GB2027794A - Touch and close fasteners - Google Patents

Abstract

A method for forming strip material adapted to be cut into lengths to provide parts of touch and close fasteners, comprising moving two strips 26 around guides 28, 30 and along parallel paths between belts 32, pressing and bonding the bights 17 of U-shaped lengths of multiple parallel monofilaments 36 first into one and then the other of the strips at the guides, severing the monofilaments between the strips using knife 44, and then heating their severed ends at platens 47 to form heads 18. <IMAGE>

Description

SPEClFlC.'4TlON ao-,os This inven':on relates to fasteners of the type includirg eiids parts, at least one of which parks incudes a field of headed projections adap*:c-d ta releasably interengage with the other pare, and in one aspect to such fasteners in which both parts include an array of headed projections which can be simultane ously engaged without regard to the relative angular relationship of the arrays.

The present invention provides an elongate strip material from which a length may be severed that forms at least one part of a fastener, which strip material includes a back ing supporting a multiplicity of headed projec tions adapted to releasably engage a second part of the fastener. One length of the strip material may be used with a length of conven tional fibrous material to form a fastener, or a iastealer can be formed from two lengths of the strip material which has its projections disposed in an array which affords firm simul taneous engagement of the projections in any angular orientation of the arrays on two lengths of the strip material.

The present invention also includes a method for rapidly producing the strip materi al at substantially less cost than the cost to cast a similarly shaped part of a fastener. Also the method provides great versatility in the length and head size of the projections and the arrays in which they are disposed as may be desired for specific applications of the strip material.

The strip material according to the present invention includes a backing comprising a uniform non-fibrous polymeric bonding layer a a predetermined thickness and having an exposed major surface, and a plurality of elongate flexible resilient generally U-shaped monofilaments of longitudinally oriented poly meric material and a diameter less than said predetermined thickness, each having a cen tral bight portion firmly bonded in the bond ing layer (i.e. by being embedded and ad hered or fused in the bonding layer) so that stem portions at the ends of the central por tion project generally at right angles to the backing. Each stem portion has an enlarged head at its terminal end adapted to engage the other part of the fastener.When the parts of the fastener are two lengths of the strip material each head has a cam surface oppo site the backing from which it is supported adapted for engagement with the cam surface on the head of one of the monofilaments of the other length of strip material to produce side deflection of at least one of the engaging heads upon movement of the heads toward each other. The U-shaped monofilaments are bonded to the backing with their central bight portions generally parallel and disposed in a series of generally parallel rows with the Ushaped elements along and between the rows spaced to position their stem portions in arrays which afford movement of the heads of the other length of strip material therebetween, but only upon resilient displacement of most of the heads.

The method according to the present invention for forming the strip material comprises the steps of moving two strips (which strips are incorporated in the backings for the strip material produced) from generally opposite directions around parallel spaced arcuate guides at a bonding station and away from the guides in the same direction along parallel paths. Spaced parallel lengths of the polymeric monofilaments are fed between the spaced guides from their sides opposite the parallel paths and in a direction generally parallel to the parallel paths. Longitudinal striking bars disposed generally transverse of the paths alternately press the monofilaments first into engagement with one and then the other of the backing strips as the strips are moved around the arcuate guides.The striking bars thus press generally U-shaped lengths of each filament against the strips where the U-shaped lengths are bonded (by means described in the next paragraph) in positions spaced longitudinally along the moving strips with the lengths of the monofilaments between the Ushaped segments extending generally normally between the strips. The monofilaments are then severed midway between the strips to form two brush-like halves. The newly severed terminal ends of the monofilaments projecting from the strips are then heated to form heads having arcuate cam surfaces opposite the strips, and the resulting strip materials can then be severed into short lengths and used as parts of fasteners.

Where the strip comprises a surface bonding layer of a heat softenable material, it may be heated on the guides until the bonding layer is sufficiently soft that the U-shaped lengths of the monofilaments will be embedded in the bonding layer by the striking bars. Alternatively the monofilaments may be bonded by coating the strip with a bonding layer of adhesive onto which the U-shaped segments are pressed.

