US2399260A - Filamentous product - Google Patents

Description

April 30, 1946. R. J. TAYLOR 9,2

FILAMENTOUS PRODUCT Filed June 8, 1943 Fig.3. /7/ 2 r -INVENTOR.

' WC: 7 V W 7 /9 C l5 ATTORNEY.

Patented Apr. 30,1946] m'rizo srA'rEs 1 erlcan Viscose G Robert 3. Taylor, Ciaont, Met, 1.

orporation,

l., a corporation or Dela Application June 8, 1943, Seriai No. 490,009 I 1943, and Serial No. 489,071, filed May 29, 1943.

Generally, the products of my prior applical tions are prepared by causing a bundle of continuous filaments to be fanned out under turbulent conditions into a filamentary sheet and to be wound in the form or a cylindrical band while the sheet as a whole is being waved or traversed either regularly or irregularly in a direction generally axially of the winding. After collection, the wound band is cuttransversely and is then expanded by stretching in a direction transverse of the band while maintaining it taut along its length. The length of the band is somewhat reduced in the expansion process, but both the width and thickness are greatly increased to produce an exceptionally light-weight fibrous product. Products comprising hollow filaments have tions are made from a mixture of different diameter filaments. As was pointed out inmy prior application, products of this type are most atisfactory and have theimost uniform texture as the result of thorough distribution of fibers in heterogeneous overlapping and interlacing relationshlp when made from filaments of finer diameters and especially when of diameters of the order of 10 microns or less. In accordance with the present invention, it has been found that the mats made from filaments of larger diameters can be greatly improved by incorporating a substantial proportion of comparatively small diameter filaments therein. The addition or the small diameter filaments not only improves the mat formation and its uniformity but also improves the cohesion and structural stability of the mat. In addition, by varying the proportion of small diameter filaments in the product, it is possible to control the air permeability of the fibrous mats produced therefrom, the greater the proportion of small diameter filaments, the lower the air permeability obtained. j

- Any method of combining the diirerently sized filaments together may be employed. Thus,. the

arrangement shown in Figure 15 or my earlier (GR. 28 t8) v prior application, in which one filamentary com ponent coming from a suitable package'thereoi is fanned out just beriore it reaches the spinnin bath in which the other component is freshly spun, may be used and is particularly advantageous when completely set filaments or large diameter are taken from an external package and fanned out into the spinning'bath in which filaments or small diameter are being spun. Alternatively, separate spinnerets may be employed in a common spinning bath, one of the spinnerets being provided. with difierently sized holes or having the filamentary material pumped through it at a different rate so that difierent sized filaments are obtained from each spinneret. Again, a single let may be employed, some of the holes therein being distinctly larger-than others therein. Again, a single spinneret may be employed where it is of the type in which separate spinning lines communicate with distinct orifices therein. This may be accomplished by the arrangement of suitable partitions back of the spinneret face and arran the connections to sep arate spinning lines so that one line c0mmuni-' cates with certain compartments and the other line communicates only with the remaining compartments back or the spinneret face. Either the same spinning solution may be pumped at difierent volumetric rates through the different lines and corresponding orifices in the spinneret or different filamentary material may be spun therethrough, or, again, the orifices associated with one spinning line may be larger than those associated with the other spinning line. Where different filamentary spinning solutions are used, one may be capable of producing hollow or infiated filaments of large diameter while the other may produce a fine diameter filament. In this modification, the orifices associated with each spinning line may be of the same size or different. Besides these methods of combining two filamentary materials, one or more filaments or twisted or 'untwisted bundles of filaments may be laid down with traverse about the wound filamentary band between the several convolutions therein as it is being formed. Thus, a band of fine filamentary material may be collected upon a rotating take-up drum while additional filaments or yarns may be wound upon the drum at a difierent point of its periphetry thus laying down the additional large filaments between the convolutions of the web-like sheet being collected uponthe drum.

The mats made in accordancewith this in vention may be of extremely low densities, this characteristic being favorably influenced by the fact that large hollow filaments can be incorporated in large proportion. At the same time, in spite of the presence of the large diameter hollow filaments, the air and gas permeabilit is maintained low by virtue of the presence of the small diameter filaments intermingled and thoroughly distributed through the mats. As in my prior applications, the essential structure of the mat comprises cries-cross filaments lying submat is substantially laminar in character. By disposing the laminations substantially perpendicular to the direction of heat flow, it will be seen that there is no path provided by the mat for a direct heat conduction along solid filaments from the hot surface to the cold surface. The laminar character of the product assures that aseaaco Figure is an elevation showing a modification of thearrangement of Figure 4.

l0 stantlally ingenerally parallel planes so that the the travel of heat by conduction will be forced to take the longest possible route between the opposit faces of the mat. Mats of hydrophobic vinyl resins in particular exhibit moisture retentions of less than 0.05% at 58% relative humidity and 75 F., are highly resistant to attack by alkalies and mineral acids of all strengths, oils, fats, waxes, alcohols, etc;, and are non-inflammable.

