US3339250A - Crimping fibers - Google Patents

Description

p 5, 1967 A. G. COMOLLI ETAL 3,339,250

CRIMPING FIBERS Filed May 29. 1962 l 2 Sheets-Sheet 1 I 2 ll INVENTORS George E. Davis Alfred G. ComoHi A T TORNE Y Sept. 5, 1967 Filed May 29, 1962 A. G. COMOLLI ETAL CRIMPING FIBERS 2 Sheets-Sheet 2 INVENTORS George E. Davis Alfred G. Comolli United. States Patent 3,339,250 CRIMPING FIBERS Alfred G. Comolli, Greenwich, and George E. Davis,

Fairfield, Conn., assignors to American Cyanamid Company, Stamford, Conn., a corporation of Maine Filed May 29, 1962, Ser. No. 198,629 7 Claims. (Cl. 281) This invention relates to new method and apparatus for crimping endless lengths of elongated material such as endless filaments or fibers.

It is an object of this invention to impart to an endless length of elongated material a crimp which is relatively stable at elevated temperatures, such as would be attained upon washing the product in hot water.

It is another object of this invention to provide a method and apparatus for preparing crimped fiber which is relatively stable .at elevated temperatures and doing so without damaging such fibers at the elevated temperatures necessary for operation to impart such a crimp.

It is yet another object of this invention to provide method and apparatus capable of crimping endless lengths of elongated material at temperatures above their softening points without damaging such materials or otherwise adversely affecting the properties thereof.

These objects, and other objects and advantages which will become apparent as the specification proceeds, are mainly achieved by heating such elongated materials or fibers to an elevated temperature under superatmospheric pressure in an enclosed zone, ejecting the thus-heated fibers from the enclosed zone by such superatmospheric pressure into a confined crimping zone, cooling such crimped fiber while maintained as part of a mass thereof in the crimping zone, and discharging the thus crimped fibers from the crimping zone. The mass of fibers is maintained within the crimping zone by use of a pressuremaintaining closure at the outlet end thereof, which preferably is a gate resiliently biased toward a closed position and which may be forced open by the pressure within the enclosed zone escaping through the crimping zone and forcing therewith a portion of the mass of the crimped fibers maintained within such crimping zone.

For a clearer and more detailed understanding of this invention, reference may be had to the subjoined description read in conjunction with the accompanying drawings wherein:

FIGURE 1 is an elevational view, partially cut away, of an embodiment of apparatus according to this invention; and

FIGURE 2 is a vertical sectional view on an enlarged scale of the upper portion of the apparatus illustrated in FIGURE 1.

Referring next to the drawings, and more particularly, to FIGURE 1 thereof, a pressurized chamber 11 is shown provided with steam-generating means 12 capable of supplying to the interior of chamber 11 steam generated at superatmospheric pressure through conduit 13. Pressurized chamber 11 is also provided with a crimping device 15 (which will be explained in greater detail in con- .nection with FIGURE 2) secured to an opening in chamber 11, such as manhole 16.

Pressurized chamber 11 is also provided with an endless conveyor 18 for conveying tow or strand 19 to a region below crimping device 15. Near the exit of crimping device 15, another endless conveyor 20 is provided for conveying the crimped product toward subsequent stages in the process and apparatus. Pressurized chamber 11 is also provided with a'condensate outlet 22 for removing condensed steam or other liquids from within the interior .thereof.

Referring next to FIGURE 2, crimping device 15 is shown as mainly consisting of a tubular member 25 having one end thereof communicating with pressurized chamber 11 and having a pressure-maintaining closure 26 at the other end thereof and being provided with means for introducing a cooling fluid to the interior of tubular member 25.

To manhole 16, a cover plate 28 is aflixed for completely closing the opening thereof. Supported in an opening in cover plate 28 is a first tube 29 which preferably has each end outwardly flared substantially as illustrated. Also secured to cover plate 28 is an elongated jacket 31 provided with a cap 32 which serves to support second tube 33. Cap 32 also supports the remainder of second tube 33 which, as illustrated herein, may be a separate extension piece 34 or may be integral with second tube 33.

It is thus seen that first tube 29 and second tube 33 are arranged to form a continuous passageway leading from pressurized chamber 11 to pressure-maintaining closure 26 and thereby define tubular member 25. It is to be noted that the ends of first tube 29 and second tube 33 that are adjacent each other are each outwardly flared and are spaced a relatively short distance from each other permitting fluid communication between the interior of tubular member 25 and the interior of elongated jacket 31 for a purpose to be explained hereinafter.

Pressure-maintaining closure 26 (which serves to close the outlet end of tubular member 25) comprises a gate 37 pivotably mounted on extension piece 34 by pivot 38 and which is resiliently biased toward a closed position by adjustable weight 39. Of course, other forms of resilient biasing means, such as springs, pistons in pneumatic cylinders, etc., may be used.

