US3438101A - Process and apparatus for texturizing yarn - Google Patents

Description

April 15, 1969 w, LE o ET AL PROCESS AND APPARATUS FOR TEXTURIZING YARN Filed Dec. 22. 1966 mdE J61 3 m .wmJ:

INVEN'I'OR 6. Km A-HM ATTORNEY I wmmozi United States Patent M 3,438,101 ERGCESS AND APPARATUS FOR EXTURHZTNG YARN Fred White Le Noir and Clarence Anderson King, Hopewell, V2 assignors to Allied Chemical Corporation,

New York, N.Y., a corporation of New York Filed Dec. 22, 1966, Ser. No. 603,912

Int. Cl. D02g 3/00; D04h 17/00; D05c 15/00 US. Cl. 281 8 Claims ABSTRACT OF THE DISCLOSURE Uniform crimp is imparted to continuous synthetic filaments and yarn by subjecting them to a heated environment to elevate the temperature 'of said filaments above their second-order transition zone and thereafter passing the heated material through a curvilinear confined space comprised of a continuously moving surface on one side moving at a slower rate than the filament feed whereby crimping is achieved and means for facilitating the removal of hot gases and cooling of the crimped filaments.

This invention relates to a process and apparatus for preparing crimped fibrous structures and more specifically to means for preparing crimped or similarly distorted textile fibrous materials in the form of synthetic filaments, yarn, tow or staple fibers.

The crimping of textile strands to increase their bulkiness is well known in the textile art and more recently includes the use of fluid-jet technology for accomplishing the bulking of the filaments within the yarn. Another wellknown method of imparting crimp to a tow of continuous filaments comprises, for example, the use of a chamber into which the continuous filaments are forced against a mass of tow already present in the chamber followed by emergence of the filaments in crimped form from the other end when the pressure of the mass exceeds a certain limit. Thus, depending upon the uniformity of crimp desired, various steps may be taken to control the conditions of the crimping, so that, for example, the frequency of the crimp may be maintained at a uniform value. However, while this particular method produces a uniform crimp, it has the disadvantage that the bends of the individual fiber lie in a single plane. Moreover, since this particular method does not provide for adequate process control, it is possible that the fibers may get damaged and thereby reduce their tensile strengths.

The ease of processing staple fibers and yarns prepared from these fibers are improved when the .fiber crimp is of a three-dimensional nature, that is, when the bends or convolutions of the crimped fiber extend radially in all directions when viewed along the center line of the fiber. Synthetic staple fibers including, for example, the polyamides, polyesters, polyacrylonitriles, etc., are prepared by cutting or breaking a continuous filament tow. To convert these staple fibers to spun yarns, they must have a finite degree of crimp. This crimp is applied most advantageously to the fibers, however, while they are in the continuous filament tow form. These tows are crimped and then subsequently cut into staples of the desired length.

It has been found that in order to obtain uniformity of crimp, etc., it is necessary to be able to control the process conditions. Thus, in accordance with this invention, the synthetic yarns and tows are passed at a regulated speed through a confined tube while simultaneously introducing into said tube a heated gas under pressure. The heated gas and its contact with the filaments are maintained through a path suiiiciently long to raise the temperature of the filaments to a point so that the crimping takes place above their second-order transition temperature but below 3,438,101 Patented Apr. 15, 1969 their melting 'or degradation temperature. The filaments are subsequently ejected into one end of a confined space or chamber, the surrounding sides of which comprise a continuously moving surface, at least one side of which is perforated to allow removal of the hot gases to facilitate cooling of the filaments before they are withdrawn from the other end of the chamber. The importance of being able to adequately control the crimping process by utilizing the apparatus of this invention is recognized in that the failure to obtain uniformity of crimp, for example, is most likely to result in streaks, etc., when the filaments are subsequently processed into knitting yarns, fabrics and the like.

Accordingly, it is an object of this invention to provide a process and the apparatus for producing synthetic fiber tows with three-dimensional convoluted crimp.

It is another object of this invention to provide an apparatus wherein the crimping process may be controlled to compensate and correct the changes in the frictional characteristics of the yarn.

It is another object of this invention to provide a process for jet-texturizing yarn wherein the yarn is not overexposed to hot air, steam or other hot compressible fluids.

It is still another object of this invention to provide an apparatus having a minimum of moving parts wherein the process of this invention can be performed with maximum control to obtain optimum crimp results.

It is still a further object of this invention to provide an apparatus and a process for texturizing yarn to impart thereto a crimp wherein the yarn so texturized has good covering power.

