US2742951A - Art of curling or kinking stretched filaments and forming pads therefrom - Google Patents

Description

April 24, 1956 H. MARC ART OF CURLING OR KINKING STRETCHED FILAMENTS AND FORMING PADS THEREFROM 7 Sheets-Sheet 1 Filed March 26 1951 INVENTOR.

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l H F April 24, 1956 H. MARC ART OF CURLING OR KINKING STRETCHED FILAMENTS AND FORMING PADS THEREFROM 7 Sheets-Sheet 2 Filed March 26. 1951 I ll l I I I I I ll llrllll N I N h \M ll'u N BW MN NW N lll HHuHH IN V EN TOR. J'finrz'Marc H. MARC April 24, 1956 2,742,951 ART OF CURLING OR KINKING STRETCHED FILAMENTS AND FORMING PADS THEREFROM 7 Sheets-Sheet 5 Filed March 26, 1951 am w April 24, 1956 H MARC 2,742,951

ART OF CURLING OR KI NKING STRETCHED FILAMENTS AND FORMING PADS THEREFROM nun-as." v IIIIIIIIEA IN V EN TOR. flenrz'jfarc BY DAV Ma x (Z22 ART OF CURLING OR KfNKING STRETCHED FILAMENTS AND FORMING PADS THEREFROM Filed March 26 1951 7 Sheets-Sheet 5 A ril 24. 1956 Filed March 26. 1951 MARC H. ART OF CURLING OR KINKING STRETCHED FILAMENTS AND FORMING PADS THEREF'ROM 7 Sheets-Sheet 6 INVENTOR.

HenrzlZ/arc BY April 24, 1956 H. MARC 2,742,951

ART OF CURLING OR KINKING STRETCHED FILAMENTS AND FORMING PADS THEREFROM Filed March 26, 1951 7 Sheets-Sheet 7 INVENTOR. finrzlflfa TC WM, JM,

United States Patent ART OF CURLING OR KINKING STRETCHED .FILAMENTS AND FORM ING. PADS THERE-1 concerned with the curling or kinking of such filaments, and their treatment to form pads of felts in which the individual curled or kinked filaments are connected from place to place. 7

By stretched filaments are understood in the art certain synthetic filaments made by the extrusion of plastic compositions, followed by hardening of the same and by stretching to the extent of three to ten times the hardened length, or even more. It is assumed that such treatments convert the structure to a form having oriented crystals. ments of this type are those made from nylon and from vinylidene halide polymers, .such as the commercially available vinylidene chloride: vinyl chloride polymer mixture; the commercial materials known asSaran are included in this vinylidene halide polymer group.. For example, a characteristic of a commercial 'vinylidene Y apparatus and process.

2,742,951 Patented Apr. 24,1956

on the accompanying drawings. in which: a 1' 'Figs. 1, la, and lb are successive parts ,of'an'appa'ratus assembly for making the product; essentially in perspective and indicating "in c'onventionalized and diagrammatic form the successive elements and steps employedin the apparatus for the purpose,

*fFig'. 2-is an upright section through the 'kinkin g and cooling chambers, substantially'on line 2'2' of Fig." 3.

- I "'15 T This invention relates to the makingof pads for cush-' ions and like uses, with the pads composed of connected 7 lengths of curled or'kinked stretched filaments: and is Among the commercially available monofila- 5 Figs. 3"and 4are upright sections through one of these chambers, substantially on lines 3 3 and 4-4 of Fig; 2.

Fig. 5 is'an upright section through the'water'spi'aying apparatus, substantially on line 5-}5 of Fig. 2.

Fig. 6 is a side elevation of a-feeding and distributing mechanism. 1 .1 I

Fig. 7 is an upright sectionthrough such a feeding mechanism. I

7 Figs. 8-10 are perspectiveviews of from the cushion pad material. v

The operation by which the stretched filament, originally essentially straight, is given an irregular .form, may be called a kinking or curling, the words defining such a change that the filament no longer has a straight form when in unstressed condition at ordinary temperature, and hereinafter kinking will be employed to refer to product made such operation.

Stretched monofilament fiber material, which may be in continuous or short lengths, is placed on a table MB-l and is fed into a guillotine cutter CT-l, which maybe of ensilage cutting and throwing type, which severs' it into lengths such'as six'to eight'inches long for-use in 'x'i'he preparation of cushion pads for automobiles, by way chloridezvinyl chloride polymer mixture is that of esof example.- The fiber preferably is of diametenfrom 2 to 15 mils, or 30 to 225 deniers, and may consist of various mixtures of fibers in which the range of diametersis limited-so that fine fibersiwill not be unduly softened throughout beforea satisfactory penetration of recovery, such as 250 .to 300 F., by which it tends to revert back to the unstretched form and length ifunrestrained. Other stretched filaments behave in thesame way. T,

A feature of the present invention is the procedure of curling or kinking such stretched filaments by forming a loose, random-arranged pile"of the same, usually in cut lengths thereof, and then passing heating gases 7 through the mass, whereby they become unevenly heated,

with a contraction at one part of the periphery of a filament and not at other parts of its periphery in the. samegeneral radial plane.

