EP0131338A1

EP0131338A1 - Method of producing a yarn from jute or simular tough staple fibres

Info

Publication number: EP0131338A1
Application number: EP84200980A
Authority: EP
Inventors: Hong Han Njo; Roelof Carel Van Essen; Gerardus Adrianus Maria Ruis
Original assignee: Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek TNO
Current assignee: Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek TNO
Priority date: 1983-07-07
Filing date: 1984-07-05
Publication date: 1985-01-16
Also published as: ATE24340T1; EP0131338B1; NL8302432A; DE3461724D1

Abstract

To produce without twisting a yarn from a slubbing of jute or similar tough fibres, said yarn being of sufficient strength and resistance to abrasion to be used in yarn processing machines, the slubbing (1) is wetted with an active adhesive and after drawing (5, 6, 7. 8) it is false twisted and compacted with the aid of an apparatus consisting of two partially overlapping wheels (10, 11) turning in opposite directions and spaced a short distance apart, the drawn slubbing being passed along the common chord between the wheels.

Description

Method of producing a yarn from jute or similar tough staple fibres.
The invention relates to a method of producing a yarn from a sliver or slubbing of jute fibres or similar tough staple fibres, wherein the slubbing is drawn out.
A method of this kind is widely known. The fibres of the slubbing, which through the drawing are displaced in the longitudinal direction relative to one another, are thereby made cohesive to form a yarn by the twisting of the stretched slubbing.
The spinning machines required for the twisting of the stretched slubbing are however expensive to purchase and to maintain and are limited in respect of production speed, so that they seriously hamper the attempt to lower production costs.
From Dutch Patent Specification 143,002 it is known that yarns can be produced from thin, supple staple fibres, such as cotton, without twisting, by drawing out a slubbing or roving of these fibres in a saturated wet state and false twisting the drawn-out slubbing pneumatically, that is to say with the aid of an air vortex chamber; the drawn-out slubbing then has sufficient cohesion to be wound into a spool and is thereupon given, through the treatment of the spool with a sizing agent, the strength and resistance to abrasion necessary for further processing as a yarn. The size, for example starch, may be added to the slubbing in an inactive form, for example as starch grains, before or during the drawing, and then activated after the winding, for example by steam treatment of the spool.
This method cannot be applied to jute and similar staple fibres, because the fibres in the stretched slubbing appear to have scarcely any cohesion, while in addition any cohesion that they do have appears to be impaired rather than improved by the pneumatic false twisting.
The invention seeks to provide a method of producing, without twisting, a yarn from jute and like staple fibres which has sufficient strength and resistance to abrasion to be used in yarn processing machines, such as a loom.
The method according to the invention is to this end characterised in that the slubbing is wetted with an active adhesive, and after the drawing operation is false twisted and compacted with the aid of an apparatus consisting of two partially overlapping wheels turning in opposite directions and spaced a short distance apart, the drawn slubbing being passed along the common chord between the two wheels.
It appears that through the rubbing, rolling and at the same time false twisting action of the wheels on the drawn slubbing the latter is compacted in such a manner that it can without difficulty be wound into a spool and, after the drying or other hardening of the adhesive, is suitable in the same way as conventional twisted yarns for further processing.
Surprisingly, the method appears to be very reliable in operation, in contrast to earlier experience with the non-twist spinning of cotton and like fibre materials, in which the impregnation with active adhesives before or during the drawing led to serious soiling of machine parts, such as drawing rollers and false twist devices, and consequently to frequent thread breakages.
The invention will now be explained more fully with the aid of the drawings.

Figure 1 shows diagrammatically an apparatus for applying the method according to the invention.
Figure 2 is an elevation of the false twisting mechanism, viewed in the direction of the yarn.

