Separable Clasp Containing High-loft, Non Woven Fabric

Abstract

A separable clasp comprising a male fastening member and a female fastening member wherein the female member contains a plurality of upstanding loops and the male member contains a plurality of upstanding functional elements such as hooks or beaded stems which can engage with the loops of the female member. The female member is comprised of a high-loft, nonwoven fabric comprising a substantially continuous backing layer of consolidated flexible adhesive, and a multiplicity of staple length fibers looped outwardly from said backing layer with the ends of such loop imbedded in said backing layer, and said loops being twisted to be in planes extending in the cross direction of the fabric.

Description

DESCRIPTION OF THE INVENTION

During the past several years, the use of a new type of separable clasp has steadily increased in applications where customary buckles, zippers, buttons, or conventional sewing had previously been employed. The clasp is perhaps best represented by those sold under the trade name "Velcro." Such clasps consist of two parts which when placed together resist separation when subjected to a shearing force but which can be readily separated by peeling. One of the parts is typically referred to as the male member and consists of a fabric containing a plurality of upstanding hook shaped elements. The other part of the clasp is the female member and consists of a fabric containing on its surface a plurality of upstanding loops. When the two members are pressed into face-to-face contact the hooks engage the loops and it is very difficult to separate the two parts by means of shearing forces. However, since the hooks are generally prepared from a resilient plastic material, when a peeling force is applied disengagement can be easily effected since, under peeling, the hooks will readily open.

It is an object of the present invention to provide a new separable clasp having characteristics as above-described wherein the female member is inexpensive to manufacture.

With respect to clasps as above-described it is desirable to provide the purchases with a wide selection of clasps with varying degrees of fastening tenacity. Such a selection is desirable since for some applications such as a buckle replacement for trousers a high degree of tenacity is required, whereas for other applications such as a neck closing for gowns where a large amount of stress is not present only a small amount of fastening tenacity is necessary. One manner in which fastening tenacity can be modified is through a modification of the loop structure of the female member. Clasps containing a female member with a high loop density wherein the loops are large generally have higher fastening tenacity than when the female member contains sparsely spaced loops of low height.

Accordingly, it is a further object of the present invention to provide a female clasp member which can be economically prepared by a process which has a high degree of flexibility with respect to changing loop density and loop height.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIG. 1 is a schematic view, in side elevation, of one form of apparatus which can be employed to prepare the high-loft, nonwoven fabrics useful in the present invention;

FIG. 2 is a fragmentary plan view of an illustrative web of base material while still supported on a conveyor belt somewhat simplified and exaggerated for the sake of clarity of illustration, with portions broken away to expose the various layers;

FIGS. 3a and 3b are greatly enlarged, simplified, and somewhat exaggerated sectional views of commercially available male clasp members.

FIGS. 4 and 5 are greatly enlarged, simplified, and somewhat exaggerated sectional views taken in the directions indicated of the fabric prepared with the apparatus illustrated in FIG. 1.

FIG. 6 is an enlarged schematic detail view, in side elevation, of the forming drum and gathering blade of the apparatus shown in FIG. 1;

FIG. 7 is an enlarged schematic side elevational view illustrating, in somewhat idealized fashion, successive stages in the sequence of gathering and looping of individual fibers;

FIG. 8 is an enlarged schematic fragmentary view, taken substantially along the line 8--8 of FIG. 7, here showing a fragment of the fiber web and adhesive pattern with illustrative fibers attached to the adhesive;

FIG. 9 is a simplified schematic view, taken substantially along the line 9--9 of FIG. 7, here showing the fragment of the fiber web and adhesive pattern depicted in FIG. 8 at a later stage in the loop forming sequence;

FIG. 10 is a photographic reproduction of a sample of one form of high-loft, nonwoven material made in accordance with the description contained herein.

FIGS. 11 and 12, respectively, are enlarged photographic reproductions of longitudinal and transverse sectional views of the material shown in FIG. 10;

While the invention is susceptible of various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but, on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as expressed in the appended claims.

