropylene fibre, 2.5 decitex with a weight
after thermal activation of 250 gsm and a gauge of 1.6 mm.
An embodiment of the present invention will now be described by way of
example only.
The lining material in accordance with the present invention is produced by
thermally bonding a needle felt composed of a blend of thermally bondable
fibres for example in a preferred embodiment, polypropylene, with grooved
or multi-lobed cross section fibres designed to wick moisture away from a
point or area of contact with the material.
It is the special nature of grooved cross section fibres which give the
lining material its moisture transporting properties. Tiny grooves within
the fibre act as capillaries actively channelling the liquid moisture away
from a source in contact with the lining material and thus themselves. In
the case of a lining material used in footwear this may be the actual
surface of the foot or damp hose. In a footwear vamp lining which extends
to the top line of a shoe or in an exposed tongue, the liquid will be
actively channelled away from the toes and the dorsal surface of the foot
to the outside environment where it may be evaporated away and at least is
not detrimental to the wearer's comfort.
The lining material includes thermally bonding fibres to allow the lining
material to be stabilised and so resistant to stretching during product
manufacture and resistance to abrasion during wear. It will be understood,
particularly with regard to manufacture of footwear, that products
including linings can be formed about forming elements such as a shoe
last. Generally, during such forming process of the product fabrication,
the lining will be stretched in order to secure the various components
together. It is important that the lining does not become distorted and so
must not tear during manufacturing.
The range of thermally bonding fibres which can be used is quite extensive
as the requirement is simply to provide upon heating a suitably tacky
surface in which the grooved cross section fibres can become bonded or
embedded such that upon cooling the grooved cross section fibres are
secured within the lining material. As indicated above it is submitted one
of the reasons that grooved cross section fibres may be susceptible to
abrasion and stretch distortion is reduced friction contact between fibres
in the felt, the bond/embedding of the grooved cross-section fibres in the
thermally bonding fibres thus supplements and enforces cross sectional
fibre location within the lining material. Alternative thermally bonding
fibres to polypropylene are bicomponent or low melting polyesters.
It will be appreciated that the bulk of the lining material is made up of
grooved cross section fibres which can be termed moisture transport fibres
within the lining structure. However, the moisture wicking facility of the
lining material is obviously only one attribute necessary of such a lining
material and therefore the requirements of other attributes of the lining
material must be considered. Consequently the proportion of transport
fibres within the lining material is chosen in balance with these other
requirements of the lining material and the proportion of thermally
bondable fibres chosen in order to anchor and secure such lining material
against stretching and abrasion during work and manufacture of the
product. The preferred transport fibre or grooved cross section fibre is
4DG (3.3 decitex) produced by The Eastman Chemical Company of Tennessee,
USA. However, alternative fibres may be used such as Dacron 702W.
It will be appreciated that grooved cross section fibres are generally more
expensive than staple fibres and thus, provided the inherent reduction in
moisture wicking capacity and possible inferior abrasion resistance is
acceptable, a proportion of the transport fibres may be replaced by
ordinary round section polyester or nylon. Similarly, other speciality
fibres may be included to enhance specific performance of the lining
material. For example, anti-bacterial or anti-static fibres may be added
to the lining material during the blending stage in order to enhance
lining performance. Such speciality fibres will be added in replacement of
the transport fibre as it will be appreciated there is a minimum
proportion of thermally bondable fibres in the lining material to ensure
adequate stabilisation through bonding with other fibres. This level as
indicated above is generally 20% by weight of the non woven felt and thus
the lining material. However, if either the transport or bonding fibres
are coated with an adhesive this blend level may be reduced.
An example of a typical lining material in accordance with the present
invention comprises a blend of, by weight, 30% polypropylene fibre (2.5
decitex) and 70% 4DG fibre (3.3 decitex). The blend of fibres are carded
and needled to produce a needle felt of approximately 220 gsm and a gauge
of 1.8 mm. This needle felt is heat treated with hot air dependant upon
the thermally bondable fibres available. This hot air may be blown by fans
etc. For the polypropylene fibres used in this example a temperature of
165.degree. C. was used. However, it will be appreciated with some low
temperature polyesters a temperature in the order of 130.degree. C. may be
acceptable. After heat treatment of the needle felt using hot air as
described previously, the lining material is passed through a mangle type
arrangement with a slight nip i.e. slightly less gauge than that presented
to it. The rollers of the mangle are relatively cool and typically will be
at room temperature. After the lining material has passed through the
mangle the finished lining material will generally have a weight of
approximately 250 gsm and a gauge of 1.6 mm. Such finished lining material
is suitable for footwear and similar applications.
