US3243861A - Method of making a textured nonwoven fabric - Google Patents

Description

p 5,19s6 v. M. KUMIN Em. 3,243,8

METHOD OF MAKING A TEXTURED NONWOVEN FABRIC Filed Feb. 13, 1965 United States Patent 3,243,861 METHOD OF MAKING A TEXTURED NQNWGVEN FABRIC Victor M. Kumin, Newton Highlands, and William J. Kennedy, Jr., Wrentham, Mass, assignors to The Ken- Gail Company, Boston, Mass, a corporation of Massachusetts Filed Feb. 13, 1963, Ser. No. 258,242 7 Claims. (Cl. 28-72) This invention relates to textured textile products and to a method of preparing the same. More particularly it relates to textured felt-like composite non-woven fabrics comprising a base of retracted unspun and non-woven fibers supporting a textured or sculptured overlay of essentially non-retracted textile material arranged in a series of convoluted ridges.

In the preparation of felt-like non-woven fabrics, as by the use of the needle-loom or fiber-punching art, it is known to prepare needled batts of retractable fibers and then to subject such batts to a shrinking process to produce a firmly felted article. Such a process and product is described in US. Patent 2,908,064, to H. G. Lanterbach. It has also been proposed to dilute such retractable fibers with a certain percentage of non-retractable fibers, and to shrink a needled batt of the mixture. The resulting products, while suitable for a number of uses, are generally of a smooth, flat, and uniform surface texture. They hear a close resemblance to the familiar wool felts of commerce, with all of the fibers lying Stratified and intermingled essentially uniformly in the plane of the fabric.

It is also known to spin retractable or shrinkable fibers into yarns, and to weave various fabric constructions from such yarns combined with non-shrinking yarns. Subsequent shrinkage of such fabrics leads to a puckered or crinkled effect in the areas occupied by the non-shrinking yarns.

We have found that a variety of novel and useful products can be made by using retractable and nonretractable fibers which are not intermingled with each other, and which are not spun into yarns, either separately or in mixture, but which are stratified in at least two distinct layers which are united to each other at selected spots only, as by needling or spot-bonding. subjecting such an assembly to a retracting process will draw the layer of retractable fibers together into a relatively firm and coherent felt, while the fibers in the non-retractable layer are thrust up out of the plane of the fabric into a series of ridges, said ridges being anchored to the base fabric by fibrous tufts created by the needling process. The resulting product, described more fully hereinbelow, may have essentially parallel ridges, resembling corduroy, or the ridges may run in random fashion, with frequent merging of ridges so that the product has a surface resemblance to caracul or Persian lamb. Depending on the nature of the fibers selected, and the extent and nature of the needling and retracting processes, products may be made ranging from those which are firm and tightly ridged, useful in the garment industry, to soft, pile-like products useful as bandaging material, cast padding, and the like.

'Although the invention will be chiefly described in terms of non-woven fibrous products, it is also within 'the scope of our invention to utilize other flexible, de-

formable non-retractable materials, such as a non-retractable woven fabric as one or more layers of the assembly, said fabric being combined with at least one layer of retractable, unspun textile-length fibers.

It is an object of this invention to provide a composite textile product with a pronounced surface texture comprising at least one layer of unspun retractable fibers, in which fiber, which shrinks when exposed to heat.

product at least one surface of the composite material is drawn up into a series of ridges.

Another object of this invention is to provide a surfacetextured non-woven fabric comprising a stratum of essentially coplanar, horizontally-oriented fibers retracted to form a felt, combined with a stratum of non-retracted fibers arranged at least in part into vertically-oriented loops projecting above the plane of the retracted fibers.

Another object of this invention is to provide processes for producing the above-mentioned articles.

Other objects of the invention will be apparent from the following description, drawings, and examples.

The invention will be more clearly understood by reference to the drawings, in which:

FIGURE 1 is a perspective view of a fragment of a product of this invention.

FIGURE 2 is a cross-sectional view of an array of two strata of fibers, suitable for the product and process of this invention.

FIGURE 3 is a cross-sectional view of the fibrous array of FIGURE 2, after needling.

FIGURE 4 is a cross-sectional view, magnified several times, of the product of the invention, representing a cross-section of a fragment of FIGURE 3 after the retracting process has been carried out.

FIGURE 5 is a perspective view of another embodiment of the invention.

