US3836416A

US3836416A - Non woven thermoplastic fabric

Info

Publication number: US3836416A
Authority: US
Inventors: R Ropiequet
Original assignee: Alta Industries Inc
Current assignee: Alta Industries Inc
Priority date: 1970-01-29
Filing date: 1972-03-27
Publication date: 1974-09-17
Anticipated expiration: 1991-09-17

Abstract

A fabric is made of filaments of solid flexible thermoplastic material which contact each other and are fused together. In certain fabrics at least some of the filaments extend parallel with each other and are fused together throughout their length. In other fabrics the filaments are fused together at spaced positions along the filaments. The filaments are extruded upon the upper surface of a moving belt or upon a previously formed fabric or previously extruded filaments on such belt. The filaments which are fused together throughout their lengths may be spaced a slight distance from each other when extruded and expand into contact with each other. Filaments which are spaced greater distances from each other when extruded have portions of the filaments displaced normal to the general direction of the filaments into contact with adjacent filaments so that they fuse to such other filaments. This can be done by regulating the rate of movement of the belt relative to the rate of extrusion of the filaments so that the filaments wander randomly on the surface of the belt or by laterally reciprocating the belt or a combination of both. Various random as well as controlled patterns including patterns having closed loops of individual filaments as well as fabrics having continuous backing sheets supporting upwardly folded filaments can be produced.

Description

United States Patent [1 1 Ropiequet NON WOVEN THERMOPLASTIC FABRIC [75] Inventor: Richard L. Ropiequet, Portland,

Oreg.

[73] Assignee: Alta Industries, Incorporated,

Portland, Oreg.

[22] Filed: Mar. 27, 1972 21 Appl. No.: 238,124

Related US. Application Data [63] Continuation of Ser. No. 6,834, Jan. 29, 1970,

abandoned.

[52] US. Cl. 161/2, 4/154, 28/72 NW, 156/167, 156/176, 156/181, 156/306, 161/1,

[51] Int. Cl 1344b l/00, D0411 3/16, D04h 3/05 [58] Field of Search 161/1, 2, 10, 60, 150, 161/156, 157, 169, 170, 179, 180; 156/167,

[56] References Cited UNITED STATES PATENTS 2,374,540 4/1945 Hall 264/6 2,687,673 8/1954 Boone 16l/D1G. 4 3,439,084 4/1969 Terumichi et a1. 264/167 3,439,084 4/1969 Ono et a1. 161/179 3,441,468 4/1969 Siggel et a1. 161/169 3,442,751 5/1969 Langlois 156/157 3,509,009 4/1970 Hartmann i 161/150 3,690,978 9/1972 Nishizawa et a1..... 161/150 3,691,004 9/1972 Werner et a1 161/150 3,692,618 9/1972 Dorshner et a1. 161/72 3,723,235 3/1973 Armstrong 161/150 [451 Sept. 17, 1974 Primary ExaminerGeorge F. Lesmes Assistant ExaminerJ. Cannon Attorney, Agent, or Firm-Klarquist, Sparkman, Campbell, Leigh, Hall & Whinston [5 7 ABSTRACT A fabric is made of filaments of solid flexible thermoplastic material which contact each other and are fused together. In certain fabrics at least some of the filaments extend parallel with each other and are fused together throughout their length. In other fabrics the filaments are fused together at spaced positions along the filaments. The filaments are extruded upon the upper surface of a moving belt or upon a previously formed fabric or previously extruded filaments on such belt. The filaments which are fused together throughout their lengths may be spaced a slight distance from each other when extruded and expand into contact with each other. Filaments which are spaced greater distances from each other when extruded have portions of the filaments displaced normal to the general direction of the filaments into contact with adjacent filaments so that they fuse to such other filaments. This can be done by regulating the rate of movement of the belt relative to the rate of extrusion of the filaments so that the filaments wander randomly on the surface of the belt or by laterally reciprocating the belt or a combination of both. Various random as well as controlled patterns including patterns having closed loops of individual filaments as well as fabrics having continuous backing sheets supporting upwardly folded filaments can be produced.

16 Claims, 29 Drawing Figures RICHARD L. ROP I EQUE T lNVE/VTOR BUG/(HORN, BLORE, KLAROU/ST 8 SPAR/(MAN ATTORNEYS PAIEmmsm 1 m4 SHEU 3 0F 4 FIG. l6

FI.G. I8

FlG

RICHARD L. ROPYIEQQUET INVENTOH I BUG/(HORN, IBLORE, KLAROU/ST a SPAR/(MAN AT T ORNE Y9 Pmmmsm mu SHEET N If Q F l r H8 H6 2 000050 000000 00 o FIG, 27

FIG. 29

RICHARD L. ROPIEQUET INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS FIG. 26

NON WOVEN THERMOPLASTIC FABRIC RELATED APPLICATION This application is a continuation of application Ser. No. 6,834, filed .Ian. 29, 1970 for NON-WOVEN THERMOPLASTIC FABRIC, and now abandoned.

BACKGROUND OF INVENTION Plastic sheet material suitable for place mats for dining tables, coasters for glasses and the like have been made by arranging a large number of small substantially uniform rounded pellets of flexible thermoplastic material upon a surface with the pellets in contact and applying heat to fuse the contacting portions together. The result has been a flexible sheet having a pebbled upper surface of pleasing appearance. The colors and sizes of the pellets can be varied but in all cases the arrangement or pattern of the pellets forming the sheet is essentially the same.

