GB1600128A

GB1600128A - Method of and apparatus for making bulked yarns

Info

Publication number: GB1600128A
Application number: GB14924/77A
Authority: GB
Original assignee: IWS Nominee Co Ltd
Current assignee: IWS Nominee Co Ltd
Priority date: 1977-04-07
Filing date: 1977-04-07
Publication date: 1981-10-14
Also published as: JPS53126338A; JPS6012466B2; PT67840B; HK9282A; PT67840A; ES468594A1; IT7822090A0; FR2386627B1; IT1095114B; FR2386627A1; ES476895A1; GR64134B

Description

(54) METHOD OF AND APPARATUS FOR MAKING BULKED YARNS (71) We, I.W.S. NOMINEE COMPANY LIMITED, a British Company of Wool House. Carlton Gardens, London, S.W.1., do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a method of making bulked yarns. It represents an improvement in or modification of the invention described and claimed in our co-pending Application No. 20171/75 (Serial No. 1 505 162).

Bulky or lofty yarns are very much desired in the textile field since they are soft, warm and give good cover for a given weight of fibre. Most methods of producing bulky yarns involve treating fibres in the form of a silver, tow or like strand, to impart crimp. When the crimped fibres are subsequently spun, the yarns so-produced have increased bulk.

Texturising processes for synthetic fibres are manifold and there have also been proposed some processes for increasing the bulk of natural fibres.

Keratinous fibres, especially wool, are naturally crimpy and hence produce lofty yarns.

However, for certain uses it can be advantageous to seek to increase the natural crimp to improve the bulk of the spun yarn, either to give a warmer or more luxurious product, or to enable relatively low crimp grades of fibre to be used in applications needing reasonably bulky yarns. Accordingly, one such process, disclosed in our UK Patents Nos. 1198613 and 1288035 involve feeding wool fibres between belts, into a crimping zone, and out again between slower-moving belts while setting the crimp with steam. Another method, disclosed in our UK Patent No. 1385700, involves treating a wool silver with an alcohol, stretching it between two sets of rollers moving at different speeds, allowing it to relax, and setting the crimp so-produced. Another proposed method, our UK Application No.

19691/75 (Serial No. 1 543 572). involves treating wool yarns with liquid ammonia which causes bulking, and then setting the yarn in its bulked configuration.

For one reason or another the above methods have not proved entirely satisfactory. For example, the increase in bulk in the final yarn given by the first method, although useful, is not always considered sufficient to justify the cost of the plant required. As yet the second method has too slow a throughput speed to be commercially acceptable; and the third process requires specialised equipment for handling liquid ammonia which is not generally available in the textile industry.

The invention seeks to overcome the disadvantages of the known processes with a method of bulking yarns which gives a significant increase in bulk on relatively inexpensive machinery at commercially acceptable throughput speeds without using noxious chemicals.

According to the present invention there is provided a method of making a bulked yarn which comprises passing a yarn containing keratin fibres in the presence of moisture through a flexible tube, and flexing the tube during the passage of the yarn at temperature in excess of 30"C.

The flexing or oscillation used in the method of the invention has a prinripal component transverse to the direction of motion of the yarn. A preferred form of the apparatus of the invention produces the requisite flexing of the flexible tube in a manner similar to the operation of a peristaltic pump.

It will be appreciated that the yarn will need to be flexed sufficiently to produce the bulked effect. Therefore, the specific number of flexions, i.e. the number of flexions per minute applied by the dwell time of the yarn in the tube (which depends on the tube length divided by the speed of throughput of the yarn) must be great enough.

It has been found, however, that the dwell time is longer than would be expected given the tube length and throughput speed of the yarn, so that the specific number of flexions is larger than would be expected from these two parameters. It is believed that the tube acts in some ways like a J-box allowing a reservoir of yarn to build up inside it before yarn emerges from it. This effect is greater as the tube cross-section/yarn count ratio increases. Thus, for a given yarn count and throughput speed, the dwell time will be greater for a larger diameter tube. In other words the specific number of flexions will increase with tube diameter.