These and other objects of the invention will become apparent from a further and more detailed description of the invention as follows.

More specifically, in accordance with this invention, yarn in a sufficiently plastic state to be crimped is aspirated with a compressible fluid into a zone provided with fluid-escape means which is defined by the peripheral recess of a hollow drum revolving at a rate less than the rate of aspiration of the yarn into said zone and with moving guide means overlapping said recess: said guide means being positioned against said drum and revolving with it for a portion of a revolution; said yarn is revolved in the zone for a portion of a revolution and subsequently the guide means and yarn are withdrawn from said drum.

Irl a preferred embodiment, the process is performed by utilizing an endless conveyor belt as the guide means Which passes over the recess in a grooved pulley wheel wherein the yarn is held. The hot gas, e.g., steam, at a temperature ranging from 300 C. to 700 C. can escape through the pores in the Walls of the peripheral recess or groove. The bottom panel of the peripheral groove of the pulley wheel is suitably constructed of fine-Wire mesh or screen, the holes of which communicate with the hollow of the drum, thus permitting the fluid, e.g., steam, to escape through the screen into the hollow of the drum out to a discharge port.

In an alternate form of this invention, the pulley wheel with the groove may be constructed entirely of screen material, since the fluid, e.g., steam, can readily escape through all sides of the groove and not only through the bottom panel thereof.

More particularly, the process of this invention comprises aspirating yarn in a sufficiently plastic state to be crimped by a jet utilizing a compressible fluid into a compaction zone. Suflicient plasticity can be imparted to the yarn by using, for example, steam at temperatures ranging from about 300 C. and 700 C. at yarn feed rates of about 3,000 feet per minute, as the yarn is propelled into the zone of compaction. If, on the other hand, the yarn is preheated to a temperature of, for example, l20 C. before being introduced into the steam jet, the steam temperatures may be reduced to approximately 200- 500 C. The steam or other compressible gas is used preferably under pressure ranging from about 110 to 180 p.s.i.g. with the feed rate of yarn to the zone of compaction being adjusted to approximately between 2,000 feet per minute to 10,000 feet per minute in commercial operations. The take-up rate of the yarn from the compaction zone or recess is always less than the feed rate of the yarn to allow yarn build-up in the compaction zone where the crimping takes place. More specifically, for example, it is preferred to withdraw the yarn from the crimping zone at a rate ranging from about 60% to 90% of the feed rate.

The invention can be more fully comprehended by reference to the accompanying drawings, wherein:

FIGURE 1 illustrates one form of the apparatus for texturizing yarn according to this invention which combines the advantages of jet-texturizing with other known processes where crimping is accomplished by compaction.

FIGURE 2 is a cross-section taken on the line 2--2 of FIGURE 1.

FIGURE 3 illustrates another form of the apparatus for carrying out the process of this invention.

FIGURES 4 and 5 are detailed sectional views taken on the lines 44 and 55 of FIGURE 3, respectively.

Referring to the drawing, yarn 2 which is to be crimped enters yarn inlet 4 of the fluid jet 6. Steam or some other compressible fiuid 7 enters the fluid inlet 8 (shown with a portion broken away) and forces yarn 2 through tube 10 into zone 12 defined by a peripheral groove or recess 14, as seen in FIGURE 2, the bottom of which is constructed of wire screen 16 and an endless-notched conveyor belt 18 having notches 20.

The conveyor belt 18 is driven by reciprocating notched wheels 22, 24 and 26 which also serve to guide the belt over the hollow drum 28 on which is located the peripheral recess 14. The wire screen 16 forming the bottom panel of the peripheral recess 14 is embedded into the hollow drum 28 at 30. The hollow drum 28 is driven by the belt 18 which, in turn, is driven by wheels 22, 24 and 26 which .are driven by a motor, not shown, operating to revolve the wheels at the same rate of speed. The periphery of the hollow drum 28 has the same linear speed as the conveyor belt 18. The hollow drum 28 is provided with discharge ports, not shown, extending axially through the drum and connecting with an annular chamber under the groove or recess 14.

As the steam, for example, enters zone 12 with the yarn 2, the yarn is impinged against the previously advanced yarn 32 which has not been withdrawn due to the greater feed rate of the yarn to the zone in comparison to the rate of take-up. As a result of this over-feed, crimp is imparted to the yarn. The yarn moves in the peripheral recess 14 for about one-half a revolution to exit 34 where it is taken-up on conventional bobbins using conventional winders, etc.

