US3548581A

US3548581A - Method and apparatus for ringless spinning of fiber-polymer yarns

Info

Publication number: US3548581A
Application number: US778714A
Authority: US
Inventors: Emilian Bobkowicz; Andrew John Bobkowicz
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-10-02
Filing date: 1968-11-25
Publication date: 1970-12-22
Anticipated expiration: 1987-12-22
Also published as: IL32557A; NL6913593A; BR6911599D0; CH1196769A4; IL32557A0; PL71388B1; BE738932A; JPS496492B1; ES367780A1; DE1947311A1; GB1279456A; NL148661B; DE1947311C3; AT323611B; DE1947311B2; CH533702A; FR2019636A1

Description

E. BOBKOWICZ HAL METHOD AND APPARATUS FOR RINGLESS SPINNING OF FIBER-POLYMER YARNS Filed Nov. 25, 1968 v 5 Sheets-Sheet l mZZ mmm WWW MUG NK EB QB N m Fm ATTORNEYS Dec. 22, 1970 Filed Nov. 25; 1968 E. BOBKOWICZ ETA! METHOD AND APPARATUS FOR RINGLESS SPINNING 0F FIBER-POLYMER YARNS 3 Sheets-Sheet 2 F I G,

INVENTORS EMILIAN BOBKGWFCZ ANDREW J. BOQKUVWCZ woww m ATTORNEYS Dec. 22,1970 5. BO BKOWI CZ ETAL 3,543,5M

METHOD AND APPARATUS FOR RINGLES s SPINNING fOE FIBER-POLYMER YARNS 3 Sheets-Sheet 5 Filed NOV. 25, 1968 FIG.11

FIG.1O

' INVENTORS EMHJAN BQBKOWFCZ Z w 0 K B O B E W E R D N A.

waflwzg a ATTORNEYS United States Patent Office Int. Cl. boz 1/02 US. Cl. 57--34 14 Claims ABSTRACT OF THE DISCLOSURE Method whereby a continuous strand of composite staple fiber-thermoplastic polymer material is linearly supplied by feed-in rolls into and through a fiber restrictive heating zone where the material is heated until the thermoplastic substrate becomes plastic but without reaching its melting point, and then twist is imparted from below to said material in this fiber restrictive heating zone so as to produce intermolecular slippage in the plastic polymer and helical rearrangement of the fibers, thereafter upon leaving the heating zone the material is cooled to coagulate the imparted twist, and finally the obtained twisted yarn is linearly wound on a collecting roll to form a yarn package, the feed-in rolls and the collecting roll constituting two fixed pinch points between which twist is imparted and substantially retained; the invention also includes an apparatus for carrying out this method.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to a novel method and apparatus for continuous linear production of composite staple fiber-thermoplastic polymer spun yarns.

More particularly the invention relates to a fundamentally novel concept of spinning yarns consisting of staple fiber-thermoplastic polymer blends or combinations, whereby the twist is imparted to said yarns and substantially retained therein between two fixed pinch points in a continuous linear sequence of operations.

(2) Description of the prior art Ever since staple fiber spinning began, there has prevailed a recognized yet unchallenged fundamental principle that in order to impart and retain a twist in a strand comprising staple fibers, by any means, one end of the strand must be free to rotate.

Accordingly, if any attempt is made to impart twist to a continuous strand of staple fibers, which is held at both ends, right hand twist will appear on the strand at one side of the twisting device and will be offset by left hand twist at the other side of said device. The net result will be yarn with zero twist, because the left and right hand twists nullify each other. This is commonly known as false twisting.

Consequently, all hitherto known methods of staple fiber spinning fall into three basic groups:

(1) Rotating the yarn collecting package (2) Rotating the fiber supply package (3) Rotating the end of the yarn to which a discontinuous loose stock is continually supplied.

Ring spinning, now predominantly used, belongs to the first category, which also includes the flyer, cap and pot spinning.

3,548,581 Patented Dec. 22, 1970 The second, rather uneconomical method, finds little practical application in the yarn spinning art.

The third method called Open End Spinning or Break Spinning is relatively new, although it has been in the development stage for many decades; it is now under test runs in some textile mills. Its main technological disadvantage is the complexity of systems required to produce the needed discontinuity of the staple fibers while maintaining an open end by centrifugal forces for reassembly into a continuous twisted yarn with retained twist. The obtained twisted yarn can however be linearly wound on a collecting roll, which constitutes the main advantage of the open end spinning, since this can approximately double the output speed as compared with ring spinning. The maximum open end turbine speed presently attainable is about 30,000 r.p.m. and the count range is 20s to 60s. Linear output speeds of -200 feet per minute have been achieved with this system.