When the polymeric material of the monofilaments is the same as the material of a heat softened bonding layer into which the monofilaments are pressed, the monofilaments can be caused to fuse in the bonding layer so completely that in some cases portions of the monofilaments are hard to separately identify from the material of the bonding layer.

With this method of production the spacing between the stems transverse of the strip can be controlled by the spacing between the monofilaments being fed between the arcuate guides. The spacing between the stem portions of the U-shaped lengths of monofilament are controlled by the thicknesses of the blades which press the filaments against the strip.

The spacing between pairs of rows of the stems longitudinally of the strip is controlled by the timing relative to the speed of the strip at which the blade presses the monofilaments into engagement therewith. Also the lengths of the stems are controlled by the spacing between the strips along their parallel paths and the diameters of the heads formed on the stem portions are controlled by the amount of heat applied to the stems.

By this production method the~ rows of stems can be disposed in a rectarigular array with the cross rows and longitudinal rows respectively normal and parallel to the edges of the strip, and with all of the stems equally spaced along each row. With such an even rectangular array, however, it has been found that the heads of the parts engage most securely when the rows of stems of the two parts are disposed at some angle to each other as opposed to being parallel, this being particularly true with respect to shearing of the parts in directions parallel to their backings and to the rows.Thus it may be desirable to do one or more of the following: (1) vary the spacings of the stems along the rows extending longitudinally of the strip by use of the techniques described above so that at least when the rows of two parts with such varied spacing are engaged at right angles to each other a greater separating and shear strengths will be developed, (2) dispose the rows of U-shaped filaments so that their stems are not aligned normal to or parallel with the edges of the strip so that when a user engages two parts cut from the strip with their edges aligned (as he would normally be expected to do) the rows on the parts will cross each other to develop the maximum strength in the fastener both in tension and shear (this can be done by orienting all or portions of the striking bars at an acute angle with respect to the edge of the strip moving through the tacking station), or (3) shift successive rows of U-shaped filaments slightly in a direction transverse of the strip so that the stems of successive rows will not be aligned and thus will not permit shearing longitudinally of the strip (this can be done by varying the position of the spaced filaments fed to the tacking station transversely of the strip).

The stem portions in the U-shaped monofilaments must be sufficiently long and flexible so that upon engagement of the parts the heads on each part can move to find spaces between the heads on the other part and permit simultaneous movement of the heads past each other in any orientation of the rows of stems of the parts relative to each other. To permit such movement the stems should have a length which is at least equal to the maximum diameter of the head, and preferably in the range of about 2-1/4 to 3 times the maximum diameter of the head.

The invention will be further described wi"th reference to the accompanying drawing wherein like numbers refer to like parts in Cile several views, and wherein: Figure 1 is a plan view of one of the parts of a fastener made from strip material according to the present invention; Figure 2 is an enlarged fragmentary view in perspective of the part of Fig. 1; Figure 3 is an enlarged section taken approximately along line 3-3 of Fig. 1; Figures 4 and 5 are both side views showing the fastener according to the present invention with its parts engaged which illustrate two different orientations of the rows of projections during engagement; Figure 6 is a schematic view illustrating a method according to the present invention for making strip material from which the part of Fig. 1 is cut;; Figures 7, 8, 9 and 10 illustrate alternate embodiments of the strip material according to the present invention; and Figure 11 illustrates an alternate embodiment of a fastener in which a length of the strip material according to the present invention can be used.

Referring now to Figs. 4 and 5 of the drawing, there is illustrated a fastener 1 0 which comprises two identical parts 11 (one of which is illustrated in Figs. 1, 2 and 3), which are lengths severed from strip material 24 according to the present invention.

Each part 11 includes a backing 1 2 comprising a non-fibrous polymeric bonding layer 1 5 in which is bonded a plurality of flexible resilient generally U-shaped monofilaments (Figs. 2 and 3) of longitudinally oriented polymeric material. Each monofilament 1 3 comprises two stem portions or stems 14 projecting at generally a right angle from an exposed major surface of the bonding layer 10 and extending from the ends of a bight portion 17 of the monofilament 1 3. As can be seen in Figs. 2, 3 and 4, the bight portions 1 7 in each part 11 lie generally parallel to and are embedded in the material of its bonding layer 1 5. A generally hemispherical head 1 8 is formed at the free end of each stem 1A.