The filamentous masses of the present invention are characterized by a high resistance to transfer of heat by conduction as well as by convection, especially in the direction of'their thickness. This is attributable to the extreme subdivision of the space'occupied by the mats, by the criss-cross filaments extending in undulated planes substantially at right angles to the thickness of the mats and to the fact that the lattice work formed by the filaments in one web is out of alignment with that in adjacent webs tying generally parallel thereto. Each web appears to consist essentially of more or less filaments of various sizes intimately and intricately criss- ,as a result of the distortion caused by the stretching. The result is a special network of filaments, none of which presents a solid path of conduction from one face to the other of the mat and across which the transfer of heat by conduction must take numerous lengthy devia-- tions along the filaments lying at angles approaching a right angle to the path of heat transfer.

The various methods of combining the different size filaments and arrangements for executing the methods are illustrated by the following drawing, in which:

Figure l is an elevation view of one embodiment of the invention,

Figure 2 is a plan view of another arrangement for executing the invention,

Figure 3 is a cross-section showing one form of spinneret for simultaneously spinning filaments from material supplied through separate lines,

Figure 4 is an elevation showing another arrangement for executing the invention and As shown in Figure 1, two spinnerets 2 and 8 are arranged one above the other and are supplied by separate feed-lines. The filaments produced proceed through a common guide I having a flared mouth and a substantially cylindrical channel and then to a suitable take-up device 5 which may or may not be traversed as it is rotated. The take-up device may comprise a drum partially immersed in the coagulating bath and, as in my prior applications, the filaments are collected in the form of an annular band 6 comprising a number of superimposed convolutions each comprising a web-like sheet of the highly intercros'sed and interlaced filaments.

One of the spinnerets shown in Figure 1 may be provided with larger size orifices and in such case, the spinneret supply lines may be connected to a common spinning pump. from a single spinning line. Alternatively, the spinneret feed lines may be connected through separate pumps to a single supply line or through separate pumps to separate supply lines. Where the spinneret supply lines are connected through separate pumps to a common spinning solution supply line, the

orifices in the spinnerets may be of the same size and the variation in size of filaments may be obtained by operating one of the pumps at a different volumetric rate than the other. Where the two spinnerets supply lines are connected through separate pumps to separate spinning solution lines, a distinct spinning solution may be supplied to each line, in which event, the arangement lends itself very readily to the production of hollow filaments of large or small diameter from one of the spinnerets and fine filaments from the other; By any of these arrangements, the proportion of the number of fine.

40 diameter filaments relative to the total number guides l0 and II and a suitable take-up drum I2 similar to that of Figure 1. The arrangement shown in Figure 3 for feeding separate solutions to separate orifices in the spinneret comprises a supply head l3 comprising two connections for the feed lines 8 and 9 and the spinneret proper I, the space betwen the back face of the spinneret and the entrances l4 and 15 for the different spinning materials being partitioned transversely by a cylindrical disk l6 into a region immediately in front of the entrances H and I5 j and another region immediately in back of the spinneret face. The former region is divided into two separate sections A and B by the partition 11. The latter region is divided by annular partitions l8 and 19 into concentric compartments C, C1 and C2 each-of which are associated with one or more separate circles of spinneret holes.

' asoaaoo ccmpartment mav comprise orifices of various diameters. The orifices may conveniently be arranged in circles of radii intermediate those of the annular partitions l8 and I9; This. arrangement lends itself readily to the spinning of separate spinning materials or soltuions and the production of filaments of different materials having either the same or difi'erent sizes or of the production of hollow filaments with solid filaments of the same or different spinning materials and either of the same or of difierent diameters. In Figure 4, a spinneret 23 having orifices of the same size throughout is associated in a spinnlng bath with suitable guides 2d and 25 and ceeding from the spinneret 23 are received upon,

the take-up device or drum 28', other filaments, yams or the like may be directed upon the winding by a suitable guide 21 which is traversed axially oi the take-up device, the filaments, yarns and the like being supplied to the traverse guide from a suitable supply package 28, such as a bobbin, cake oi rayon, and the like. While the traverse oi the guide 2i may have any desired rate,

it is preferred that it be controlled to such a rate that the helix angle oi the yarn or filaments laid down upon the take-up device does not exceed about 10 and preferably is less, especially where a high proportion of filaments are to be combined with those spun from the spinneret in this manner.

