US 3142611 A
Description (OCR text may contain errors)
y 23, 1954 J. T. MILLS 3,142,611
NON-WOVEN FILE FABRICS AND METHODS OF THEIR MANUFACTURE Filed Dec. 12, 1960 2 Sheets-Sheet 1 I. u I n I l I J. T. MILLS 3,142,611 ABRICS AND METHODS OF THEIR MANUFACTURE July 28, 1964 NON-WOVEN FILE Filed Dec. 12, 1960- 2 Sheets-Sheet 2 United States Patent 3,142,611 NON-WOVEN PILE FABRICS AND METHODS OF THEIR MANUFACTURE .lohn Thompson Mills, Elkins Park, Pa, assignor to Jennings Engineering Company, Philadelphia, Pa. Filed Dec. 12, 1960, Ser. No. 75,281 22 Claims. (Cl. 161-66) The present invention relates to non-woven pile fabrics and to their methods of manufacture, and has for an object the production of pile fabrics of improved quality at high speed and at relatively low cost.
In accordance with the present invention there has been combined the characteristics of certain of the synthetic resins used for the production of the textile material with the characteristics of certain of the thermoplastic resins to produce a non-woven pile fabric characterized by the presence of a plurality of loops of the synthetic resin which has its base loops fusion-bonded to the thermoplastic backing layer. In the preferred form of the invention, the textile material is of nylon, a synthetic linear polyamide. The textile material of which the loops are formed is preferably twisted multiple filament nylon. Nylon has a melting temperature of about 480 F. Polyethylene may be heated well above 480 F. without degradation and may be extruded at temperatures in the range of 600 F.650 F., well below its degradation temperature. Accordingly, there may be achieved a fusion bond or welding of the base loops of the multiple filament nylon to form a non-woven pile fabric and which fusion bonds may be additionally augmented as to strength by reason of shrinkage cooling of the polyethylene backing material in surrounding relation with at least portions of the base loops. The net result is a non-woven fabric in which the strength of the bond is greater than the force required to break the yarn. With the base loops so bonded to the web of polyethylene, it is to be understood that the loops may extend upwardly to the same height to provide a uniform surface or the loops may be of different heights to provide an embossed surface pattern. In both examples, some or all of the loops may be cut or trimmed to provide a surface which is tufted in whole or in part. The thermoplastic web or backing layer may be made thin for flexibility; and where it is desired to heat-shape or to provide contoured stair treads, car mats and the like, the backing layer will be made thicker to provide the needed rigidity. Since the non-woven pile fabric of the present invention has no selvage edges, strips, squares or other geometrical configurations may be laid side-by-side in abutting relation to provide desired patterns in the surface and there may be easily provided wall-to-wall covering unbroken by any visible line of demarcation. Thus, the thermoplastic backing may be butt-welded with such linear welds reenforced if desired by adhesive strips or strips alone may be utilized to join the adjacent sections of the nonwoven fabric without production of any visible seam.
In the preferred form of the invention, the nonwoven fabric is produced by feeding the looped warp strands with their base or root portions of the loops in a plane intersecting the path of a hot plastic web flowing from an extruder. The relative temperatures of the root portions of the loops and the hot plastic web is controlled in relation to their speed of movement in the 'ice region where they meet so that the heat available from the thermoplastic web is adequate to bring the root portions of the loops to their melting temperature to form the foregoing fusion bonds with the material of the plastic Web. At this time or immediately following, there is then applied pressure to force inwardly of the base loops material of the plastic Web, thus partly to enclose each base loop. During this action, the temperature of the plastic material is decreasing, and this cooling may be augmented by a cooling roll to assure shrinkage of the plastic material of the web around and about the root portions to enhance the bonding of the root portions of the loops to the thermoplastic backing layer. As will later be explained, the invention is applicable to thermoplastic backing layers other than polyethylene and to textile materials other than nylon. Where the textile material is wool or cotton which does not have melting temperatures, the shrinkage bond described above suifices to provide adequate strength for highly useful non-woven pile fabrics. As for the thermoplastic materials which are suitable, it is preferred that they comprise polyethylene, mentioned above, though nylon, Delrin, or polypropylene may be utilized. Polyvinyl chloride has been utilized for the production of non-woven pile fabrics where the mechanical bond alone has been relied upon for strength.