In general, the objects of this invention are accomplished by providing two unspun and non-woven fibrous strata which differ in their refractive behavior in a shrinkage process; anchoring the fibers of one layer to the fibers of the other layer at selected and spaced-apart intervals, as by needling or the like, and then shrinking the re.- tractable fibers by appropriate means to form a compacted felt base carrying a sculptured ridge-like pattern of the non-retractive fibers arranged in a series of convoluted arches extending across the face of the product.

By retractable fibers We mean fibers which are stable to carding and other fiber-dispersing processes, but which are nevertheless so internally stressed that an appropriate treatment of a batt or fleece of such fibers will cause a substantial area decrease in the batt or fleece, preferably of the order of 20% or more. The retractive behavior may be substantially one of fiber shrinkage, as exemplified by the behavior of Dacron 61, a Du Pont polyester Plasticized cellulose acetate fibers display analagous behavior on heating, as do fibrous c-opolymers of polyvinyl chloride and polyvinyl acetate, of the type known as Vinyon, a product of American Viscose Corporation.

Other types of suitable retractable fibers do not decrease substantially in length, but under appropriate treatment wil twist, bend, curl, and interlock together to draw a batt of such fibers together. The behavior of such fibers in batt form is set forth in Secrist Patent.2,774,l-29, wherein the retractable fibers are natural cellulosi-c fibers and the retracting agent is sodium hydroxide'solution of suitable concentration.

Polyvinyl alcohol fibers which have not been formalde hyde-treated to a state of complete water insensitivity also show definite retraction and twisting together when immersed in water. Other suitable fibers and retracting mechanism will readily occur to those skilled in'the art.

By non-retractable we do not mean that the fibrous material cannot be shrunk together under any circumstances, but instead we refer to fibrous material which is inert to the particular retracting operation which is to be carried out on the retractable fibers. This distinction is necessary, because it is possible for a fiber to be retracting or non-retracting, depending on the conditions of the retracting operation. For example, if-a stratified batt of Vinyon fibers and a separate batt of cotton fibers are 1 needled together and then heated, the heat-sensitive Vinyon fibers will be drawn together to form a condensed felt, while the cotton fibers, which are not affected by the heat, are physically drawn up into ridges on the surface of the Vinyon feltwith which they are associated.

On the other hand, if the same needled assembly of two stratified layers of fibers is subjected to the influence of cold sodium hydroxide solution of mercerizing strength, the batt of cotton fibers will contract to form a firm unitary felt, while the Vinyon fibers, inert in the caustic solution, form arched ridges creating a surface texture on the cotton felt. It will be apparent that the basic demand of this invention can be met by a wide range of types of fibers, it being necessary only that one type of fiber be capable of being shrunk down to a felt under conditions to which the other type of fiber. is substantially inert.

The methods of forming the fibrous batts which are the starting material for this invention include carding, garnetting, air-laying, and so on, and are so well known in the textile art as to require no further comment here. The fibers in the individual batts should ideally be substantially oriented in a horizontal plane, in which they are internally comingled and dispersed for the most part in two dimensions. For maximum effect there is preferably no extensive comingling or intermixing of the fibers of one type of batt with the fibers of another type of batt prior to the needling or punching operation lest the force of the retracting operation be diluted. In general, we have found that if the fibers in the batt to be retracted are diluted with more than 50% of fibers which will not retract, the force of retraction is so weakened that the surface texture provided by the fibers in the non-retracting batt may be rather poorly defined, and the anchorage of the convoluted surface ridges to the base felt is also adversely affected. It is, of course, possible to use more than one type of non-retractable fiber comingled with each other or stratified, in the one batt, and to use more than one type of retractable fiber in another batt.

In simplest form, a batt of non-retractable fibers, of FIGURE 2, is superimposed on a batt of retractable fibers, 12. of FIGURE 2, and the two are needled together, for example, by passing the sandwich through a Hunter needle loom equipped with needles spaced so as to impart what is termed a random-punched pattern of about 96 penetrations per inch at each passage through the loom. As a result of this operation, the non-retractable batt 10 becomes attached to the retractable batt 12 by a series of tie-points, or stitch-like points 14 where non-retractable fibers are brought down from the upper plane by the needles of the loom. As indicated at 16 of FIGURE 3, however, the surface of the sandwich is still an essentially smooth continuous plan, pock-marked by the needled punctures.