Figure is similar ,to Figure 4 but discloses an agement in which a plurality of separaw yarns, or twisted or untwisted bundles of fila-= ments are supplied to the take-up drum 2b by means of separate traverse guides Elm'tlb, and die. Th traverse guides are offset vertically so that their traverse motions do not interfere. The

' rate of traverse of the several guides may be the same or difierent, preferably the latter. In either of the embodiments of Figures 4 and 5, the take-mp device it may be somewhat traversed asi or it maybe rotated in fixed position.

Emmple Two spinning solutions were extruded through separate groups of orifices in a spinneret of the type shown in Figures 2 and 3 into an aqueous sulfuric acid solution oi.20%' concentration. One of the solutions was formed in acetone of 8% by weight of a copolymer of vinyl acetate and vinyl chloride having a softening point 65 to 70 0., said copolymer having 90% by weight of vinyl chloride. The other solution comprised of the same copolymer in acetone and about 2% of calcium carbonate. Spinning was performed with the coagulating bath at about C. and the pump speeds and the speed of the take-up drum were adjusted so that the solid filaments had a diameter averaging 5 microns and the hollow filaments had a diameter of about microns, the spinneret used being of the type shown in Figure 3 and being provided with concentric circles of holes, through 850 of which hollow filaments were produced and through 641 oi which solid filaments were produced, the orifices yieldbit ternating with those circles from which the hollow filaments were obtained.

After collection or the desired thickness or bandit was cut from the'drum and stretched transversely of the general direction in which the filaments lie in the band to produce the expanded mat or bat-oi the type disclosed in my copending applications above referred to. In the final expanded bat, the hollow filaments were uniformly distributed among the solid filaments and the product exhibited an enhanced bulk as the result of the incorporation or the hollow filaments and improved structural stability as well as low air and water permeabilities which was imparted by the finer diameter filaments.

Asin my copending applications, the products of this invention may be produced from any artificial continuous filaments, such as those of regenerated cellulose l'rom viscos or cuprammonium cellulose, of cellulose organic derivatives, such as cellulose ethers and esters and particularly cellulose acetate, of vinyl resins. such as D W- vinyl chloride, copolymers of vinyl chloride and vinyl acetate, after-chlorinated polyvinyl chloride, after-chlorinated copolymers of vinyl chloride and vinyl acetate and copolymers of vinyl chloride and acrylonitrile, or from anyother material whether organic or inorganic, such as glass or mineral wool filaments. Natural continuous filaments, such as silk may also'be used.

In addition, as disclosed in my prior application Serial No. 479,889, the product may, be modiflediby subjecting the band before expanding it to shrinkage. Again, as suggested in that earlier application, the wound bands may be produced from a mixture of shrinkable filaments with nonshrinkable filaments or with a mixture of two or more types of filaments having different shrinkage characteristics. And, before expansion of the band, it may be subjected to a shrinkage agent which effects shrinkage of the more sensitive of the several materials of which the products are composed. Either the hollow filaments or the solid filaments, where products comprising a mixture of such are involved, may be mor sensitive to shrinkage than the other type of filaments.

Another advantageous combination is obtained by mixing a minor proportion of potentially adhesive filaments with a relatively large proportion of filaments oi non-adhesive material which, after collection upon the winding drum, may be subjected to an activating agent for the potentially adhesive filaments, such as heat, a solvent or" swelling agent to render the potentially adhesiv fibers tacky and to cause them'to adhere to the nonadhesive filaments. In this case, either the hollow or solid filaments may be the potentially adhesive filaments.

Another variation involves the incorporation of filaments or a rubbery elasticity, such as rubber itself or any synthetic or substitute for rubber, for example a plasticized copolymer of vinyl chloride and vinyl acetate. The filaments of the rubber-like material may be of any diameter and may be combined in any proportion with the other filaments of the band, and the band, after cutting and removal from the takeupdrum, exhibits a crinkled or corrugated surface. As a modification of this procedure, the rubber-like filaments may be incorporated within the band by means of the arrangement of Figures-4 and 5, the non-rubber-like filaments ,being produced -fromthe spinneret and the lug solid filaments being arranged in circles 91- id rubber-like filaments beingwrapped about the I convolutions thereof upon the drum under ten- 's'ion.

