US 3477218 A
Description (OCR text may contain errors)
'Nov. 11, 1969 s. G. HAWTIN ET AL 3,477,218
APPARATUS AND METHOD FOR PRODUCING CRIMPED FILAMENTARY MATERIALS 2 Sheets-Sheet l Filed July 6. 1967 SELWYN GEORGE HAW'I'IN DAVID ROGER SMI'fl-X' DENNIS RONALD FIELD Inventor N5 11, 1969 s. G. HAWTIN ET AL 3,477,218
APPARATUS AND METHOD FOR PRODUCING CRIMPED FILAMENTARY MATERIALS Filed July 6, 1967 L) LL.
Q) g N SELWYN GEORGE HAW'I Q 8 DAVID ROGER ,sm'm DENNIS 120mm FIE! I lnvenlors T 9 1 7w Lk u /w Attorney:
2 Sheets-Sheet 2 United States Patent ce 2,821 66 Int. Cl. D02g 3/02; D01h 13/00, 7/00 U.S. C]. 57-34 10 Claims ABSTRACT OF THE DISCLOSURE Crimped bulked yarns and tows of continuous filaments are obtained by feeding plasticized filaments into a zone where they are twisted by the action of a fluid, passing the fluid while it is carrying the filaments through a constriction and then reducing the degree of plasticization of the filaments.
The invention is concerned with the production of crimped bulked yarns and tows, particularly those containing continuous filaments.
It is well known to prepare crimped filaments by twisting thermoplastic filaments, setting the twist by heating and then untwisting the filaments. The twist may be a true twist or a false twist with the process being performable in a continuous manner. Other methods include the use of a stuffing box or a device for deforming the filaments, such as intermeshed gear teeth, with the :application of heat to the thermoplastic filaments to set them while still in the deformed position. Crimping processes may also be employed with non-thermoplastic filaments, for example, by the application of a thermoplastic resin or polymer to the filaments before deforming them, the deformation being set by heating. It is also well-known to bulk yarns by various processes, for example, by heating a mixture of heat-shrinkable fibres and of non-shrinkable fibres. An alternative method is to pass filaments through a turbulent zone so as to interlace the filaments into a bulky yarn. The present invention provides a simultaneously crimped and bulked yarn or tow.
According to the present invention a process for the production of a crimped, bulked yarn or tow comprises feeding a plurality of plasticised filaments into a zone of turbulent fluid which fluid is supplied continuously to the zone and wherein twist is imparted to the filaments and subsequently passing the fluid carrying the filaments through a constriction, thereby crimping and intermingling the filaments and reducing the degree of plasticismg.
The filaments forming the yarns or tows which may be treated by the process of the invention are preferably thermoplastic, for example, celloulose acetate, including both diacetate and triacetate, polyamides, polyethylene, polypropylene, polyacrylonitrile, and polyesters. The filaments may also be non-thermoplastic for examples, viscose rayon. They may also be composite, for example, bicomponent filaments.
As stated above, the filaments are plasticised before being fed into the twisting zone and through the constriction. The form which the plasticising takes will depend on the nature of filaments used. The thermoplastic filaments may be heated before they are passed into the twisting zone, for example, by steam, by contact with a heated roller, or by infrared heating. Preferably the heating raises the temperature of the filaments to above 3,477,218 Patented Nov. 11, 1969 the second order transition point and below the melting point. An alternative method involves treatment of the filaments with a swelling agent for the filamentary material, for example, the agent may take the form of a partial solvent for the material applied to the filament or it may be residual spinning solvent. Thus, if the filaments are of cellulose triacetate, the filaments may advantageously be plasticised by the retention in them of a quantity of methylene chloride, or other solvent, used in their spinning; this is convenient when the crimping operation follows immediately after dry spinning. As another preferred example of a plasticising action, polyamide filaments are passed through a chamber filled with steam immediately before entering the twisting zone.
During the passage through the twisting zone and the constriction, the filaments are crimped and intermingled and the plasticising is reduced. Thus, for example, where the plasticising is caused by the application of heat, the temperature of the filaments is lowered during the passage through the apparatus; where the plasticising is caused by solvent action, the solvent will be removed, to some extent though not necessarily completely, during the treatment.