SUMMARY The present invention produces flexible sheets in the form of non woven fabrics made of extruded plastic filaments. A plurality of such filaments extend in the same general direction and have at least portions which contact and are fused to other filaments. This fusion of the filaments together occurs immediately after the filaments are extruded and while the plastic material of the filaments is still heat softened or'partly molten as a result of the extrusion operation. The number of possible patterns or arrangements of the filaments is almost unlimited and in many cases the product resembles a woven fabric.

By proper choice of material and operating procedure the individual extruded filaments may be made to be of substantially uniform diameter and shape and have a substantially uniformly smooth outer surface. On the other hand the filaments can be made to have randomly varying diameters and cross-sectional shapes along the filaments. This occurs as a result of partial fractures of the filaments including intermittent partial necking down and changes in direction of the filaments as they emerge from extrusion orifices in an extrusion die. The distances along the filaments at which these changes occur also vary randomly and, in general, the average of these distances are of the same order as the average diameter of the filaments. The result is that the surfaces of the filaments have a plurality of irregularly distributed angularly disposed surfaces providing a beaded appearance. These surfaces of the filaments usually have a polished appearance and act as facets for differentially reflecting light and particularly, ifthe particular plastic employed is transparent or semi transparent, so that differential light refraction also occurs, the fabric has a scintillating or sparkling appearance.

The fabrics can be produced in reticulated irregular patterns in which the filaments have laterally displaced portions providing contact and fusion between the filaments at randomly spaced positions along the filaments. On the contrary the pattern may be made quite regular along the fabric and in an almost endless variety of different arrangements of the filaments including intermixtures of filament of different or periodically varying average diameters and colors. Furthermore the density of the filaments per unit area of the fabric can be increased with either random or regular patterns until almost a solid sheet is produced. The resultant fabrics can have a thickness not substantially greater than two or three times the thickness of the filaments or the extruded filaments may be piled on top of each other or have vertical displacements or loops as a single sheet is being produced, or can be extruded upon previously formed fabrics as laminations so that fabrics of substantially any desired thickness can be produced. Also a continuous backing sheet free from openings therethrough may also be formed from extruded filaments and other filaments then extruded on such backing sheet.

These various patterns or arrangements of the filaments as well as the form and appearance of the filaments themselves can be controlled by employing plastics having different physical characteristics, and varying the rates of movement of the surfaces upon which the extruded filaments are deposited relative to rate of extrusion of the filaments as well as the direction and extent of movement of such surface as is explained in greater detail below.

The fabrics of the present invention are capable of being used for a variety of purposes. Thus the various types of fabrics which can be produced are suitable for table cloths, place mats, ornamental ribbons, upholstery, rugs and carpets, dress fabrics, shower curtains, draperies and the like.

It is therefor an object of the present invention to provide a novel method of making of non woven fabric of. thermoplastic material in which extruded filaments of such material extending in the same general direction are caused to contact adjacent filaments while still in a fused condition.

A further object of the present invention is to provide a novel non woven fabric made of filaments of thermoplastic material extending in the same general direction and having at least portions of said filaments fused to adjacent filaments.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a side elevation showing an example of apparatus for making fabrics in accordance with the present invention with the driving mechanism for a filament receiving belt omitted;

FIG. 2 is an end elevation of the apparatus of FIG. 1;

3 is a plan view of a portion of the apparatus of FIGS. 1 and 2, showing a drive mechanism which can be employed with such apparatus;

FIG. 4 is a vertical cross section on an enlarged scale through the extrusion die of the apparatus of FIGS. 1 and 2;

FIG. 5 is a fragmentary side elevation showing an alternative position of the extrusion die of FIG. 1;

FIG. 6 is a fragmentary diagrammatic view showing apparatus useful for producing one type of the fabric;

FIG. 7 is a fragmentary plan view on an enlarged scale of a fabric having random lateral displacement of the filaments along such filaments;

FIG. 8 is a view similar to FIG. 7 showing filaments also having random variations in shape and thickness along the filaments;

FIG. 9 is a view similar to FIG. 8 showing an increase in density of the fabric due to a decrease in the rate of movement of the surface upon which the filaments are extruded;

FIG. is a fragmentary plan view on a smaller scale showing the appearance of the fabric when the rate of movement of the belt upon which the filaments are extruded is periodically varied;

FIG. 11 is a fragmentary cross section of a thick fabric made by piling the extruded filaments upon each other and in which the filaments have substantial vertical displacements as well as lateral displacements;

FIG. 12 is a view similar to FIG. 11 showing a laminated fabric having laininations of different thickness;

FIG. 13 is a view similar to FIG. 11 showing a fabric having a pair of thick laminations;

FIG. 14 is a fragmentary plan view of a fabric having substantially straight filament portions alternating with laterally displaced connecting portions;

FIG. 15 is a fragmentary cross section of the fabric of FIG. 14;

FIG. 16 is a fragmentary plan view on a smaller scale showing a fabric similar to that of FIG. 15 and having a sinuous pattern;

FIG. 17 is a fragmentary plan view of a fabric on an enlarged scale having a regular pattern and filaments of uniform diameter;

FIG. 18 is a view similar to FIG. 17 showing a similar fabric with filaments which vary in shape and diameter randomly along the filaments;

FIG. 19 is a view similar to FIG. 17 showing a different pattern;

FIG. 20 is a vertical section on an enlarged scale through an extrusion die for making a different type of fabric;

FIG. 21 is a fragmentary front elevation of the die of FIG. 20;

FIG. 22 is a fragmentary top view of a fabric which can be produced by employing the die of FIGS. 20 and 21 on the same enlarged scale as such die;

FIG. 23 is a fragmentary longitudinal cross section of the fabric of FIG. 22 taken on the line 2323 of FIG. 22;

FIG. 24 is a fragmentary cross section taken on the line 2424 of FIG. 22;

FIG. 25 is a view similar to FIG. 20 of another extrusion die;

FIG. 26 is a fragmentary front elevation of the die of FIG. 25;

FIG. 27 is a fragmentary top view of a fabric which can be produced by the die of FIGS. 25 and 26 on a smaller scale than that of such die;

FIG. 28 is a fragmentary longitudinal cross section through the fabric of FIG. 27 taken on the line 2828 of FIG. 27 but in the same enlarged scale as that of such die, and showing the five fibers nearest the plane of the section only; and

FIG. 29 is a fragmentary cross section taken on the line 29-29 of FIG. 27 on the same enlarged scale as FIG. 28.