SUMMARY OF THE INVENTION Applicants have now found a new way of producing spun yarn based on a technologically novel principle and applicable to any composite staple fiber-thermoplastic polymer material, whereby contrary to the above mentioned fundamental concept, twist will be imparted and retained in the yarn between two fixed pinch points, such as linear feed-in rolls and linear collection rolls.

It is therefore a principal object of the present invention to provide a novel method and apparatus which will make it possible to impart to a composite staple fiber-thermoplastic polymer strand, web, tape or the like material, a predetermined twist and to retain a substantial portion of said twist without the necessity of either revolving the feed-in end or the collecting package and without the need to create a discontinuity in the fiber mass at the feed-in end, as is the case with all open end spinning methods.

A further object of the invention is to provide a method and an apparatus which will enable manufacture of staple fiber-thermoplastic polymer yarns by means of a totally linear operation and at substantially higher production speeds than those of the presently known systems.

A still further object of the invention is to provide a relatively simple method and apparatus which will adequately exploit the technological advantages of applicants novel principle and achieve at high speeds and in a continuous sequence of operations linearly wound packages of spun staple fiber-thermoplastic polymer yarns ready for utilization.

Other objects and advantages of the invention will be apparent from the following more detailed description.

The technological feasibility and important economical advantages of the present invention are based on the possibility to retain, to a substantial degree, the twist imparted to a consolidated, composite, continuous staple fiber-thermoplastic polymer stock-in material (tape, strand or the like) between two fixed pinch points, for example the stock-in material supply rolls. and the linear yarn collecting rolls, by providing between said pinch points a suitable heating zone through which the composite tape, strand or the like material passes and wherein it is heated to a point where the thermoplastic polymer substrate of the composite material becomes plastic without reaching the melting point of said polymer. The composite material is then twisted in said zone while the polymer substrate is in such plastic condition to achieve interslippage of the polymer molecules and helical rearrangement of the fibers, and finally it is cooled to coagulate the polymer while the material is in such twisted condition, thus substantially retaining the achieved twist.

The basic method according to the present invention will therefore comprise the following steps:

(a) linearly supplying through feed-in rolls a continuous strand or tape of substantially consolidated staple fiberthermoplastic polymer composite material;

(b) heating said strand or tape to a point where the polymer substrate of the composite material becomes plastic without reaching the melting point of said polymer;

(c) subjecting said heated strand or tape to a torque within a fiber-restrictive zone for imparting a predetermined twist to said strand or tape through intermolecular slippage of the polymer molecules as well as interfiber slippage and consequent helical rearrangement of the fibers;

(d) cooling to coagulate the polymer substrate while the strand or tape is in such twisted condition to substantially retain the twist; and

(e) linearly winding up the obtained spun yarn on a collecting roll.

Consequently, the basic apparatus according to the invention will comprise the following combination:

(a) feed-in rolls for linearly supplying a continuous fibrous strand or tape of substantially consolidated staple fiber-thermoplastic polymer material;

(b) a heater with proper temperature control means and a fiber-restrictive zone, through which said fibrous strand or tape is adapted to pass and in which it is heated until the polymer substrate becomes plastic without reaching the melting point of said polymer;

(c) a torque imparting device following said heater for twisting said strand or tape while the polymer is in plastic condition to enable intermolecular slippage of the polymer molecules and accompanying helical rearrangement of the fibers bonded to said polymer due to interfiber slippage caused by friction within the fiberrestrictive zone;

(d) means for cooling said strand or tape in twisted condition provided between the heater and the torque imparting device; and I (e) a collecting roll for linearly winding-up the obtained spun yarn.

In the above method and apparatus the feed-in rolls for linearly supplying the continuous composite strand or tape and the collecting roll for linearly winding-up the obtained yarn constitute two fixed pinch points between which the twisting operation is effected.

There are, of course, many additional preferential features included within the scope of this invention which may be summarized as follows:

From the practical standpoint, it is by far preferable to provide in combination with the basic method and apparatus, the necessary additional steps and means respectively for the formation of the desired continuous strand or tape, or rather of a plurality of such strands or tapes since it would be uneconomical to operate with only one strand or tape at a time. This is usually done by extrusion of a plurality of parallel thermoplastic resin strands from an extrusion die and lamination as well as consolidation thereof with suitable webs of staple fibers arranged at random or in parallel. The extruded thermoplastic strands can also be stretched to achieve an initial degree of molecular orientation of the polymer.

The heating of the composite fibrous strands or tapes to the point of rendering the polymer substrate plastic but without reaching the melting point of said polymer substrate can be effectively accomplished by passing said composite strands or'tapes in a heater provided with longitudinal grooves generally in the form of V.