For further objects and advantages of the invention, suitable apparatus which may be utilized and for details as to the method of formation of the products, reference is to be had to the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a diagrammatic longitudinal sectional view of an apparatus for performing the method of the present invention to produce a non-woven pile fabric in accordance with the invention;
FIG. 2 is an enlarged fragmentary view of a modification of part of the apparatus shown in FIG. 1;
FIGS. 3 and 4 are respectively sectional views taken on the line 33 and 44 of FIG. 2;
FIG. 5 is an enlarged view of a portion of the nonwoven pile fabric made in accordance with the arrangement of FIG. 1 and illustrating how there has been eliminated undesired grinning;
FIG. 6 is a view showing a fabric with a thick backing layer and preformed to an irregular contour;
FIG. 7 is a transverse sectional view of a modified loop-forming mechanism;
FIG. 8 is an enlarged sectional view taken on the line 77 of FIG. 7; and
FIG. 9 is a longitudinal sectional view of a tufted non-woven pile fabric embodying the invention.
Referring to FIGS. 1-4, there has been illustrated an apparatus or machine for performing the preferred meth- 0d of making the non-woven fabric of this invention. The preferred apparatus is described and claimed in copending application Serial No. 93,611, filed March 6, 1961.
As shown in FIG. 1, textile strands S are drawn from a suitable supply, in the present instance a creel 10: the supply may be in the form of a warp beam if that is preferred. It is desirable that the textile material be 3/ 30s 15 denier, 3 /2" staple, 66 nylon polymer yarn. This is a twisted multiple filament nylon. The strands S are drawn onto a traveling conveyor 11 which in the present instance consists of a plurality of interconnected sections 12 having a number of spaced parallel upstanding blades, bars or rods 14 extending the full width of the apparatus. The strands S are guided into overlying relationship with the blades 14 by a suitable guide roller 15, and then are depressed into the clearance space between the blades 14 by a suitable mans.
In the present instance, such means comprises a roll 16 driven in synchronism with the conveyor 11 and having a plurality of blades 17 projecting radially therefrom and spaced apart a distance corresponding to the spacing between the blades 14 so as to mesh with the latter. The blades 17 of roll 16 form the strand S into the pile loops P, FIG. 2, intermediate the blades 14 and base loops B intermediate the blades 17, the pile loops and the base loops being interconnected by pile legs L. The radius of the roll 16 is sufficiently large to insure that a number of the blades 17 are meshed with the blades 14 at one time so to prevent the pile strand S from being drawn from the previously formed loops and legs rather than from the yarn supply lil. It is understood that in lieu of the loop-forming roll 16, blades or similar loop-forming elements may be vertically reciprocated into and out of the gaps intermediate the upstanding blades 14.
The pile strands being advanced by the conveyor 11 receive a layer of plastic material. To this end, a joining station 31 is positioned to unite a backing layer or web of thermoplastic material with the pile strands. The thermoplastic material is preferably first formed into a uniform film just prior to application to the base loops B. The material at the joining station 31 is first passed through an extruder and die 32 which is heated, as indicated at 33 to form a uniform film which is deposited directly on the base loops B. With the conveyor traveling at 1.08 feet per minute, the plastic being extruded onto the yarn loops in a layer having a thickness of 54 mils and with a melt temperature of 650 F, the web has sufficient heat content to melt or fuse nylon yarn to a depth of over 3.2 mils, in accordance with the coeificient of heat transfer of the two materials. If the plastic layer is increased in thickness to 75 mils, a melt temperature of 600 F. provides sufiicient heat content to cause the fusion to penetrate 3.2 mils into the nylon pile yarn. It has been found that the best union between the yarn and backing is obtained when the penetration of the fusion into the pile yarn is greater than 3 mils (.003").