A further feature of the invention is the subjection of cut lengths of such filament material to irregular and unilateral heating, wherebya highly heated portion shortens whereas a less heatedportion remains essentially at the original length as when introduced to the operation, and then the characteristic is fixed by a rapid cooling operation.

A further feature of the invention is that of a procedure in which cut lengths of stretched filaments are subjected to irregular and highly localized heatings to above the temperature of plastic recovery, followed by a fixing of the material in its curled or kinked forms: these curled or kinked lengths are mixed and distributed as a mass which is given a coating, for the individual fibers, of a material which can produce local bonding, and

' finally the coated mass is subjected to an operation for heat into the coarser fibers has occurred. Thus, a range of about 2 mils in'diameter is desirable for fibers of to 225 deniers, and a correspondingly lesser range when the fibers are smaller than 105 deniers. Thus, a mixture'of fibers of 105 to deniers can be employed. The feasible range is determinedby the ratiogof'niass to surface area and by the heat conduction and softening range of the specific material. In the above ranges, the largest filaments are notover about 28% greater-in diameter than the smallest ones.

The cutlengths are delivered 'througha duct 10 which maybe of any desired length, and are then delivered by a fan F-l and duct ll into a first Bramwellfeeder BF-1. The material moves from the'feed box of the feeder BF-l and is distributed by this feeder onto a continuous metalmesh belt B-1 which moves around the end turning'rollers 12,13. The purpose of the successive ha'ndlingby cutters, throwers, fans and feeders is to separate thepieces from one another. The belt B-l moves the deposited mass thereon through two separated chambers C O-1 and CO-2. These chambers have casings through which the flights of the belt B-1 move. I

The chambers 00-1 and C O-2 maybe connected as a unit as indicated in Figs. 2 to 5.

Each chamber has end, side,.bottom and top walls 80, 81, 82, 83 which may be of insulating structure. Upright baflle walls 85, 86 are provided, essentially parallel to the direction of movement of the conveyor B 1: these walls have projections on which edges of thej conveyor B'- 1;

conveyor B-l is also supported 'by a flangeonthe'ba'ifie 3 8 and by an angle iron 89. Beneath it may be positioned n n l t n l to a i xces i di e ran fer f heat from the hot lower part of the chamber. A gas burner 92 can deliver hot gases into a sleeve 93, carrying steam formed by the combustion or into which steam may be injected through the pipe 93a: itis preferred to maintain a wet steam condition, and a waterpan WP may be present in the chamber. These gases pass in the direction shown by the arrows to a circulating blower 95 which causes them to move upwardly in the space between the bafile 85 and the adjacent side Wall 81, and then downwardly (Fig. 3) through the mass M of fibers on the upper flight of conveyor B1, passing through the perforated conveyor, and then following the further course as indicated by arrows in Fig. 3, in part returning in a circulation, and in part passing to the outlet 97 which may be exhausted by a blower 98. l l

The first chamber CO-1, when working on finer sizes of filaments, may have (Fig. 3) an upright transverse partition 85 (Fig. 2) and the longitudinal baffle 85 extended to the top 83 while leaving a gap 85x beneath the upper flight of the conveyor B-l. The bathe 86 is also continued downward to the pan 87: and has a restricted top opening to the chamber space which leads downward to the lowermost chamber. This provides a reverse movement for a part of the circulating hot gases, so that they move relatively upward through the mass M after the latter has had a primary heating and kinking effect produced therein by the downward flow described for Fig. 3. In this way a better kinking effect, through the mass, is obtained in some instances.

It will be understood that when heating is being conducted in the chamber section, the gas burner 92 is lit and operating, and hot air is thus being circulated onto and through the mass M. When the chamber section is being used for cooling to below hot-gas temperatures, the gas burner 92 is shut off, and cool outside air is permitted to enter and be circulated, being drawn off by the exhaust fan 98.

In Fig. 5, the upper flight of the conveyor B1, with the mass M thereon, is shown as passing through an opening 101 in a chamber end wall 80. A valved water supply pipe 102 extends across the conveyor and has nozzles through which jets of cooling water may be directed downwardly upon the mass M. A catchscreen 103 is located beneath the upper flight of conveyor B-l to collect any fibers which fall therefrom: and a sump pan 104 is mounted beneath the screen 103, and may be provided with a drain hose 105 through which excess water may be withdrawn. The lower or return flight of conveyor B-l is preferably located within an enclosing tubular structure 107 which extends from one oven to the other. The drive pulleys 110 for the blowers 95 may be located between the chambers.