The composite fibrous strands or tapes are progressively heated while passing in these grooves to the point where the polymer substrate present therein acquires the desired plasticity. The V shaped grooves can also be gradually narrowing towards the exit end of the heater so that the composite strands or tapes, passing therein, are simultaneously compressed, thus achieving a better interaction and consolidation between the polymer and the staple fibers, and ensuring the helical rearrangement of the loose staple ends during the twist imparting operation.

The heater should also be provided with adequate temperature control means because it is essential to adjust the temperature to the point where, as mentioned above, the polymer substrate will attain the desired degree of plasticity without reaching however the melting temperature of said polymer.

This point of plasticity varies from polymer to polymer but it can be easily ascertained by a man familiar with the art. Also, the melting points of most thermoplastic polymers are readily available from the literature. The reason, of course, why the polymer must have a degree of plasticity is to achieve interslippage of the polymer molecules and inter-fiber slippage of the staple fibers embedded in the polymer substrate when torque is imparted to the fibrous composite tapes, thus enabling helical rearrangement and cohesion of the staple fibers, with the polymer in plastic state playing essentially the role of a binder and a lubricant; and the reason why it should not exceed the melting point is because at this point the strand or tape will lose its continuity (since the polymer will become liquid) and also the material will become very tacky and will stick to the surface of the heater thus preventing proper function of the operation and the achievement of the desired result.

The torque is imparted to the composite fiborus strand or tape below the above-mentioned heating zone and the created twist travels upwards to the point of the greatest plasticity of the polymer where it is melted-in thus preventing formation of a counter torque which would tend to nullify the imparted twist. It can, for example, be imparted by means of any false twisting device which may revolve at speeds of up to 500,000 r.p.m.

It should also be noted that even though the polymer substrate may reach a temperature very close to its melting point during the above described operation, it will not lose its formerly acquired molecular orientation because the polymer will be held at this temperature only for a very short period of time, in the order of a second of so, which however is sufiicient to impart the desired twist. With such short residence times, there is no danger of losing the orientation of the polymer but, on the contrary, said orientation may, if desired, be further increased by driving the rolls which constitute the second pinch point at a higher speed than the first pinch point rolls. The molecular orientation of the polymer is also increased by the twist imparting torque due to its consequent circular polymer stretching action.

The novel universal apparatus of the present invention may therefore comprise in a preferred embodiment the following combination:

an extruder and an extruder die from which a curtain of thermoplastic polymer strands or strips of a desired configuration can be extruded;

a pair of circumferentially grooved consolidating rolls below said extruder die, said rolls being positioned side by side and so that the male members or protrusions of the grooved surface of one roll enter and press into female members or grooves of the other roll; the polymer extrudates being directed into the nip of said rolls so that at least one extrudate strand or strip enters into each consolidating groove;

means for simultaneously forwarding from at least one side of said polymer curtain and into the nip of said rolls a plurality of staple fiber webs, one into each consolidating groove of the rolls;

means for pressing said rolls against each other;

means for rotating said rolls toward each other at a speed higher than the extrusion speed of the polymer curtain; means for cooling said rolls or the material passing therethrough;

thus the product issuing from these rolls, which constitute the first fixed pinch point, consists of consolidated and partly oriented composite staple fiber-thermoplastic polymer fibrous strands or tapes;

then, following the consolidating rolls, there is provided a preferably V grooved heater having as many grooves of gradually narrowing V cross-section as there are composite strands or tapes coming out of the consolidating rolls so that each strand or tape can enter one groove of the heater; the V grooves preferably gradually narrow towards the exit end in order to produce a further compaction and improved co-action between the stable fibers and the polymer material as well as to ensure the helical rearrangement of the loose ends of the staple fibers during twisting; I

means for adjusting and controlling the temperature of said heater;

a plurality of torque imparting devices, e.g. of the false twisting type, following said heater, one for each strand or tape, for imparting to the latter a predetermined twist inside the grooves of the heater;

means for cooling the twisted composite strands or tapes provided between the heater and the torque imparting devices;

a pair of pick-up rolls following the torque imparting devices constituting the second fixed pinch point and adapted to linearly collect and hold under tension the final twisted yarns coming out of the twist imparting devices; and

one or more collecting rolls following these pick-up rolls for linearly winding-up the obtained twisted yarn.

BRIEF DESCRIPTION OF THE DRAWINGS There are also many further preferential features of the present invention which will be discussed in greater detail in the following non-limitative embodiments given with reference to the appended drawings in which:

FIG. 1 is a generally schematic view of the basic method and apparatus of the present invention;

FIG. 2 is another generally schematic view of a device which may be used in combination with the apparatus of FIG. 1;

FIG. 3 is a view of circumferentially grooved rolls in engaged condition, along line AA of FIG. 2;

FIG. 4 is a schematic illustration of one preferred complete operation according to the present invention;

FIG. 5 is a side view of a complete universal apparatus according to the present invention; and

FIG. 6 is a view, partly in section, along line BB of FIG. 5.