If this sandwich is then subjected to a retracting op eration, the fibers 12 of the retractable batt are drawn together, shrinlh'ng to form a more or less firm felt 18, the fibers of which after retraction may be in a fused state, an interlocked and intertwined state, or a combination of both depending on the nature of the retractable fibers :and' the nature of the retracting operation. During this drawing-together and area shrinkage of the retractable fibers, the non-retractable fibers It) are neither shortened in length nor caused to entangle and twist together, since by definition the fibers are indifferent to this operation. They are, therefore, thrust upward out of the plane of the base felt 18, into a series of buckled ridges 20, which provide a novel and appealing surface-textured effect in the fabric. These ridges are firmly adherent to the base felt 18 due to the shrinkage of the retractable fibers around the tie-points 14 during the retracting process.

This sort of surface sculpturing by means of a retracting substrate bears a rough analogy to the geological formation of mountains by the shrinking of the earths crust. Indeed, particularly when the needle pattern is random, the ridges of non-retractable fibers are arched into a pattern of synclines and anticlines, which may merge together and ramify in a cursive and tortuous path across the face of the fabric, as shown in FIGURE 1. The buckled bundles or ridges of non-retractable fibers are usually lifted so far from the base web that air spaces appear, as at 22 in FIGURE 4.

Microscopic examination of the products of this invention show that the tie-points 14 have drawn together in closer proximity during the retracting operation. By this process, as shown in FIGURE 4, the ridges 20 are formed.

Much to our surprise, it seems to make no very significant difference in the products of this invention whether the non-retractable layer is needled into the retractable layer, or vice versa. In either case, a pronounced sculptured, corrugated surface is produced on the face layer comprising the non-retractable fibers.

The amplitude and spacing of the surface ridges has been found to vary with the number and spacing of the contact points between the layer of retractable fibers and the non-retractable layer. For example, when the uniting of the two layers is done by needle-punching, it is found that repeated passes through the needle loom, before retraction, result in a finer and finer surface grain, or texture. Using a needle loom with needles set onehalf inch apart in transverse rows, and approximately one-half apart longitudinally, with needles arranged in a modified herringbone pattern, a single pass of the assembly at a rate of one-quarter inch per stroke will unify two fibrous layers so that a subsequent retraction of the sensitive layer will cause a pronounced pattern of fibrous ridges on the non-retractable face. These ridges are, with the modified herringbone needle pattern, in general, broken; that is, they extend transversely across the direction of fiber orientation in the carded webs, but due to the needle arrangement, they curve or change direction, as illustrated in FIGURE 1. In the above instance, with a single pass through the needle loom, the ridges are generally between one-quarter inch and three-quarter inches in length. With two passes through the loom, the ridges average between one-eighth and three-eighths of an inch in length: with three passes through the loom, the average ridge is one-eighth inch long or less.

These dimensions are for the effect obtained when the area shrinkage of the retractable portion of the assembly was 66%. The area shrinkage is another important variable in the process of this invention. For example, when a batt of Dacron 54 fibers (a non-retractable polyester fiber by Du Pont) was needled to a batt of polyvinyl chloride fibers and the assembly was treated with boiling water, the polyvinyl chloride fibrous stratum retracted to give an area shrinkage of 44%, and a flexible product with readily visible ridges of Dacron fibers was produced. When the same assembly was heated to 320 F. for 3 minutes, the area shrinkage was 89%. The surface of the resulting product was so fine grained as to appear essentially smooth and felt-like, and microscopic inspection was necessary to detect the tie-points and ridges characteristic of the products of this invention.

If it is desired to create a corduroy effect of unbroken ridges, the needles in the loom should be placed in a square pattern of even rows, and the advance of the assembled batts should be rather carefully controlled to avoid randomizing the tieiointsv created by the needling. It will also be apparent that by bunching the needles in one place in a design, or by multiple needlings on different needle looms with different needle placements, a variety of pleasing geometric or even pseudofioral sculptured designs can be effected.

Additional sculptured or relief effects may be obtained by overlaying the non-retractable fibrous layer with pieces or strips of additional non-retractable fiber, needling the thus-patterned layer to a layer of retractable fibers, and conducting a shrinkage operation on the layer of retractable fibers. The products of such a process are deeply sculptured, and are suitable'for use as inexpensive rugs of pleasing and interesting surface texture.

Another available method of ornamentation of the products of this invention lies in the application to'the non-retracting surface of a colored design, as by screen printing or other well-known methods. Preferably this is done after the two layers of fiber are needled together, but before the retraction process, while the two layers are in extended and generally planar configuration as in FIGURE 3. Subsequent shrinkage of the retractable fibrous layer not only decreases the size of the applied design in proportion to the area shrinkage eifected, but the design appears in depth on the shrunken product, resembling products made by tufting, piling, or interweaving yarns of different colors through a backing fabric. Such in-depth designs are particularly soft and appealing, and cannot be brought about by printing on already retracted surfaces.