The chamber CO-l is heated by hot gases so that the cut lengths of monofilament on the belt 3-1 are heated superficially to a temperature of 260 to 310 F. for an illustrative employment with vinylidene chloride filament material. It is preferred to introduce wet steam at atmospheric pressure with the air, to serve as a surface-moistening or anti-sticking agent and to increase the rate of heat transfer to the fibers. As a specific example with stretched vinylidene chloride polymer filament, the chamber C O1 can have a length of about six feet, and the belt B-1 may move at the speed of about one foot per second, that is, each fiber is exposed for a contact time of about six seconds: the pile of filaments deposited on a belt B-l having a width of about 36 inches, by the feeder BF-l, may be about one-fourth to one-half inch. Under these conditions, the heated gases moving through the mass M and the belt B-1, which essentially extends from side to side of the chamber CO-l, act through the conductive metal of the belt and also directly to cause highly localized beatings of the fibers as they lay in ran dom positions on the belt and upon one another, so that each fiber is heated at some points, and is essentially without heating to the stated high temperature at other and adjacent points: e. g. at crossing points, the fibers protect one another from heating by diverting the gas flow. Particularly, each fiber receives a highly variable heating effeet at each radial plane therethrough, so that at one side it contracts while at the opposed side no such tendency occurs. Furthermore, the heat transmission of the fibers is low, so that the heat which is delivered against the fiber at one point is essentially active at that point only, and does not penetrate through the diameter of the individual fibers during the course of its passage through the chamber CO-1. As a result, the fibers kink in a highly irregular manner in the chamber CO-l and, in actual practice, the fibers twist and move individually of one another, under the contraction effects, so that there is no repetition or regularity in the heating and kinking of these fibers.

As the belt B-1 continues in its movement, it carries the overlying mass of kinked fibers out of the chamber CO4 and beneath a water spray WS-l which is projected down upon all of the fibers, and rapidly brings their temperature downward to around 200 F. or below. The effect of this is to immediately fix the shape and form of the individual fibers, and stop any action toward excessive contraction of the fibers or toward fusion by which sticking or welding may result.

The wetted mass now continues into the second chamber CO-Z, which is a drying oven and is maintained at a temperature below 212 F., for example. This chamber has a length of about six feet, and is provided with ducts 14, 15 by which hot or cold gases may be dclivered into the chamber CO-Z to control and maintain its temperature. Thus, when the cooling spray WS-l is so adjusted as to bring the temperature down to 200 F., it is customary to operate the ducts 15 for further reduction'of the temperature of the individual fibers: whereas when the cooling effect is greater, and more water may be present in the mass, wherewith the temperature falls below 200 F., such as a temperature of F., it is customary to employ hotter air from the duct 14, to make sure of the evaporation of the water from the mass, before it is given further handling treatment. A further desirable control in the process and apparatus is that of having the minimum temperature of the continuous belt B-l very little below 200", so that this belt requires only a minor warm-up time as it enters the first chamber CO-l. The cooling occurring in the chamber CO-2 provides at least a superficial cooling throughout the fibers, so that they can be removed by the doffer roll DR of soft fibers, which serves to remove the kinked fibers from the mesh belt B-1; and this doffing can be accomplished without re-straightening the individual fibers of the mass.

In the illustrated arrangement, the fibers are brought to a temperature of about 200 before they are discharged from the belt B-1, in part by gravity and in part by the doffer roll; DR, as the belt B-l leaves the second chamber CO-2 and moves around the turning pulley 13. The mass is delivered into the hopper 17 sometimes as a continuous felting, and sometimes as pieces of greater or lesser lengths and of various shapes, along with some individual fibers which have been stripped by the doffer roll DR. From the hopper 17, the material is taken up by a canvas belt B-2 which leads it upwardly and delivers it onto a further horizontal canvas belt B3, from which the material is delivered to a Bramwell feeder for disintegrating the material and depositing the individual fibers in the form of a mass which can be handled for further disintegration and distribution. Thus, the Bramwell feeder BF-2 disintegrates the material coming from the belt B3 and delivers it to the canvas belt B-4, and this belt in turn passes it in succession beneath theBramwell feeders BF-3 and BF-4,

which may be fed with scraps obtained from the final cutting-operation, whereby the net loss of input material is reduced. I

Commercial Bramwell feeder structures, as employed on'straight fibers such as cotton, may be utilized, but

it. is necessary to. operate them at a much lower speed than employed in cotton service, so that the massesof I tangled and kinked fibers are pulled apart gently instead'of being torn violently, to avoid a condition by which the feeder pullers would tend to accumulate fibers without discharging then i, even to a stag e where the mass may bind the high's eed roller to the stationary frame structure.

The loosely felted material is then deposited in, a hopper 18 by the feeder BF.4, from which it is taken by the elevating belt B-5, which may be of canvas, and delivered into the "final Bramwell :feeder BF-S, by which it is again separated and intermixed, and deposited in the form of loosely piled fibers on a delivery belt B4. At

this point, the mass can be'inspected, to determine that it is' of uniform thickness and density and, if any serious holes are found therein, an operator can deposit amass of the picked material at such a-hole: in normal and regular operation this is not required.