A specific number of flexions in excess of 300 is required to produce significant bulking and for best results this number should be in excess of 400 and preferably above 500. There is for each tube a rate of flexion above which an increase of the flexion rate does not greatly increase the bulking effect, and is therefore not preferred. For a silicone tube this maximum rate is about 1000, but for a polyurethane tube it is found to be 1500 or more and for this reason a polyurethane tube is greatly preferred, permitting a substantially higher throughput of the apparatus.

The temperature at which the method is carried out should exceed 30"C, but temperatures in excess of 65"C do not give improved results, and can even lead to poorer results. Accordingly, the preferred temperature range is from 30"C to 650C, especially about 60"C.

The process of the invention is applicable to spun yarns of keratinous fibres. In particular worsted, and especially semi-worsted spun, yarns may be bulked. While yarns of any count may be bulked (depending on the tube cross-section as explained more fully hereinafter) the process is particularly useful in relation to semi-worsted spun carpet yarns, having counts in the range 600 to 3000 tex, when the bulked product has very much better cover and increased stability over the original yarn.

When passing one (or more) yarns through the tube, the ratio of tube cross-section to yarn count (or total yarn count) should be greater than 15 mm2/k.tex, preferably greater than 20, and advantageously about 40. Ratios in excess of 60 are too great in that the yarn can fold back on itself and become tangled and irregular.

The method of the invention using an oscillating guide tube a few decimeter long, can produce bulked yarns with an acceptable degree of bulking at a production rate which is comparable with that of conventional spinning processes.

If the oscillating motion is that of a transverse wave then the yarn is subjected to forces which tend to transport the wool through the tube. Thus if there is no tension on the wool at either end of the tube, a direct relationship between the rate of transport and the frequency of the wave can be observed. This makes it possible to transport the wool without tension through the guide tubes, although it is preferred to take off the bulked yarn on driven rollers and utilizing the transporting action only to draw the unbulked yarn into the tube.

At its simplest, the apparatus of the invention may consist of a straight tube which is brought into a reciprocatory flexing motion through a crank, cam or similar mechanism.

The internal section of the tube is preferably circular, as other shapes might lead to an undesired shape of the yarn.

The bulking process is accelerated markedly by the use of a flexible tube which is connected at only one or a few places to the remainder of the apparatus. A tube of elastic material, such as rubber, or a helical spring with a small pitch can be used to provide the flexible tube. As the recovery rate of the flexible tube is relatively low, a wave motion results, which appears to have a favourable effect on the bulking process. In the simplst case, a stationary wave motion will be generated. By a proper setting of the device which creates the motion, however, a travelling wave can be generated. In that case, besides the bulking action, the transporting action is also obtained.

As the invention utilises the unique properties of keratinous fibres, and especially wool, it is preferred that the proportion of such fibres be as high as possible to produce the best results. However. blends of wool with other fibres may be employed provided that the proportion of wool is not too low for effective bulking to occur.

The bulking should take place in the presence of moisture; ideally an aqueous milling solution (e.g. an acid or alkaline solution containing soap or detergent) is passed through the tube with a yarn. Ideally the temperature of above 30"C is maintained by heating a reservoir of milling liquid to the desired temperature by means of, for example, immersion heaters or steam pipes, and circulating this from the reservoir through the tube and back to the reservoir.

Yarn throughput speed of up to 20 metres/min can be obtained, although for general purposes speeds of 6 to 12 metres/min are preferred.

The invention will be described further, by way of example, with reference to the accompanying drawings in which: Figure I is a diagrammatic side view of an apparatus constructed according to the invention; and Figure 2 is a front view of the apparatus of Figure 1.

As shown in the drawings, a shaft 10 carries a pair of end-plates 12 attached to which are six equally spaced rotor members 14. The rotor members 14 comprise rollers 16 of smooth plastics material mounted on axles 18 carried between the end plates 12 and a number of supporting discs 20. The shaft 10 is mounted on bearings 22 carried in the frame of the apparatus and is rotated by means of a drive belt to a pulley 24.