DESCRIPTION OF PREFERRED EMBODIMENTS Apparatus of the general type shown diagrammatically in FIGS. 1 to 4, inclusive, can be employed to make any of the different types of fabric shown in the present application. This apparatus includes an extruder 30 which may be of any known or suitable type. In general, such extruders include a screw conveyor element (not shown) driven by a worm gear drive 32 and are provided with a hopper 34 through which powdered thermoplastic material can be introduced into the extruder. The discharge end of the extruder is provided with an extrusion die 36 and also it will be understood that the extruder 30 will be provided with a conventional heating device surrounding its casing, for example, a plurality of electrical heating elements positioned in a heat insulated jacket, for plasticizing or partially melting the thermoplastic material. The extrusion die 36 may be of the general type shown in FIG. 4 having an interior chamber 38 connected to the end of the extrusion device 30 through a conduit 40. The die 36 also includes a lower extrusion element 42 having a plurality of extrusion orifices 44 extending from the chamber 38 to the exterior lower surface of the extrusion element 42 for simultaneously extruding a plurality of filaments.

It has been found that the form of the extrusion chamber 38 shown in FIG. 4 in conjunction with a variation in length of the extrusion orifices 44 along the length of the extrusion element, produces extruded filaments at substantially the same extrusion rate. Thus the plastic or partly molten thermoplastic material being extruded through the orifices 44 in the die 36 is, in general, made up of molecules in the form of long chain polymers and the flow characteristics of such material depend upon a number of factors including the amount of agitation or rate of shear of the material. The employment of extrusion orifices of uniform length with an extrusion chamber which is uniform in cross section, even though of relative large diameter, results in different rates of flow of the plastic material through the various extrusion orifices. Even with an extrusion die of the type shown in FIG. 4, it may be necessary when the type of polymer is changed, to change the dimensions or slopes of the surfaces 46 near the center of the top surface of the element 42, or to change the cross section of the chamber 38, or slope of the upper surface of this element adjacent its ends in order to control the extrusion so as to secure the same rates of flow through the various extrusion orifices.

Other types of extrusion dies which produce controlled extrusions through a plurality of orifices are known and can be employed for extruding the fabrics of the present invention. Such dies include a plurality of movable members in the extrusion chamber known as choker bars, which are adjustable to provide controlled rates of extrusion through the various orifices. It will also be understood that, in general, the extrusion dies employed for extruding the filaments will also be equipped with heating devices in a heat insulating jacket for maintaining the thermoplastic material at a desired temperature.

As shown in FIG. 1, an endless belt 48 is mounted on

rolls

50 and 52 at opposite ends of the belt. Filaments from the die 36 are deposited on one end of the belt.

' This belt is driven at constant speed in the direction shown by the arrow 53 for making certain fabrics so as to continuously move the extruded filaments on the belt toward the right in FIG. 1. For other fabrics this movement may be intermittent or even periodically retrograde. Thus, for example, the roll 52 may be driven by a motor 54 shown in FIG. 3 through a gear 55 on the shaft of the roll 52 and a pinion 56 on the shaft of the motor 54. Periodic lateral movement or reciprocation of the belt 48 is also employed for making certain fabrics and in order to provide such movement, the frame 57 in which the

rolls

50 and 52 are journalled is shown as being mounted upon rollers 58, also shown in FIG. 2. The frame 57 can be reciprocated laterally through a rack 59 shown in FIG. 2 and 3, as being connected to the frame. The rack can be driven from a motor 60 through a pinion 61 on the shaft of the motor 60.

The

motors

54 and 60 may, for example, both be of the reversible stepping type capable of being controlled by known control systems to provide substantially any desired speeds and directions of rotation of the motors as a function of time. Thus the rate of movement and direction of movement of the belt 48 at any given time, either longitudinally or laterally of the belt, can be accurately controlled.

Any contacting portions of the heated filaments fuse together and the resulting fabric is allowed to cool on the belt until it develops sufficient mechanical strength to enable its removal from the belt. The belt 48 has an outer surface to which the extruded molten thermoplastic material will not adhere. A particularly suitable material for the belt is a woven fabric made of fibers of a polymerized fluorocarbon resin, for example, polytetrafluoroethylene or a copolymer of tetrafluoroethylene and hexafluoropropene, both sold under the trademark TEFLON. A belt of this type provides a filament receiving surface which enables the filaments extruded upon the upper surface of the belt 48 and any fabric from such filaments to be easily stripped from the discharge end of the belt 48.

In some cases, it is desirable to deposit the filaments from the extrusion die 36 on the belt 48 while it is traveling around the curved surface of the roll 50, as shown in FIG. 5. This compacts the fabric longitudinally of the fabric and, particularly with fabrics having disposed portions of the filaments distributed randomly along the filaments as described below, a greater number of fused connections between the various filaments are obtained.

The fabric shown in FIG. 7 and more fully described below, was produced by employing a constant rate of movement of the top portion of the belt 48 to the right in FIGS. 1 and 3 without lateral movement of the belt. For this operation the motor 54 can be operated at constant speed and the motor 60 rendered inoperative.