From this belt B-6, the material is delivered onto a sprayer belt ,B-7 which moves over the turning pulleys or rollers '22, 23, and passes through a first spraying chamber SB1 in which by a transversely reciprocating nozzle 19 it is given a spray of a bonding composition. The bonding composition enters the mass, and with preferred compositions'is brought to crossing points of the filaments by flow and capillary action.

The belt B-7 carries the sprayed mass forward through the oven OV-l, having a heater H-1 and a duct 21 from the heater to points beneath the Upperflight of belt B-7. The vehicle of the bonding composition is eliminated in the oven OV-l; and the mass is then delivered bythe belt B-7 over its' turning roller 22 onto the lower belt'B-S, the mass being reversed or, turned upside down during this transfer operation, butstill retainirig essentially a coherent 'form due to the interlockingj 'of the kinked filaments The; mass of deposited fibers, with latex thereon, is not ofuniform consistency as the latex deposit does not penetrate consistently through the thickness of the matted felt.

fThe belt B-8 carries the material back beneath the oven OV-1 and the first spraying apparatus SB1, and

through a second spraying apparatusSB-Z, where bond- I ingcomposition isagain sprayed thereon, but now from the opposite side due to the reversal. The belt B3' thendelivers the loosely deposited, but how individually coated, mass of fibers onto a further metal-mesh belt B 9- which travels around the end turning rollers 27, 28 and carries the mass through a chamber OV 1a in which the water vehicle of this second sprayed coating is dried away: and thence the belt 13-9 carries the material forward and beneath an upper belt B- "which moves about the turning rollers 29, 30, and also has. pressure rollers 32 distributed along its length, to prevent undesired and excessive upward movement of the lower flight of this upper belt B-10. Similarly, pressure rollers 33 are employed for the upper or conveying flight of the belt 13-9. The rollers 29, 30, 32 are preferably mounted on a frame (Fig. 11) which can be adjusted in height and downward pressure thereby exerted upon the mass which is' traveling on the upper flight of the belt B-9. It is preferred, in present practice, to have the pressure upon the mass around 25 to 50 pounds per square inch under the stated illustrative conditions, wherewith the mass which was originally about two and one-half inches thick at, the outlet of the feeder BF-S, is compressed downward to a thickness of about one and one-half inches; With finer sizes, lesser pressures may be employed: but it has been found undesirable to use higher pressures than, say, 200 pounds per square inch, with the coarsest stretched filaments used as a random mass.

Under this condition of pressure, between the two belts of metal-mesh or other reticulate material, the mass cons tinues forward through a heater H-2 and an oven sec tion OV -2, in which the temperature is' raisedto 220 to 240- F., that is, a temperature adequate 'to accomplish the curing of the rubber particles delivered onto the individual fibers from the spraying chambers SB-l, SB-Z, but below thetemperature at which any significant softening of the individual fibers may occur...

As a result, the individual fibers are brought into I cooled toa temperature at which the bonds are stable.

Thereafter the compression pressure is removed, and the mass is thenfdelivered by the belts B-9, B-10 onto a delivery belt or platform B1-1,' passing beneath a talcapplying apparatus TM 2 which is'supplied with talc powder from ahopper and blower TM1. This talc serves to prevent any prevailing tackiness of the cured rubber composition flOlIL causing undesired sticking. Unconsumed talc is recovered to a hopper TM-3.

The mass can then be carried forward beneath a cutting knife 40 by which the material, which theretofore has existed as an essentially continuous length from the feeder BF-Sto the knife 40, can be cut into proper lengths to form'the cushion pads. The scrap may be returned to the 'feeders BF-2a and. BF-Zb for reincorporation.

- The speed of transit of the material through the several zones, the length of these-zones, and the temperatureof the gases and material'inthese zones are interrelated, and in .turn arerelatedtothe sectional shape and diameter of the filaments, the, composition of the fialrnents in determining thesoftening and fushion points, and the heat conductivity .of the;r'naterial. For exam; pie, with the illustrative 'vinylidene chloride polymer, a speed of belt B-1 of one foot per second or roughly sixty, feet per minute, will produce a very satisfactory curling and kinking of fibers in the range of 10 to 12 mils, with atemperature of the gases and steam of 285 F. Filaments around 5 mils demonstrate some caking, but with such. it is preferred to increase the gas temperature or to decrease the belt speed for a given length of softening oven. With fibers in the 4 to 5 mils range, the softening is excessive, and some fibers lose shape andstick to the belt under the first stated conditions: and correspondingly the belt speed should be increased or the temperature reduced; for example, a temperature of 250 .maybe employed for fibers, at

'2 to 3 mils diameter, about 285 .for 10' to 12 mils fibers, and 310 to 320 for 15 mils fibers. The stated polymer has a thermo-conductivity of the order of 2.2 l0- vcal./sec./cm. C./cm., and thus a high superficial temperature, produced by a high gas temperature, requires a greater time for satisfactory softening of 'a coarse fiber than for a fine fiber, noting that the fibers originally enter at essentially room temperature, and that the smaller fibers have a greater relative varea per volume than the larger fibers. V

The purpose of the feeding and distributing mechanisms is to separate the fibers from one another and to provide a uniform deposit of individual fibers upon the respective conveyor. Commercially available. types of structures can be employed for this purpose, and the following conventionalized description is of a commercial feeder and distributor of the so-called Bramwell'type.