Flexible guide tubes 26 made from urethane rubber are fixed in bosses 28, 30 in the top of the apparatus. The tension of the guide tubes 26 is such that during rotation of the assembly of shafts and rotor members contact is maintained between the tube 26 and the rollers 16, but flattening of the tube does not take place. The inlet bosses 28 each carry a short metal tube 32 which projects into a header tank 34 (omitted from Figure 2 for clarity) filled with milling solution 36. An immersion heater (not shown) maintains the temperature at 60"C.

Ingoing yarn 38 is wetted by this solution 36 and carries a portion of it through the guide tubes 26. The exit bosses 30 each have a longer guide tube 40 projecting above the liquid surface. Holes 42 in the tube 40 allow the bulk of the solution carried through the guide tubes 26 to return to the tank 34 without interfering with the egress of bulked yarn 44.

Supporting rollers 46 are provided to steady both the ingoing yarn 38 and the resultant bulked yarn 44.

As can be seen from Figure 1, the guide tubes 26 bend where they are in contact with the rollers 16 and are straight in between. Thus when the shaft is driven, the bends in the tubes 26 move with the rollers 16 and the parts of the tubes between the rollers show an amplitude of displacement towards the central shaft 10. The result appears as a travelling transverse wave motion of the guide tubes 26. The yarn 38 is bulked by this wave motion to a bulked yarn 44 which is led off for storage or further use.

Despite the fact that the rollers 16 are free to rotate about their axes 18, it has been found that at operating speeds a great deal of slippage takes place between the rollers 16 and the tube 26. It is therefore beneficial to provide lubrication. Water or excess milling solution accomplishes this lubrication and greatly reduces wear on the tubes 26.

The yarn may be removed by means of driven take-off rollers at the desired throughput speed. Typical shaft speeds lie in the range 400 - 1500 rpm with speeds of 700 to 900 rpm giving good results.

The degree of bulking is usually sufficient for normal applications of wool yarns at throughput speeds of about 6 m/min. If, however, a higher degree of bulking is required, for instance when the yarn only partly consists of wool, the throughput speed can be decreased and/or the rotor speed increased i.e. the specific number of flexions increased.

Alternatively, longer tubes can be employed, or two or more devices in series.

In order to protect the tubes and to prolong the time they can be used, a belt can be placed between the rollers and the tube. This belt is fixed to the frame of the machine and consists of a material which is flexible but cannot be stretched, for example reinforced rubber.

As the movement of the end of the tubes may be large, which could weaken and eventually damage the tubes, a buffer of elastic material may be mounted on the frame to restrain the oscillating movement of the tube near the bosses 30. Such a buffer can for instance be made from foam rubber. Other ways of reducing this oscillation include providing the bosses 30 with a flexible downwardly tapering connection to the tubes 26, or increasing the distance of the bosses 30 from the rotor assembly. The provision of a polyurethane conical boss 31 moulded on to the polyurethane tubes 26 is preferred.

The yarns may be fed into the apparatus of the invention either in the direction of, or counter to, the rotation of the members although the former is preferred.

The following are examples of the production of bulked yarns according to the invention.

Examples I to III Using the above apparatus with a milling solution comprising 3 g/l SM13 (soap/phosphate buffer-Stevensons) maintained at 60"C a 1335 tex fourfold carpet yarn was treated as follows. The rotor speed was held at 800 r.p.m. and the throughput speed at 20 ft/min (6.1 m/min) over a tube length of 41.5 cm. This results in observed dwell time of 0.107 minutes as opposed to a calculated time of 0.068 min. The observed dwell times differed for each tube diameter. Values for the specific number of flexions of 6 (rotor members) x 800 (f.p.m.) x Dwell time (minutes) are given below. Yarns are processed through tubes of 3 diameters as follows: Dwell Ex.No.Tube Diameter Tube X-section mm2lK tex Flexions time I Smm 0.196 mm2 14.7 458 5.73s II 6mm 0.283 mm2 21.2 513 6.41s III 8mm 0.503 mm2 37.7 875 10.94s The bulked yarn properties were as follows: Control Ex.l Ex.ll Ex.lII (untreated) Length contraction (% of initial length) 90.7 86.3 80.1 100 Strength (g/tex) 3.24 3.27 2.46 3.52 Elongation at Break (%) 35.0 38.2 47.2 30.7 Packing factor (%)* 6.20 5.44 5.02 6.40 %' Bulk increase 3.12% 15.0% 21.6% 0 * The packing factor is the ratio of the actual volume occupied by fibres to the overall volume of a firm length of yarn, expressed as a percentage. As can be seen from the above the bulking produced in Example I is marginal since the mm K tex ratio is low.

