FR2680375A1 - METHOD FOR MANUFACTURING A LINEN YARN IN MOUILLE AND LINEN YARN OBTAINED - Google Patents

Abstract

According to the invention, the fibres originating from stripping are subjected to the following preliminary operations: a. cutting to a length of between 150 and 400 mm, b. preimpregnation with water, c. action of steam at a pressure of between 10 and 15 bars for a period of between 20 and 60 seconds, d. decompression to atmospheric pressure, e. washing and drying, which are subjected to the preparation stages on any type of material: linen, wool or cotton; the fibre sliver obtained is finally spun wet. The linen yarn obtained has the appearance and the structure of a linen yarn produced by the wet method and has a flexibility which makes it suitable for use in millinery and on a knitting loom.

Description

PROCESS FOR PRODUCING A WIRE THREAD IN WET

AND LINEN WIRE OBTAINED

  The present invention relates to the spinning of flax and more particularly the milling of wet flax in which the wick or ribbon consisting of substantially parallelized fibers is immersed in a bath for softening the cements and gums which bind together the elementary fibers The present invention relates to a process for improving the existing technique, in particular in that, under certain conditions, it makes it possible to avoid the passage on a bench. pin; on the other hand, it relates to a wet-type linen yarn having improved properties, especially in that it can be used knitwear on a knitting machine. The spinning of flax is well known It consists of fibers derived from scutching, either linseed proper, or linseed under-rotted, or scutching tows, to make these fibers different preparation operations combing and / or carding, stretch-doubling for the purpose of producing a stretching ribbon, that is to say a thin and regular ribbon, of substantially parallelized fibers, and finally to perform the spinning by passing over a bench to pinch the stretching ribbon is turned into a wick that is a weakly ribbon

  twisted, then passing over a wet spinning bench.

  The flax yarn obtained by the wet technique has a natural appearance and a specific apparent structure, which are due to the presence of residual organic cements and to the dissociation and sliding mode of the elementary fibers.

  compared to others during stretching.

  However, the presence of these organic cements (pectins, hemicellulose, lignin), which makes it possible to give the yarn a better cohesion, presents a major disadvantage which is to increase its rigidity. Thus a yarn of wet linen obtained traditionally does not have the sufficient flexibility to be used in hosiery, on knitting machines, which limits

  considerably its business opportunities.

  The aim set by the applicant is to propose a process for manufacturing a flax yarn, according to the wet technique, which overcomes the aforementioned drawbacks, in that the yarn obtained on the one hand keeps the appearance and the structure of a wet flax yarn but on the other hand has sufficient flexibility to

that it be used in hosiery.

  This object is perfectly achieved by the process of the invention. It is a process for manufacturing a wet-linen yarn which consists, in a known manner, in the preparation of a fiber ribbon and in its wet spinning. Characteristically, the fibers originating from the scutch have been subjected, prior to the preparation steps, to the following successive operations: cutting at a length of between 150 and 400 mm, pre-impregnation with water, action of the steam under pressure between 10 and 15 bar for a period of between 20 and 60 seconds, expansion at atmospheric pressure,

e washing and drying.

  In addition the preparation of the fiber ribbon can be performed on any type of preparation material, linen, wool or cotton. These preliminary operations have the effect of significantly reducing the amount of organic cements, while maintaining a sufficient amount to allow the wet spinning and keep the natural appearance of the yarn Moreover, the combination of the aforementioned treatment with steam under pressure and wet spinning gives the wire obtained a very good regular distribution of residual cements It is this regularity and the least amount of cement that allows to obtain the desired result, namely the improved flexibility while

  keeping the aspect and the traditional structure.

  On the other hand, it is thanks to the cutting length of between 150 and 400 mm that the preparation of the ribbon can be performed on preparation materials that are not necessarily

  of the linen type, but which can be wool type or even cotton.

  Thus, thanks to the method of the invention, it becomes possible to produce a wet linen yarn, by means of a

  simpler and less expensive preparation.

  It is of course known, in particular from GB A 388 561, GB A 476 569 and US Pat. No. 2,633,421, treatments in which a fiber plant is subjected to the action of steam under pressure and then relaxed at atmospheric pressure and subsequent washing But this is high-pressure treatment, aimed at shelling of fiber plants in the form of straw, leaves, grass, that is to say the separation of

  the bark or the woody part of the fibers themselves.

  The pressures involved are between 38 and 62 bar.

  EP 0 253 828 also discloses a process for the treatment of pre-cut underroot flax of the above type, in which the action of the steam is at a pressure of the order of 30 bar for a period of time. of the order of 10 seconds, or at a pressure of the order of 15 bars for a period of the order of 90 seconds but after the fibers have undergone pretreatment consisting of an impregnation with a basic solution or acid The purpose of this document is to obtain by this method a linen which is substantially free of encrusting materials. It is understood that the object of the present invention is quite different and that the conditions of the action of the steam under pressure are precisely determined so that a smaller but sufficient quantity of organic cements for

  allow the smooth running of the wet spinning.