Briefly stated, the present invention centers on the discovery that certain of the new high-loft, nonwoven fabrics described in my co-pending application, Ser. No. 31,225, filed Apr. 23, 1970, which is a continuation-in-part of U.S. application, Ser. No. 769,959, filed Oct. 23, 1968, which is now abandoned, are particularly suitable for use as the female member in a separable clasp such as previously described. Particularly useful are those high-loft, nonwoven fabrics described in Ser. No. 31,225 which are comprised of a substantially continuous backing layer of consolidated flexible adhesive and a multiplicity of staple length fibers looped outwardly from said backing layer with the ends of each loop imbedded in said backing layer, and said loops being twisted to lie in a plane extending in the cross direction of the fabric. Female clasp members of such fabrics can be inexpensively prepared. Moreover, the height and density of the loops contained in the fabric can be easily varied and, accordingly, a clasp with any desired degree of fastening tenacity can be conveniently fashioned. Those fabrics described in my aforementioned application wherein the loops vary in height throughout the fabric are particularly preferred here for use as a female member in a separable clasp.

As described in detail in my co-pending application, Ser. No. 31,225, high-loft, nonwoven fabrics can be prepared by taking a base web of fibers, applying to one side of the web an open pattern of adhesive, and then imbedding the fibers in the adhesive. Different procedures can be used in preparing the base web. For example, textile length fibers may be processed through conventional cotton card machinery to produce a carded web for the base web. In such a carded web 50 to 70 percent of the fibers may be oriented substantially parallel with the machine direction. It has been found, however, that the most uniform product has been obtained by using base webs having a higher percentage of the fibers alined with the machine direction such, merely by way of example, as a highly drafted web in which, as a result of the drafting process, 80 to 95 percent of the fibers may be alined with the machine direction.

After obtaining the adhesive containing base material, the high loft, nonwoven fabric is prepared by preforming the subsequent steps of: 1) reactivating the open pattern of adhesive in which the fibers are imbedded and, 2) consolidating the adhesive into a substantially continuous backing layer, while 3) simultaneously looping the portions of the fibers across the open spaces of the adhesive outwardly from the backing layer formed by the consolidated adhesive. The resulting product is characterized by the high loft or deep pile of the loops of fibers which extend outwardly from the adhesive backing. The particular depth of pile or degree of loft of the loops, of course, depends upon a combination of control parameters including, for example: the type and denier of the base fibers; the amount and spacing of the original adhesive pattern; the angle of the gathering balde; and the relative speeds of fiber delivery to and fabric discharge from the gathering blade; as will be discussed below.

Turning now to the drawings, FIG. 1 schematically illustrates an exemplary apparatus for preparing the fabrics useful herein as female clasp members. This apparatus includes a web forming section 10 and an adhesive compacting and fiber looping section 30. As shown in FIG. 1, multiple silvers 11 of textile fibers are drawn from their respective supply cans (not shown) into a draw frame 12 which comprises a series of pairs of grooved rolls 13; the rolls of each pair being driven by appropriate gearing (not shown, but well known in the art) at a peripheral rate of speed somewhat faster than the rate of operation of the preceding pair. Merely by way of example, the pairs of rolls 13 may be adjusted to provide an over-all increase in speed and, therefore, an extent of fiber draw on the order of 15:1 through the draw frame 12. As the juxtaposed slivers pass through draw frame 12, the individual fibers are drafted and spread out to form a flat, striated web of substantially alined fibers as shown at 14. Web 14 is maintained adjacent a supporting conveyor sheet 15 on the surface of which adhesive has been previously applied in a preselected pattern.

In this embodiment, the conveyor sheet 15 comprises an endless conveyor belt treated on at least its upper surface with a release agent. One example of such a belt comprises woven glass fiber with a surface coating of tetrafluoroethylene resin. Other examples of release coatings are well known, and comprise such materials as silicone, fatty acid metal complexes, certain acrylic polymers, and the like. Heat resistant films or thin metal sheets treated with release agents may also be used as the carrier sheet.