FIGS. 7-12 are enlarged views of selected elements of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic principle of the invention is illustrated in FIG. 1. A composite fibrous staple fiber-thermoplastic polymer tape 10 is supplied to the pinch point of a pair of pick-up rolls 11, 12 which constitute the first fixed point within the scope of the invention. Then, said tape 10 is linearly fed by these rolls 11, 12 to the grooved heater 13 with heating means 14 which operate so as to enable adequate temperature control in the heater 13. It should be pointed out that the shape of the heater is preferential and by no means limitative and any heater with a proper temperature adjustment and control as well as with a proper fiber-restrictive zone can be used.

In all instances, however, the heater should be such as to enable to achieve temperature and fiber-friction conditions which will render the thermoplastic polymer substrate of the composite tape 10 sufficiently plastic as to enable interslippage of its molecules and inter fiber slippage of the staple fibers and consequently twisting of the staple fibers bonded to the polymer substrate into a substantially helical arrangement. This twisting is imparted from below by twister 16, preferably of the false-twister type, which is positioned below the heater 13 and at such a distance from the exit end 15 of said heater as to achieve cooling of the yarn twisted within the heater 13 and its coagulation in such twisted condition. It should also be mentioned that cooling and coagulation of the yarn in twisted form can result simply due to its passage through atmospheric air after its exit from the heater, however, one may also include suitable cooling means for that purpose, such as a water cooled jacket and/or a compressed air cooling zone.

During the twisting operation, the twist, therefore, travels upwards from twister 16 to the heater 13 where it is melted-in into the continuous composite strand or tape having its polymer substrate in plastic condition.

After passing through twister 16, the yarn is picked up by a pair of pressure rolls 17, 18 which constitute the second fixed point according to the invention, and thereafter it is linearly wound on a collecting roll 19 to form the final spun yarn package 20. It is possible to eliminate

rolls

17, 18 entirely since the collecting roll 19 itself may constitute the second fixed point, however, said rolls 17, 18 are preferred to keep the yarn under proper tension.

FIG. 2 shows an arrangement for direct production of composite tape 10 which can be used in combination with that of FIG. 1. According to this arrangement, tape 10 can be produced by direct extrusion of a thermoplastic polymer strand or extrudate 23 from extruder die 22 of extruder 21 and its lamination and consolidation with a web of staple fibers 24 between rolls 11a and 12a. The web of staple fibers 24 may be supplied from one or both sides of extrudate 23 towards the nip point of the laminating and consolidating rolls 11a, 12a, simultaneously with said extrudate 21 which is still in tacky condition after its extrusion from die 22. Said web is then laminated and consolidated with said extrudate by pressure and cooling, ie by the action of said rolls 11a, 12a which may be internally cooled by cooling water or air. The employed staple fiber webs may easily be produced by means of a drafting frame 25 such as used in the drawing of slivers or rovings or by aerodynamic systems which are well known in the art.

The rolls 11a and 12a in this instance serve the same purpose as rolls 11, 12 in FIG. 1, namely for supplying composite tape 10 to the heater 13. Thus, in combination comprising the arrangement of FIG. 2 together with that of FIG. 1, rolls 11, 12 of FIG. 1 would be replaced by rolls 11a, 12a of FIG. 2.

Furthermore, it would be rather uneconomical to operate according to this invention with only one composite tape 10. Thus, rolls 11a, 12a preferably have the form shown in FIG. 3. In the case illustrated in FIG. 3, six tapes at a time can be processed. This, of course, would require extrusion of a curtain of six strands 23 from die 22 and their simultaneous consolidation and lamination within the grooves 27 with six Webs 24 to form six composite tapes at a time. The form of the rolls illustrated in FIG. 3 is particularly effective since it will directly produce the required composite tapes due to pressure exerted by protruding members 28 of rolls 12a within circumferential grooves 27 of rolls 11a and any material that may overflow or slip into the pointed grooves 29 of roll 12a will be cut by cutting edges of protruding members 26 of roll 11a, or it will be kept separated from its adjacent material stream by the protruding members 26 of roll 11a. However, this particular form is in no way limitative and any rolls or drums that will produce the same function are acceptable (e.g. all the circumferential grooves of the consolidating rolls may be of square cross section); also, the number of grooves within which the composite tapes are produced is not limitative.

In case a pair of rolls 11a, 120, such as shown in FIG. 3, are used, the heater 13 will be modified to have the number of V grooves that will correspond to the number of composite tapes supplied by said rolls, in this particular example, six. Also, six twisting devices 16 will be required, one for each tape. Six collecting rolls 19 may also be used to form six packages 20 of spun yarn.