After cutting the band. the rubber-like filaments contract and draw up the band to "crinkle it. After expansion by stretching transversely of the length of the filaments therein,

the crinkliness is converted into a'puckered or pebbled efiect of finer grained quality than that in the original band. a

Whil preferred embodiments of the invention have been disclosed, it is to be understood that ments having an average diameter between about 1 and microns and hollow filaments having an average diameter of at least 10 microns.

2. A wound filamentous product comprising convolutions of a thin sheet of continuous filaments, the filaments in the convoluted sheet being irregularly disposed with respect to each other through the length of the convoluted sheet and comprising filaments having an average diameter 4 between about i and 10 microns, the successive convolutions of the winding being haphazardly disposed with respect to each' other, additional convolutlons of hollow continuous filaments having an average diameter substantially larger than that of the first-mentioned continuous filaments and having their convolutions disposed between the convolutions of the sheet,

3. A low-density filamentous product comprising a bulky expanded mass of filaments exhibiting internal surfaces of cleavage, the strata comprising an irregular net work of intercrossing filaments extending substantially entirely across the mass, the filaments in the mass comprising a mixture of small-diameter filaments and comparatively large-diameter filaments heterogeneously distributed therethrough.

4. A low-density filamentous product comprising a bulky expanded mass of filaments exhibiting internal surfaces of cleavage, the strata comprising an irregular network of intercrossing filaments extending substantially entirely across the mass, the filaments in the mass comprising a mix! ture of solid filaments of small diameter and hollow filaments of larger diameter. 4 g

5. A low-density filamentous product comprising a bulky expanded mass of filaments exhibiting internal surfaces of cleavage, the strata comprising an irregular network of intercrossing filaments extending substantially entirely across the mass, the filaments in the mass comprising a mixture of solid filaments having an average diameter of about 1 to 10 microns and hollow filamentstending substantially entirely across the mass, the

large-diameter filaments heterogeneously distributed therethroueh.

7. A low-density filamentous product comprising a bulky expanded mass of filaments of a synthetic linear polymer, said mass exhibiting internal surfaces of cleavage, the strata comprising an irregular network of intercrossing filaments extending substantially entirely across the mass, the filaments in the mass comprising a mixture of solid filaments having an average diameter of about 1 to 10 microns and hollow filaments having an average dimetergreater than 10 microns heterogeneously distributed therethrough.

8. A low-density filamentous product comprising a bulky expanded mass having a specific gravity between 0.001 and 0.1 of filaments of a vinyl resin exhibiting internal surfaces of cleavage, the strata comprising an irregular network of intercrossing filaments extending substantially across the mass, the filaments in the mass comprising a mixture of solid filaments of small diameter and hollow filaments of larger diameter.

, ing a bulky expanded mass having a specific gravfilaments in the mass comprising a mixture of small-diameter filaments and comparatively ity between 0.001 and 0.1 of filaments of a copolymer of vinyl acetate and vinyl chloride, said mass mixture of solid filaments having an average diameter of about 1 to 10 microns and hollow filaments having an average diameter of about 10 miorons heterogeneously distributed therethrough.

10. A low-density filamentous product comprising a bulky expanded mass comprising a mixture of hollow filaments with solid filaments having an average diameter between 1 and 10 microns distributed therethrough, the bulk of the mass being constituted of the hollow filaments and a sulficient proportion of small filaments being present to impart a predetermined texture, stability, and impermeability to fluid.

11. A low-density filamentous product comprising a bulky expanded mass comprising a mixture of hollow filaments of a synthetic linear polymer with filaments of a synthetic linear polymer having an average diameter between 1 and 10 microns distributed therethrough, the bulk of the mass being constituted of the hollow filaments and a sufiicient proportion of small filaments. being present to impart a predetermined texture, stability, and impermeability to fluid.

12. A low-density filamentous product comprising a bullw expanded mass comprising a mixture of hollow hydrophobic vinyl resin filaments with hydrophobic vinyl resin filaments having an average diameter between 1 and 10 microns distributed therethrough, the bulk of the mass being constituted of the hollow filaments and a sumcient proportion of small filaments being present to impart a predetermined texture, stability, and impermeabilityto fluid.

13. A low-density filamentous product comprising a bulky expanded mass comprising a mixture of hollow filaments of a copolymer of vinyl chloride and vinyl acetate with filaments of a copolytexture, stability and impermeability to fluid.

ROBERT J. TAYLOR.

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