Note: Descriptions are shown in the official language in which they were submitted.
1
PREFORM AND KNITTED TUBULAR ITEM HAVING A RETAINING
EDGE OF A SINGLE THICKNESS AND METHOD OF PRODUCING SUCH
AN ITEM
TECHNICAL FIELD
The present invention relates to a knitted textile item, comprising a tubular
part terminated by a retaining edge.
The invention relates more particularly to a pair of tights of which the
retaining edge is constituted by the waistband part which surrounds the waist
of the
wearer. It may relate to other knitted tubular items, in particular items for
the lower
body, such as panties or footwear items intended for dressing the lower body
to the
foot, in particular, apart from the already mentioned pair of tights,
stockings, knee-
high stockings, socks and even high socks. The retaining edge is typically
achieved
in the form of an extensible knitted strip suitable for exerting a retaining
pressure of
the item in place, a pressure higher than that exerted by the rest of the
item,
particularly the tubular part thereof
BACKGROUND
In the case of a footwear item, in order to ensure the hold on the leg while
.. preventing the item from rolling, the retaining edge is usually made by a
rib
trimming in a double knit layer, of which the dimensions and texture vary
according to the features of construction and thickness of the tubular part of
the
item. This technique is illustrated for knee-high stockings in document FR
2 946 668.
It is known, for example by documents GB 1 427 777, EP 0 034 981 or FR
2 819 827, to produce a pair of tights by knitting two tubes on a circular
knitting
machine, by opening the top of each tube along a substantially vertical
seaming and
by assembling by confection the two tubes at the edges of said seamings in
such a
manner as to form the panty part of the pair of tights. The waistband part of
the pair
of tights may be formed by sewing an added waistband strip or more
traditionally
CA 2883829 2019-09-03
2
by a double knit layer obtained during the knitting itself and of which the
dimensions and
texture vary according to the features of construction and thickness of the
part below the
waistband. This double thickness may be obtained by knitting a welt which is
fastened by
knitting to the tube of the item, according to what is called "hanging plate";
this double
layer part visually offers a rather significant demarcation with the rest of
the outline, which
may even be visible beneath clothes. With the purpose of reducing this
traditional double
layer, it has been proposed in document FR 2 942 109 a fine elastic knitted
lingerie item,
having an elastic retaining edge, comprising a fine elastic knit layer and a
strip of elastic
material thermally bonded on said fine elastic knit layer, this elastic
material being also
advantageously knitted in fine knit. Although this item is very popular, it
requires an
additional thermal bonding operation in the production of the pair of tights.
It would be desirable to propose items with a single thickness waistband
without
demarcation, obtained directly by knitting on a circular knitting machine.
However, in practice it is difficult to obtain a satisfactory retaining edge
by knitting
such an item on a circular knitting machine. For technical reasons, the first
knitted courses
cannot be knitted on all the needles, as opposed to the "normal" courses of
the basic
tubular item; for example first they are knitted 1 needle out of 4, then 1
needle out of 2;
hence, in these first courses there is less length of absorbed yarn (LFA) and
consequently
these first courses have less extensibility than the subsequent courses and
those of the rest
of the item, thus making the item more constraint at the edge of the waistband
than on the
rest of the item; it is a cause of discomfort for the wearer. Hence, in many
cases one is
compelled to have to cut this edge, thereby leading to an additional operation
and a loss of
time, thus also leading to an edge of a quality which is not necessarily
irreproachable,
possibly with the risk of the item running.
BRIEF SUMMARY
The purpose of the invention is to propose a method of producing and a tubular
item thus produced which do not have these drawbacks.
The invention reaches its purpose by a method of producing a knitted tubular
item
according to which the item is knitted on a circular knitting machine provided
with an n
CA 2883829 2019-09-03
3
number of needles and a c number of feeders, the knit being at the start
knitted on a
p number of first courses on only some of the n needles before being knitted
on all
the needles on a q number of subsequent courses, after which the basic knit is
knitted normally, characterized in that it is knitted on said p first courses
and on
said subsequent q courses an elastane yarn covered with a water-soluble yarn,
and
in that it then undergoes, once the item knitted, an aqueous treatment in such
a
manner as to make the covering water-soluble yarn disappear, whereby it is
kept on
the edge of the item p+q courses of bare knitted elastane which precede the
normal
basic knit. The numbers n, c, p and q are integers.
Due to the fact that this remaining knitted border is in pure elastane, even
the p courses knitted on only one portion of the needles do not exert an
unpleasant
restraint for the wearer. Hence, the waistband is comfortable. Moreover, these
p+q
courses knitted in elastane prevent the item from running. Hence, thanks to
the
invention it is obtained a waistband in single layer with a short border
practically
invisible and undetectable by the wearer.
The water-soluble yarns, which may be dissolved in steam or preferably in
hot water, are well known per se. They have already been used in the textile
industry for separating assembly line knitted items, for example according to
documents FR 2 272 213 and EP 0 037 629. Usually, yarns in polyvinyl alcohol
(PVA) are used, for example sold under brands SOLVRONO or DURAFIL .
The item obtained after this first stage of the method of the invention is a
preform of the end product, which requires diverse treatments of which usually
at
least one confection treatment (for example for assembling the two tubes of
the pair
of tights) and one dyeing treatment.
According to a preferred method, the aqueous treatment to make the water-
soluble yam disappear is combined with the dyeing treatment, to make only one
operation. The dyeing operation also operates the pre-fixation of the item. It
is then
followed by the confection treatment required for finishing the final item (in
particular assembling together the two tubes of the pair of tights in order to
form
CA 2883829 2019-09-03
4
the panty part of the pair of tights), the confection then using dyed yarn
since the preforms
have already been dyed.