Furthermore, consolidating rolls 11a, 12a can be driven at a substantially higher speed (e.g. 10 times higher) than the extrusion rate of the polymer strand 23, thus producing stretching and, consequently, a good degree of molecular orientation of said polymer strand. This, together with the additional effects of helical fiber rearrangement as well as further stretching due to twisting, will enable achievement of a product of excellent strength and stability.

Another way of carrying out the method of the present invention, while achieving ultimate strength in the final yarn, is illustrated in FIG. 4. According to this embodiment, polymer strand 23 (or a plurality of such strands) is extruded from extruder 21 through die 22 and is thereafter stretched and oriented to a very high degree by means of orienting arrangement 30. This arrangement is known in the art and usually consists of a pair of sets of godet rolls (each set having three rolls with each set running at a higher speed than the preceding set) interposed with a heater with proper temperature control. Strand 23 is thus first stretched to a desired degree by the first set of godet rolls then heated and finally stretched again by the second set of godet rolls. Such treatment gives a very high degree of molecular orientation to the strand 23. Thereafter, the oriented strand is passed through a heater arrangement 31, which preferably consists of a tunnel heater with adequate temperature control. Here, the strand 23 is heated only to such a degree that it will become tacky on the surface at the exit end of the heater without losing its previously acquired internal molecular orientation. It should be noted here that it is certainly possible to impart to a thermoplastic extrudate, through such operation, a desired degree of tackiness Without impairing the molecular orientation of the polymer. Indeed, complete relaxation will only occur in the thermoplastic material when the latter is held at or about its melt temperature for a period of time. The time will depend on the degree of orientation, thickness of material and the surface area of contact. For example, in the case of polypropylene no shrinkage due to relaxation will occur when the extrudate is held at 40 C. for thirty minutes, although some shrinkage will occur if if is held at that temperature for forty-five minutes. Also, if an extrudate of polypropylene is heated in air for thirty minutes at 100 C., less than five percent shrinkage will occur while a further thirty minutes heating at 145 C. will produce an additional seven percent shrinkage. It is therefore quite evident that when, in our case, the oriented strand 23 passes through the heating arrangement 31, the latter may easily be adjusted so that some degree of surface tackiness will be imparted to the strand with very little if any loss in its molecular orientation. This is especially true since the strand 23 will travel at a speed of perhaps one thousand feet per minute or so and its residence time in the heating arrangement 31 will be insufficient to obtain relaxation of the polymer even if high temperatures prevail in said heater, although it will be sufiicient for imparting to said polymer strand a desired degree of tackiness.

The tackiness of strand 23, is, of course, necessary in order that it may be laminated and consolidated by rolls 11a, 12a with the web of staple fibers 24 to form a composite tape 10. The staple fiber web 24 is supplied by supply arrangement 25 to the nip of rolls 11a, 12a and actually two such webs can be supplied for each strand, one from each side, so that the final composite tape 10 would consist of a polymer substrate fully surrounded with staple fibers having numerous loose ends sticking out and providing the desired fibrous surface texture.

This composite tape 10 is then processed as in the previous cases through heater 13 which preferably has its heating surface in the form of a gradually narrowing V groove toward exit end 15, so that further compaction between the polymer substrate and the surrounding staple fibers can be achieved as they pass through said heater. At a predetermined point inside the heater 13, the polymer substrate of the composite tape 10 is sufficiently plastic that the twist imparted by twister 16 and travelling upwards will produce interslippage of the polymer molecules and of the staple fibers bonded to the polymer substrate as well as coagulation of the yarn in such helically twisted condition due to subsequent cooling. Thereafter the twisted yarn passes linearly through the twister 16 and tension rolls 17, 18 and is linearly wound, at speeds up to and in some cases in excess of one thousand feet per minute, on the collecting roll 19 to form the final spun yarn package 20.

FIG. 5 illustrates one possible construction of a universal yet relatively simple and compact apparatus embodying the necessary features of the present invention while FIG. 6 shows a detail there of along line B-B.

In the apparatus illustrated in these figures, a curtain of strands 23 as shown in the enlarged view, FIG. 7 is extruded through the extrusion die 22 of extruder 21 which is held by member 32 mounted on a height adjusting column 33. In this manner, the position of the die 22 over the consolidating rolls 11a, 12a can be easily controlled. The extruder is also provided with hopper 34 into which the thermoplastic material can be introduced in its cheapest form, namely in the form of lumps or granules.

The continuously extruded strands 23 may be of any desired cross-section; the simplest cross-section, i.e. the round one as indicated in FIG. 7, is actually the preferred.