Due to the ability to control the rotational speed of the hollow drum 28 together with the linear speed of the belt 18, it is possible to maintain a constant degree of crimp in terms of crimp index and crimp frequency. Thus, for example, if a high degree of crimp is desirable, the rotational speed of the hollow drum may be decreased to provide the desired crimp level. Likewise, the rotational speed of the hollow drum 28 may be held constant and the feed rate of the yarn through the tube 10 may be increased to provide a higher level of crimp. Thus, suitable changes in the yarn feed or the speed of the belt are possible to control the process to obtain the desired crimp without having to effect changes in steam temperature or pressure, for example. If it were not for the ability to control the process, changes of the condition of the steam might otherwise be necessary in order to obtain uniformity in the crimped product. This uniformity is neces sary to avoid the possibility of streaks or other mark- 4 ings which may be observed when the yarns are further processed into dyed articles.

Consequently, one of the outstanding advantages of the apparatus and process of this invention lies in the fact that it is possible to change the degree of compaction and thus secure a different degree of crimp merely by changing the speed of the yarn with respect to the speed of the belt. Moreover, by independently varying the belt speed, it is possible to vary the resident time of the yarn in comp-acted form which is another means of controlling the process to secure uniformity of the yarn product.

As shown in FIGURE 3, another form of the apparatus comprises a pulley wheel 28' constructed of screen wire or other perforated material having a U-shaped peripheral groove 14. The pulley wheel may be driven :by a belt 18 having a circular section fitting snugly between the sides of the -U-shaped groove to provide the driving friction for the pulley wheel. A gauge wheel 42 is used to provide the proper spacing of the belt from the bottom of the groove to form the moving chamber 12. of the desired depth around substantially more than 180 of the periphery of the wheel 28'. At the other end of this chamber, a nip wheel 46 may be employed to provide a constant load on the belt for the bottom of the groove so as to nip the yarn 32' as it comes out of said chamber and segregate the crimp zone in the chamber from take-up tensions. The yarn is led from this point to take-up reels (not shown) which are driven to provide a take-up speed which is greater than the speed of the moving chamber but less than the feeding speed of the filaments to said moving chamber.

In order to more completely understand the nature of the invention and the manner of practicing same, the following example is presented:

EXAMPLE I In using the apparatus shown in FIGURES 1 and 2 wherein the depth of the recess or groove is one-quarter inch and the width of the porous bottom panel is onequarter inch, a 2400 denier, 140 filament polycaproamide nylon yarn was aspirated through the tube 10 at a rate of about 2,000 feet per minute with steam entering the fluid inlet 8 at a temperature of about 420 C. at a pres sure of about psig. The rotational speed of the hollow drum 28 was about 50 feet per minute. A plug was formed at zone 12 and emerged at exit 34 at :which point it was taken up onto conventional parallel wound packages rotated on conventional winders by means of a pair of rollers (not shown). The speed of the rolls which fed the winder was approximately 1,400 feet per minute.

The yarn obtained in accordance with this method was characterized as having a three-dimensional crimp. This yarn was characterized also as having a before-boil crimp of 9% and an after-boil crimp of 29% and was highly suitable for carpet yarn as it provided superior covering power.

It is obvious that the process of this invention may be performed by utilizing various compressible fluids known generally for jet-texturizing processes. However, it is preferred to use steam, particularly with the thermoplastic yarns, since it provides the necessary heat-transfer to semiplasticize the yarn to a condition inductive to receiving the crimp. In addition, however, air, for example, may be used also and in some instances with some of the yarns, may be preferred. Likewise, while this invention has been described primarily in terms of texturizing thermoplastic yarns, especially the nylon yarns, it is obvious that the process and apparatus may be used for crimping or texturizing a wide variety of other yarns. More specifically, the process may be used to texturize nylon yarn, e.g., polyhexamethylene adipamide or polycaproamide, acrylic fibers, cellulose acetate fibers, polyester fibers, and a number of other commercial fibers available on the market. It is further obvious that While various yarns may be texturized in accordance with this invention, the process conditions will have to vary in accordance with the specific fibers being texturized.