It will be seen that gate 37 tends to be urged towards its closed position obstructing the end of tubular member 35 by means of weight 39 and tends to be opened by the action of pressure from within pressurized chamber 11 escaping through tubular member 25. In order to prevent gate 37 from slipping completely open, stop 40 may be provided.

Elongated jacket 31 is provided with a cooling liquid inlet 41 for introducing cooling liquid to within jacket 31 where it is permitted to flow through small opening 43 between the adjacent ends of tubes 29 and 33 comprising tubular member 25 into tubular member 25. A portion of such liquid will fall downwardly through first tube 29 into pressurized chamber 11 and will be removed therefrom through condensate outlet 22. The remainder of the cooling liquid will flow upwardly through second tube 33 out from elongated jacket 31 through cap 32, out through orifices 45 in extension piece 34 into well 46 in cap 32 and through outlet 47.

In operation, the fibers to be crimped are heated to a temperature above their softening point within pressurized chamber 11. This may be accomplished by heat alone, or

by heat in conjunction with other agents such as moisture depending upon the particular fiber to be crimped. Such heating most eflicaciously can be performed by introducing wet or saturated steam under super-atmospheric pressure into pressurized chamber 11 and permitting it to contact tow or strand 19 for a sufficient time to cause softening thereof. The thus softened fibers 19 are ejected into tubular member 25 of crimping device 15 by the action of the superatmospheric pressure trying to escape from pressurized chamber 11 thereby compacting fibers 19 into the upper portion of tubular member 25 and imparting thereto a crimped configuration. Cooling liquid, such as water at room temperature, entering through inlet 41 passes into tubular member 25 and cools the crimped fiber in second tube 33 to below the softening point while such fibers are maintained crimped as a compacted mass under the action of the pressure from chamber 11. The thus cooled crimped fibers pas outwardly from tubular member 25 through pressure-maintaining closure 26 from whence they may be conveyed away therefrom by endless conveyor 20.

In a typical operation of the present invention, a tow or strand of oriented polyacrylonitrile filamentary material, specifically one made from a copolymer, more particularly a ternary polymer, of copolymerizable ingredients including by weight, about 85% acrylonitrile, about 7.5% vinyl acetate, and about 7.5% 2-methyl-5-vinylpyridine, having a total denier of about 500,000, was crimped in accordance with the teachings herein. Within pressurized chamber 11, saturated steam under pressure was utilized to heat tow 19 to a temperature of above about 190 F., e.g., about 127 C. thus softening the fibers thereof. The escaping steam compacted the fibers within crimping device 15 into which cooling water at ambient temperature (about 30 C.) was introduced. The resulting fiber was found to have a permanent three-dimensional crimp.

It will be understood, of course, by those skilled in the art that our invention is not limited to the processing of a tow of polyacrylonitrile filamentary material of the kind described in the preceding paragraphs. Thus, instead of using such a tow of filamentary material we may use a tow of filamentary material comprised of a homopolymer of acrylonitrile or a copolymer of about 90% by weight of acrylonitrile and about by weight of methyl acrylate. Other acrylonitrile copolymers (thermoplastic, fiber-formable copolymers) of which the tow may be composed or comprised are acrylonitrile copolymers containing in the polymer molecules an average of, for example, at least about 70%, preferably at least about 80% by weight of combined acrylonitrile. Taking as an example the expression an acrylonitrile polymer containing in the polymer molecules an average of at least 70% by weight of combined acrylonitrile, this means herein a polymerization product (homopolymer, copolymer or graft polymer or mixtures thereof) containing in the molecules thereof an average of at least about 70% by weight of the acrylonitrile unit, which is considered to be present in the individual polymer molecule as the group or, otherwise stated, at least 70% by weight of the reactant substance converted into and forming the polymerization product is acrylonitrile. The expression an acrylonitrile polymer containing in the polymer molecules an average of at least 80% by weight of combined acrylonitrile has a similar meaning herein.