The heads 1 8 have arcuate generally semispherical cam surfaces 20 opposite the backing 1 2 adapted for engagement with the cam surfaces 20 on the heads 1 8 of the other part 11 to produce the necessary side deflection of the stems 14 upon movement of the heads 18 toward each other with the backings 12 2 generally parallel so that the heads 1 8 may simultaneously pass to engage the parts 11 in the manners illustrated in Figs. 4 or 5.Also the heads 1 8 each have a generally planar latching surface 21 extending radially outwardly of the stem 14 and adapted to engage the latching surface 21 on one of the heads 1 8 of the other part 11 to retain the engaged heads 1 8 in engagement until a predetermined force is applied to separate the parts 11. Since engagement of the latching surfaces 21 do not produce as much camming action as engagement of the cam surfaces 20, the configuration of the heads 1 8 desirably requires a force to engage the parts 11 which is not much larger than the force required to separate them.

The monofilaments 1 3 are bonded to the backing 1 2 with their bight portions 1 7 parallel to each other and to parallel edges 1 9 of the backing 1 2. The bight portions 1 7 of groups of the monofilaments 1 3 are disposed side by side to form a series of generally parallel rows, with each row of monofilaments 1 3 providing two corresponding rows of aligned stem portions 1 4 and heads 1 8 which are disposed generally normal to the edges 19.

The stem portions 14 on each U-shaped monofilament 1 3 and the adjacent stem portions 14 along the rows (i.e. in a direction normal to the length of the bight portions 1 7 and to the edges 19) are spaced apart so that the head 1 8 of another monofilament 1 3 may be positioned therebetween without substantially spreading the stems 14. The heads 1 8 on these stems 14, however, are spaced apart a distance less than their own diameter so that a head 1 8 on a mating part 11 may only move therebetween upon separation of the heads 18 by resilient deflection of the stems 14.

The heads 1 8 of adjacent rows of the Ushaped monofilaments 1 3 are spaced apart a distance somewhat greater than the distance between the heads 1 8 of each U-shaped monofilament or the distance between adjacent heads 1 8 along each row to provide the aforementioned advantage with respect to the shear strength of the fastener 1 0. This larger spacing is experimentally determined so that it is sufficient to afford movement of the heads 1 8 on each of the parts 11 simultaneously past each other with the backings 1 2 of the parts 11 maintained parallel to each other and with the rows of U-shaped monofilaments 1 3 in any relative angular orientation.This spacing, however, is generally no greater than that required for such engagement so as to provide the maximum disengagement force for the parts 11.

In addition to the surface layer 15, the backing 1 2 as illustrated includes a layer of pressure sensitive adhesive 22 on the surface of the bonding layer 1 5 opposite the Ushaped monofilaments 13, and a removable release liner 23 over the layer of adhesive 22.

The layer of adhesive 22 affords firm adhesion of the parts 11 to rigid surfaces to be releasably joined thereby.

Fig. 6 schematically illustrates a method according to the present invention for continuous forming of the strip material 24 from which may be cut desired lengths to provide the parts 11. Two strips 26 of heat softenable polymeric material to be incorporated as the bonding layer 1 5 in the backing 1 2 extend from generally opposite directions from supply rolls 27, each extending from the supply roll 27 around a guide roller 28 mounted via a friction clutch to provide a desired tension in the strip 26.From the guide roller 28, each strip 26 passes onto an endless support belt 29 (such as of aluminum) extending around the arcuate surface 30 of a platen 31 heated to a temperature adapted to soften the polymeric strip 26 and between one cushion belt 32 of a commercial extrusion take-off device 33 (e.g. a Model No. 3-650-VT as manufactured by Teledyne Farris Eng. Co. Palisades Park, New Jersey). The portions of the support belts 29 passing around the adjacent ends of the heated platens 31 provide arcuate spaced parallel support surfaces around which the strips 26 are moved onto parallel paths between portions of the support belts 29 passing between the cushion belts 32 of the take-off device 33.