Prior to the time the web 14 is picked up by the belt 15, the latter has imprinted on its release-treated surface a pattern of flexible, thermoplastic adhesive such as is shown at 16 in FIG. 2. It will be understood that, as shown in FIG. 1, the adhesive is actually on the underside of belt 15 which becomes the upper surface after passing around roll 17, at which time the adhesive pattern 16 directly contacts the fiber web 14. The pattern is shown as being visible in FIG. 2 only for illustrative purposes.

The belt 15 is fed around roll 17 at a speed slightly in excess of the delivery speed of the final pair of rolls 13 of draw frame 12 in order to maintain web 14 under slight tension, whereby the individual highly drafted fibers are retained in their alined and tensioned condition. Drive rolls 18, 19 are rotated (by suitable drive means, not shown) to drive belt 15 at a speed sufficient to maintain the proper tension on the web 14.

In the method shown for applying adhesive, the belt 15 is fed through a nip formed between a printing roll 20 and a back-up roll 21 maintained in very light pressure engagement therewith. The surface of printing roll 20 is provided with an intaglio pattern to which adhesive may be supplied in various ways well known to those skilled in the art. For example, in patent application, Ser. No. 769,959, a system is schematically disclosed wherein the lower portion of the printing roll 20 picks up adhesive directly from a dip pan, with excess adhesive being removed by a doctor blade, thus leaving only the intaglio patterned surface filled. However, in the practice of the present invention, it has been found that more satisfactory results are obtained by pumping or otherwise transferring adhesive 22 from a supply pan 23 to a reservoir located immediately above an inclined doctor blade 24--the reservoir being defined in part by the upper surface of the inclined doctor blade and the adjacent portion of the rotating peripheral surface of the printing roll 20. Thus, as the printing roll 20 rotates (in a counterclockwise direction as viewed in FIG. 1), the intaglio patterned surface thereof is filled with adhesive 22, excess adhesive is removed by the doctor blade 24, and a metered amount of adhesive is then transferred to the underside of release coated belt 15 in a preselected pattern. The pattern shown in FIG. 2 is in the form of an open diamond pattern of adhesive.

The particular dimensions of the intaglio pattern employed and, indeed, the actual pattern itself, are not critical in the preparation of fabrics useful as female clasp members. Thus, patterns other than the illustrative diamond pattern hereinabove referred to can be utilized as will hereinafter be discussed. For illustrative purposes, however, it is noted that excellent results have been achieved where a diamond pattern was employed in which adjacent lines of adhesive were spaced apart in both directions by one-half inch, and wherein the intaglio printing roll 20 had adhesive cells or lines 0.010 inch deep and 0.050 inch wide.

Since the surface of belt 15 is treated with a release coating, the adhesive remains substantially on the surface with no penetration therein and is preferably in a somewhat tacky condition. The printed belt is drawn from the printing nip around roll 17 positioned closely adjacent the output end of draw frame 12 and, as stated above, at a speed slightly in excess of the delivery speed of the last two rolls in the draw frame. The web 14 emerging from the draw frame 12 is deposited on the tacky adhesive 16 on belt 15 and held in tensioned engagement therewith by the adhesive and the above-mentioned speed differential. This continuous tension prevents the fibers in the web from losing their highly-drafted and alined condition.

Following deposit of web component 14 on the adhesive printed belt 15, the belt is drawn around a heated curing drum 29 where fusing and curing of the adhesive is substantially completed while the web 14 is maintained in firm contact therewith to bond the individual fibers. To insure effective heating and fusing of the adhesive, it is desirable that travel of the combined belt and web be around a substantial portion of the drum 29. In the illustrated embodiment, a fly roll 29a is positioned to apply tension on the combined belt and web as they travel around the drum 29 to insure complete imbedment of the fibers in the adhesive. The fibers of the web 14 are thus bonded together while retaining their highly drafted and substantially alined condition in the particular pattern in which they were deposited on the open pattern of adhesive 16 printed on the belt 15.

