US3169089A

US3169089A - Filaments

Info

Publication number: US3169089A
Application number: US24025A
Authority: US
Inventors: Miller William Burton; Bishop Clarence Edward
Original assignee: Celanese Corp
Current assignee: Celanese Corp
Priority date: 1960-04-22
Filing date: 1960-04-22
Publication date: 1965-02-09
Anticipated expiration: 1982-02-09

Description

Feb. 9, 1965 w. B. MILLER ETAL 3,%9,9

FILAMENTS Filed April 22. 1960 FILAMENTS William Burton Miller, Pearishurg, and Clarence Edward Eishop, Narrows, Va, assignors to Celanese Corporation of America, New York, N.Y., a corporation of Delaware Filed Apr. 22, 1960, Ser. No. 24,025 3 Claims. (Cl. 161-477) the production of filamentary material of the aforesaid type.

Still another object of the present invention is to provide yarns or filamentary material affording, for a given denier, a larger surface area, superior bulking properties and a higher beam strength than bulbous filaments dry spun through circular orifices.

A further object of the filamentary material of the aforesaid type which does not pack tightly and exhibits improved resilience, air permeability and filtering power for its denier as compared with conventional filaments, whereby it is particularly suited not only for use in the manufacture of carpeting, upholstery, drape and other textile fabrics but also for use as cigarette filters and such non-textile materials as padding or filling.

A related object of the present invention is to provide such filamentary material which is composed of a blend or mixture of individual filaments of diiferent crossscctional shapes.

Concurrently, therefore, it is also an object of the present invention to provide novel spinnerettes each having a plurality of jet openings, with the configurations of one set of such openings ditfering from the configurations of another set of said openings, so as to produce the abovedescribed blend of cross-sectional shapes.

The foregoing and other objects, characteristics and advantages of the present invention will be more fully understood from the following detailed description thereof when read in conjunction with the accompanying drawing, in which:

FIG. 1 is a plan view of a spinnerette constructed with a plurality of jet openings specially shaped according to one embodiment of the present invention;

FIG. 2 is a cross-sectional view, on an enlarged scale, of the filamentary material produced by means of a spinnerette having jet openings as shown in FIG. 1;

FIG. 3 is a graphic representation of the manner of construction and dimensioning of the jet openings shown in FIG. 1;

FIG. 4 is a plan view of a spinnerette having jet openings of the type shown in FIG. 1 alternating with circular jet openings; and

FIG. 5 is a cross-sectional view, on an enlarged scale, of the blend of filaments produced by means of the spinnerette of FIG. 4.

In accordance with the invention generally, filamentforming material in liquid phase, e.g. a solution in a volatile solvent, is dry spun by extrusion through the openings or orifices of a spinnerette into an evaporative atmosphere or heated air. A dry spinning system equipped with such a spinnerette for converting derivatives of celpresent invention is to provide lulose, more particularly a cellulose organic acid ester solution such as cellulose acetate in a volatile solvent, into filaments, yarn or tow is well known and need not be illustrated or described in detail herein.

According to the present invention, there is provided a novel spinnerette having a plurality of jet openings-each of which is shaped substantially in the form of a cross defined by a large square out of'the corners of which there are removed small squares the sides of which range from about 20 to 30% and preferably about 24 to 28% of the sides of the largesquare. The cross-sectional shapes of the filaments produced by means of such jet openings resemble four-leaf clovers or shamrocks.

In accordance with a modification of the invention, the aforesaid jet openings are alternated with jet openings having different shapes, such as circles, semicircles, crescents and the like. Although the jet openings are shown in the drawing as being oriented in their respective spin nerettes in a predetermined manner, it will be understood that these openings may be oriented differently with respect to one another and to the outer periphery of the spinnerette.

Filamentary materials in accordance with the present invention may comprise organic derivatives of cellulose such as the esters or ethers thereof, for example, cellulose organic acid esters such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose benzoate, cellulose acetate formate, cellulose acetate propionate, cellulose acetate butyrate, and the like, ethyl cellulose, etc. The esters may be ripened and acetone-soluble, such as conventional cellulose acetate, or may be substantially fully esterified, that is, contain fewer than 0.29 free hydroxyl groups per anhydroglucose unit, e.g. cellulose triacetate.

The filament-forrning material may also comprise other thermoplastic or solvent-soluble polymeric materials such as superpolyamides, e.g. nylon, superpolyesters such as polyethylene terephthalate, polyglycolic acid and copolymers thereof, acrylonitrile polymers and copolymers, polymers and copolymers of vinylidene compounds such as ethylene, propylene, vinylchloride, vinylidene chloride, acrylonitrile, vinylidene cyanide, vinyl acetate, and the like.