Examples IV to Vl Examples I to III were repeated using a 6 mm diameter tube and varying the rotor speed.

The results were as follows: Ex.lV Ex. V Ex. VI Control Rotor speed (rpm) 700 800 900 0 Length contraction 92.7 86.3 82.1 100 Strength 3.35 3.27 2.86 3.52 Elongation 36.1 38.2 38.7 30.7 Packing factor 5.53 5.44 5.4 6.4 % bulk increase 13.6cue 15.0% 15.6% 0 Specific No. of flexions 420 513 619 0 Dwell time (s.) 6.0 6.41 6.88 0 Examples Vll to IX Examples I to III were repeated holding the tube diameter at 6 mm and varying the throughput speed.The results were as follows: Ex.VII Ex.VIII Ex.IX Control Throughput speed (ft/min) 10 20 40 Length contraction 83.6 86.3 92.9 100 Strength 2.87 3.27 3.42 3.52 Elongation 39.7 38.2 30.1 30.7 Packing factor 5.16 5.44 5.98 6.4 % bulk increase 19.4% 15.0% 6.56% 0 Dwell time (s.) 13 6.41 3.75 0 Specific no. of flexions 1040 513 300 0 It can be seen from Example IX that as the specific number of flexions drops toward 300 the bulking effect is markedly less.

Thus it can be seen that, using the process of the invention, very high bulk increases (e.g.

nearly 22% in Example III) can be obtained at fast throughput speeds with simple equipment. The bulked yarns so-produced perform very well in carpets and a variety of other end-uses.

As already mentioned, considerable advantages result from the use of a flexible tube of polyurethane instead of a silicone rubber tube. These tubes are preferably as thin-walled as practicable and a wall thickness of about lmm is preferred as balancing the advantage of thinness with ease of manufacture.

The present preferred polyurethane tubes are those sold by Dunlop Plastics Division (Wrexham, England) under the Trade Mark PRESCOLLAN PCE 1589. The material itself, Grade 23017. has a density of 1.17 Mg/m2, a Shore hardness (ASTM D2240) A:88 and B: 37, a tensile strength (ASTM D412 DicD) of 45 MN/m2, an elongation at break (ASTM D412) of 610%, and a resilience (Dunlop Tripsometer BS903) of 49.

The conical boss, restraining oscillation of the tube, may be moulded directly on the ends of a tube of polyurethane using a urethane prepolymer moulding composition, such as that sold by Compounding Ingredients Ltd. under the name CIL-Monothane, which is a one-component polyester-based polyurethane moulding composition.

The effective diameter of the tube can be varied by fitting a restrictor of the desired internal diameter at the outlet end of the the tube. This may enable a wider tube to be employed with a given yarn than would otherwise be suitable. It is advantageous to employ driven withdrawal means to withdraw the yarn from the tube when the diameter of the tube is restricted in relation to the size of the yarn.

WHAT WE CLAIM IS: 1. A method of making a bulked yarn which comprises passing a yarn containing keratin fibres in the presence of moisture through a flexible tube, and flexing the tube during passage of the yarn at a temperature in excess of 30"C.

2. A method according to claim 1 wherein the yarn is passed through a flexible tube composed of polyurethane.

3. A method according to claim 1 or 2 wherein the temperature is between 30 and 65"C.

4. A method according to claim 1, 2 or 3 wherein the specific number of flexions (as herein defined) is above 300.

5. A method according to claim 2 wherein the tube is of polyurethane and the specific number of flexions is between 400 and 1500.

6. A method according to any of claims 1 to 5 wherein the tube is flexed by the motion of a plurality of members mounted for orbital movement about a common centre.