After leaving the fly roll 29a, the combined web 14 and belt 15 are preferably passed over the drive roll 19, which also serves as a cooling drum to set the adhesive. The bonded web 14 is stripped from the release-coated surface of the belt 15 by the guide roll 31 as the web leaves the cooling drum 19.

While various well-known adhesives may be employed in the foregoing process, advantages reside in the use of plastisols, which are colloidal dispersions of synthetic resins in a suitable organic ester plasticizer, and which, under the influence of heat, provide good binding power while remaining soft and flexible. While many adhesives of this type are known, those found particularly useful for incorporation in the product of this invention include vinyl chloride polymers, and copolymers of vinyl chloride with other vinyl resins, plasticized by organic phthalates, sebacates, or adipates. These provide a fast curing plastisol adhesive characterized by relatively low viscosity, low migration tendencies, and minimum volatility. Such adhesives remain soft and flexible after curing, and can be reactivated by subsequent heating.

It has been found that other adhesives may be employed in the process--for example, organisols utilizing resins such as the vinyl chloride polymers and copolymers. Furthermore, still other adhesives may be employed provided that they satisfy specified characteristics in the base web produced in the web forming section 10, and in the finished fabric produced in the adhesive compacting and fiber looping section 30 (FIG. 1). In general, such adhesives should be applied to the base web by procedures which will not disarrange the fibrous structure of the web; such adhesives should heat-set at temperatures below the degradation temperature of the fibers in the base web 14 to secure bonding of the fibers to the adhesive; such adhesives should be reactivatable in the subsequent adhesive gathering and consolidation stage of the process; and such adhesives should form a flexible backing layer for the finished fabric and should strongly bond the fiber loops in place. For example, emulsions of thermoplastic resins such as acrylics and rubber-like compounds, illustratively ABS, have the requisite properties to serve as the bonding adhesive for the web 14.

In carrying out the illustrated process, the base material, made as heretofore described and comprising a web 14 of highly drafted fibers imbedded in an open adhesive pattern, is fed into the adhesive consolidating and fiber looping section 30 of the apparatus shown in FIG. 1. As shown here, the web 14 continues directly from the web forming section 10 to the consolidating and looping section 30. It should be appreciated, however, that the web 14 discharged from section 10 could be rolled up for storage or transport and then subsequently unrolled and fed into section 30.

As illustrated in FIG. 1, the web 14, while still under tension, is fed around an idler roll 32 and on to the surface of a heated forming drum 37. In its preferred embodiment, the drum 37 is made of metal with a highly polished, chromium plated surface which is heated and maintained at a temperature of approximately 250.degree. F. Also, the web 14 is arranged to travel a substantial distance around the drum 37 with the open pattern of adhesive 16 in contact with the heated rum surface. As the web 14 is fed onto the drum 37, the heat from the drum surface reactivates and softens the adhesive printed on the underside of the web, causing it to be tacky and to adhere slightly to the drum surface, thereby maintaining the web under constant tension. The drum temperature, which is maintained at about 250.degree. F., is, however, maintained below the melting point of the adhesive to prevent dispersion of the adhesive into the fibers of the web.

Further with respect to the illustrated process, the web 14 of fibers and softened adhesive is reformed by the cooperative action of the drum 37 and a gathering blade 38 having a flat edge 39. The blade edge 39 operates to consolidate the open adhesive pattern 16 into a substantially continuous backing layer of adhesive, while simultaneously looping the fibers of the web outwardly from between the open spaces in the original adhesive pattern. The reformed and consolidated material 40 then leaves the blade edge 39 and moves onto a flat take-off surface 41 and a discharge conveyor 52.

The fabric can be taken from the discharge conveyor and then cut into appropriate sizes for use in a clasp as the female member in combination with a suitable male member. FIGS. 3a and 3b illustrate, in cross-section, two commercially available types of male members, though it is to be understood that the high-loft, nonwoven female members described herein can be used in combination with any male member which contains functional elements which will engage with the loops of the high-loft, nonwoven fabric to form a clasp having the separation characteristics previously described. The male member shown in FIG. 3a is illustrative of the "Velcro" type of fastener and contains a base sheet of material containing, as the functional elements, a plurality of upstanding hooks of a flexible resilient material extending generally vertically from the base sheet. The male member shown in FIG. 3b illustrates a further type of commercially available male member. As can be seen the functional elements of this member are beads contained on the ends of resilient stems which vertically extend from a base sheet of material.