As shown in Figs. 6 and 7, the mechanism has a general housing including side plates which at the bottom provide an open-top receiving box 151 in which is located a conveying belt 152 which is advanced by the driven end roller 153. The material upon the belt 152 is brought adjacent to the so-called spike apron 154 which engages the fibers and carries them in a generally upward direction. This apron is endless and moves about the idler rollers 155, 156 and is moved by the upper driven roller 157. Support rollers 156a may be provided along its length. As the fibers are carried over the upper roller 157, they come into the path of operation of the doffer roll 158 which engages them and disintegrates clumps, projecting the individual fibers in a general downward direction as indicated by the arrows 159. A hood 160 may be used, to confine the'fibers to a general path. In Fig; 6, a driving system is shown in which a main driven shaft 163 has a sprocket for a chain 164 for driving a sprocket on the shaft 165 for the conveyor roll 153. The shaft 165 also has a sprocket for the chain 167 which engages the sprocket 168 on the shaft 169. The shaft 169 has a sprocket 170 by which its acts through chain 171 to drive the sprocket 172 on the shaft 173 of the upper apron roller 157. A belt 175 connects the pulley 176 on the shaft 177 of the doffer roll 158 with the pulley 178 on the main power shaft 163.

The employment of successive feeding and distributing devices assures uniformity in the final product. A characteristic of the feeders is that they are most effective in providing a uniform layer of material when they are operating upon fibers within a close range of diameter, length, and conformation: and their effectiveness also frequently depends upon the thickness of the deposit being made by the individual feeder. This is particularly true where the feeders and distributors are being employed also for breaking up semi-coherent masses of tangled fibers, as is the case for the feeder BF-2, which serves for disintegrating the material and then depositing the disintegrated fibers upon the belt B-4.

While the above operation has been described with employment of a latex, such as a water-dispersed oilresistant natural or synthetic rubber composition including a vulcanizing agent, it is feasible to employ other bonding materials. In general, elastomers may be used, such as oxidizable oil, blown asphalt, and plasticized resins including vinylidene chloride and linear polyamide polymers themselves. For example, boiled linseed oil, made up as an emulsion, may be used in the sprayer chambers. A blown asphalt having a softening point of 180 to 220 F., made up as a suspension in water, can be utilized. The commercially available latex containing as solids a polymer with 95% of vinylidene chloride and 5% of vinyl chloride, and adjusted by plasticizer to a fluid point below the softening range of the stretched filament material itself, is useful. In general, the bonding agent can be selected from emulsions, solutions, or solids heated above the softening points thereof, in each of which the effective element is a substance which is cohesive and exhibits elasticity over the normal range of atmospheric temperatures and is essentially free of deterioration under ordinary atmospheric conditions, and more specifically under the conditions to which an article comprising the selected stretched filament materials may be made.

The foregoing apparatus and procedure has been set out by way of example of preparation of a continuous length of cushion pad material having a randomly felted mass of individually kinked stretched filaments, these filaments being interconnected at points of contact and being individually under initial stress in the pad, due to the curing of the bonding regions while the pad is under compression.

The apparatus and procedure have been described with respect to a presently preferred form of actual practice,

in which the cushion pad is made of vinylidene chloride stretched filaments of 15 mils diameter bonded by cured latex composition and having a final thickness of about 1 inch. When a greater thickness of pad material is desired, several plies may be connected together by a light coating of the same latex composition at the surfaces to be abutted, followed by compressing and curing under pressure.

Such cushion pads are described and claimed in my copending application, Serial No. 528,338, filed August 15, 1955; and are here illustrated as useful employments of the method and apparatus herein claimed. As indicated above, it is also feasible to prepare cushion pad material of other stretched filaments, and of filaments of other diameters. A particularly advantageous structure can be made up by preparing a layer of the above-indicated 15 mils vinylidene chloride stretched filaments, bonded into a cushion mass having a thickness of about 1 inch in cured and cooled condition: and then providing surface layers each having a thickness of about of an inch and formed from vinylidene chloride stretched filaments of 5 mils diameter: the three thicknesses are bonded by applying latex composition, and curing while holding the parts together under pressure: the product is a reversible cushion pad, having the desirable attributes that the outer layers of finer filaments yield more readily and establish a general conformation to the body being brought thereon, and finally the thicker central mass yields more as a unit than locally and hence the cushion pad tends to conform itself to the body and then yields over the general area of contact. Such a pad structure is indicated in Fig. 8 where the upper and lower layers 120, 121 are of finer filament stock than the middle layer 122.