It is also within the scope of this invention to produce surface-sculptured textile products embodying more than two uniformly coextensive layers of fibers. By uniting a batt of non-retractable fibers to each face of a batt of retractable fibers, an assembly is produced which after retraction has a surface-sculptured effect on both faces. On the other hand, if a batt of retractable fibers is needled to both faces of a batt of non-retractable fibers, retraction of the outside layers yields a product which has a firm shrunken fibrous layer on both faces. Such a material may be cut, skived, or split lengthwise through the non-retracted fibrous layer, to give two similar layers of fabric each comprising a retracted fibrous base tufted with a velvet or plush-like pile of unretracted fibers bound to the base by tie-points.

As mentioned above, it is possible to utilize other materials as one or more non-retractable strata, in combination with at least one stratum of retractable unspun fibers in creating the products of this invention. As set forth below in Example 3, woven textile fabrics are quite suitable provided that they are not so stiff as to resist being thrust up into ridges and folds by the contraction of the unspun fibrous retractable layer. All that is required is that the layer of retractable fibers shown a sufficiently strong shrinking power to dominate the other layer of material to which it is united at discrete and spaced-apart points. i

In general, we have found that an area shrink in the retractable layer of the assembly of at least to is necessary in order for a readily-apparent surface texture to be developed. Products in this range are soft and flexible, gene-rally still entirely fibrous in nature, and are suitable for cast padding, ornamental wadding, bandages, and the like. Products in the to 75% area shrinkage range are generally firmer, with more pronounced and deeply-textured surface ridges, and are suitable for use as decorative coverings, imitation Persian lamb, garment ornamentation, and the like. As mentioned above, products which have been shrunk more than 75% are very firm and dense, with fine-grained surface, and may be used where the denser types of felt find application. In general, the area shrinkage of the product by fiber reaction is between 15% and 80%.

The following examples will illustrate various embodiments of the invention.

EXAMPLE 1 A carded batt of Vinal VP-10l fibers, a polyvinyl alcohol fiber produced by the Kurashiki Rayon Company, was needled on a Hunter needle loom set with needles in modified herringbone pattern at A-inch advance rate per stroke to provide about 96 penetrations per square inch. The needled batt weighed grams per square yard.

A similar batt of Dacron 54 fibers, a polyester fiber The same two types of fiber were used in a similar experiment, with the following differences: both carded batts weighed 100 grams per square yard; the batts were not needled separately before combining, but were in cardedbatt form; the Dacron fiber layer was needled down into the polyvinyl alcoholfiber in a single pass through the Hunter needle loom set as before. After immersion in water at 30 C. and drying, a product similar to Example 1 was obtained. The area shrinkage was 71%.

EXAMPLE 3 A batt of heat-retractable polyvinyl chloride fibers weighing about grams per square yard was needled by passing once through a needle loom set as in Example 1. The batt was then sewn between two layers of broadcloth, the stitches being about oneeighth inch apart in rows spaced one-quarter inch apart. When the quilted assembly was exposed to dry heat at 100 C., an area shrinkage of about 50% occurred, and the broadcloth on both surfaces was crinkled into a plisse-like appearance, as shown in FIGURE 5.

. EXAMPLE 4 g A IOO-gram-per-squa-re-yard batt of bleached absorbent cotton fibers was needled by one pass through a Hunter needle loom set as in the previous examples. A similar batt, of similar weight, was prepared from Orlon fibers, a polyacrylonitrile fiber produced by Du Pont. The two battsvwere then needled together by another pass through the needle loom.

The assembly was then immersed in 13% sodium hydroxide solution at 0 C., whereupon the cotton fibers retracted to form a felt. The final rinsed and dried product showed an area shrinkage of 18%, and consisted of a cotton felt base with an adherent overlay of Orlon fibers folded into a series of ridges extending more or less irregularly across the upper surface of the product,

EXAMPLE 5 A 75-gram-per-square-yard Vinal VPl01 fiber batt and a -gram-per-square-yard wool batt were needled sepa rately as in Example 1. The wool batt Was then needled into the Vinal batt by another pass through the needle loom. The assembly was then immersed in water at 30 C., after which it was dried. V

The final product resembled the product of FIGURE 1, and has a marked resemblance to the material known as Persian lamb, since it consists of wool fibers organized into tightly looped ridges bound to a flexible, skin-like base of unified polyvinyl alcohol fibers.