Illustrative examples of monomers which may be copolymerized with acrylonitrile to yield a polymerization product containing in the polymer molecules an average of at least 70%, preferably at least about 80%, by weight of combined acrylonitrile are compounds containing a single CH =C grouping, for instance, the vinyl esters and especially the vinyl esters of saturated aliphatic monocarboxylic acids, e.g., vinyl acetate, vinyl propion-ate, vinyl butyrate, etc.; vinyl halides, e.g., the vinyl chlorides, bromides and fluorides; allyl-type alcohols, e.g., allyl alcohol, methallyl alcohol, ethallyl alcohol, etc.; allyl, methallyl and other unsaturated monohydric alcohol esters of monobasic acids, e.g., allyl and methallyl acetates, laurates, cyanides, etc.; acrylic and alkacrylic acids (e.g., methacrylic, ethacrylic, etc.) and esters and amides of such acids (e.g., methyl, ethyl, propyl, butyl etc., acrylates and methacrylates; acrylamide, methacrylamide, N-methyl, -ethyl, -propyl, -butyl, etc., acrylamides and methacrylamides, etc.); methacrylonitrile, ethacrylonitrile and other hydrocarbon-substituted acrylonitriles; unsaturated aliphatic hydrocarbons containing a single CH =C grouping, e.g., isobutylene, etc.; and numerous other vinyl, acrylic and other compounds containing a single CH C grouping which are copolymerizable with acrylonitrile to yield thermoplastic, fiber-formable copolymers. Alkyl esters of alpha, beta-unsaturated polycarboxylic acids also may be copolymerized with acrylonitrile to form copolymers, e.g., the dimethyl, -ethyl, -propyl, -butyl, etc., esters of maleic, fumaric, citraconic, etc., acids.

Ordinarily, the molecular weight (average molecular weight) of the polyacrylonitriles (homopolymeric or copolymeric acrylonitriles) used in making the tow of filaments is within the range of 25,000 or 30,000 to 200,000 or 300,000 or higher, and advantageously is of the order of 50,000 to 100,000, e.g., about 65,000 to 75,000, as calculated from a viscosity measurement of the said polymerization product in dimethylformamide using the Staudinger equation (reference: U.S. Patent No. 2,404,713).

The tow of polyacrylonitrile filamentary material may be produced from an acrylonitrile polymerization product by any suitable method and using any suitable apparatus, but advantageously is produced as is described in, for instance, Sonnino Patent No. 2,849,751, dated Sept. 2, 1958.

The present invention is applicable to the treatment of various kinds of strands in addition to those previously mentioned, among which may be mentioned strands of natural filamentary materials, and the various synthetic filamentary materials such as cellulose ethers and esters, among which may be specifically mentioned ethyl cellulose, hydroxyethyl cellulose, etc., cellulose acetate, cellulose nitrate, cellulose butyrate, cellulose acetate butyrate, cellulose propionate butyrate, the various mixed cellulose esters and ethers, and the various vinyl resins including the various polyacrylonitriles of which numerous examples have hereinbefore been given. Additional examples of synthetic filamentary materials to which the present invention is applicable include those strands made from polyethylene, polypropylene and other polyolefins, the various polyvinyl halides including polyvinyl chloride, polyvinyl fluoride, etc., copolymers of vinyl chloride with, for example, vinyl acetate or acrylonitrile, after-chlorinated polymers, e.g., after-chlorinated vinyl and vinylidene homopolymers and copolymers, also homopolymeric and copolymeric vinylidene halides including the chlorides and fluorides, and the various condensation polymers including the various polyesters, polyamides, polyanhydrides, etc.

With some of the aforementioned materials, heating to above the softening point within pressurized chamber 11 may be accomplished by the use of hot gases or radient heaters producing softening by heat alone. With other of the aforementioned materials, heating to above the softening point may require the use of other agents in addition to heat, such as the use of moisture, solventtype vapors, etc. For example, for softening polyacrylonitrile fibers of the type hereinbefore described, it is preferred that the softening be accomplished by the use of saturated steam under pressure to take advantage of the softening effect of moisture at elevated temperatures.

While tubular member 25 is shown as comprising a first tube 29 and a second tube 33 separated by a relatively small opening 43, tubular member 25 may be a single tube having a plurality of orifices located therein. While it is preferred that tubular member 25 have a circular cross-section and that the bundle of fibers being crimped therein likewise be in the form of a tow of circular cross-section, tubular member 25 may have a noncircular cross-section (such as an elongated oval) for handling fibers grouped as a tow of non-circular crosssection.

It will thus be seen that there has been provided herein a novel method and apparatus for preparing crimped fibers, which method and apparatus make possible the use of conditions wherein the fibers are heated to above their softening point prior to crimping and yet are not damaged by the crimping operation, such conditions being important for obtaining a stable crimp.

We claim:

1. A process for crimping fibers comprising heating said fibers to an elevated temperature above their softening point under superatmospheric pressure in an enclosed zone; ejecting the thus heated and softened fibers from said enclosed zone by such superatmospheric pressure into a confined crimping zone thus causing them to fold and crimp by pressing against a mass of crimped fibers already in said crimping zone; cooling such crimped fibers to below their softening point while maintained in said crimping zone; and discharging the thus cooled crimped fibers from said crimping zone.

2. A process as defined in claim 1 wherein said cooling is performed by flowing an aqueous liquid through said mass of crimped fibers in said crimping zone.

3. A process as defined in claim 1 including discharging the thus crimped fibers from said crimping zone through a pressure-maintaining closure.