According to another method, the aqueous treatment is washing which allows at
the
same time to pre-fix the item dimensionally. It is then followed with the
confection
treatment for forming the finished item, the confection able to use ecru yarn
as the item has
not yet been dyed, and the confectioned item is then sent to be dyed.
The invention also relates to the intermediate product formed by knitting and
before
disappearance of the water-soluble yarn, namely the preform of the knitted
tubular item.
More particularly, the invention relates to a preform of knitted tubular item
comprising a
start knitted on p first courses with skipped columns followed with q
subsequent courses
knitted on all the columns, after which the knit is the normal basic knit,
characterized in
that said p first courses and said q subsequent courses are made in an
elastanc yarn covered
with a water-soluble yarn.
Finally, the invention relates to the end product obtained after disappearance
of the
water-soluble yarn. More particularly, the invention relates to a knitted
tubular item
comprising a start knitted on p first courses with skipped columns followed
with q
subsequent knitted courses on all the columns, after which the knit is the
normal basic knit,
characterized in that said p first courses and said q subsequent courses are
made in an
elastane yarn. It will be noted that the end product, the first p + q courses
are in pure bare
elastane, which it is very difficult, even impossible, to obtain without the
method of the
invention. Particularly, it is known by document EP 1 956 125 a knit of which
the border is
made by elastic polyurethane yarn based courses, but this yarn is surrounded
with nylon,
thereby making the border thus made not at all invisible as that of the
invention.
Advantageously, the item is knitted in jersey on a circular knitting machine,
for
example a knitting machine of 400 needles with four feeders (n=400, c=4). The
number p
of first courses for knitting on only one portion of the needles is
advantageously equal to 2
and the number q is higher than or equal to 1 and preferably higher than or
equal to 2.
Advantageously, the yarn used for the p first courses, an elastane yarn (for
example
Roica0) covered with a PVA yarn (for example Solvront), is knitted 1 needle
out of 4 the
first course, 1 needle out of 2 the second, and on all the needles in the q
(=2) subsequent
CA 2883829 2019-09-03
5
courses of the border. The elastane yarn is advantageously a yarn of numbering
less
than 20 dtex, for example 17 dtex, and composed of many filaments, typically
more
than 20, for example 31, thus allowing it to hold the dye well and thereby be
substantially undetectable to the eye on the border of the finished dyed item.
BRIEF DESCRIPTION OF THE DRAWING
Other features and advantages of the invention will become apparent upon
reading the following description, given by way of non limiting indication,
with
reference to the accompanying drawing on which the unique figure 1 represents
in a
traditional manner the knitting diagram of a leg for a pair of tights.
DETAILED DESCRIPTION
The leg for a pair of tights of the invention may be knitted by using a
knitting machine of the Lonati type 404MJ brand (4 feeders).
Figure 1 shows a tubular leg 10 in several successive sections: a start part T
to which the invention particularly relates, a waistband part C, a panty and
thigh
part S, an actual leg part J, a part SM called "mesh stop" and a toe part P.
Knitting
all the parts except for the start part T is what is called here a classic or
normal
basic knit for this type of item. It has been illustrated here for the four
feeders 1, 2,
3, 4 in a polyamide based jersey stitch 6.6 (PA66) plated or not with elastane
(R22).
It could consist of other fibers, the invention not relating to making a
normal knit.
The figure details the knitting of the start part T and schematically shows
the four courses of stitches 11, 12, 13, 14 prior to the aqueous treatment
(right part,
stage of the preform of the product) and after the aqueous treatment (left
part, stage
of the end product). According to the invention, the four feeders of the
knitting
machine are knitted in one same yarn 20 constituted of an elastane 21 of the
Roica0 brand 17 dtex of 31 mono filaments, covered in simple flat covering
(SGP)
of a water-soluble yam 22 of PVA (polyvinyl alcohol) of the SOLVRON brand.
Such a covered yam 20 is much easier to knit than a bare elastane yarn, which
is
very difficult to knit. In order to initiate knitting, it is not easy to knit
directly on all
CA 2883829 2019-09-03
6
the needles in simple feeder; it must be knitted gradually on a quarter of the
needles, then
on half the needles, then on all the needles. Hence, as the diagram shows, the
knitting
comprises a first knitted course 11, 1 needle out of 4 (hence on 100 needles
out of the 400
needles of the knitting machine), leaving three skipped stitches on three
adjacent columns
between the formed stitches (each skipped column has been represented by a
cross), then a
second knitted course 12 1 needle out of 2 (hence 200 needles out of the 400
needles of the
knitting machine), then finally two courses 13, 14 or more knitted on the 400
needles. All
these courses 11-14 are thereby in elastane covered with water-soluble yarn,
at the product
preform.
Once a suitable preferably hot, aqueous treatment is carried out, the covering
water-
soluble yarn 22 is dissolved in water and is eliminated, leaving the elastane
21 bare, in
such a manner that the stitches represented on the left part of the figure are
obtained, where
the first courses of stitches are in bare elastane, first 1 needle out of 4,
then 1 needle out of
2, then on all the needles. These courses 11-14 of bare elastane are easily
stretched, even
.. for the first two courses which are not knitted on all the needles, due to
the fact that the
elastane is pure and highly elastic. These first courses, here four courses,
hardly visible to
the naked eye, do not cause any discomfort to wear and then allow continuing
normal
knitting. The waistband C may hence be knitted in a single thickness, like the
rest of the
pair of tights.
CA 2883829 2019-09-03