Another desirable form of practice, for a one-sided or non-reversible cushion is to provide the layer of successively thicker stretched filament stock, as indicated in Fig. 9, for example, in which the lower layer 125 is about 1 inch thick and formed as described above from vinylidene chloride stretched filaments having a stretched diameter of 15 mils. The next higher layer 126 is an inch thick and similarly formed of vinylidene chloride stretched filaments having a stretched diameter of 10 mils; while the topmost layer 127 is an inch thick and of such filaments having a stretched diameter of 5 mils. This type of cushion pad likewise conforms rapidly to the body shape, and then successively greater resistance is built up over the general area of contact: so that the actual body weight is absorbed over the larger area and with essentially a uniform pressure in pounds per square inch per unit area of exposure.

A desirable form for a mattress or couch pad is shown in Fig. 10, in which the lower layers 130, 131 are each 1 inch thick in the stressed normal condition and formed of 15 mils fibers: while the upper layer 132 is of 10 mils It is also feasible to form such cushion pads as connected structures with their coverings. Thus, in Fig. 10, parts of the pad are shown as covered by woven vinylidene fabric 133, which can be secured in place by applying latex bonding composition to the pad surface and to the inner surface of the covering, pressing into firm contact over areas of the top and bottom, and curing. This produces a structure which has, for example, all of the virtues of resistance to atmospheric and other infiuences which are exhibited by the pad material itself: and the outer covering also assists in maintaining the individual filaments in position. Likewise, cushions may be made from one or more layers of connected or disconnected material made as above, and enclosed within a woven fabric of like stretched filament material surrounding but not adhesively connected to the pad material.

Pads and mattresses so formed rely upon the springiness of .the bonded and connected fibers, in lieu of the presence of air-filled cushion cells as insponge rubber.

Accordingly, the springiness is essentially constant over a wide range of temperatures: and there is at all times without escape from within, the mass;

, 'I claimz,

of the piecesoverlie other pieces at randomangles. and 1 points, passing a moisture-saturated current of hot gas therethrough, the temperature of the gas being above the initial softening temperature of the'filament material and below the temperature of chemical degradation thereof and beingeifective in the absenceof wetting or solvent agents in the material to"provoke shrinkage of the stretched material, terminating said gas passage after heat penetration into thepieces has occurred at unsupported points thereof/to the extent of producing a unilateral and random surface relaxation of the stretched condition and prior to total peripheral surface relaxation at such points of a majority of the fibers'and essentially prior to fushion of any of the pieces and prior to cohesion thereof, thereupon quickly cooling the mass to prevent further action by heat on'the pieces, thereafterdisintegrating the mass essentially to separation of each individual curled piece from the others, redepositing the piecesto form a pad, and incorporating a bonding material for joining the pieces at crossing points thereof.

2. The method of forming a coherent cushion pad, as in claim 1, and in which the bonding material is incorporated by spraying the pad at both sides with a waterborne bonding material, curable at a temperature below that of relaxation of the stretched condition, and thereafter drying the Water; and wherein thereafter the pad is compressed to thickness less-than half, the bonding material'is cured by heating while the pad is so compressed, the pad is cooled essentially to room temperature, and

only thereafter the compression pressure'is released.

3. The method as in claim-2, in which the pad de' posited as a felt in the horizontal plan and in which the pad is sprayed successively at its opposite sides prior to the curing, with, the step of turning the pad upside down between the sprayings. j I I 4. The method as in-claim 2, in which the pad is deposited as a continuous web of felt in a horizontal plane, and in which the pad isspraye'd successively at its opposite'sides prior to the curing, with the step of turning the web upside down between the sprayings and returning it beneath said plane on its way to the second spraying step.

5. The method of forming a cushion pad from stretched filaments, which consists of randomly depositing cut pieces of the filaments whereby some of the pieces overlie other pieces at random angles and points, passing a current of hot gas therethrough, the temperature of, the gas being above the initial softening point of the'filament material, terminating said gas passage after random unilateral surface relaxation of the stretched condition has occurred at unsupported points of the pieces and prior to total peripheral relaxation at a majority of such points, quickly cooling the random relaxed and curledrnass, disintegrating the same intoindividual fibersand redepositing to form a pad, applying a water-borne bonding ma-v terial curable at a temperature below that of relaxation of the stretched condition and in a quantity to provide accumulations thereof at crossing points of the pieces while leaving the general mass open and free for gas' flow, compressing the pad, heating and thereby drying and then curing the bonding materi-al, and cooling the pad before releasing the pressure. 7

.6. The method of forming a cushion pad from stretched filaments, which consists of randomly depositing cut pieces of the filaments whereby some of the pieces overlie other a thorough ventilation, and dust is not trapped tand held pieces at random angles and points, passing a current Ofhot gas therethrough, the temperature ofthe gas beingv above the initial softening point of the filament material, terminating said gas passage after random unilateral surface' relaxatio'n of the stretched condition has occurred at unsupported points of the pieces and prior to total peripheral relaxation atamajority of such points, quickly cooling the random relaxed andcurled mass, disintegrating the same into individwalfibers and redepositing to form a pad, applying a bonding material dispersed in a volatile vehicle in a quantity to provide accumulations thereof at crossing points of the pieces while leaving the general mass open and free for gas flow, compressing the pad, heating and thereby drying and setting the bonding' material, and cool-ing the pad before releasing the pressure.