Turning now to FIGS. 7-9, the method of making the high-loft, nonwoven fabric 40 useful as the female member will be explained in greater detail in connection with an illustrative sequence of the gathering and looping of a single fiber of the web 14 and the consolidation of its two original points of adhesive attachment in the pattern 16. As seen in FIG. 8, the fiber has a portion P which extends across the open space of the diamond pattern of adhesive 16 from point A to point B where it is imbedded in the adhesive. Referring to FIG. 7, the series of views in this Figure illustrates how the portion P of the fiber is formed into a loop; viz., when point A being carried around the heated drum 37 impinges against the gathering blade edge 39, its forward motion is halted and it is scraped along the surface of the drum, while point B continues to advance with the drum surface since, due to its softened and tacky condition, it adheres to the smooth drum surface. As point B advances relative to point A, the portion P of the fiber between points A and B is caused to bow outwardly from the drum surface. Finally, point B overtakes point A and these points of adhesive are substantially consolidated as seen in FIG. 9. In the meantime, fiber portion P has been looped outwardly from the drum surface.

It will, of course, be understood that while looping of fiber portion P is occurring, additional adhesive points C-D, etc., travelling around the drum 37 impinge against the gathering blade edge 39 causing a consolidation of these adhesive points and looping of their intermediate fiber portions P.sub.1 as is also indicated in FIG. 9. This occurs simultaneously at all points across the web at the blade edge, producing a substantially continuous backing layer of adhesive from which extends the multiplicity of loops formed by the fibers of the base web. The thus formed substantially consolidated layer of adhesive is carried away from the blade edge 39 along the take-off surface 41 and provides a substantially continuous backing layer for the outwardly looped fibers, thus producing the fabric 40.

While in the process for forming the high loft, nonwoven fabric illustrated herein, it is desired to achieve substantially complete consolidation of the adhesive into a continuous backing layer, in practice it has been found that the degree of consolidation varies randomly throughout the substantially continuous backing and, therefore, it is possible to draw the fabric slightly, thus producing a substantially continuous adhesive backing layer with random openings therethrough. Since complete consolidation, while desirable, is not necessarily always attained, the degree of consolidation is defined herein, and in the appended claims, in terms such as "to consolidate" the "open adhesive pattern into a substantially continuous adhesive layer." Thus, those skilled in the art will appreciate that terms such as "consolidate" as used herein and in the appended claims are intended to connote an arrangement for consolidating or compacting the open adhesive pattern into a substantially continuous adhesive backing layer--albeit that such "substantially continuous backing" may have, and often will have, small random fissures and gaps therein.

Another important characteristic of the illustrated fabric is that not only does each fiber portion P loop outwardly from the drum surface but, also, as the loop is formed it turns, reaching a position in the fabric 40 generally perpendicular to the direction of the original alinement of fiber portion P. Thus, the fiber loops arrange themselves so that the plane of each loop is substantially normal to the original fiber alinement shown in FIG. 8. The reason for the loop twisting as it is formed may be explained by this observation. If two spaced points of a single fiber not in a web are brought together, it has been observed that the fiber will form a loop and, as the loop is formed, it twists towards a position of minimum internal stress, turning through an angle which tends to approach 180.degree. F. In carrying out the method of the invention, because of the great number of fibers in the web and their proximity one to another, each fiber loop engages the neighboring fiber loops with the result that all the loops are blocked from turning beyond the plane substantially normal to the machine direction, and are constrained in that position by the interference between the loops.

