(19) |
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(11) |
EP 0 114 121 A2 |
(12) |
EUROPEAN PATENT APPLICATION |
(43) |
Date of publication: |
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25.07.1984 Bulletin 1984/30 |
(22) |
Date of filing: 17.01.1984 |
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(84) |
Designated Contracting States: |
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AT BE CH DE FR IT LI LU NL SE |
(30) |
Priority: |
18.01.1983 GB 8301319
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(71) |
Applicant: SCOTT & FYFE LIMITED |
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Tayport
Fife DD6 9DQ
Scotland (GB) |
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(72) |
Inventor: |
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- Tough, William Hamish
Tayport
Fife
Scotland (GB)
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(57) A woven fabric material is formed from tapes of synthetic resinous material such
as polypropylene, either the warp tapes or the weft tapes having discontinuous longitudinally
extending localised weakened areas formed in them, for example discontinuous longitudinally
extending grooves in the tapes. The woven fabric is then stretched by stretching longitudinally
and at a raised temperature that set of warp tapes or weft tapes which does not have
the weakened areas, thereby causing the tapes with the weakened areas to split at
those areas and open up to take on the appearance of a network. The stretched woven
fabric material is cooled in the stretched condition so that the final stretched woven
fabric material obtained has a substantially greater area and a lesser overall thickness
than the base woven fabric, i.e. the fabric before it was streched.
[0001] The present invention relates to fabric materials and particularly to woven fabric
materials including tapes of stretchable synthetic resinous material. The present
invention is an improvement in and modification of one aspect of the invention disclosed
in our co-pending European Patent Application No. 82.3036322.
[0002] In the said co-pending patent application there is disclosed in relation to Figures
1 and 2 a woven construction formed from flat polypropylene tapes which constitute
both the warp and weft elements of a base fabric material. The weft tapes are produced
with longitudinal zones of weakness which are localised weakened areas extending longitudinally
in each weft tape before the tape is woven into the base fabric material. After weaving
these weft tapes with longitudinally extendable warp tapes the woven fabric material
is heated to a temperature at which the synthetic resinous material becomes softened,
and is tensioned in the warp direction to stretch the fabric in the warp direction
to approximately twice its original length.
[0003] As the heated warp tapes are stretched and extend longitudinally they interact on
the weft tapes with which they are in frictional contact so that the weft tapes tend
to split, either continuously or intermittently, along the weakened areas or zones
into strips which are pulled apart. When the degree of stretch of the warp tape is
sufficient, each longitudinally weakened weft tape splits into a series of narrow
strips so that the number of weft tapes in the fabric is multiplied. On subsequent
cooling of the stretched fabric under tension, the warp tapes bond to the subdivided
weft tapes at the intersections to give a final product which is a stretched fabric
with a high degree of dimensional stability.
[0004] Instead of providing continuous longitudinally extending localised weakened areas,
for example continuous grooves extending longitudinally in the weft tape, the method
according to the present invention provides for the formation of discontinuous longitudinally
extending localised weakened areas in each weft tape.
[0005] The discontinuous longitudinally extending localised weakened areas may be arranged
in groups of such areas with untreated portions of the tape between each group. Alternatively
the discontinuous longitudinally extending localised weakened areas may be staggered
so that most, if not all, of the length of the tape has one or more longitudinally
extending area of laterally localised weakening within it.
[0006] When a woven fabric with weft tapes having discontinuous longitudinally extending
localised weakened areas is heated and stretched under tension in the warp direction,
the weft tapes tend to split at these discontinuous weakened areas so that each weft
tape is broken down into a series of interconnected strips. The strips are pulled
apart from one another by frictional contact with the warp tapes so that each weft
tape takes on the appearance of a network, which may be regular or irregular depending
on the arrangement of the discontinuous weakened areas in the original weft tape.
[0007] If the degree of stretch of the warp tapes is very high, the splits formed at the
discontinuous weakened areas may be propagated lengthwise so that substantial lengths,
and possibly the whole length, of the weft tapes are subdivided into separate weft
tapes.
[0008] The treatment of the woven fabric formed with weft tapes as described is carried
out substantially as described in our said co-pending European Patent Application
No. 82.3036322 and the resulting product has similar advantages to those described
for the product of the said co-pending patent application, including greater tenacity
of the fabric (in grammes/dtex) in the warp direction, greater area of fabric for
a given quantity of material, and good dimensional stability of the fabric when stretching
of the fabric is undertaken under conditions permitting bonding of the warp and weft
tapes at their intersections.
[0009] Instead of using the tapes with the discontinuous longitudinally extending localised
weakened areas as weft tapes, they may be used as warp tapes in a fabric which is
stretched transversely instead of longitudinally.
1. A method of manufacturing a fabric material comprising the steps of forming a woven
base fabric of warp and weft tapes, stretching the base fabric to stretch longitudinally
either the warp or the weft tapes and thereby obtain a stretched fabric having greater
area than the original base fabric, characterised in that the other of the warp and
weft tapes include discontinuous longitudinally extending zones of weakness and that,
during stretching, at least some of the other tapes split at the zones of weakness.
2. A method according to Claim 1, characterised in that the weft tapes include discontinuous
longitudinally extending localised weakened areas.