.7. The method of forming a cushion pad from stretched filaments, which consists of randomly depositing cut pieces of the filaments as a loose mass upon a perforated surface whereby some of the pieces overlie other piecesat random angles and points, passing a moisture saturated current of hot gas therethrough, the temperature of the gas being above {the initial softening temperature of the filament material and below the temperature of chemical degradation thereof and being effective in the absence of wetting or solvent agents in the material to provoke shrinkage of the stretched material, permitting the individual filaments to move in response to the heating, terminating said gas passage after heat penetration into the pieces has occurred at unsupported points thereof to the extent of producing a unilateral and random surface relaxation of the stretched condition and prior to total peripheral surface relaxation at such points of a majority of the fibers and essentially prior to fusion of any of the pieces and prior to cohesion thereof, thereupon quickly cooling the mass to prevent further action by heat on thepieces, thereafter disintegrating the .mass essentially to separationof each individual curled piece from the others, redepositiug the pieces to form a pad, and incorporating a bonding material for joining the pieces at crossing points thereof.

,8. An apparatus for forming a coherent cushionpad,

comprising first and second chambers and conveyor means for moving a mass successively through the chambers,

a feederfor distributing cut lengths of stretched mono filaments upon said means prior to its entry into the first T chamber, gas circulating and heat-ing means in said first chamber, means for moistening the atmosphere in said first chamber, walls included in'saidfirst chamber for causinghot moist gas at a temperature above the softening point to move through the mass of filaments on said conveyor means, water spraying devices located between said chambers for delivering 'water upon the hot mass exiting from the first chamber, means for circulating a I drying gas in saidsecond chamber and through the mass travelling therethrough, a conveyor belt, a second feeder for receiving the mass from the second chamber and for disintegrating the same and delivering the filaments thereof to said conveyor belt, and means for introducing a bonding material to the filaments for joining the same at crossing points thereof. V

9. The method of forming a cushion pad from stretched filaments, which comprises selecting a group of stretched filaments of vinylidene halide polymer within the range of 2 to 15 mils diameter, the selected group having the largest filaments not over about 28% greater in diameter than the smallest filaments, cutting the filamentsof the group to lengths not exceeding eight inches, randomly depositing the cut pieces of the filaments upon a perforated surface whereby some of the pieces overlie other pieces at random angles and points to form a mass, having a substantially uniform thickness of A to /2 inch, preparing a moisture-saturated gas at a temperature of 250 to 320 degrees F., passing the moisture-saturated current of hot gas through the surface andthe deposited mass thereon for a contact time of about 6 seconds, spraying the mass with water for thereby effecting a quick cooling thereof to a temperature not over 200 degrees F. while on said surface, disintegrating the mass, redepositing the pieces to form a pad, and incorporating a bonding material for joining the pieces at crossing points thereof.

10. The method of forming a cushion pad from stretched vinylidene halide polymer filaments, which comprises randomly depositing cut pieces of such filaments having diameters of 105 to 125 deniers upon a perforated surface whereby some of the pieces overlie other pieces at random angles and points to form a mass having a substantially uniform thickness of A to /2 inch, passing a moisture-saturated current of hot gas at a tempera? ture of 260 to 3l0 degrees F. through the surface and the deposited mass thereon, spraying the mass with water after unilateral surface relaxation of the stretched condition has occurred at unsupported points of the pieces and prior to total peripheral relaxation at a majority of such points, for thereby effecting a quick cooling thereof to a temperature not over 200 degrees F. while on said surface, disintegrating the mass, reds-positing the pieces to form a pad, and incorporating a bonding material for joining the pieces at crossing points thereof.

1]. An apparatus for forming a cushion pad frorn stretched filaments,v comprising a structure providing a perforated surface, means for randomly depositing cut pieces of the filaments upon the perforated surface whereby some of the pieces overlie other pieces at random angles and points to form a mass, means for supplying a moisture-saturated hot gas at a temperature above the initial softening temperature of the filament material and below the temperature of chemical degradation thereof,

means for passing a current of said hot gas through the surface and the deposited mass thereon, means for spraying the mass with water for thereby effecting a quick cooling thereof while on said surface, means for disintegrating tnc mass and redepositing the pieces to form a pad, and means for introducing a bonding material to the filaments for joining the same at crossing points thereof.