In choice of the fibre decitex, both for the thermally bondable fibres and
for the transport fibres it is important to remember that too fine a
decitex is susceptible to abrasion due to fibre weakness, whilst too
coarse a fibre is susceptible to abrasion due to the fibre being too
strong and causing the formation of pills which speed up abrasion.
Furthermore, most grooved cross section fibres e.g. 4DG is only available
in certain decitex sizes and so generally the appropriate decitex for the
lining material is dependant upon the fibre used. Typically, the transport
fibres, i.e. grooved cross section fibres will be in the range of 2-4
decitex. The thermo bondable fibres, as indicated above, should not
completely melt within the needle felt and so generally a decitex of
sufficient gauge is used to ensure that a surface portion of the fibre
becomes tacky to allow embedding or bonding of the transport fibre to it.
Typically, bondable fibres in the range 1.7-5 decitex are acceptable.
A major determining factor with regard to the lining material is the actual
degree of concentration of the needle felt through the entanglement
procedure and heat treatment. This degree of concentration is determined
generally by the density which in turn is a product of the particular
fibres used i.e. in terms of their density. However, with the 30%
polypropylene/70% 4DG fibre, the example given above, it has been found
that a lining material density in the range 150-160 kg per cubic meter and
preferably 156 kg per cubic meter is acceptable. Thus a preferred finished
lining material as indicated above may have a weight of 250 g per square
meter and 1.6 mm gauge. However, the weight of the material may vary
between 1000 gsm and 400 gsm with appropriate alteration in the gauge of
the material. Lining materials below 100 gsm are generally too fragile for
lining whilst materials in excess of 400 gsm generally may be too stiff
for most lining materials.
It will be appreciated that the grooved cross section fibre may be used in
addition to a moisture wicking agent as a recepticle for reagents.
Furthermore, within footwear and clothing the lining material including
the grooved cross section, transport fibres could be adapted to release
perfume or deodorant by incorporating reagents, activated carbon or
microbubbles of such perfumes within the grooves or channels of the
transport fibres. Such reagents or microbubbles of perfume etc. would be
released upon contact with moisture. Such incorporating of reagents etc.
within the grooved cross section fibres may occur either prior to blending
or during blending or after the lining material has been manufactured. It
will be appreciated that if such adaptation of the grooved cross section
of fibres occurs prior to blending or lining material manufacture it will
be possible to treat different weight proportions of the grooved cross
section fibres in the lining material with different treatments i.e. some
perfumed, some anti-static whilst others have a deodorant in order to
provide respectively these facilities within the lining material. The
ability to provide such value added features to lining materials will be
of significant advantage with regard to consumer goods such as footwear,
clothing and haberdashery.
Finally, the grooves of the transport fibre may be used to incorporate
germicides, anti-bacterial agents and even pesticides or insect repellent
agents used to deter moths or mosquitos e.g. mothball type deterrents in
clothing.
The use of grooved cross section fibres in lining materials in accordance
with the present invention is particularly advantageous in that due to the
active capillary action drawing the moisture/liquid away it will be
understood that such movement can be substantially against gravity, within
limits, and therefore upwards. This is of course a great benefit with
regard to footwear linings where the lining will generally be in a
vertical aspect. Furthermore, due to the capillary nature of retention
i.e. physical rather than chemical absorption, the capacity to retain
moisture within the fibre may be increased irrespective of orientation and
such liquid can be readily evaporated as compared to chemical
absorption/retention within some hydrophilic fibres.
As an alternative to hot air activation of the fibre entangled felt it may
be possible to use hot rollers or flats or simply an oven at an
appropriate temperature.
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