The fact that the fiber loops are constrained from achieving a condition of minimum internal stress is felt to be a contributing factor which renders the illustrated fabrics particularly useful as female members. In such an unrelaxed condition, the loops tend to be very resilient and readily engageable with the functional element of the male fastening member. In this respect, it should be noted that in actual use the female member should be positioned such that the plane of the loops is at substantially a right angle with respect to the direction in which shear forces are anticipated. For example, when the clasp is used as a belt buckle replacement, the female member should be secured to the belt, e.g., by adhesive attachment, such that the plane of the loops, i.e., the cross machine direction of the fabric as made, is substantially perpendicular to the length of the belt.

The above-discussed arrangement of the loops normal to the machine direction is clearly evidenced by reference to FIG. 11, which is a reproduction of an enlarged photograph of a transverse sectional view of fabric made in accordance with the method discussed above. The fiber loops and their attachment to the adhesive layer appear in FIG. 11, while in FIG. 12, which is a sectional view taken parallel to the machine direction and, thus, at right angles to FIG. 11, the fiber loops are viewed from their edge and for the main part are not discernible in this view as loops.

It is important to note, however, that throughout the fabric the heights of the fiber loops vary according to the spacing between the points of attachment of each fiber to the open adhesive pattern in the base web. Referring to FIGS. 4, 8 and 9, it will be seen, for example, that the loop formed by the fiber portion P.sub.1 between the points of adhesive attachment C, D will have a lower height than the loop formed by the longer fiber portion P between the points A, B. On the other hand, however, successive loops in adjacent diamonds, when viewed in a vertical section taken along the machine direction (FIG. 5), will have the same height since the fiber length P will remain the same between successive sets of points A, B. This results in a dense fabric with the lower loops supporting and filling around the higher loops and the top surface of the fabric being formed by the tops of the higher loops.

While a fabric such as above-discussed wherein the loops vary in height regularly throughout the fabric is preferred for use as a female clasp member since the lower loops tend to maintain the higher loops in an upright position where they can be most readily engaged by the functional element of the male member, fabrics with a uniform loop height can be employed. Similarly, fabrics with varying loop heights prepared by using adhesive patterns other than the above-illustrated diamond patterned are useful as female clasp members. The previously referred to co-pending application, Ser. No. 31,225, contains numerous illustrations of adhesive patterns which can be used in order to prepare fabrics with various surface textures and reference is directed thereto.

The loop height of the high-loft, nonwoven fabrics useful as female clasp members is important in achieving a desired degree of fastening tenacity. As explained in detail in Ser. No. 31,225, a major factor affecting the loop height is the spacing between points of fiber adhesive attachment A-B, C-D, etc (FIG. 8). Greater spacing will result in higher loop heights. Moreover, to obtain maximum thickness (loop height) of a fabric with a given adhesive pattern, the blade edge angle .alpha. (FIG. 6) should be such as to produce not only sufficient consolidation of the adhesive layer to provide good fiber attachment throughout the fabric but, also, sufficient consolidation to insure the production of a maximum number of full height fiber loops. Thus, the blade angle should not be so great as to skive the web off the roll nor so low as to prevent the fabric from flowing evenly and smoothly off the drum surface.

The combination of a diamond adhesive pattern such as illustrated in FIG. 2 wherein adjacent line of adhesive are spaced about 0.75 inch--0.5 inch apart and a blade edge angle .alpha. of about 45.degree.-53.degree. has been found to provide a fabric which is useful as a female clasp member where high fastening tenacity is required. Where a fabric with a somewhat lesser degree of fastening tenacity is wanted, such can be easily obtained by progressively increasing the blade angle, e.g., up to about 60.degree.. Less tenacity can also be achieved by decreasing the adhesive line spacing e.g., down to about 0.25 inch, in which case blade angles of about 17.degree.-34.degree. inch are particularly useful. Thus, by appropriately varying either or both the blade angle or adhesive pattern, a clasp can be fashioned with a desired degree of tenacity.