The extrusion of a small filament of molten or heat plasticized thermoplastic material upon a stationary or slowly moving surface causes the lower end of the filament to wander randomly over this surface to form a pile of the material usually including a series of closed loops. Ifa plurality of such filaments are extruded close together, they will repeatedly overlap each other. Also if the surface upon which the filaments are extruded is moved in one general direction at a rate which is of the same order as the velocity of extrusion, each of the filaments will extend along the surface in this general direction. When the velocity of extrusion of the filament exceeds the rate of movement of the surface, each filament will, in general, wander laterally of the general direction of the filaments to provide random lateral displacements of this filament. Thus a plurality of filaments extruded relatively close together at a velocity substantially greater than that of the receiving surface and displaced from each other laterally of the general direction of movement of the surface will have portions which contact or cross portions of adjacent filaments. This occurs shortly after the filaments emerge from the extrusion orifice and the result is that the contacting portions of the filaments fuse together to connect adjacent filaments together. These points of connection are disposed randomly along the filaments.

When the rate of movement of the surface upon which the filaments are deposited is approximately one-half the rate of extrusion of the filaments, or less, many of the lateral displacements of the respective filaments will be in the form of loops and this is illustrated in FIG. 7, in which the various filaments 65 extend in a general direction to the left and have loops 66 as well as other lateral displacements 67 of the filament randomly distributed along their lengths. Wherever the various filaments touch each other, they fuse together to produce a fabric which is essentially one filament thick with the portion in which filaments overlap being somewhat thicker.

The filaments 65 illustrated in FIG. 7 are shown as being of substantially uniform diameter and as having a smooth surface. The nature of the filament produced is largely controlledby the physical properties of the particular thermoplastic employed. Thus certain thermoplastic materials tend to produce filaments of substantially uniform diameter along their lengths and with smooth surfaces. Other thermoplastic materials tend to produce filaments having rapid and abrupt changes in thickness or diameter as they emerge from the extrusion orifices. That is to say, the filaments tend to alternately neck down and thicken and to abruptly change direction as they emerge from the extrusion orifices to produce a beadlike appearance along the lengths of the filaments. In other words, the filaments vary randomly in diameter along their lengths to produce a beadlike appearance, and, as in FIG. 8, the filaments vary randomly in direction along their length to produce, with the variation in diameter, a plurality of differently oriented reflective surfaces.

The tendency of certain thermoplastic materials to produce extruded filaments having the beadlike appearance referred to is known in the art and discussed in various publications, the phenomenon being referred to as melt-fracture. An attempt has been made to illus trate this beadlike appearance of the filaments in FIG. 8 in which the filaments 68 are made up of a series of beadlike portions 69. These beadlike portions present a multiplicity of randomly directed reflective surfaces and if the thermoplastic material being extruded into filaments is transparent or semitransparent, light is also randomly refracted as well as reflected so as to give a sparkling appearance to the fabric. For purposes of comparison, the filaments 68 of FIG. 8 have been drawn to have the same loops 66 and lateral displacements 64 as the smooth filaments of FIG. 7.

Although, as indicated above, the form of the filament extruded depends primarily upon the properties of the thermoplastic material being extruded, the form of the filament also depends somewhat upon the construction of the extrusion die. Thus if the orifices 44 of the extrusion die 36 of FIG. 4 are tapered from a slightly larger diameter where they communicate with the chamber 38 to a slightly smaller diameter at their discharge ends, the filaments being extruded tend to have smoother surfaces and more uniform diameters. Orifices of uniform diameter, such as shown in FIG. 4, tend to produce the irregular or beaded filaments of the type shown in FIG. 8, except in the case of thermoplastic materials of the elastomer type as above discussed. Extrusion orifices 44 which are tapered the opposite direction so as to have their larger diameter at their discharge ends tend to produce filaments which are extremely broken up and in many cases discontinuous.

Mixtures of thermoplastic materials which tend to produce smooth filaments with thermoplastic materials which tend to produce filaments having a beadlike appearance, in general, produce filaments of intermediate characteristics between the smooth filaments shown in FIG. 7 and the beaded type filaments shown in FIG. 8, if the mixed materials are otherwise compatible. By varying the type of thermoplastic material and the form of the extrusion orifices 44 of FIG. 4, substantially any type of filament between extremely irregular filaments to substantially uniform smooth filaments can be produced.

The fabrics shown in FIGS. 7 and 8 are relatively open or netlike materials in that the areas not occupied by the

filaments

65 or 68 are as great as or greater than the areas occupied by the filaments. The density of the filaments per unit area of fabric can be increased by merely slowing down the rate of movement of the sur face upon which the filaments are deposited with respect to the rate of extrusion of filaments. This is illustrated in FIG. 9 in which very much more of the area of the fabric is covered by the filaments 70 of this figure. It is apparent that this density can also beincreased by decreasing the lateral spacing between extrusion orifices.

By periodically varying the rate of movement of the surface upon which the filaments are deposited, for example by driving the belt 48 of FIG. 3 at a speed producing a density of filaments such as that shown in FIG.

