US2933774A - Batt formation - Google Patents

Description

April 26, 1960 B. F. ADAMS, JR

BATT FORMATION Filed Sept. 26. 1955 INVENTOR BENJAMIN F ADAMS, JR.

BY m

ATTORNEY BAIT FORMATION Benjamin F. Adams, Jr., Wilmington, DeL, assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Application September 26, 1955, Serial No. 536,559

4 Claims. c1. 19-144 This invention relates to formation of non-woven fibrous articles, concerning particularly production of batts with high content of synthetic staple fibers.

face characteristics, such as coefiicientv of friction, and

other physical properties synthetic fibers dilfer sutliciently from wool that they adhere to one another with less facility, and articles so composed are subject to dimensional non-uniformity, notably in thickness, brought about during formation of the batts from which the felts are made. As one would expect, this handicap is most serious in thin light-weight synthetic felts.

A primary object of the present invention is provision of dimensionally uniform batts composed of synthetic fibers. An object is improvement in formation of batts on moving collecting surfaces upon which fiber layers are 1 superimposed in batt buildup. Other objects of this invention, together with means and methods for attaining the various objects, will be apparent from the followin description andthe accompanying diagrams.

Figure 1 is an oblique view of apparatus used in practice of the present invention. Figure 2 is a side elevation showing in .detail a portion of the apparatus of Figure l and product being formed by it at a later stage in opera tion. Figure 3 is a schematic side elevation of another embodiment of this invention. Figure 4 is a detail of part of the apparatus of Figure 3 showing also formation of product at a later stage.

In general, the objects of the present invention are accomplished by superimposing non-woven fiber layers and confining each layer in resultingbatt form by contacting the topmost surface with a warp of yarns or similarly suitable flexible, longitudinally continuous structure. The invention comprehends both maintaining the contact between yarn warp and each fibrous layer until completion ofthe batt and, alternatively, discontinuing the contact at the deposition location during superposition of each successive layer, and it contemplates eventual separation of the warp yarns in both cases from the formed batt. The present invention extends to apparatus adapted to this process, such as an endless collecting belt in the form of a loop with means for driving the belt unidirectionally throughout the loop, means for depositing fibers in superimposed layers on the belt, and means for contacting the exposed surface of the outermost fibrous layer with a warp of yarns to confine the fibers on the belt.

Figure 1 shows collecting apron or belt 1, which forms a closed loop about supportingend rollers 2 and 3, lo-

cated directly above and in contact withbelt 5 carried in a loop onrollers 6 and 7, one or more of the rollers connecting with drive means (not shown). Located above the collecting belt at one side is crosser-lapper 10 composed of similarsmall aprons 111 and 12, carried on rollers at opposite ends of each, withweb 13 passing (from a card, garnett, or like source, not shown) between juxtaposed faces of the respective aprons onto the top surface of the collecting belt approximately midway between the ends. Extending transversely of the collecting surface closer to one end ispresser roll 15, over whichwarp yarns 16 pass from reel 17 into contact withfiber layer 18 laid back and forth from edge to edge of the belt.Tape 19 alfixed to the collecting surface holds the end of each warp yarn in place, keeping the unreeling yarn taut about the belt and the intervening layered fiber, which move as a unit in the direction indicated by arrows. During operation of this apparatus the crosser-lapper moves back and forth, depositing a zig-zag layer of fiber where the collecting surface moves toward the presser roll, which itself rotates at the same linear speed as the belt and brings the warp yarns down against the fibers without disturbing them. As the collecting belt proceeds on about the first end roller, where the fiber layer tends to separateand wrinkle, the warp holds the fibers against the belt and prevents them from shifting location, so that when the collecting belt straightens out again the fiber.

layer remains unwrinkled. The belt underlying the collecting belt aids in preventing sagging between the supporting rollers. Each complete circuit of the collecting belt brings on another warp length equivalent to the belt circumference, and the warp previously laid down is sandwiched between the layer covered by it and the layer deposited most recently; thus, viewed from the side, the warp has the configuration of a spiral, instead of a closed loop. Inasmuch as the wrinkling tendency decreases with buildup of successive layers in the batt, application of the confining warp to the surface of the forming batt may be discontinued after several revolutions of the collecting belt, if desired.

Figure Zrepresents the appearance of the edge of the batt during formation atthe location where the warp passes from about the presser roll onto the forming batt.