As again fully explained in co-pending application, Ser. No. 31,225, a further method by which the structure of the fabric prepared by the process illustrated herein can be varied is by controlling the take away speed ratio of the fabric from the blade edge (i.e., the ratio of the surface speed of the drum 37 to the actual take away speed). Thus, increasing the take away speed ratio serves to increase the density of the fabric produced. In combination with the above-discussed adhesive patterns and blade angles, a take away speed ratio of about 10:1 - 20:1 is generally useful while most fabrics will be prepared with a ratio of about 13:1 - 17:1. The higher ratios are associated with the preparation of female members for use in clasps having greater fastening tenacity.

The amount of adhesive used in forming the fabric, the type and amount of fiber employed, and the length and denier of the fiber can also be important in obtaining an appropriate female clasp member. In general the amount of adhesive used is based on the amount of fiber present and should be sufficient to effect completely secure attachment of the fiber ends. On a weight basis, the adhesive should be present in an amount at least equal to the fiber weight and, preferably, at least equal to about twice fiber weight. The amount of fiber used directly influences the bulk of the fabric. For use as a female member in a clasp, fabrics with a basis weight of about 200-500, and preferably 300-400, grms./yd..sup.2 are useful, and an amount of fiber should be employed to achieve this weight, keeping in mind that certain process conditions such as take away speed can also influence fabric weight.

Concerning fiber type, fibers prepared from a thermoplastic polymer such as a polyester are preferred, but other fibers such as those of regenerated cellulose, acrylics, and polypropylene can also be used. Polyesters, however, are preferred since they are readily available at high tenacity and the loops of such fibers can be heat set in their looped shape on the forming drum 37 and are thus less susceptible to collapse or distortion on repeated openings and closings of the clasp. While, at a minimum, fiber length should be such that individual fibers span over adjacent lines of adhesive, it is preferred that individual fibers span over three or more adhesive lines in order to enhance fiber securement in the fabric. To this end, fibers with a length of about 2-4 inches are preferably employed. The denier of useful fibers is also important since fiber loops of very thin fibers, e.g., less that about 1.5 denier, tend to break as the clasp is repeatedly opened and closed. Fibers having deniers in the range of about 4-8 are preferred. While fibers with higher deniers, e.g., up to about 15, can be used, it should be noted that, for a given fabric weight, the use of high denier fibers reduces the number of fibers and, accordingly, the number of loops which are present.

The following example illustrates the preparation of a high-loft, nonwoven fabric which can be used as a female member in a separable clasp containing a male and female member.

EXAMPLE

The apparatus illustrated in FIG. 1 was used. The base web was made from 3 inch staple, 6 denier polyester fiber and had a weight as it came off the curing drum 29 of 27 grams./sq.yd. This weight was made up of 8 grams of fiber and 19 grams of adhesive in the base web material. The adhesive was a plastisol containing 100 parts Geon 135 polyvinyl chloride resin, 60 parts dioctyl phthalate plasticizer, and 2 parts Cab-O-Sil pyrogenic silica. The adhesive was applied in diagonal lines one-half inch apart in both directions forming a diamond pattern in which the lines of adhesive were approximately 0.010 inch deep and 0.050 inch wide. In the first stage of forming the base web 14, the curing drum 29 was operated at 350.degree. F. and at a surface speed of 50 ft./minute. The base web 14 was then carried at 50 ft./minute lineal speed to the heating drum 37 which was operated at 320.degree. F., and around the drum to the gathering blade 38. The lip of the take away surface 41 was positioned tight against the blade edge and less than one thirty-second inch below the corner of the blade edge. The blade angle .alpha. was 53.degree. and the take away speed was 15:1.

The fabric so prepared is suitable for use as the female member in a separable clasp, and clasps containing this fabric can be used in the many applications where clasps of this type are finding increasing use. Due to the fact that the female member described herein is inexpensive to prepare, clasps containing such are particularly suitable for use in applications where adjustability such as that provided by a belt is desired. Being comparatively inexpensive, adjustability can be achieved by using a long strip of this female member in combination with only a short strip of the normally more expensive male member without an appreciable increase in clasp cost compared with an unadjustable clasp wherein both male and female members are short strips. Thus, clasps containing the present high-loft, nonwoven fabric are expected to find considerable use in applications such as gown closing means where adjustability of the gown to fit various sizes of people is a necessary requirement.