As indicated above, another form of the apparatus as illustrated in FIGURE 3, has been used successfully to prepare jet-texturized yarn by using a crimping chamber 14 which is continuously moving by reason of being formed between the O-ring or belt 18 and the U-shaped groove bottom in the periphery of the crimp wheel 28. The gauge wheel 42 fixes the depth of the chambers cross-sectional area While the nip wheel 46 grips the end of the yarn plug and isolates the crimping zone 32' from the take-up tensions. The speed of the yarn feed to the moving chamber in this particular example was approximately 2,000 feet per minute with the pressure of the hot air being about 50 p.s.i.g. at a temperature of about 460 F. The speed of the yarn plug in the peripheral groove was approximately 12 feet per minute. These process conditions resulted in a product characterized as having a 9% bulk level. However, it was noted that when the air was heated to temperatures above 520 F. and the pressure maintained at about 80 p.s.i.g. or above, the yarn filaments began to fuse.

It was also found that by using lower pulley speeds, a higher bulk level could be obtained. For example, a 15% bulk level was obtained at an eight-turn speed setting of the pulley wheel which provided about 9 feet per minute of yarn. The lower speeds require a more uniform crosssection in the crimp zone to prevent stalling of the aspirator. In this particular example, butyl rubber O-rings were used, but it is obvious that other suitable materials such as neoprene may be used for the belts, particularly at higher temperatures.

As previously stated, by changing thespeed of the yarn or the speed of the belt, it is possible to control the degree of crimp imparted to the yarn without having to make other changes in the process which may be more difficult to control. To illustrate the effect of the change in the belt speed, a nylon yarn was crimped under the following conditions:

TABLE I.STEAM TEMPERATURES, 350 C.

It should be noted from the above data, for example, that as the speed of the belt decreased, the percent crimp, before and after boil, increased, while the feed of the yarn and temperature of the steam was held constant.

While the above-described process and apparatus are illustrations, it is obvious that there are other modifications which may be made in the details and arrangement of parts without departing from the spirit and scope of the invention.

We claim:

1. A method for crimping continuous linear synthetic filaments which comprises:

(a) forming a moving arcuate chamber in the peripheral groove of a grooved pulley wheel by passing a belt over an arcuate portion of the groove, said belt being partially disposed within said groove;

(b) feeding the filaments by aspiration into a stream of hot gas and delivering said filaments in plasticized 6 condition at a high feed rate to the inlet end of the arcuate chamber;

(c) driving the grooved pulley wheel by movement of the belt to advance the moving arcuate chamber at a speed to cause overfeeding of the filaments into said chamber whereby said filaments are compacted therein to impart a crimped condition;

(d) releasing the hot gas and allowing the filaments to cool whereby the crimped condition is set before the filaments exit said crimping chamber to a point of take-up; and

(e) applying sufiicient compressive force against the belt localized at said point of exit to isolate the said crimping chamber from take-up tensions.

2. The method of claim 1 wherein isolation of said crimping chamber from take-up tensions is accomplished by compressing the belt and crimped yarn against the bottom of said groove, said groove being of U-shaped configuration.

3. The method of claim 2 wherein said compressive force is applied by a rotating nip wheel.

4. Apparatus for textun'zing yarn comprising:

(a) a freely rotatable pulley wheel having a grooved peripheral surface;

(b) a belt disposed in said groove for drivingthe pulley wheel by friction with said wheel against the opposite walls of said groove, said belt being spaced in close proximity to the bottom of said groove to form a continuously moving curvilinear chamber at least a part of the distance around said wheel;

(c) means for overfeeding plasticized yarn into the moving curvilinear chamber to impart crimp to said yarn; and

(d) means for setting the crimp in the yarn before being released from said chamber.

5. Apparatus for texturizing yarn as described in claim 4 wherein the means for setting the crimp comprises a perforated bottom in the groove for releasing some of the heat from the plasticized yarn after crimping.

6. The apparatus as described in claim 4 wherein the pulley wheel is comprised of sheet screen material to facilitate the removal of heat thereby setting the crimp in the yarn.

7. The apparatus as described in claim 6 wherein the belt has a circular cross section fitting snugly between the sides of the groove with sufiicient friction to drive the freely rotatable pulley wheel.

8. The apparatus as described in claim 7 wherein nipping means is associated with the outlet of said chamber.

References Cited UNITED STATES PATENTS 2,974,392 3/1961 Timbie 264-168 XR 3,367,005 2/1968 Clarkson 264-168 XR 2,435,891 2/1948 Lodge. 3,146,512 9/1964 Heijnis. 3,156,028 11/1964 Weiss et al. 3,363,041 1/1968 Shichman et a1.

FOREIGN PATENTS 703,672 2/ 1965 Canada.

20,597 1/1961 East Germany.

ROBERT R. MACKEY, Primary Examiner.

US. Cl. X.R.

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