The filaments are preferably fed to the apparatus as a bundle with little or zero twist to aid the intermingling and give a more highly bulked product. The speed at which the filaments are fed to the apparatus affects the degree of bulking in the product. Preferably the filaments are fed into the apparatus at a speed lower than that at which they would be drawn into the apparatus by the fluid in the absence of any restraint.
The fluid used in the process of the invention is preferably gaseous, for example, air. However, any other gas or liquid, for example, water, may be used which does not adversely affect the filaments being processed.
A suitable apparatus for use in this invention comprises a chamber with an inlet for filaments, a second inlet for a fluid to carry the filaments through the apparatus and an outlet for both the filaments and the fluid, the second inlet connecting to an annular space Within the apparatus whereby fluid, when passed into the apparatus, meets the filaments in a surrounding inwardly directed turbulent flow imparting twist to the filaments and drawing them through the apparatus, and a constriction between the second inlet for the fluid and the outlet or at the outlet.
The constriction preferably takes the form of a flattened part within or at the end of a tube and it may be adjustable to provide an additional control on the degree of crimping and bulking. This may conveniently be done by using a flexible tube as part of the apparatus and causing the constriction with, for example, a screwthreaded clamping device about the tube.
The degree of crimping and bulking may be varied over a wide range by altering the rate of feeding the fluid used through the apparatus, the speed of the filaments through the apparatus, the size of the constriction, the extent of plasticising or the degree of twisting. It will be appreciated that the twisting is in the nature of a false twist which is only temporary, the product having, on average, the same twist as the feed material, usually zero twist.
As indicated, the filaments may be in yarn or tow form. By cutting tows of filaments crimped in this Way, crimped staple fibres may be produced economically. Moreover, products, for example non-woven fabrics, incorporating such crimped staple fibers have improved properties in certain respects compared with similar products incorporating conventionally crimped fibers. The tows treated may be from, say, five thousand denier to several hundred thousand denier, so that the correct design of the apparatus, so as to impart to the filaments as high as possible a twist in the twisting zone, is important. In one such apparatus the fluid follows a helical path immediately before entering the zone.
An example of apparatus according to the invention for treating yarns is illustrated in FIGURES 1 to 3 of the accompanying drawings, in which:
FIGURE 1 is an elevation, partly in section, of the apparatus, and
FIGURES 2 and 3 are plan views, partly in section, of parts of the apparatus shown in FIGURE 1.
FIGURE 4 is a view in elevation, partly in section, of apparatus according to the invention for the treatment of tow.
The apparatus shown in FIGURES 1 to 3 comprises a tube 1 having a mouth 2 and a chamfered end 3, the tube being a sliding fit in a holder 4. The tube 1 is locked in position in the holder 4 by a grub screw 5. One end of the holder 4 is externally screw-threaded and is surrounded by a correspondingly internally screw-threaded cylindrical tailpiece 6 which co-operates with the holder and the tube 1 projecting therefrom to define an annular chamber 7, and has an end tube 8 attached to it. The mouth 9 of the end tube 8 is chamfered in like manner to the chamfered end 3 of the tube 1. The tailpiece 6 is fitted with a screw-threaded hole 10 into which a correspondingly screw-threaded air inlet pipe 11 is fitted as shown in FIGURE 1. On to the end tube 8 of the tailpiece 6 is fitted a flexible tube 12 which terminates in a constriction 13 caused by an adjustable clamping device 14, shown diagrammatically in FIGURE 1. The flexible tube may advantageously be transparent.
In operation of the above-described apparatus by the process according to the invention, continuous filaments to be treated are introduced into the mouth 2 of the tube 1 and are passed through the apparatus to emerge eventually as a crimped, bulked yarn from the open end of the flexible tube past the constriction 13. Air or another gas is introduced through the pipe 11 under pressure and passes through the annular chamber 7 to impart a twist to the filaments where it meets them in a surrounding inwardly directed turbulent flow. The appearance of the yarn issuing from the flexible tube may be varied over a wide range by altering the size of the constriction.
An example of apparatus according to the process of the invention for treating tows is illustrated in FIGURE 4 of the accompanying drawing which is a part-sectional elevation of a filament crimping apparatus.