Shown in addition to the belt and the roll are the deposited fibers, as totally confined lower.layer 21 along with upper layer 22,-which itself has warp superimposed on it only to the left of the nip between roll and fiber layer. Upon fiber deposition to desired depth, the batt is removed conveniently from the belt by slitting from side to side, after which it optionally can be laid out flat, whereupon the left end (though often consisting of more than the illustrated number of layers) will resemble that of the left of this diagram. Easy removal of the warp yarns merely by pulling them out from the end manually or otherwise is readily appreciated. Of course, ribbons of textile or other flexible material (e. g., metal or paper) may. replace these yarns with like effect.

drawal of lengths of warp yarn or the like from the interior of the-batt. As represented in Figure 3, collectingbelt 31 travels aboutend rollers 32 and33 in contact for somewhat under half its length with underlyingbelt 35 carried onrollers 36 and.3 7. Presser rolls 38 and 39 flank the mid-portion of the top'run of the collecting'belt, where crosser-lapper 30deposits fiber web 28. Located above the crosser-lapper are rolls 40 and 41, also extending transverse to the belt surface; warp 26 passes continuously about all the remaining run of the belt but in this top central region extends outward up and over the additional rolls to complete a closed loop of warp yarns. Operation of this apparatus modification differs in Patented Apr. 26, 1960 An embodiment of this invention eliminates the with-.

obvious respect from that described above. Instead of contacting the fiber throughout all rotation of the belt after passing under the presser roll toward which the collecting surface moves from under the crosser-lapper, the warp maintains that contact only until again approaching the fiber-deposition place, whereupon it leaves the belt to return just after the belt receives an additional layer of fiber. This leaves unconfined the layers deposited previously, but only at a location where the fibers exhibit slight tendency to move with respect to the belt or to one another. Figure 4 corresponds for this modification to Figure 2 for that previously given;belt 31 has consolidatedunconfined layers 42 on it to the right ofroll 38 and to the left has confined layers 43 'Withwarp 45 overlying. flexible non-woven material may replace the continuous warp in this modification.

In an example of the use of apparatus of the type shown in Figures 1 and 2 abatt 12 feet long and 30 inches wide was made from about pound of 1 /2 denier, 3-inch fibers composed of a copolymer of 94% polyacrylonitrile and 6% methyl acrylate. The nonwoven web of these fibers was cross-lapped from a garnett onto the collecting belt in 5 complete revolutions of the belt, being confined by a warp composed of half a dozen evenly spaced multifilament yarns of like composition. The batt was cut widthwise and the taped ends of the warp yarns were detached manually, the 12 /2 foot lengths of warp yarn being removed by pulling them lengthwise from the batt. The batt was smooth-surfaced and of constant density and thickness (0.035 inch) throughout; it was transformed into a felt-likeproduct weighing about 5 ounces per square yard by needle-punching, plying,

and shrinking in boiling 26% aqueous ethylene carbonate. This nonfwoven fabric, suitable as a light-weight suiting,

reinforcements for plastic laminates, especially in light:

weight synthetic overlays. Felt-like products composed wholly or in large part of synthetic fibers are highly re-.

organisms, and to filling up with dirt or other foreign If desired, a sheet of woven or suitably substances. Where not objectionable in the product, as in plastic laminates, warp yarns employed to confine the fiber layers during formation of the predecessor batt can be left in as extra reinforcement.

The claimed invention:

l. Process of batt formation comprising continuously superimposing successive non-woven layers of synthetic fibers in the configuration of an endless loop, confining each layer at least at all points deviating -from a horizontal path in the' loop form by contacting the topmost fibrous surface with a warp of yarns running along the loop, and separating the warp from the batt after superposition of the last layer.

2. Apparatus comprising a unidirec'tionally movable conveyor belt passing about end rollers between which the belt extends substantially level, a crosser-lapper located above the topmost surface of the belt, a'presser roll extending substantially the width of the belt close to that surface near the end roller toward which that surface of the belt moves immediately after passage under the crosser-lapper, and a warp of yarns passing between the presser roll and the belt surface and about the end rollers with the belt intervening.

3. The apparatus ofclaim 2 including a presser roll extending substantially the width of the .belt close to the topmost surface of the belt near'the roller away from which that surface moves immediately before passage underneath the crosser-lapper and at least one additional roll located between the two presser rolls and above the sistant to abrasion, to attack by chemicals and micro-" crosser-lapper and adapted to, hold the yarn warp taut in endless form in passage to and from the respective presser rolls and about the belt.

4, in the formation of a fibrous batt by superimposing a plurality of non-woven synthetic fiber layers in the form ofman endless loop, the improvement comprising confining each layer by contact at the topmost surface witha flexible, longitudinally continuous yarn Warp, said yarn warp remaining in contact with each layer throughout deposition of successive layers, cutting the batt loop transversely, and pulling said yarn warp out of said batt as individual lengths equivalent to one circuit about the loop;

References Cited in the file of this patent] UNITED STATES PATENTS"

Images