If the pile yarn is heated prior to the joining operation, the heat content of the plastic layer may be reduced. For example, as shown in FIG. 5, the joining station 31 includes a heater 38 positioned in advance of the extruder 32 to preheat the yarn whereby the heat content of the yarn augments the heat content of the extruded layer which may therefor be reduced in thickness or heated to a lower temperature, or both. For example, a 3 mils penetration of the fusion is obtained with a 54 mil polyethylene layer by preheating the nylon to 200 F. and using a reduced melt temperature of 600 F. Without such preheating, the layer would have to have a thickness of 7S mils.
Instead of increasing the heat content at the joining station by preheating the plastic layer or the thermoplastic pile yarn, the heat may be added directly at the point where the two materials come together as by heater 33.
The welding of the yarn to the backing requires the use of thermoplastic yarn. Although the foregoing examples involve the use of nylon yarn, other thermoplastic yarns may be used. Such yarns may include other synthetic resin yarns, blends of thermoplastic synthetics and natural fibers, as well as natural fibers which have been treated to exhibit thermoplastic qualities. It is only necessary to choose materials whose melting temperatures are below the degradation temperature of the other component. A roll 34 operates to press the material into the interstices between the blades 14. The press roll 34 may be cooled so as to serve as a chill roll which will congeal and harden the plastic material into self-sustaining form. The chill roll 34 may be water-cooled to approximately 50 F. Preferably, the chill roll is positioned immediately adjacent the die so as to immediately press the molten layer into the base loops.
When using nylon staple carpet yarn and polyethylene backing, it has been found possible to obtain a loop anchorage that exceeds the tensile strength of the yarn. In other words, the force required to disengage the base loop of the pile yarn from the backing is greater than the force required to separate the yarn. As a result, when one attempts to pull the yarn away from the backing, the yarn breaks before the base loop disengages. This results from the welding of the yarn to the backing. When the plastic is sufficiently thick and of sufficiently high temperature, there is enough heat content in the plastic layer to raise the temperature of the yarn from room temperature to its melting point in the areas of contact.
The foregoing has been illustrated in FIGS. 2 and 3 where it will be observed that the extruded plastic backing layer C at the joining or welding station directly below and somewhat beyond the extruder die 32 transfers heat to the twisted multiple filament nylon loops to raise a portion of them to the melting temperature to form a fusion bond or weld W between them and the backing material. As soon as the thermoplastic backing C leaves the extruding die 32, its temperature rapidly falls. Accordingly, the die-exit temperature for the backing material will in terms of its speed of extrusion and its thickness be controlled so as to assure that in conjunction with the temperature of the nylon loops, the foregoing welding or fusion bond is accomplished to provide maximum strength in the anchorage of the loops to the backing material. As the thermoplastic backing C and the loops are transported by the conveyor 11, they arrive at the pressure roll 34 which is effective to cause flow of the still plastic backing material around and about the base loops. In this connection, a comparison of the extension of the backing material about the base loops as appearing in FIGS. 2 and 4 will demonstrate the manner in which the backing material surrounds portions of the base loops. Since the temperature has been progressively decreasing and the cooling thereof hastened for modifications where the roll 34 is cooled as described above, there will be assured the shrinkage or formation of a mechanical bond between the backing layer and the nylon loops and which ,is in addition to the fusion bond just described.
While various materials have already been described in respect to the textile material, it is preferred that the thermoplastic backing layer have the property of some shrinkage upon rapid cooling to enhance the effectiveness of the mechanical bond just described. Thus, polyethylene, nylon, Delrin and polypropylene exhibit these properties. Though less desirable, polyvinyl chloride has been utilized.
Referring again to the nylon textile material and the thermoplastic backing layer of polyethylene, it is desirable to maintain the non-woven pile fabric flat or in the planar position in which it is transported by the conveyor until its temperature has been reduced below the memory temperature of that material, that is to say, the temperature reduction should be below that at which thermoplastic material will tend to harden in other than a flat condition. To assure this reduction with a minimum length of conveyor, additional cooling means such as exemplified by blasts of cold air from the cooling device 27 may be utilized.