4. A process as defined in claim 1 wherein said fibers comprise an acrylonitrile polymer and said fibers are heated to a temperature above about 190 F. in said enclosed zone prior to ejection into said crimping zone.

5. A process as defined in claim 4 utilizing wet steam under superatmospheric pressure for heating said acrylonitrile polymer fibers under pressure.

6. Apparatus for crimping fibers comprising:

a pressurized chamber having an opening therein;

means for supplying gas under pressure to the interior of said chamber;

means for heating said gas to a temperature above the softening point of said fibers;

means for supporting said fibers in a relaxed condition within said pressurized chamber for a time sufiicient to permit said fibers to be heated to above their softening point;

a tubular member operatively associated with said opening having one end thereof communicating with the interior of said chamber and a second end thereof communicating with the exterior of said chamber;

a pressure-maintaining closure for constricting said second end of said tubular member; and

means for cooling the contents of said tubular memher.

7. Apparatus for crimping fibers comprising:

a pressurized chamber having an opening therein;

means for supplying gas under pressure to the interior of said chamber;

means for heating said gas to a temperature above the softening point of said fibers;

an elongated jacket secured to said pressurized chamher;

a tubular member supported by said elongated jacket, said tubular member comprising a first tube and a second tube defining a continuous passageway through said elongated jacket,

said first tube having a first end communicating with the interior of said pressurized chamber through said opening therein and having a second end communieating with the interior of said elongated jacket,

said second tube having a first end communicating with the interior of said elongated jacket closely adjacent said second end of said first tube, and having a second end communicating with the exterior of said elongated jacket and the exterior of said pressurized chamber;

means for supplying a cooling liquid under pressure to the interior of said elongated jacket; and

a pressure-maintaining closure for constricting said second end of said second tube comprising a gate means resiliently biased toward a closed position.

References Cited UNITED STATES PATENTS 2,575,839 11/1951 Rainard 19-66 2,758,357 8/1956 Goodhue 28-1 2,854,701 10/ 1958 Rainard 28-1 2,854,728 10/1958 Rainard et al, 28-1 2,865,080 12/ 1958 Hentschel 281 2,914,835 12/1958 Slayter et al. 281 2,949,659 8/ 1960 Haijnis et a1. 281 3,031,734 5/1962 Pike 28-72 3,036,357 5/1962 Cook et a1. 28-1 FOREIGN PATENTS 20,597 1/ 1961 Germany. 535,340 11/1955 Italy.

FRANK J. COHEN, Primary Examiner. R. C. MADER, D. W. PARKER, Examiners. J. PETRAKES, Assistant Examiner.

Claims (2)

1. A PROCESS FOR CRIMPING FIBERS COMPRISING HEATING SAID FIBERS TO AN ELEVATED TEMPERATURE ABOVE THEIR SOFTENING POINT UNDER SUPERATMOSPHERIC PRESSURE IN AN ENCLOSED ZONE; EJECTING THE THUS HEATED AND SOFTENED FIBERS FROM SAID ENCLOSED ZONE BY SUCH SUPERATMOSHPERIC PRESSURE INTO A CONFINED CRIMPING ZONE THUS CAUSING THEM TO FOLD AND CRIMP BY PRESSING AGAINST THE MASS OF CRIMPED FIBERS ALREADY IN SAID CRIMPING ZONE; COOLING SUCH CRIMPED FIBERS ALTO BELOW THEIR SOFTENING POINT WHILE MAINTAINED IN SAID CRIMPING ZONE; AND DISHCARGING THE THUS COOLED CRIMPED FIBERS FROM SAID CRIMPING ZONE.

6. APPARATUS FOR CRIMPING FIBERS CONPRISING: A PRESSURIZED CHAMBER HAVING AN OPENING THEREIN; MEANS FOR SUPPLYING GAS UNDER PRESSURE TO THE INTERIOR OF SAID CHAMBER; MEANS FOR HEATING SAID GAS TO A TEMPERATURE ABOVE THE SOFTENING POINT OF SAID FIBERS; MEANS FOR SUPPORTING AND FIBERS IN A RELAXED CONDITION WITHIN SAID PRESSURIZED CHAMBER FOR A TIME SUFFICIENT TO PERMIT SAID FIBERS TO BE HEATED TO ABOVE THEIT SOFTENING POINT; A TUBULAR MEMBER OPERATIVELY ASSOCIATED WITH SAID OPENING HAVING ONE END THEREOF COMMUNICATING WITH THE INTERIOR OF SAID CHAMBER AND A SECOND END THEREOF COMMUNICATING WITH THE EXTERIOR OF SAID CHAMBERS; A PRESSURE-MAINTAINING CLOSURE FOR CONSTRICTING SAID SECOND END OF SAID TUBULAR MEMBER; AND MEANS FOR COOLING THE CONTENTS OF SAID TUBULAR MEMBER.

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