9 for a short distance and then driving this belt at an increased rateof speed for a short distance to produce a fabric such as that shown in FIG. 8 and then repeating these operations, an effect similar to that indicated in FIG. is obtained. Thus a fabric of the nature shown at FIG. 9 is produced as laterally extending strips 72 when-the belt 48 is being driven at the slower speed, and a fabric such as shown in FIG. 8 is produced alternate strips 74 when the belt 48 is driven at a slightly higher speed. 8

Although the fabric illustrated in FIGS. 7, 8, 9 and 10 may be essentially a single filament thick or on the average about 2 filaments thick where the filaments overlap each other, the belt 48 may be driven at a slow enough speed that the filaments pile up into a fabric in the form of a mat or considerable thickness, such as illustrated by the mat 75 of FIG. 11. Also a relatively thin fabric 76 can be deposited upon a previously produced fabric 77 to produce a laminated structure such as shown in FIG. 12. It will be apparent that both of the laminations may be of the same thickness or one may be thicker than the other and that the number of laminations is not limited to two. Thus in FIG. 13 two separate laminations having substantially the

same thickness

78 and 80 are shown. These laminations may be By increasing the rate of movement of the surface upon which the filaments are extruded, for example by increasing the speed of the belt 48 of FIG. 3, control of the pattern of the filaments is obtained. If the surface is moved in a straight line and the speed of movement of the belt 48 is at least equal to the rate of extrusion of the filaments, the filaments will be laid upon the surface of the belt 48 in alignment with each other. Anything slower than this rate of movement of the belt will cause some lateral wandering of the filaments randomly along the lengths of the filaments. Also any movement of the belt greater than that just discussed, will cause stretching of the filament. Any lateral movement of the belt will cause corresponding lateral displacements of the filaments.

The fabric shown in FIGS. 14 and 15 was produced by intermittently moving the surface upon which the filaments were extruded in one direction at a rate which was sufficiently great to stretch the fibers extruded from an extrusion die such as that shown in FIG. 4. The result was relatively straight parallel filament portions 82 on such surface. This movement of the filament receiving surface in the direction of the filament portions82 was periodically stopped to produce the portions 84 of the filaments which join adjacent filaments together. In making the fabric shown in FIGS. 14 and 15, the filament receiving surface was reciprocated laterally with respect to such direction at a lesser rate of movement than the rate of the movement in the direction of the filament portions 82. This resulted in causing semicontrolled lateral displacement of the filaments in both directions to form'the filament portions 84. Thus the movement of the surface in a direction longitudinally of the straight portions 82 of the filaments was intermittent, and the rate of lateral movement of the surface was such that the laterally disgeneral direction of movement which produced the filament portions 82 was of slightly different frequency than the frequency of the intermittent motion discussed above. This caused the successive substantially straight portions 82 of the extruded filaments to be angularly disposed with respect to each other along the general direction of the filaments to produce a sinuous pattern such as shown in FIG. 16.

Another fabric shown in FIG. 17 in which the pattern is more accurately controlled than is the case of the fabric of FIGS. l4, l5 and 16. The fabric of FIG. 12 has a plurality of

filaments

89 and 90, all of which have similar sinuous patterns in the direction of general movement of the filament receiving surface, this direction being to the right in FIG. 17. The lateral displacements of the filaments 86 and 88 in FIG. 17 at a given distance along the fabric in this general direction are in opposite directions. It is also apparent that the filaments 89 were laid down in advance of the filaments 90, since the filaments 90 appear on top of the filaments 89.

The pattern of FIG. 17 was produced in the manner shown diagrammatically in FIG. 6 in which the filament receiving surface is indicated as being moved in the general direction of the arrow 91. The filament 89 was extruded from an orifice in an extrusion die 36. This orifice is not only spaced laterally from the extrusion orifice for the filament 90 with respect to the filament receiving surface, but is also spaced longitudinally and rearwardly from the extrusion orifice for the filament 90. The filament 89 was therefore deposited on the filament receiving surface prior to the filament 90. The filament receiving surface was also reciprocated laterally of the direction of the arrow 91 with a motion at least approximately a sine wave. The extent and the rate of reciprocation with respect to the rate of motion of this surface in the direction of the arrow 91, which were selected, causes the

filaments

89 and 90 to be displaced laterally in opposite directions along the length of the filaments as shown in FIG. 6. The extrusion of a plurality of properly spaced

filaments

89 and 90 under these conditions produced the fabric of FIG. 17. The required movement of the filament receiving surface can be obtained, for example, by driving the belt 48 of FIG. 3 at a uniform rate of speed by the motor 54 while reciprocating the frame 57 carrying the belt 48 and belt rolls 50 and 52 laterally through the connecting rack 59 by the motor 60. The lateral reciprocation may, for example, be simple harmonic motion.

The rate of total movement of the surface of the belt 48 upon which the filaments are deposited will under these conditions vary to some extent. If the rate of Iongitudinal movement of the belt is approximately that of the rate of the extrusion of the filaments from the extrusion orifices, the filaments will not be stretched when the direction of the filament is parallel to the longitudinal movement of the belt. This is when the belt is in one of its extreme lateral positions. At other times, when the deposition of the filament is at an angle to the longitudinal movement of the belt, the acutal rate of movement of the surface is somewhat greater than the rate of extrusion of the filaments, stretching of the filaments will occur. This effect under the conditions just described is relatively small and no attempt has been made to illustrate it in the FIG. 17. Thus the filaments are substantially unstretched or undrawn.

The

filaments

89 and 90 of FIG. 17 are shown as having a smooth outer surface and as being of substantially uniform diameter. As discussed above irregular or beaded

filaments

98 and 100, such as shown in FIG. 18,

can be produced. In any event, the fabric of FIG. 18 has a regular mesh pattern throughout and is of pleasing appearance.

Another type of pattern is shown in FIG. 19. The production of this pattern requires two separate extrusion dies, one of which is laterally reciprocated with respect to the general direction of movement of the filament receiving surface and the other of which is held against lateral movement with respect to such direction of movement of the filament receiving surface. Thus the pattern of FIG. 19 can be produced by extruding the filaments 102 from laterally aligned extrusion orifices in a die which has no lateral movement with respect to a belt, such as the belt 48 of FIGS. 1 to 3, and extruding the filaments 104 from another die which has laterally aligned orifices and which is reciprocated laterally with respect to the belt 48 to cause the filaments 104 to be laid down in a sinuous pattern crossing adjacent filaments 102.