The filament-forming material is initially in liquid phase. In operation, a solution of the filament-forming material in a volatile solvent is extruded through the jet openings of a spinnerette into an evaporative atmosphere. The filaments formed upon extrusion of the solution are taken up at a linear speed ranging from about meters per minute to about 900 meters per minute and preferably from about 200 meters per minute to about 600 meters per minute. The ratio of the take-up speed to the linear speed at which the solution is extruded through the jet openings, i.e. the drawdown ratio, may range from about 0.6 to 2.0 and preferably ranges from about 0.8 to about 1.6. When dry spinning a solution of secondary cellulose acetate in acetone, the temperature of the dope being extruded generally ranges from about 40 C. to about C. and preferably from about 60 C. to about 85 C.

In forming filaments in accordance with the present invention, each spinnerette may be provided with as many as 300 or more jet openings or orifices. The denier per filament may be 55 or more, but generally ranges from about 2 to 25 and preferably from about 3 to 20. The spun filaments can be collected into yarn ends having the desired number of filaments. When necessary, large bundles or tows of filaments can be formed directly from the spun filaments, or alternatively by combining several smaller bundles of spun filaments, for facilitating the formation of staple fibers by cutting. Prior to any processing subsequent to the extrusion, the filaments as a unit may be subjected to any desired volumnizing treatment to increase the bulk thereof, as by crimping, eg to impart about to 20 and preferably 7 to 12 crimps per inch.

Referring now more particularly to FIG. 1, it will be seen that the spinnerette 10 according to the present invention is provided with a plurality of jet openings 11 each of which is shaped substantially in the form of a special cross.

The formation, dimensioning and other structural characteristics of the jet openings 11 may be somewhat better understood by reference to FIG. 3 which shows, on a greatly enlarged scale, a graphical representation of such an opening and its relationship to its circumscribed square and circle. As can be seen in FIG. 3, the shape of the cross-like polygon AB-CD-E-F-G-H JKL-MA illustrated in solid lines corresponds to that of any of the openings 11 shown in FIG. 1. There are also shown points N, O, P, Q and dotted lines connecting these points to the cross-shaped opening. The points N, O, P, Q define a large square; the cross-shaped opening A-BCD-EFGH-]KL-M- A is the result of removing from each corner of large square N-O-PQ a small square, e.g. LM--AQ, the sides of which range from about 20 to 30% and preferably about 24 to 28% of the length of the sides of the large square. While illustrated as straight, lines A-B, D-E, 6-H and K-L might be slightly bowed or arcuatc as would occur if the basic shape from which the small squares were cut out were a circle rather than a large square.

As previously intimated, the number of jet openings or holes 11 may be quite high and it is, therefore, apparent that the locus of all the jet openings in the spinnerette 10 need not be one circle, as indicated in broken lines in FIG. 1. Merely by way of example, the loci of the different sets of jet openings 11 may be a plurality of concentric circles. Moreover, although with the openings as illustrated one of the axes of each opening is oriented radially of the spinnerette, it is to be understood that in accordance with the present invention other, possibly random and certainly not necessarily uniform, orientations of the axes of the jet openings are possible. Referring now to FIG. 2, it will be seen that the yarn or filamentary material produced by extrusion of the filament-forming substance through the spinnerette 10 is composed of a bundle of filaments 20 which resemble, in cross-sectional shape, four-leaf clovers or Shamrocks. Thus, each filament 20 has a core 20a and four lobelike arms 20b, 20c, 20d and 20.2 extending from the core. The cross-sectional periphery, and hence the filament surface area of each of the novel filaments 20 is about 10% to 50% greater than that of a filament of equal denier spun through a circular jet opening and having a bulbous cross-section. The filaments 20, moreover, have a considerably greater beam strength and elasticity than filaments of bulbous, or similar cross-sectional shapes and also have good bulking properties, while fabrics produced from such filaments exhibit the advantageous property of high dye absorbency and are also characterized by high tenacity, elongation, bulk and abrasion resistance. Such fabrics, furthermore, are thick and of relatively low compressibility and are characterized by high air permeability. The filaments are also characterized by marked crosssection fidelity, i.e. substantial uniformity, along each filament and from filament to filament.

Referring now to FIGS. 4 and 5, the spinnerette 21 shown in FIG. 4 differs from the spinnerette 10 in that the substantially cross-shaped jet openings 11 are arranged in alternating sequence with other jet openings having different cross-sectional shapes. More specifically, in the spinnerette 21 the jet openings 11 alternate with circular jet openings 22, but it will be understood that the jet openings 11 can be alternated with jet openings of dillerent shapes, such as semicircles, crescents, etc.