The laminating and consolidating rolls 11a, 12a are provided on their surfaces with a plurality of circumferential grooves and one or more strands 23 are introduced into each groove of said rolls, directly upon extrusion and while still in tacky condition, for compression and consolidation with staple fibers webs 24 which are also conveyed into said grooves from one or both sides by fiber web supply means 25 shown, in this case, schematically and in broken line as two superimposed rollers. These means may, for example, be a drawing frame or any other device capable of producing a plurality of webs consisting of parallel or at random arranged staple fibers.

The rolls 11a, 12a may be driven at substantially higher speed than the extrusion rate of strands 23, thus producing stretching of said strands and increase in their strength due to the resultant molecular orientation of the polymer. It will usually be sufiicient to drive only roll 12a, for example, by motor 42 and belt 43, while roll Will be driven through sliding, due to its frictional engagement with roll 12a. Alternatively gear engagement can be utilized on both rolls 11a and 12a thus achieving a positive driving force on each roll. The sliding roll 11a can be pressed with its grooved surface into the grooved surface of the driven roll 12a by means of an air cylinder 37 which is secured to frame 35 and which actuates bracket 39 that holds at both ends the axle of roll 11:! by rod 38, so as to press said bracket together with the roll 11a against roll 1211 or, alternatively to disengage said rolls from one another. Other means for pressing one roll against the other and disengaging the same, if need be, can also be used and the mechanism shown in FIGS. 5 and 6 has been given 9 for illustration purposes only without any restriction whatsoever.

The apparatus is then provided with heater 13 which is suitably mounted within the frame 35. The heating surface of this heater has a plurality of gradually narrowing V grooves as shown in the enlarged cross-sectional view, FIG. 8 so that when the composite tapes 10, shown in the enlarged view, FIG. 9 after consolidation and lamination by rolls 11a, 12a, are guided within said grooves, they are not only heated to the desired temperature but also the staple fibers are further compacted and helically rearranged with the polymer material. Within the grooves of the heater 13, as shown in the enlarged view, FIG. the polymer material reaches such plastic condition that a twisting torque imparted from below by twister 16 will be melted-in and retained therein due to interslippage of the polymer molecules and of the staple fibers. The staple fibers will be helically rearranged and better amalgamated with the polymer due to the prevailing conditions of twisting arld polymer plasticity, thus resulting in utilization of the staple fiber strength in twisted structure form towards the toal yarn strength. Efficiency of fiber strength to yarn strength conversion, generally no more than 50% in conventional staple fiber spun yarns, is considerably increased by the binding according to this invention of the staple fibers to a thermoplastic polymer substrate thus arresting their slippage in the axial direction in the final composite yarn. For instance, a fibrous tape which has a tenacity of about 4 g./tex. can by applicants new method be converted into a yarn of about 12 g./tex. tenacity.

Upon its exit from heater 13-, in twisted condition as shown in the enlarged view, FIG. 11, the composite material will be cooled in an air feeding and cooling injector 36 whereby the twist in the polymer becomes permanently coagulated. Twisted yarn is thus obtained and after passing through the torque imparting device 16 and tensioning rolls 17, 18, as well as a conventional guiding arrangement 41, it is linearly wound on collecting roll 19 at speeds that may reach and even exceed one thousand feet per minute, to form the final spun yarn package 20. The twist is therefore imparted according to the present invention and according to the embodiment illustrated in these figures between two fixed pinch points, in this case between rolls 11a, 12a and rolls 17, 18, in a totally continuous linear operation with quality spun yarn being produced 'at considerably higher speeds than those of hitherto known systems.

The apparatus is relatively simple in nature and very easy to operate. Thus, the thermoplastic polymer, for example of the group of polyamides, polyolefins, acrylics and the like, can be introduced into the hopper 34 in granular form and extruded at a rate of about one hundred feet per minute through extruder die 22 in the form of a curtain of strands 23 of round or any other preferred cross-section.

The strands are extruded toward the nip of circumferentially grooved laminating and consolidating rolls 11a, 1211 which can be driven at a speed of-about one thousand feet per minute, thus with a ratio of about 10 to 1 relative to the speed of extrusion. A substantial molecular orientation of strands 22 will thus be achieved.