In the fabrics described above the extrusion orifices of the various filaments were far enough apart that substantial lateral displacement of at least portions of the filaments was necessary to produce contact between the filaments and fusions of the filaments together. By placing the extrusion orifices as close together as practicable across the face of the extrusion die, and particularly if these orifices also terminate in the bottom of a groove in the face of the die which has substantially parallel sides and a width substantially that of the diameter of the extrusion orifices, the adjacent filaments can be made to fuse together substantially throughout their lengths. A continuous ribbon or sheet in which the individual filaments are visible but having no openings extending through the sheet can be produced.

A sheet of the type just discussed is illustrated in FIGS. 22, 23 and 24. In these figures, a sheet 106 forms the backing member ofa fabric also having ornamental stripes 108, each formed of a plurality of filaments also adhered together throughout their lengths. The filaments of the sheet 106 are extruded through a plurality of extrusion orifices 110 in an extrusion die 112 of the general type shown in FIGS. 20 and 21. The orifices 110 extend from the extrusion chamber 114 of the die and terminate in the bottom of a groove 116 extending across the face of the die in alignment with the orifices 110. The sides of the groove 116 are parallel andd are spaced from each other a distance approximately equal to the diameter of the orifices 110.

In making the sheet 106 of FIGS. 21 to 24, a receiving surface such as the upper surface of the belt 48 of FIGS. 1 to 4 is moved longitudinally at a rate substantially equal to and preferably slightly less than the velocity of extrusion of the filaments of the sheet 106. A slight expansion of these filaments takes place as they are extruded from the orifices 110. They are prevented from expanding in a direction perpendicular to the sheet 106 by the groove 116 and the result is that they expand in the plane of this sheet into contact with each other and fuse together along their lengths. The separate filaments, however, are still apparent in the resulting sheet to provide an ornamental backing sheet.

Groups of filaments are also extruded from groups of orifices 118 to form the stripes 108 at a greater velocity of extrusion. The orifices 118, as shown in FIG. 20, are of substantially less axial length than the orifices 110 and in the example shown, may be of the same diameter as the orifices 110. Thus the velocity of extrusion rate through the orifices 118 may be several times that of the extrusion rate through the orifices 110 and several times the rate of travel of the belt 48 of FIGS. 1 to 4. The result is that the filaments extruded through the orifices 118 expand approximately equally in all radial directions and that the adjacent sides of the filaments contact each other and fuse together.

As shown in FIG. 21, the groups of orifices 118 are spaced from each other laterally of the die 112 so that the resulting stripes 108 are likewise spaced from each other. These stripes are deposited on the upper surface of the backing sheet 106 while both the stripes and the backing sheets are still sufficiently heated to fuse together, a preferred position of the die being similar to that of the die 36 of FIG. 5, or the die may be inclined downwardly toward the top run of the belt and in the direction of travel of the belt.

Since the sheet 106 is traveling at a rate which is substantially less than the rate of formation of the stripe 108, the stripes tend to fold along lines extending across the stripe. If the relative velocities of the sheet 106 and stripe 108 are correct, portions of the filaments of the stripe 108 will be vertically displaced in both directions normal to the receiving surface of the backing sheet so as to fold into an approximation of a nearly regular sine wave with the waves of the filaments of each stripe in phase. This produces upstanding ridges 120 extending across the stripes and having heights which are several times the diameter of the filaments, for example 3 to 5 times. Thus, for example, the velocity of extrusion of the filaments of the stripe 108 may be about 2 to 4 times that of the velocity of extrusion of the filaments of the sheet 106 and the substantially equal velocity of the sheet. The folds of the different stripe 108 will, in general, not be in alignment, i.e., they will be out of phase. The lower portion of the folds of each stripe fuse to the-backing sheet to provide an attractive fabric material, particularly suitable for place mats, decorative ribbons, or the like.

The scale of the FIGS. 20 to 24 is substantially enlarged as the overall thickness of an actual fabric including the height of the ridges 120 was approximately 1/10 inch. As examples, all of the orifices 110 and 118 of FIGS. 20 and 21 may have a diameter of .0145 inch with adjacent orifices spaced laterally .020 inch on centers or may have a diameter of .0l6 inch with adjacent orifices spaced laterally .025 inch on centers.

It will be apparent that any of the fabrics of FIGS. 7 to 16 or other similar fabrics can be formed on the upper surface of the backing sheet 106, either in laterally spaced strips or continuously over such sheet, or that relatively widely spaced filaments with random lateral displacements can be employed to decorate the upper surface of such sheet. Strips of such fabrics or such individual strips can be intermixed with the stripes 108 of FIGS. 22 to 24. Particularly attractive decorative ribbons have been produced having a strip of backing sheet 106 with narrow borders of stripes 108 along the edges of the strip and several individual filaments with random lateral displacements on the surface of the backing strip between the border stripes.

Another type of fabric particularly useful for floor coverings or the like is shown in FIGS. 27 to 29. This fabric can be produced by employing an extrusion die of the general type shown in FIGS. 25 and 26. The die 122 has a plurality of closely spaced orifices 124 of substantial length extending from an extrusion chamber 126 and terminating in the bottom ofa groove 128 extending across the face of the die. The orifices 124 and groove 128 may be similar to the orifices 110 and groove 116 of FIGS. 20 and 21, and may be employed in the same manner to produce a backing sheet 130. The orifices 124 may, for example, be .0145 inch in diameter and spaced .020 inch on centers, the groove 124 having a width of approximately .0145 inch.