It will be apparent to those skilled in the art that the retracting layer of fibers does not always have to consist of retractable fibers, nor does the non-retracting layer have to be free from retractable fibers. A certain minor dilution is possible in each layer, provided that the retracting layer exerts a dominating influence on the relatively non-retracting layer, which is thereby buckled up out of the plane of the fabric.

Having thus described our invention, we claim:

1. The method of making a textured nonwoven fabric with an unspun and unwoven fibrous surface sculptured into ridges resembling caracul which comprises bringing together a batt comprising retractable fibers and a batt of aeaaser fibers which are relatively non-retractable under the conditions by which the retractable fibers may be caused to shrink, the fibers of each batt being internally intermingled with each other to the exclusion of any substantial comingling of the fibers of one batt with the fibers of the other batt, needling the fibers of one batt into the fibers of the other batt, and causing the fibers of the retractable batt to shrink, whereby the fibers of the nonretractable batt are buckled into a pattern of convoluted arches extending across the face of the fabric, thereby imparting a sculptured and three-dimensional textured effect to the surface of said non-woven fabric.

2. The process according to claim 1 wherein the retractable fibers are thermoretractive and the shrinkage is effected by heating.

3. The process according to claim 1 wherein the retractable fibers are naturally-occurring cellulosic fibers and the shrinkage is effected by treating the material with sodium hydroxide solution of mercerizing strength.

4. The process according to claim 1 wherein the retractable fibers are water-shrinkable and the shrinkage is effected by treating the material with water.

5. The process according to claim 1 where the area shrinkage of the product by fiber retraction is between 15% and 80%.

6. The method of making a textured nonwoven fabric with an unspun and unwoven fibrous surface sculptured into ridges resembling caracul, said fibrous surface being ornamented with an in-depth colored design, which comprises bringing together a batt comprising retractable fibers and a batt of fibers which are relatively nonretractable under the conditions by which the retractable fibers may be caused to shrink, the fibers of each batt being internally intermingled with each other to the exclusion of any substantial comingling of the fibers of one batt into the fibers of the other batt; needling the fibers of one batt into the fibers of the other batt; printing a colored design onto the surface comprising the nonretractable fibers; and causing the fibers of the retractable 8 batt to shrink, whereby the fibers of the non-retractable batt are buckled into a pattern of ridges imparting a sculptured and three-dimensional textured effect to the surface of said nonwoven fabric, said surface bearing a colored design extending in depth down into the retracted fibrous base.

7. The method of making a textured nonwoven fabric with a sculptured plush-like pile surface which comprises bringing together two batts comprising retractable fibers and a third fibrous batt sandwiched therein between the fibers of said third batt being relatively non-retractable under conditions by which the retractable fiber batts may be caused to shrink, the fibers of each individual batt being internally intermingled with each other to the exclusion of any substantial comingling of the fibers of any one batt with the fibers of any other batt; needling together the fibers of all three batts; causing the fibers of the retractable batts to. shrink, whereby the fibers of the non-retractable batt are buckled into a pattern of ridges; and splitting the product through the internal layer of non-retracted fibers to form two sheets of nonwoven fabric, each comprising a retracted fibrous base and a sculptured pile-like fibrous surface.

References Cited by the Examiner UNITED STATES PATENTS 2,401,830 6/1946 Kahil 2872 2,450,948 10/1948 Foster 28-73 2,622,051 12/1952 Hermanson et al. 161128 3,010,180 11/1961 Hoffman 28-722 3,015,149 -1/1962 Foster et, al. 161-63 FOREIGN PATENTS 17,322 4/1934 Australia.

DONALD W. PARKER, Primary Examiner.

H. G. GARNER, L. K. RIMRODT, Assistant Examiners.

Claims (1)

1. THE METHOD OF MAKING A TEXTURED NONWOVEN FABRIC WITH AN UNSPUN AND UNWOVEN FIBROUS SURFACE SCULPTURED INTO RIDGES RESEMBLING CARACUL WHICH COMPRISES BRINGING TOGETHER A BATT COMPRISING RETRACTABLE FIBERS AND A BATT OF FIBERS WHICH ARE RELATIVELY NON-RETRACTABLE UNDER THE CONDITIONS BY WHICH THE RETRACTABLE FIBERS MAY BE CAUSED TO SHRINK, THE FIBERS OF EACH BATT BEING INTERNALLY INTERMINGLED WITH EACH OTHER TO THE EXCLUSION OF ANY SUBSTANTIAL COMINGLING OF THE FIBERS OF ONE BATT WITH THE FIBERS

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