Claims

I claim as my invention:

1. In a separable clasp comprising a male fastening member and a female fastening member, said female member containing a plurality of loops and said male member containing a plurality of functional elements which engage with the loops of the female member such that it is difficult to separate the clasp by means of a shearing force but that a peeling force can readily effect separation, the improvement wherein the female member is comprised of a high-loft, nonwoven fabric comprising a substantially continuous backing layer of a consolidated open pattern of flexible adhesive, and a multiplicity of staple length fibers, each of which are individually looped outwardly from said backing layer with the ends of each loop embedded in said backing layer, and said loops being twisted to be in planes extending in the cross direction of the fabric.

2. The separable clasp of claim 1 wherein the loops of the high-loft, nonwoven fabric vary in height throughout the fabric.

3. The separable clasp of claim 1 wherein the loops of the high-loft, nonwoven fabric vary regularly in height throughout the fabric.

4. In a separable clasp comprising a male fastening member and a female fastening member, said female member containing a plurality of loops and said male member containing a plurality of functional elements adapted to engage the loops of the female member such that it is difficult to separate the clasp by means of a shearing force but that a peeling force can more easily effect separation, the improvement wherein the female member is comprised of a high-loft, nonwoven fabric comprising a substantially continuous backing layer of consolidated flexible adhesive and a multiplicity of staple length fibers each of which are individually looped outwardly from said backing layer with the ends of each loop embedded in said backing layer, each of said loops being twisted to lie in planes extending in the cross direction of the fabric, said loops varying in height regularly throughout the fabric and presenting a plurality of loops extending above the average height of all of said loops, said loops extending above said average height being adapted to readily engage said functional elements of said male member when said members were pressed into mutual engagement.

5. In a separable clasp comprising a male fastening member and a female fastening member, said female member containing a plurality of loops and said male member containing a plurality of functional elements adapted to engage the loops of the female member such that it is difficult to separate the clasp by means of a shearing force but that a peeling force can more easily effect separation, the improvement wherein the female member is comprised of a high-loft, nonwoven fabric comprising a substantially continuous backing layer of consolidated flexible adhesive and a multiplicity of staple length fibers each of which are individually looped outwardly from said backing layer with the ends of each loop embedded in said backing layer, each of said loops being twisted to lie in planes extending in the cross direction of the fabric, said loops varying in height regularly throughout the fabric, the lower of said loops tending to fill around and thereby support the higher loops so that the top surface of the fabric is formed by the tops of the higher loops, the higher loops being adapted to readily engage said functional elements of said male member when said members are pressed into mutual engagement.

6. The separable clasp of claim 5 wherein said fibers are heat set in their looped condition such that said loops are less susceptible to collapse or distortion due to repeated openings and closings of said clasp.

7. The separable clasp of claim 6 wherein said heat set fibers are polyester.

8. The separable clasp of claim 5 wherein said fibers have a denier within the range of about 1.5 to about 15.

9. The separable clasp of claim 8 wherein said fibers have a denier within the range of about 4 to about 8.

10. In a separable clasp comprising a male fastening member and a female fastening member, said female member containing a plurality of loops and said male member containing a plurality of functional elements adapted to engage the loops of the female member such that it is difficult to separate the clasp by means of a shearing force but that a peeling force can more easily effect separation, the improvement wherein the female member is comprised of a high-loft, nonwoven fabric comprising a substantially continuous backing layer of consolidated flexible adhesive and a multiplicity of staple length fibers each of which are individually looped outwardly from said backing layer with the ends of each loop embedded in said backing layer, each of said loops being twisted to lie in planes extending in the cross direction of the fabric, said loops varying in height regularly throughout the fabric, and occurring in sufficient density whereby the lower of said loops fill around and maintain the upper loops in a generally perpendicular position relative to the plane of said backing layer, said functional elements of said male member being readily engaged with said higher loops when said members are brought into mutual engagement subject to a lower contact pressure and engaged with said lower loops when said contact pressure is increased.