Where the thickness of the thermoplastic backing layer is of a low order, such for example as 54 mils for the purpose of a non-woven pile fabric of considerable flexibility, it will be desirable to preheat the base loops as for example by a heating means illustrated at 38. By so elevating the temperature of the base loops, the requirement imposed upon the hot extruded backing layer is reduced to a point where it can provide additional heat necessary for melting even though its volume is t3 small by reason of its limited thickness. In this way, higher conveyor speeds may be utilized with the operation of the extruder at preferred temperatures below about 650 F.
Further in accordance with the invention, the preferred polyethylene for the thermoplastic backing layer will be that grade available under the trade name Alathon-l4 which because of its relatively low cost, low density and low melt index appears ideally suited for the manufacture of non-woven pile fabric. Where other polyethylenes, such as that sold under the tradename of Alathon 18 are used, the thickness will be modified to take into account its lower viscosity as compared with Alathon 14. Thus, because the extrusion temperature will be lower, it will be necessary for thin backing layers to preheat the nylon textile material to an adequate degree to assure the fusion bond above described.
Further in accordance with the invention, it has been found that the extrusion of the polyethylene at a temperature within the range above about 480 F. and not substantially exceeding 650 F. produces an unexpected and advantageous property in the end product. More particularly, it is believed that the foregoing treatment, i.e., the various steps performed, results in a slight uninjurious oxidation of the exposed surface of the polyethylene backing layer and thus unexpectedly imparts to it a non-slippery character which is of wholly different order than polyethylene which has not been so treated. The non-slippery character of the exposed surface of the backing layer makes it particularly advantageous for throw rugs and fioor coverings in general since the hazards incident to slippage of rugs in general has been largely, if not wholly, eliminated.
In accordance with the invention, the pile fabric of the present invention may be formed as shown in FIG. 6 to conform to irregular contours such as automobile floors. In order to prevent grinning or appearance of the base layer between the pile projections, continuous pile yarns are employed, forming pile loops on the face of the fabric. The pile yarns are laid-in in laterally abutting relation. The base layer is interlocked with only the outermost portions of the fibrous pile strands S, even when bent outwardly as shown in FIG. 5. It is noted that in the present instance, the contiguous pile strands form a sheet of textile material of undulating form which is united with the base layer only on its undersurface.
For producing the non-woven fabric thus far described, the loop-forming blades of roll 16 are of uniform height. The outer loops P may be cut or sheared to provide a tufted instead of a looped surface. To provide a nonwoven pile fabric having a carved or embossed effect, the blades 16, as shown in FIG. 7, are serrated or formed of varying heights so as to position the pile loops P at varying depths below the base loops B in the plane of the tips of conveyor blades 14.
Also, as shown in FIG. 8, the higher loops P may be severed to form tufts T (see FIG. 9) projecting above the lower loops P. The base loops B of the pile strands S are bonded together as before described by being embedded in a layer C of plastic material which is settable into a self-sustaining layer. Preferably, the set layer C is flexible and resilient so as to conform to the underlying supporting surface (not shown) whereby it may be readily employed as a floor covering for floors and stairs. In the alternative, these fabrics may be pre-formed as shown in FIG. 6 to conform to a selected irregular contour.
In all of the non-woven fabrics herein described, the density of the pile may be changed within wide limits by changing the spacing between the blades 14 or increasing or decreasing the number of strands along the length of the blades. Colored pile patterns may be produced by selectively dyeing the pile strands S in accordance with a predetermined pattern, or by using different 6 colored strands and pressing only selected strands between the blades 14 and floating the non-selected strands over the tips of the blades. The selected strands will therefore form pile and the non-selected strands will be embedded in the base layer to form an elongated base loop or float, as shown at F in FIG. 9, to form a void in the pile surface. By proper selection of pile density and strand thickness, the void formed by floats F will be obscured by the surrounding pile. A preferred arrangement includes 7 ends per inch transversely, and 5 rows per inch longitudinally.
The present invention provides a pile fabric which is highly economical to produce in a single operation. The pile strand S may be standard yarns if desired, but other strand material may be used since it is not necessary to thread the strands through heddle eyes, tuft tubes, tufting needles or the like. For this reason, highly bulked yarns may be employed as well as yarns having limited resistance to wear and limited tensile strength. In lieu of yarns, a web of carded fibers or other textile material may be employed to produce pile in a similar manner. Thus, the invention may permit the use of less expensive textile material in the fabric and utilizes the material to a maximum extent in forming the pile of the fabric.