In FIGURE 4 a hollow body member 101 surrounds a core member comprising a hollow cylindrical stern 102 and an integral flange 103 which fits into a rebate in one end of the body member 101. The end of the stem 102 furtherest from the flange 103 has external helical vanes 104, the diameter of which is such that the vanes are a sliding fit in the body member 101. Between the vanes 104 and the flange 103 an annular chamber 105 is formed within the body member 101. An inlet 106 in the wall of the body member 101 communicates with the chamber 105, for admitting fluid to the apparatus.
On the end of the body member remote from the rebate is an outlet pipe 107 which is coaxial with the stem 103. One end of a flexible tube 108 is fitted over the outlet pipe 107. At the other end of the tube 108 a constriction is formed by compressing the tube between two members 109 which are connected together in such a way that the dimensions of the constriction may be varied by rotation of a screw-threaded part (not shown).
Further constrictions may be formed in the tube, for example midway along its length, if desired.
To use the apparatus a tow of filaments, plasticised for example by being passed through a steam chamber, is fed through the apparatus in the direction of the arrow A whilst a fluid, usually air, is fed under pressure through the inlet 106 to the chamber 105 where it follows a helical path past the vanes 104 to meet the tow within the pipe 107. The tow is thus twisted by the fluid and the twist is 4 retained by the tow whilst it travels through the tube 108 until it meets the constriction. At this point the venturi effect of the constriction causes the filaments in the tow to be separated.
In a modification of the apparatus shown in the drawing, the end nearer to the chamber 105 of the part of the bore in the body member 101 which surrounds the vanes 104 is enlarged so that the bore tapers towards the pipe 107, and the vanes are also enlarged to the point where their peripheries lie on the locus of a frusto-cone and they are a good fit within the tapering bore. With this apparatus an increased twisting motion can be imparted to tow passed through the apparatus.
The crimped tow is commonly collected in a bin adjacent to the end of the tube so as to avoid subjecting the tow to any tension until the crimps are fully set in the filaments. Collection can be assisted by placing a perforated canopy above the bins.
The process of the invention is illustrated by the following examples; in Examples 1 and 2, apparatus as shown in FIGURES l-3 Was used to crimp yarn and in Examples 3 to 6 apparatus as shown in FIGURE 4 was used to crimp tow.
EXAMPLE 1 A solution of 21 percent by weight of cellulose triacetate in a solvent containing parts by volume of methylene chloride and 10 parts by volume of ethyl alcohol was dry spun through a jet which had 30 holes of 63 microns diameter to give a yarn of 400 denier. The yarn was passed directly after spinning around a godet rotating at a peripheral speed of 110 metres per minute and then at this speed was passed into the apparatus illustrated in the drawing. The total length of the apparatus was approximately 22 inches of which the last 18 inches was constituted by the tube 12, which was made of polyvinyl chloride and had an approximate diameter of V2 inch. Air at 30 p.s.i.g. was admitted to the side tube 11 to carry the filaments through the apparatus. The constriction 13 took the form of a narrow slot about one sixteenth of an inch wide at the outlet end of the tube 12. Yarn emerging from the apparatus had appreciable bulk and the individual filaments were crimped. The bulked yarn had an average denier of about 550.
EXAMPLE 2 A nylon 6 yarn of 3000 denier and having 204 filaments was passed through the apparatus shown in the drawing after having been heated by passage through a steam jacket 18 inches long, filled with steam at C. The air pressure employed was 30 p.s.i.g. and the speed of the filaments entering the apparatus was 40 metres/minute. The product was a bulked yarn of, on average 3750 denier having individually crimped filaments.
In both of the above examples, when the constriction 13 was removed, there was no appreciable bulking of the product.
EXAMPLE 3 The apparatus of FIGURE 4 was used with a stem 102 having a diameter of about /2 inch and having four separate vanes 104 each having a helix angle of 45. The tube 108 had an internal diameter of about 1 inch and was about 9 feet 6 inches long. The tube was constricted at two points, at the end of the tube and at a point 4 feet from the end of the tube, to about inch across.
A 22,000 denier tow of cellulose triacetate filaments having a C-shaped cross-section was fed through the apparatus at 33 metres per minute after having been heated by passage through a steam chest one foot in length and supplied with steam at 25 p.s.i.g. Air at 50 p.s.i.g. was also fed to the apparatus through the inlet 106.
The filaments of the tow emerging from the tube were individually crimped and had about 7 crimps per inch. It will be appreciated that the crimp is a helical-type crimp so that the crimp is in' fact measured as the number of turns per inch.