Figure 1 shows a slubbing 1, which comes from a store of some kind and which is passed through a tank 2 containing an adhesive known per se, which may consist of carboxymethylcellulose. In the tank 2 the slubbing 1 is passed under pins 3 and 4. 5 and 6 are the inlet rollers of the drawing mechanism, and 7 and 8 are the outlet rollers of the drawing mechanism, which turn at a higher peripheral speed than the rollers 5 and 6, the ratio between the peripheral speed of the rollers 5 and 6 to that of the rollers 7 and 8 determining the drawing ratio.
At 9 is disposed a scraper for cleaning the roller 8. Downstream of the drawing mechanism is disposed the apparatus resembling a false twisting device, consisting of the wheels 10 and 11, each of which has a diameter of 182 mm. These wheels turn in opposite directions, as indicated by the arrows 12 and 13. Figure 2 shows how the strand of fibres or yarn 14 is gripped between the wheels 10 and 11. These wheels may be covered with a friction coating 15 and 16 respectively. This may be a layer, of a thickness of a few millimetres, of polyurethane having a Shore hardness of 65, or else a layer of neoprene rubber. The distance between the axes of the wheels is 120 mm.
In the region 17 the wheels 10 and 11 give the yarn 14 a twist, indicated by the arrow 18, this twist extending upstream to the nip between the rollers 7 and 8 of the drawing mechanism. In the region 19 this twist is untwisted, so that the final yarn 20 is practically free from twist and, via the traversing guide 21, can be wound into a yarn package 22.
The slubbing 1 may be a curly slubbing of jute staple fibres with a minimum fibre length of 9 cm, a maximum fibre length of 34 cm, and a mean fibre length of 14 cm, the linear density of the slubbing amounts to 3.2 ktex.
The distance between the rollers 5 and 6 on the one hand and the rollers 7 and 8 of the drawing mechanism on the other hand amounts to 19 cm, the pressure between the rollers 5 and 6 is 16 kg per cm, and the pressure between the rollers 7 and 8 is 23 kg per cm, the roller 8 being covered with rubber having a Shore hardness of 65.
This slubbing, with a twist of 15 turns per metre, was passed in the tank 2 through a 3.0% solution of carboxymethylcellulose (hereinafter referred to as CMC), and in the drawing mechanism was drawn into a yarn of 250 tex. The wheels 10 and 11 were adjusted in the first test to a spacing of 0.50 mm, and in the second to a spacing of 0.75mm a spinning speed of 100 metres per minute being maintained, corresponding to the speed at which the yard leaves the outlet rollers 7, 8.
The yarns obtained were tested for abrasion resistance in a wear test apparatus. In this apparatus, which is described by N.J. Faasen and K. van Harten in "Journal of the Textile Institute" 57, No. 7, T269, 1966, two yarns loaded by a weight are guided cross-wise one over the other and against one another in a part of the tester moving vertically up and down, the two yarns, guided over pins, rubbing over one another. When a yarn breaks, the number of vertical movements is a measure of abrasion resistance.
Table I shows that the dried yarn contains slightly more CMC when the distance between the wheels 10 and 11 is increased. This is probably due to a reduction of the rubbing action of the wheels.
In addition, this table shows that the abrasion resistance values rise when the yarn contains more adhesive.
Table II shows what happens when, while maintaining the distance of 0,75 mm between the wheels 10 and 11, the spinning speed is halved to 50 metres per minute without hanging the drawing ratio. This variation of the spinning speed has practically the same influence on the CMC content in the dried yarn as the reduction of the distance between the wheels 10 and 11. The values of abrasion resistance are, however, higher.
Table III shows that modification of the concentration of CMC solution has little influence on the abrasion resistance of the yarn. It was however found that the yarn became too stiff.
Table IV shows the effect of modifying the hardness of the rubber roller 9 of the drawing mechanism. In the case of flax it is known that there is a connection between the moisture content of twist-free yarn and the hardness of the rubber coated outlet roller of the drawing mechanism. In the tests which led to Table IV, use was made of two hardnesses, namely 65 and 78 Shore respectively, and it is clear that the harder roller leads to a higher CMC content in the dried yarn, with correspondingly higher values of abrasion resistance. This test was carried out with a curly slubbing of 3.2 ktex, and drawing took place at a speed of 50 metres per minute to form a yarn of 390 tex, the wheels 10 and 11 being spaced 0.75 mm apart, while the adhesive used was a 3.0% solution of CMC.
If the value for abrasion resistance in this test are compared with the preceding values, it will be seen that they are proportionately poor.
Table V relates to a test for determining the effect of the speed of the wheels 10 and 11 in the false twist device again, the starting material is a curly slubbing of 3.2 ktex, drawn to a yarn of 390 tex at a speed of 50 metres per minute. The CMC solution had a concentration of 3.5% and the distance between the wheels 10 and 11 was 1.0 mm.
The wheels 10 and 11 were first given a speed of 157 revolutions per minute, and afterwards a speed of 200 revolutions per minute. The wheels 10 and 11 were in this case not coated with polyurethane but neoprene.
This table shows that the CMC content is relatively low.
In addition, Table V shows that the values for abrasion resistance could not be further improved by raising the speed of the friction wheels.
The principle underlying the present invention consists essentially in selecting a special false twist apparatus which, with staple fibres which are difficult to process, surprisingly makes it possible to produce a usable yarn. Instead of jute fibres, it is here also possible to contemplate other tough fibres, such as hemp fibres, sisal fibres, and non-disintegrated flax, and also some plastics fibres or mixtures of natural and plastics fibres. In general, therefore, staple fibres which need an adhesive in order to be able to be processed.

Claims

Method of producing a yarn from a slubbing of staple fibres of jute and similar tough fibres, wherein the slubbing is drawn out, characterized in that the slubbing is wetted with an active adhesive and after the drawing is false twisted and compacted with the aid of an apparatus consisting of two partially overlapping wheels turning in opposite directions and spaced a short distance apart, the drawn slubbing being passed along the common chord between the wheels.