The base layer C is formed of any suitable thermoplastic material and may provide a fabric structure which is free from possible damage by water or corrosive liquids. Polyethyl plastics have been found to be satisfactory, but other materials of similar characteristics with or without fillers, may be used. The base layer is resistant to aging and flaking or powdering and forms a self-contained in sulating and supporting layer underlying the pile surface. By cooling the material while the layer is in a fiat state on the conveyor, the layer assumes a set which resists curling of the base while the fabric is in use. This is particularly important when the fabric is used as a floor covering since it reduces to a minimum the chance of a person tripping over an upturned edge of the carpet. When it is desired to form an irregularly contoured fabric such as shown in FIG. 6, the fabric is removed from the conveyor while the layer is still slightly soft. It is then put on a forming die and is allowed to assume a set conforming to the die. Thus, by proper selection of the textile material and the backing material, it is possible to make fabrics in accordance with the present invention for installation in locations where fabrics of the prior art were entirely unsuitable. It has been found that by using a smooth chill roll against the polyethylene base material, an extremely smooth undersurface is formed on the fabric. Thus surface because of aforesaid oxidation exhibits highly unexpected slip-resistance when the fabric is laid on a smooth surface, thereby eliminating the requirement for anti-skid devices underlying the fabric.
This application is a continuation-in-part of my copending application Serial No. 70,218, filed November 18, 1960, now abandoned.
It is to be understood that other forms of apparatus may be employed for performing the methods of the present invention and producing the product thereof. It is not intended to limit the invention to such disclosure but changes and modifications may be made therein and thereto within the scope of the following claims.
What is claimed is:
l. A pile fabric comprising an imperforate base layer of thermoplastic material and a pile portion of textile material having a plurality of upstanding pile legs interconnected by base loops, said legs being disposed in a plurality of longitudinally spaced transversely disposed parallel rows and extending freely from said base layer, said textile material comprising thermoplastic yarn, the base loops of said yarn being at least partially embedded in and fused to said base layer for mutual thermal-bond anchorage between the base layer and the upstanding pile legs.
2. A pile fabric according to claim 1 wherein the penetration of the thermal fusion into the yarn loops is at least 3 mils.
3. A non-skid pile fabric comprising an unbacked flexible base layer of thermoplastic material having a smooth oxidized undersurface affording slip-resistance of the fabric, and a pile surface consisting of pile yarns having thermoplastic qualities and formed into a plurality of upstanding pile legs interconnected by base loops engaging the upper surface of said layer, each of said base loops being welded to said upper surface for mutual thermal-bond anchorage between the base layer and the upstanding pile legs.
4. A pile fabric according to claim 3 wherein said base loops are at least partially embedded in said upper surface to provide a mechanical bond supplementing the weld between them and said base layer.
5. A non-woven fabric comprising thermoplastic textile strands and an imperforate thermoplastic backing layer, said fabric being characterized by the interlocking of a plurality of the strands with said layer by mutual thermal-weld connections between portions of said strands and said backing layer and wherein said portions of the strands are embedded in said layer to a depth less than their thickness to provide mechanical bonding supplementing said welded connections.
6. A non-woven pile fabric comprising a textile material of twisted multi-filament nylon and disposed in a plurality of base loops, and a thermoplastic imperforate backing layer of polyethylene, said fabric being characterized by the absence of weft threads and by the welding of a multiplicity of the nylon strands forming portions of each of the base loops together with the upper surface of the polyethylene backing layer.
7. A non-woven pile fabric as in claim 6 in which the undersurface of the polyethylene backing layer is oxidized to impart non-skid properties to the fabric.
8. The non-woven pile fabric of claim 6 in which said polyethylene has a density of the order of 0.914 and a melt-index of about 1.8 to provide a backing characterized by its flexibility and adaptability to uneven surfaces.