The die 122 also has a row of orifices 132 of the same size and length as the orifices 124 spaced upwardly from the orifices 124 and spaced laterally from each other a greater distance than the lateral spacing of the orifices 124. For example, the orifices 132 may be .0l45 inch in diameter spaced .125 inch apart on centers and spaced upwardly from the row of orifices .050 inch on centers. The extrusion velocity through these orifices is substantially the same as that through the orifices 124. This extrusion produced spaced filaments 134 which extended generally parallel with each other and with the filaments of the backing sheet 130. The filaments 134 rested upon and were fused to the upper surface of the sheet substantially throughout their length.

Another row of orifices 136 was provided in the die 122 of greater size than the orifices 124. These orifices were spaced .050 inch upwardly from the orifices 132. They were spaced from each other .125 inch and were positioned so as to be equidistant from the orifice 132. The orifices 136 were of the same length as the orifices 124 but their increased size resulted in a velocity of extrusion several times that of the velocity of extrusion through the orifices 124. In a specific extrusion die, the orifices 136 had a diameter of .0225 inch and the velocity of extrusion was sufficient that a plurality of displacements in the form of folds were formed in the resulting filaments 138 as indicated in FIG. 28. These folds extended predominantly upwardly since the filaments 134 tended to direct the filaments 138 upwardly and also random contact between adjacent filaments 138 tended to hold the folds of such filaments in upright position. These filaments fused together and to the filaments 134 or the sheet 130 wherever contact occurred to provide a relatively open structure.

The die also had another row of orifices spaced .050 inch upwardly from the row of orifices 136. The orifices 140 were of the same size and length as the orifices 132 ane were aligned vertically with the orifices 132. The filaments 142 extruded from the orifices 140 were similar to the filaments 134 and extended generally parallel to the latter filaments. The filaments 142 fused to the tops of the folds of the filaments 138 to brace the open structure provided by the filaments 138.

Additional filaments 144 were extruded from orifices 146 of the die 122 which were also arranged in a row spaced upwardly .050 inch from the row of orifices 140. These orifices 146 were in vertical alignment with and of the same size and length as the orifices 136 and the filaments 142 were similar to the filaments 138. The filaments 144 also formed folds similar to the folds of the filaments 138 having the tops of the folds exposed as indicated in FIG. 27. The general appearance of the top surface is that ofa looped pile fabric rug with the tops of the loops or folds angularly disposed with respect to the direction of the filaments of the backing sheet 130 but with some of them generally parallel with the filaments of the sheet 130. In a specific fabric formed as discussed above the total thickness of the fabric was approximately 0.3 inch.

A large member of thermoplastic materials may be employed to produce fabrics in accordance with the present invention; Examples of such thermoplastic materials having very much different physical characteristics are a styrene butadiene thermoplastic rubber sold under the tradename KRATON-PI-Il04, and an ethylene-vinyl acetate copolymer containing about 82 percent ethylene and 18 percent vinyl acetate, the particular polymer employed being sold under the tradename EVA-308. Mixtures of these two materials in various proportions have physical properties between these two extremes.

The styrene butadiene rubber produced filaments of substantially uniform diameter and having a smooth surface when extruded through orifices on the order of .010 to .060 inch in diameter, while the ethylene-vinyl acetate copolymer produced filaments of the irregular or beaded appearance described above.

The extent to which the filaments will be laterally displaced when directed downwardly onto a stationary receiving surface depends upon the extent of melting of the plastic material, i.e., its viscosity when extruded, the distance above the surface the filaments are discharged from the extrusion die and the rate of extrusion of the filaments. The greater the viscosity and the greater the distance referred to and the greater the rate of extrusion, the greater the lateral displacement and the size of the loops formed. A decrease in either of these factors will cause a smaller pattern to form on the surface. Thus vertical distances between the receiving surface and the extrusion orifices ranging from 1/16 inch to several inches have been employed to produce fabrics in accordance with the present invention.

Moving the filament receiving surface with respect to the filaments in one direction only with respect to the filaments being extruded will produce progressively less lateral displacement of the filaments as the rate of movement increases until the rate of movement substantially equals the rate of extrusion of the filaments. At this rate of movement, the filaments will be deposited on the surface in substantially straight lines. If the surface is also moved laterally, the deposited filaments will then substantially follow the pattern of movement of the surface. A greater rate of movement will cause stretching of the filaments and a tendency of the extruded filaments to cut across corners to increase the radius of curvature of any movement of the surface along a curved line. it is thus apparent that variations in the rate and direction oflateral movement of the surface will vary the pattern obtained and the same is true of any vertical movement of the surface relative to the extrusion orifices.

Similar considerations apply when the filaments from an extrusion die are directed against a receiving surface at an angle less than a right angle. Such direction of extrusion tends to form vertical folds as well as horizontal folds when the receiving surface is moved in the plane of such surface at a less velocity than the velocity of extrusion, and the direction of extrusion has a component in the same direction as the direction of movement of the receiving surface. It will be apparent that a large number of novel fabrics can be obtained by complex relative movement between the extrusion die and the receiving surface including relative movement at an angle to the plane of the surface as well as retrograde movement in conjunction with the employment of different size orifices in various arrangements in the die. In each of the fabrics disclosed at least some of the extruded filaments have portions which are displaced from other portions of such filaments in a direction normal to the general direction of such filaments.