By the action of said rolls 11a, 12a, the strands are consolidated with webs of staple fibers 24 which are simultaneously supplied by device 25 into the grooves of said rolls, thus achieving formation of composite tapes 10 having, for example, a fiber-polymer ratio of :50. Other ratios of fiber-polymer can, of course, also be used. The composite tapes are then guided through heater 13 provided with fiber-restrictive grooves or zones and an adequately controlled temperature and wherein the polymer substrate of said tapes reaches a plastic, lubricating condition which makes it possible to impart to said tapes, from below, a predetermined twist by twister 16 which may run at speeds of up to 500,000 r.p.m. Then, the twisted yarn, coming out of the heater, is cooled to coagulate and permanently retain to a substantial degree the imparted twist. Therefore, upon linearly passing through a pair of tensioning rolls 17, 18, which may be driven at a higher speed than that of rolls 11a, 12a so as to elfect further stretching and orientation of the polymer (thus achieving even further increase in the strength of the final yarn), the obtained spun yarn is continuously and linearly wound on collecting roll 19 to form a commercially acceptable spun yarn package 20. Means 50 may be provided for automatic replacement of collecting roll 19 when filled by an empty roll, as shown, for example, in US. Pats. 2,663,507 and 3,345,003.

It should, of course, be understood that many modifications in the process and apparatus of the present invention are possible and Would be evident to those familiar with the art. For example, the apparatus illustrated in FIG. 5 could, if desired, be combined with the arrangement shown in FIG. 4 or any other similar arrangement without, in any way, affecting the basic concept of this invention. Thus, although the optimum production output of a 16 twist per inch staple fiber yarn, for ring spindles, is known to be about 100 feet per minute and in open-end spinning about l00200 feet per minute, applicants ringless continuous yarn production enables output speeds of 5'001000 and, in some cases, exceeding 1000 feet per minute, which is unattainable by any hitherto known yarn making methods.

We claim:

1. Method of making fibrous spun yarns of composite staple fiber-thermoplastic polymer material comprising: linearly supplying through feed-in rolls a continuous strand or tape of substantially consolidated composite fibrous material consisting of staple fibers and a thermoplastic polymer substrate; heating said strand or tape Within a fiber restrictive zone to a point where the polymer substrate of said composite material becomes plastic without reaching the melting point of said polymer; subjecting said strand or tape within said fiber restrictive Zone to a twisting torque for imparting thereto, while the polymer substrate is in plastic condition, a predetermined twist with consequent helical rearrangement of the fibers; cooling to coagulate the polymer while the strand or tape is in twisted condition; and linearly winding-up the obtained consolidated spun yarn on a collecting roll; said feed-in rolls and said collecting roll constituting two fixed pinch points between which the twist is applied and substantially retained.

2. Method of producing composite staple fiber-thermoplastic polymer spun yarn in a continuous linear sequence of operations comprising: extruding a curtain of thermoplastic polymer strands downwardly from an extruder die and toward the nip of a pair of circumferentially grooved consolidating rolls positioned side by side so that male members of the grooved surface of one roll enter and press into female members of the other roll, said curtain being directed so that at least one strand enters into each consolidating groove of said rolls; rotating said rolls at a greater speed than the rate of extrusion of the polymer strands so as to stretch the latter and achieve molecular orientation of the extruded polymer strands; simultaneously forwarding from at least one side of the polymer curtain and into the nip of said rolls a plurality of staple fiber webs, one into each consolidating groove of the rolls; laminating and consolidating said strands with said webs by pressure within the grooves of said rolls and cooling to form a plurality of laminated staple fiber-thermoplastic polymer composite fibrous tapes; passing each of said composite fibrous tapes through a fiber restrictive heating zone and subjecting it therein to a thermal treatment which will render the polymer plastic without reaching the melting point there- 1 1 of; imparting within said fiber restrictive heating zone to the tape with the polymer in such plastic condition a predetermined twist with consequent helical rearrangement of the fibers on said tape; cooling to coagulate the polymer while the tape is in such twisted condition; and linearly and continuously winding-up the obtained twisted yarn on a collecting roll.

3. Method of producing composite staple fiber-thermoplastic polymer spun yarn in a continuous linear sequence of operations comprising: extruding a curtain of thermoplastic polymer strands; stretching said strands to achieve a predetermined orientation of the polymer molecules; passing the so oriented strands in a heater in which the temperature is so adjusted and controlled as to render the strands tacky on the surface while substantially retaining their previously acquired molecular orientation; introducing the tacky strands into the nip of a pair of circumferentially grooved consolidating rolls positioned side by side so that the male members of the grooved surface of one roll enter and press into female members of the other roll, said strands being directed so that at least one strand enters into each consolidating groove of said rolls; simultaneously forwarding from at least one side of the polymer curtain and into the nip of said rolls a plurality of staple fiber webs, one into each consolidating groove of the rolls; laminating and consolidating said strands with said webs by pressure within the grooves of said rolls and cooling to form a plurality of laminated staple fiber-thermoplastic polymer composite fibrous tapes; passing each of said composite fibrous tapes through a fiber restrictive heating zone and heating it therein to a point where the polymer becomes plastic without reaching the melting point of said polymer; imparting 'within said fiber restrictive heating zone to the tapes with the polymer in such plastic condition a predetermined twist with consequent helical rearrangement of the fibers on said tape; cooling to coagulate the polymer while the tape is in such twisted condition; and linearly winding-up the obtained spun yarn on a collecting roll.