  Preferably, the wet spinning is carried out with a draw ratio of between 50 and 140 from a ribbon which has not undergone a spindle bed. Thus, it is possible to avoid the first step of the spooling. spinning which consists in the passage to the spindle bench, by simply increasing spinning draw ratios without prejudice to the

regularity of the wire obtained.

  Advantageously, prior to wet spinning, the ribbon is subjected to an alkaline pretreatment, which makes it possible to improve the sliding of the elementary fibers during

  the stretching and homogeneity of the distribution of the cements.

  Advantageously, prior to wet spinning, the ribbon has undergone a bleaching operation, for example with hydrogen peroxide. It is another object of the invention to claim a linen yarn obtained according to the aforementioned method, characterized in that it has the appearance and the structure of a yarn in the wet and in that it has a flexibility sufficient to be used in hosiery

on knitting machine.

  The invention will be better understood on reading the

  description that will be made of an example of making a

  wet linen yarn for crocheted use.

  The starting material consists of scutching tows from the scutching of a rennet flax It is for example a flax that was prematurely picked up in the case of retting on land Compared to flax normally rusted, Under-retted flax always contains more encrusting materials, insofar as the cements which bind the fibers together have not been sufficiently degraded by the agents.

bacteriological retting.

  These tows undergo a preliminary cleaning treatment on finishing card, which also presents them under

  ribbon shape This ribbon is cut into sections of 300 mm.

  The material thus cut is introduced into a reactor where it is impregnated with pure water and then subjected to hydrolysis treatment with steam at 15 bar pressure for a period of 40 seconds; at the end of this period, the opening of the discharge orifice of the reactor causes a sudden expansion by passage of the pressure of 15 bar at atmospheric pressure and therefore ejection through said opening of the flax in a container containing a slightly alkaline water where it is

washed and rinsed.

  The flax fibers thus treated, after drying, are converted into a tape of 4 g / m per passage in the preparation machines, namely successively a passage in a finishing card, a passage in a doubleuse-stretching machine GN 4, two passes in a small combing machine, a GN 4 doubleuse-stretching passage and two GN 5 doubling-pulling passages without a spindle bench. At the end of the preparation, the fineness of the ribbon is characterized by an IFS of 16.74 and a CV% of 5.07 It should be noted that with an untreated linen according to the process the IFS is normally greater than 20, that which shows an increase

  the fineness of the fibers in the ribbon according to the invention.

  The ribbon undergoes a slight degumming treatment using

  a solution of 2.5 g / l of sodium carbonate.

  Wet spinning is carried out on a continuous spinning machine, with two drawing zones. The pressure of the drawing rolls is obtained by means of a counterweight system. The ribbon passes into a container filled with cold water. ; he is guided to the entrance as to the

  output of the drawing train by ceramic guides.

  In a specific example, but not limiting, realiza- tion, the spacing of the rolls was 80 mm for the rear zone and 60 mm for the front zone; the twist was 410 rpm and the receiving speed was in the order of 13 m / mm. The resulting wet flax yarn had a metric number of 23, a resistance

  Rk of 17 (CV% 20 to 25), an elongation of 1.6 to 1.8%.

  This yarn, whose appearance and structure are those of a traditional yarn of wet linen, has compared to a yarn obtained by the traditional method a very great flexibility which makes it suitable for use in acceptable operating conditions on knitting machines, in particular

  circular, and therefore able to be used in hosiery.

  The invention is not limited to the embodiment which has been described by way of non-limiting example. In particular, the length of the cut must be determined by the person skilled in the art according to the preparation circuit, linen, wool On the other hand, the ribbon, before wet spinning, can undergo various treatments, for example a whitening treatment, which leads to the manufacture of a whitened linen yarn.

Claims (5)

  A process for producing a wet-linen yarn, consisting in the preparation of a fiber ribbon and in its wet-spinning, characterized in that the fibers originating from the scutch have, prior to the preparation steps, been subjected to the operations successive successive: a cut to a length of between 150 and 400 mm, b pre-impregnation with water, c action of steam under a pressure of between 10 and 15 bar for a period of between 20 and 60 seconds, relaxation at atmospheric pressure, washing and drying and that the preparation of the tape is carried out on any type   preparation material: linen, wool or cotton.   2 Method according to claim 1 characterized in that the wet spinning is carried out with a draw ratio of between 50 and 140 from a tape that has not passed through to the pin bench.   3 Method according to one of claims 1 or 2 characterized in that   that, the fibers coming from the scutching being tows of scutching, these undergo a cleaning on carde finishing finisher the cutting operation.   4 Process according to claim 1 characterized in that prior to wet spinning, the fiber ribbon is subjected to an alkaline pretreatment in particular by a solution of sodium carbonate.   Process according to Claim 1, characterized in that, prior to wet spinning, the fiber ribbon is subjected to   bleaching treatment, including hydrogen peroxide.   6 Linen yarn obtained by the method of claim 1 characterized in that it has the appearance and structure of a linen yarn in the wet and that it has a flexibility making it suitable for a   knitted use, on knitting machine.