The yarn formed by the extrusion of the filament-forming material through the spinnerette 21 is illustrated in FIG. 5. As shown there, the yarn produced by means of the spinnerette 21 is composed of a mixture or blend of the substantially four-leaf clover or lobed filaments 2% with filaments 23 being formed from the material extruded through the circular jet openings 22.

As hereinbeforc stated, the yarns produced in accordance with the present invention are capable of being used in a variety of ways. In particular, blends or mixturcs of filaments such as 20-23 may be especially advantageously employed in the manufacture of cigarette filters (not shown), inasmuch as these blends of filaments do not pack too tightly, thereby retaining their high air permeability and ease of drawing while being characterized by a relatively great filtering capacity.

The following examples will serve to illustrate the principles of the present invention more clearly.

Example I An acetone solution of secondary cellulose acetate having an acetyl value of 55% is extruded at a linear speed of 250 meters per minute through a spinnerette provided with 200 jet openings each having the shape of a cross-like polygon as shown in FIG. 1. The length of each of the sides of the large square is 0.058 mm, and the length of each of the sides of the small squares is 0.016 mm. The temperature of the dope at the jet face is approximately 65 C. The filaments are withdrawn at a drawdown ratio of 1.10. Upon analysis, the resulting yarn is found to have a denier of 1,000, i.e., a denier per filament of about 5.0, and is shaped in cross-section as shown in FIG. 2. The filaments have a relatively great beam strength and are also characterized by a high resistance to abrasion and by even dyeing.

70 such bundles of filaments can be gathered into a tow, crimped to impart about 8 crimps per inch, opened, sprayed to pick up about 6% by weight of glycerine triacetate, wrapped with paper, out into predetermined lengths, cured and incorporated into cigarettes as filter tips.

Example 11 The procedure set forth in Example I is repeated, using a spinnerette provided with jet openings each having the shape of a cross-like polygon as shown in FIG. 1 and alternating with 75 jet openings of circular shape, in the manner illustrated in FIG. 4. The yarn is extracted from the metier at a drawdown ratio of about 1.0.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made in the invention without departing from the spirit thereof.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. Filamentary material having a four-leaf clover crosssection which is substantially uniform along the length of the filamentary material, said cross-section including four substantially smooth rounded lobes extending independently and substantially symmetrically from a central core, each of said lobes being narrowest where it is joined to said core and having its maximum width nearer to the outermost extremity of said lobe than to said core and continuously increasing in Width from said narrowest portion to said maximum width, said lobes completely surrounding said core except for the narrow radial spaces, of lesser width than said lobes, between said lobes.

2. Filamentary material according to claim 1, comprising cellulose acetate.

3. Filamentary material comprising a plurality of filaments having four-leaf clover cross-sections which are References eaea in the file of this patent substantially uniform along each filament and amongst V the several filaments of such cross-section, sm'd cross-section including four substantially smooth rounded lobes extending independently and substantially symmetrically from a central core, each of said lobes being narrowest Where it is joined to said core and having its maximum width nearer to the outermost extremity of said lobe than to said core and continuously increasing in width from said narrowest portion to said maximum Width, said lobes completely surrounding said core except for the narrow radial spaces, of lesser width than said lobes, between said lobes.

UNITED STATES PATENTS Dreyfus Aug. 26, Thenoz Ian. 23, Marshall .ay 23, White a- June 19, Wi liams Nov. 20, Holland June 7, Holland June 7, Swerdloff, et al. Jan. 24,

OTHER REFERENCES Erith: White Clover-A Monograph, Duckworth 15 and Co., 1924, London (pp. 37 and 121 of interest only).

Claims

1. FILAMENTARY MATERIAL HAVING A FOUR-LEAF CLOVER CROSSSECTION WHICH IS SUBSTANTIALLY UNIFORM ALONG THE LENGTH OF THE FILAMENTARY MATERIAL, SAID CROSS-SECTION INCLUDING FOUR SUBSTANTIALLY SMOOTH ROUNDED LOBES EXTENDING INDEPENDENTLY AND SUBSTANTIALLY SYMMETRICALLY FROM A CENTRAL CORE, EACH OF SAID LOBES BEING NARROWEST WHERE IT IS JOINED TO SAID CORE AND HAVING ITS MACIMUM WIDTH NEARER TO THE OUTERMOST EXTREMITY OF SAID LOBE THAN TO SAID CORE AND CONTINUOUSLY INCREASING IN WIDTH FROM SAID NARROWEST PORTION TO SAID MAXIMUM WIDTH, SAID LOBES COMPLETELY SURROUNDING SAID CORE EXCEPT FOR THE NARROW RADIAL SPACES, OF LESSER WIDTH THAN SAID LOBES, BETWEEN SAID LOBES.