4. Method according to claim 1, in which the obtained spun yarn is linearly wound on the collecting roll at speeds in the order of 500-1000 feet per minute.

5. Apparatus for producing composite staple fiberthermoplastic polymer spun yarn comprising:

(a) feed-in rolls for linearly supplying at least one continuous strand or tape of substantially consolidated staple fiber-thermoplastic polymer composite fibrous material;

(b) a heater wvith temperature control means and a fiber restrictive zone through which said strand or tape is adapted to pass and in which it can be heated until the polymer becomes plastic without reaching the melting point of said polymer;

(c) a torque imparting device following said heater for twisting said strand or tape within said fiberrestrictive zone while the polymer is in plastic condition;

(d) means for cooling said strand or tape in twisted condition, provided between the heater and the twisting device; and

(e) a collecting roll and means for linearly windingup the obtained spun yarn thereon.

6. Apparatus according to claim 5, further comprising means for forming a plurality of said continuous strands or tapes of substantially consolidated staple fiberthermoplastic polymer composite material.

7. Apparatus according to claim 6, in which said means for forming a plurality of said continuous composite strands or tapes comprise: an extruder with an extruder die having a plurality of orifices alined in a substantially straight line and adapted to extrude a curtain of polymer strands; a pair of circumferentially grooved consolidating rolls positioned side by side below said extruder die and so that male members of the grooved surface of one roll enter and press into female members of the other roll, the rolls being so arranged that at least one polymer strand extruded through the extruder die enters into each consolidating groove thereof; means for rotating said consolidating rolls at a greater speed than the rate of extrusion of the polymer strands from the extruder die; means for simultaneously conveying from at least one side of the extruded curtain of polymer strands and into the nip of said consolidating rolls a plurality of staple fiber webs, one into each consolidating groove of the rolls; and means for cooling the material during lamination and consolidation by said rolls; said circumferentially grooved rolls thus constituting the feed-in rolls which linearly supply a plurality of continuous strands or tapes of substantially consolidated staple fiber-thermoplastic polymer composite material.

8. Apparatus according to claim 6, in which said means for forming a plurality of said continuous strands or tapes comprise: an extruder with an extruder die having a plurality of orifices aligned in a substantially straight line and adapted to extrude a curtain of polymer strands; means for stretching said polymer strands to achieve a predetermined orientation of the polymer molecules; a heater with temperature control means for passing the so oriented polymer strands therein to render them tacky on the surface while substantially retaining their previously acquired molecular orientation; a pair of circumferentially grooved consolidating rolls, following said heater, positioned side by side so that male members of the grooved surface of one roll enter and press into female members of the other roll, said rolls being positioned so that at least one polymer strand coming out of the heater enters into each consolidating groove thereof; means for simultaneously forwarding on at least one side of the curtain of the polymer strands and into the nip of said consolidating rolls a plurality of staple fiber webs, one into each consolidating groove of the rolls; and means for cooling the material during its lamination and consolidation by said rolls; said circumferentially grooved rolls constituting the feed-in rolls linearly supplying a plurality of continuous strands or tapes of substantially consolidated staple fiberthermoplastic polymer composite material.

9. Apparatus according to claim 5, in which the heater has a heating fiber restrictive zone in a V-grooved form, there being as many grooves of V cross-section as there are strands or tapes to be heat treated.

10. Apparatus as claimed in claim. 9, in which the V- shaped grooves of the heater are gradually narrowing towards the exit end of said heater, whereby the composite strands or tapes passing therethrough are simultaneously compressed for better restrictive eifect and interbonding.

11. Apparatus according to claim 5, in which the twist imparting device is of a false twister type adapted to rotate at speeds of up to 500,000 r.p.m.

12. Apparatus according. to claim 5, in which the cooling means provided between the heater and the twisting device consist of a compressed air injector.

13. Apparatus according to claim 5, in which there is further provided a pair of tensioning rolls positioned between the twist imparting device and the collecting roll and adapted to be driven at higher speed than that of the feed-in rolls.

14. Apparatus according to claim 5, in which the means for linearly winding-up the obtained spun yarn comprise 13 14 a yarn guiding member and a device for automatic re- 3,154,908 11/1964 Cilker et a1. 5735 placement of the collecting rolls. 3,279,161 10/ 1966 Chisholm et a1 5735 References Cited STANLEY N. GILREATH, Primary Examiner 2,743,572 5/1956 I-I-iensch 5734 US. Cl. X.R.

2,773,297 12/1956 Cotchett Q. 57164X 57-35, 140, 157, 164;,1264176