9. A non-woven pile fabric comprising a textile material of synthetic resin and disposed in a plurality of base loops, and an imperforate thermoplastic backing layer, said synthetic resin and said thermoplastic backing layer each having a melting temperature below the degradation temperature of the other and both being melted together in the region of the base loops to form thermal-fusion bonds between them and the backing layer.
10. The method of producing a non-woven pile fabric composed of a thermoplastic sheet layer and thermoplastic pile strands, comprising the steps of forming said strands into pile projections having upstanding pile legs terminating at one end at a common level, applying said sheet layer while molten hot to said pile legs at said one end to fuse said applied layer and said legs together in' the areas of contact, and thereafter cooling the same to form a welded interlock therebetween.
11, The method of producing a non-woven pile fabric composed of a thermoplastic sheet layer and thermoplastic strands, comprising the steps of forming said strands into pile projections having upstanding pile legs terminating at one end at a common level, applying said sheet layer while molten hot to said pile legs at said one end to fuse said applied layer and said legs together in the areas of contact, supplying sufiicient pressure to the hot molten layer to force it beyond said fused areas of contact, and thereafter cooling the applied layer and legs to form a combined mechanical and welded interlock therebetween.
12. The method of forming a non-woven fabric comprising the steps of extruding a thermoplastic backing layer of polyethylene for producing in it a molten-state temperature which at a joining station has a predetermined value, advancing to said joining station a nylon textile material, at said joining station bringing together said backing layer and selected portions of said textile material, said temperature of said predetermined value being selected in relation to the thickness of said backing layer to provide a predetermined heat content, and applying the heat from said layer to said nylon textile material to melt at least portions thereof in the areas in contact with said molten backing layer for formation of interfusion bonds.
13. The method of making a non-woven pile fabric from nylon and polyethylene which comprises extruding the polyethylene as a molten sheet at a temperature above the melting point of nylon, and feeding strands of nylon side-by-side into contact with the extruded sheet, a mutual fusion-interlock between the sheet of polyethylene and the nylon strands being effected by the heat content of the molten polyethylene sheet.
14-. The method according to claim 13 wherein the nylon strands are preheated in advance of contact with the sheet to a temperature below the melting temperature of nylon to permit reduction of the thickness of the polyethylene sheeting and yet have heat content sufficient to effect said mutual fusion-interlock and to obtain enhanced flexibility of the fabric.
15. The method according to claim 13 including the step of applying pressure to said molten sheet and melted nylon to form a strong fused interlock therebetween.
16. The method according to claim 15 including the step of chilling said backing layer simultaneously with the application of pressure.
17. A method according to claim 13 in which the outer surface of the polyethylene backing layer is oxidized to impart non-skid properties to the non-woven fabric.
18. The method of forming a non-woven pile fabric 7 comprising the steps of advancing textile material at least in part including thermoplastic strands to a forming station, forming said material into base loops interconnected by pile legs, advancing said formed material to a joining station, continuously extruding a molten layer of thermoplastic material onto said base loops at a temperature above the melting point of said thermoplastic strands and immediately pressing said molten layer into said base loops at said joining station and simultaneously chilling said thermoplastic material to form a self-sustaining fabric composed of the textile material and said thermoplastic layer.
19. A method according to claim 18 wherein said molten thermoplastic layer is heated to a temperature at which its heat content is sufiicient to fuse the textile material at said joining station to a depth of at least 3 mils.
20. A method according to claim 19 wherein said supplying of heat includes preheating said textile material at said joining station.
21. The method of forming a non-woven pile fabric comprising the steps of advancing a textile material having thermoplastic qualities to a forming station, continuously forming said material into base loops interconnected by pile legs, each of said base loops having at least a portion intersecting a common imaginary plane, heating the portions of said base loops in said plane. continuously advancing the formed material to a depositing station, continuously depositing a layer of heated molten thermoplastic material onto said base loops, the heat of said layer and said textile material combining to weld the preheated base loops of said material to the molten layer, and cooling the thermoplastic layer to form a self-sustaining fabric composed of the textile material and the thermoplastic layer.
22. The method according to claim 21 wherein said cooling operation is performed rapidly while the fabric is in a fiat state to cause the layer to assume a set which resists curling.
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