12. An apparatus for forming a cushion pad from stretched filaments, comprising a first traveling conveyor having a perforated surface, a first feeder for randomly depositing cut lengths of the filaments upon said first conveyor, means for supolying a moisture-saturated current of hot gas at a temperature above the initial softening temperature of the filament material and below the temperature of chemical degradation thereof, means for passing said hot gas through the mass on the aforesaid perforated surface, means for spraying the mass on said surface with water for thereby effecting a quick cooling thereof, a second traveling conveyor, a second feeder for receiving the mass from the first conveyor and disintegrating the same and depositing the disintegrated curled pieces upon the said second conveyor to form a pad thereon, and means for introducing a bonding material to the filaments for joining the same at crossing points thereof.

13. The method of forming a mass of kinked filaments from stretched filament material, which comprises randomly depositing cut pieces of the filament material upon a perforated surface whereby some of the pieces overlie other pieces at random angles and points, passing a moisture-saturated current of hot gas therethrough, the temperature of the gas being above the initial softening temperature of the filament material and below the temper-attire of chemical degradation thereof and being effective in the absence of wetting or solvent agents in the material to provoke shrinkage of the stretched material, terminating said gas passage after heat penetration into the pieces has occurred at unsupported points thereof to the extent of producing a unilateral and random surface relaxation of the stretched condition and prior to total peripheral surface relaxation at such points of a majority of the fibers and essentially prior to fusion of any of the pieces and prior to cohesion thereof, thereupon quickly cooling the mass to prevent further action by heat on the pieces, thereafter disintegrating the mass essentially to separation of each individual curled piece from the others, and redepositing the pieces to form a mass of essentially uniform thickness and density.

14. The method of forming a mass of kinked filaments from stretched filament material, which comprises randomly depositing cut pieces of the filament material upon a perforated surface whereby some of the pieces overlie other pieces at random angles and points, passing a moisture-saturated current of hot gas therethrough, the temperature of the gas being above the initial softening temperature of the filament material and below the temperature of chemical degradation thereof and being effective in the absence of Wetting or solvent agents in the material to provoke shrinkage of the stretched material, terminating said gas passage after heat penetration into the pieces has occurred at unsupported points thereof to the extent of producing a unilateral and random surface relaxation of the stretched condition and prior to total peripheral surface relaxation at such points of a majority of the fibers and essentially prior to fusion of any of the pieces and prior to cohesion thereof, thereupon spraying water and thereby quickly cooling the mass to prevent further action by heat on the pieces, thereafter disintegrating the mass essentially to separation of each individual curled pieces from the others, and redepositing the pieces to form a pad.

15. An apparatus for forming a mass of kinked filaments from stretched filament material, comprising first and second chambers and conveyor means for moving a mass successively through the chambers, a feeder for distributing cut lengths of stretched monofilaments upon said means prior to its entry into the first chamber, gas circulating and heating means in said first chamber, means for moistening the atmosphere in said first chamber, walls included in said first chamber for causing hot moist gas at a temperature above the softening point to move through the mass of filaments on said conveyor means, water spraying devices located between said chambers for delivering water upon the hot mess exiting from the first chamber, means for circulating a drying gas in said second chamber and through the mass travelling therethrough, a conveyor belt, and a second feeder for receiving the mass from the second chamber and for disintegrating the same and delivering the filaments thereof to said conveyor belt as a mass of essentially uniform thickness and density.

16. The method of forming a cushion pad, which comprises randomly depositing randomly kinked and curled pieces of filament material upon a surface to provide a mass of essentially uniform thickness and density, applying at the top of the mass a bonding material curable at a temperature below that of relaxation of the pieces and in a quantity to provide accumulations thereof at crossing points of the pieces in the region at and below the top thereof while leaving the general mass open and free for gas flow therethrough, compressing the mass, heating and thereby drying and then curing the bonding material while the mass is compressed and at a temperature below that of relaxation of the pieces, cooling the pad, and thereafter releasing the pressure.

17. The method of forming a cushion pad, which comprises randomly depositing randomly kinked and curled pieces of stretched filament material upon a sur face to provide a mass of essentially uniform thickness and density, spraying upon the mass a water-borne bonding material curable at a temperature below that of relaxation of the pieces and in a quantity to provide accumulations thereof at crossing points of the pieces in the region at and below the top thereof while leaving the general mass open and free for gas flow therethrough, turning the mass upside down and placing it upon a surface, spraying 13 upon the top of the turned mass a further quantity of such bonding material in a quantity to provide accumulations thereof at crossing points of the pieces in the region at and below the top of the turned mass while leaving the general mass open and free for gas flow therethrough, compressing the mass between perforated surfaces, passing through the perforated surfaces and the compressed mass a heated gas at a temperature. for curing the bonding material and below the temperature or relaxation of the pieces, and thereby drying and then curing the bonding material,

and cooling the pad, and thereafter releasing the pressure.

References Cited in the file ofthis patent UNITED STATES PATENTS Miles Apr. 23, Dreyfus July 23, Rugeley Aug. 24, Robbins. June 5, Hlavaty 1; Nov. 16, Heiuo Jan. 3, Joa June 6, Von Kohorn et al.' Apr. 10, Cremer et a1. Sept. 18, Talalay et a1. Dec. 25,

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