7. Apparatus for making bulked yarn comprising a flexible tube composed of polyurethane and defining a path for yarn, means for supplying a moistened yarn to the tube and at least one member mounted for gyration in an orbit intersecting the path of the yarn. whereby gyration of the member flexes the tube and the yarn therein.

X. Apparatus according to claim 7 wherein the tube is provided with tapering bosses

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

Examples Vll to IX Examples I to III were repeated holding the tube diameter at 6 mm and varying the throughput speed. The results were as follows: Ex.VII Ex.VIII Ex.IX Control Throughput speed (ft/min) 10 20 40 Length contraction 83.6 86.3 92.9 100 Strength 2.87 3.27 3.42 3.52 Elongation 39.7 38.2 30.1 30.7 Packing factor 5.16 5.44 5.98 6.4 % bulk increase 19.4% 15.0% 6.56% 0 Dwell time (s.) 13 6.41 3.75 0 Specific no. of flexions 1040 513 300 0 It can be seen from Example IX that as the specific number of flexions drops toward 300 the bulking effect is markedly less.

Thus it can be seen that, using the process of the invention, very high bulk increases (e.g.

nearly 22% in Example III) can be obtained at fast throughput speeds with simple equipment. The bulked yarns so-produced perform very well in carpets and a variety of other end-uses.

As already mentioned, considerable advantages result from the use of a flexible tube of polyurethane instead of a silicone rubber tube. These tubes are preferably as thin-walled as practicable and a wall thickness of about lmm is preferred as balancing the advantage of thinness with ease of manufacture.

The present preferred polyurethane tubes are those sold by Dunlop Plastics Division (Wrexham, England) under the Trade Mark PRESCOLLAN PCE 1589. The material itself, Grade 23017. has a density of 1.17 Mg/m2, a Shore hardness (ASTM D2240) A:88 and B: 37, a tensile strength (ASTM D412 DicD) of 45 MN/m2, an elongation at break (ASTM D412) of 610%, and a resilience (Dunlop Tripsometer BS903) of 49.

The conical boss, restraining oscillation of the tube, may be moulded directly on the ends of a tube of polyurethane using a urethane prepolymer moulding composition, such as that sold by Compounding Ingredients Ltd. under the name CIL-Monothane, which is a one-component polyester-based polyurethane moulding composition.

The effective diameter of the tube can be varied by fitting a restrictor of the desired internal diameter at the outlet end of the the tube. This may enable a wider tube to be employed with a given yarn than would otherwise be suitable. It is advantageous to employ driven withdrawal means to withdraw the yarn from the tube when the diameter of the tube is restricted in relation to the size of the yarn.

WHAT WE CLAIM IS:

1. A method of making a bulked yarn which comprises passing a yarn containing keratin fibres in the presence of moisture through a flexible tube, and flexing the tube during passage of the yarn at a temperature in excess of 30"C.

2. A method according to claim 1 wherein the yarn is passed through a flexible tube composed of polyurethane.

3. A method according to claim 1 or 2 wherein the temperature is between 30 and 65"C.

4. A method according to claim 1, 2 or 3 wherein the specific number of flexions (as herein defined) is above 300.

5. A method according to claim 2 wherein the tube is of polyurethane and the specific number of flexions is between 400 and 1500.

6. A method according to any of claims 1 to 5 wherein the tube is flexed by the motion of a plurality of members mounted for orbital movement about a common centre.

7. Apparatus for making bulked yarn comprising a flexible tube composed of polyurethane and defining a path for yarn, means for supplying a moistened yarn to the tube and at least one member mounted for gyration in an orbit intersecting the path of the yarn. whereby gyration of the member flexes the tube and the yarn therein.

X. Apparatus according to claim 7 wherein the tube is provided with tapering bosses

adjacent the ends thereof to reduce oscillation during flexion.

9. Apparatus according to claim 7 or 8 including means for heating a supply of an aqueous liquid for moistening the yarn to a temperature of at least 30"C.

10. Apparatus according to claim 7, 8 or 9 wherein a plurality of rollers are mounted at equal radial spacing on a disc or wheel rotatable about its centre, each roller flexing the said tube during rotation.

11. Apparatus according to any of claims 7 to 10 including means for withdrawing the yarn from the tube.