In general, the extruded filaments will contain sufficient heat to fuse together when they contact each other but additional heating, for example, by passing the fabric through an oven while still supported on a receiving surface or floating on a heated liquid, can be employed to further fuse the filaments together. It is also possible to pass an extruded fabric through the nip of calendering rolls while in a heated condition in order to form a stronger bond between the various filaments. Also such fabrics while in heated condition can be subjected to an embossing operation employing a cooled embossing die to produce embossed patterns, or a cutting die can be employed to separate the extruded fabric into individual pieces, it being apparent that both an embossing and cutting operation can be performed by a suitably constructed die.

Further heating can also be employed to adhere any of the fabrics above described to other fabrics or to metal, wood and the like. The temperature of the thermoplastic material during extrusion of the filaments will vary with the fusing or melting characteristics of such materials, but will in general be between 200 and 350 F. and any further heating of the fabric for the purpose of further fusing the filaments together or to other materials will in general be to temperatures within this range.

Other thermoplastic materials may be employed to produce the fabrics of the present invention, for example, other thermoplastic elastomers and also such materials as polymers of vinyl acetate, vinyl chloride, vinyl acrylic acid, etc., and various copolymers of these materials, with or without additions such as plasticizers and the like. Also, one or more of the components of various copolymers may be partly polymerized prior to being mixed and copolymerized. It is also possible to stabilize the resulting fabrics by causing cross linking of the chain of molecules by procedures known in the prior art including subjecting the fabrics to various types of radiation or by treating the fabrics with chemical cross linking agents.

1 claim:

1. A non-woven plastic fabric comprising:

a plurality of substantially unstretched melt spun flexible filaments of thermoplastic material extending generally in one direction of said fabric and adjacent each other;

at least certain of said filaments having portions spaced from others of said filaments and having other portions displaced in a direction normal to the general direction of said filaments into contact with portions of said other filaments;

the contacting portions of said filaments being fused together to produce said fabric;

certain of said filaments having been spun from a melt fracturable thermoplastic polymer and varying randomly in diameter and direction along their lengths to provide a plurality of differently oriented reflective surfaces producing a beadlike appearance of said filaments;

and certain of said filaments having a substantially uniform diameter along their lengths and a smooth surface.

2. A fabric in accordance with claim 1 in which the displaced portions of said filaments occurs randomly along said filaments and certain of said portions of said filaments overlap and are fused to portions of others of said filaments.

3. A fabric in accordance with claim 2 in which the said displaced portions of said filaments include closed loops in which portions of a single filament cross each other and are fused together.

4. A fabric in accordance with claim 3 in which the occurrence of said loops is random along said filaments and said loops are intermixed randomly along said filaments with other displaced portions of said filaments.

5. A fabric in accordance with claim 1 in which said filaments overlap repeatedly to provide a fabric which has a thickness several times the thickness of a single filament.

. 6. A fabric in accordance with claim 1 in which the average number of displaced portions of said filaments in a given distance along said fabric in said one direction periodically varies.

7. A fabric in accordance with claim 6 in which first portions of adjacent filaments spaced along said filaments and aligned laterally of each other with respect to said one direction are substantially straight and extend generally parallel to each other in said one direction, and second portions of said filaments between said spaced portions are displaced laterally with respect to said one direction into lapping contact with an adjacent filament.

8. A fabric in accordance with claim 1 in which at least certain of said filaments are displaced laterally with respect to said one direction in a substantially regular repeating pattern.

9. A fabric in accordance with claim 8 in which certain of said filaments are displaced laterally of said one direction in a sinuous pattern to overlap adjacent filaments.

10. A fabric in accordance with claim 8 in which each of said filaments is displaced laterally of said directions in a sinuous pattern, the lateral displacements of laterally aligned portions of adjacent filaments being in opposite directions.

11. A fabric in accordance with claim 8 in which at least certain of said filaments are displaced laterally of said one direction in closed loops in which portions of a single filament cross each other.

12. A fabric in accordance with claim 1 in which the displacements of certain of said filaments are predominantly normal to the general plane of said fabric.

13. A fabric in accordance with claim I which includes a backing sheet having a plurality of parallel filaments all parallel to the general plane of the sheet with adjacent filaments in contact with each other and fused together throughout the lengths of such filaments.

14. A fabric in accordance with claim 13 also including groups of filaments in the form of stripes in which the adjacent filaments in each stripe are disposed laterally of said fabric and are in contact with each other and fused together throughout their lengths and said stripes are formed into folds extending in a direction normal to said general plane, said stripes extending in spaced parallel relationship in said general direction along one face of said backing sheet and having portions of said folds fused to said backing sheet.

15. A fabric in accordance with claim 1 in which the filaments of said fabric are of light transmitting plastic and vary randomly in diameter and direction along their length to provide a plurality of differently oriented reflective and refractive surfaces.

16. A laminate of layers of the fabric of claim 1 wherein filaments of adjacent layers are adhered together.

Claims

1. A non-woven plastic fabric comprising: a plurality of substantially unstretched melt spun flexible filaments of thermoplastic material extending generally in one direction of said fabric and adjacent each other; at least certain of said filaments having portions spaced from others of said filaments and having other portions displaced in a direction normal to the general direction of said filaments into contact with portions of said other filaments; the contacting portions of said filaments being fused together to produce said fabric; certain of said filaments having been spun from a melt fracturable thermoplastic polymer and varying randomly in diameter and direction along their lengths to provide a plurality of differently oriented reflective surfaces producing a beadlike appearance of said filaments; and certain of said filaments having a substantially uniform diameter along their lengths and a smooth surface.

6. A fabric in accordance with claim 1 in which the average number of displaced portions of said filaments in a given distance along said fabric in said one direction periodically varies.

13. A fabric in accordance with claim 1 which includes a backing sheet having a plurality of parallel filaments all parallel to the general plane of the sheet with adjacent filaments in contact with each other and fused together throughout the lengths of such filaments.