The tow was cut to form fibres of 2 inches staple length which were; heat set in loose form in an autoclave supplied with steam at 15 p.s.i.g. A wadding, formed in a conventional way from the staple fibres was' found to have a bulk density of 0.73 pound per cubic foot. This figure may be compared with a bulk density of 1 pound per cubic foot fora wadding made by an identical process from staple fibres derived from a tow crimped in a conventional stuffing-box process.
EXAMPLE 4 The process of Example 3 was repeated with the excep tion that the apparatus used had a cone-shaped stem 102, instead of a parallel sided stem, with an internal diameter of V Additionally the tow was fed through the apparatus at an increased speed of 85 metres per minute.
The crimped tow produced was cut into staple fibres of 2" length and a' wadding formed from the staple fibres was found to have a bulk density in the region of from 0.65 to 0.70 pound per cubic foot.
EXAMPLE 5 The procedure of Example 3 was repeated using a 20,000 denier tow of modacrylic filaments. The speed of passage of the filaments through the apparatus was 90 metres per minute and the pressures of the steam in the steam chest and air fed to the inlet 106 were 15 p.s.i.g. and 35 p.s.i.g. respectively.
The filaments in the crimped tow were found to have a helical crimp of about 7 crimps per inch.
EXAMPLE 6 A 20,000 denier tow of 15 denier nylon 6 polyamide filaments was fed through the apparatus at a rate of 30 metres per minute. The steam pressure used was 25 p.s.i.g. and the air pressure 15 p.s.i.g., and the bore of the stem 102 was atthe point where the tow met the air stream.
The crimped filaments produced were cut to form 2" staple fibres and a wadding made from them had a bulk density of 0.81 pound per cubic foot, compared with 1.37 pounds per cubic foot for a similar material made from stufiing box crimped nylon 6 filaments.
What we claim is:
1. A process for the production of crimped, bulked yarn or tow which comprises continuously moving a bundle of plasticized continuous filaments intqa twisting zone, continuously delivering a fluid into said twisting zone under conditions to create turbulence in said zone and to impart a twist to said bundle, passing the fluid and filaments from said twisting zone to an untwisting zone where the bundle is untwisted and the degree of plasticizing is reduced, and withdrawing said bundle from the untwisting zone through a constriction, thereby to fiufl out the filaments.
2. A process as claimed in claim 1 wherein the continuous filaments are thermoplastic and the filaments are plasticised by the application of heat.
3. A process as claimed in claim 2 wherein the heat is supplied by steam.
4. A process as claimed in claim 1 wherein the filaments are plasticised by a swelling agent.
5. A process according to claim 4 wherein the swelling agent is residual spinning solvent.
6. A process as claimed in claim 1 wherein the fluid used is air.
7. A process as claimed in claim 1 wherein a tow of filaments is crimped and bulked and the tow is then cut to staple lengths. T
8. Apparatus for the production of crimped, bulked yarn or tow comprising a chamber with an inlet for the filaments of the yarn or tow, a second inlet for a fluid to carry the filaments through the apparatus and an outlet for both the filaments and the fluid, the second inlet connecting to an annular space Within the apparatus whereby fluid, when passed into the apparatus, meets the filaments in a surrounding?inwardly-directed turbulent flow imparting twist to the filaments and drawing them through the apparatus, and a constriction between the second inlet for the fluid and the outlet or at the outlet.
9. Apparatus according to claim 8 wherein the constriction takes the formjof a flattened part of the tube.
10. Apparatus according to claim 9 wherein at least a part of the tube is flexible and the restriction is caused by a clamping device about the tube.
References Cited UNITED STATES PATENTS 2,924,000 2/1960 ,Griset et al 281 3,009,309 11/ 1961 'Breen et al.
3,036,357 5/1962 Cook et al 281 3,147,533 9/1964 Baer 281 3,281,913 11/1966 Morehead et al. 2872 XR 3,296,677 l/1967 Chase 281 3,303,546 2/l967 Van Blerk 281 3,341,914 9/1967 Van Blerk 2872 3,343,240 9/1967 Parmeggiani et al. 28-1 3,373,470 '3/1968 Joly 2872 3,390,438 7/1968 Epstein 28-1 JOHN PETRAKES, Primary Examiner US. Cl. X.R.