A plurality of flexible resilient monofilaments 36 are guided between the adjacent ends of the platens 31 by a guide 37 comprising a plurality of small parallel side by side evenly spaced tubes through each of which one of the monofilaments 36 is positioned. A pair of longitudinal striking bars 39 are mounted on opposite sides of the path for the monofilaments with each one being mounted for reciprocal motion in a guide 40 by activation of a driving means such as an air cylinder 41 between a retracted position (shown for the upper striker bar 39) spaced from the monofilaments 36, and a pressing position (shown for the lower striker bar 39) at which an end surface 42 on the striker bar 39 presses the monofilaments 36 into the softened polymeric strip material 26 on the support belt 29 along the curved surface of the heated platen 31. The end surfaces 42 of the striker bars 39 are convex to match the adjacent contour of the platen 31, have a width sufficient to contact all of the monofilaments 36 guided between the platens 31, and have thicknesses adapted to form U-shaped lengths of the monofilaments 36 having base segments of a predetermined width when they press the monofilaments 36 into the strips 26 so that the base segments are embedded in and bonded to the strips 26.

The striker bars 39 are controlled to alternately strike the platen 31 so that the monofilaments 36 will be bonded first to one and then to the other of the strips 26 with the lengths of monofilaments 36 therebetween extending generally normal to their opposing surfaces to form a laminated structure 43.

The operational frequency of the striker bars 39 and/or the speed of the take-off device 33 are regulated to provide a desired spacing between the U-shaped lengths of monofilaments bonded to the strips 26. After the laminated structure 43 has passed through the take-off device 33 so that the polymeric strips 26 have again solidified, the laminated structure 43 engages a sharp transversely positioned blade 44 which is parallel to and midway between the opposing surfaces of the strips 26 in the structure 43. The blade 44 is reciprocated, as by a saber saw drive mechanism 45, to cut the laminated structure 43 into two brush-like halves 46, each of which halves 46 comprises one of the strips 26 and a multiplicity of generally U-shaped lengths of the monofilaments 36 having projecting end portions.Each half 46 is then guided along a separate path past a heated platen 47 which heats the air at the ends of the projecting end portions of the monofilaments 36 to cause those ends to soften and form into generally hemispherically shaped heads. From the platens 47 the headed halves 46 are guided to devices which wind them on reels 49 ready to be cut to length for use as parts 11 for fasteners 10.

As will be understood, many modifications may be made in the method illustrated in Fig.

6 without departing from the spirit of the present invention. For example, the strips 26 of polymeric material may be formed by extruder heads positioned adjacent the arcuate guides 31. The monofilaments may be adhered in surface layers deposited on the strips 26 by adhesive applying devices between the roller and guides 31, and the guides need not be heated unless heat is required to cure the adhesive. Also the knife 44 may be replaced with a hot wire for providing the cutting step, which hot wire may provide at least a portion of the heat required for heading.

Figs. 7, 8, 9 and 10 illustrate alternate embodiments of parts of a fastener made from strip material according to the present invention, in which structures similar to structures in the part 11 are similarly numbered except for the respective addition of one of the suffixes "a", "b", "c" or "d".

The part 50 of a fastener illustrated in Fig.

7 can be made according to the method illustrated in Fig. 6 after a modification to the striker bars 39 which press the monofilaments 36 against the strips 26 so that the end surfaces 42 of the striking bars are set at an acute angle with the edges of the path for the strips 26. Like the part 10, the part 50 comprises an elongate backing 1 2a having parallel edges 19a. In the backing 1 2a are bonded a multiplicity of flexible resilient generally U-shaped monofilaments 1 3a of longitudinally oriented polymeric material. Each monofilament 1 3a includes a central bight portion 1 7a, and two projecting stem portions 1 4a each terminating in a head 1 8a defining an outer cam surface 20a.Also like the part 11, the bight portions 1 7a of the U-shaped monofilament 1 3a are disposed generally parallel to each other and to the edges 1 9a, and a plurality of groups of the bight portions 1 7a are disposed generally side by side to form a plurality of generally parallel straight rows of monofilaments 1 3a and heads 1 8a. In the part 50 of Fig. 7, however, the rows of monofilaments 1 3a are disposed at an acute angle with the parallel edges 1 9a of the part 50 which angle corresponds to the angle at which the striking bars are set.

Figs. 8, 9 and 10 illustrate second, third and fourth alternate embodiments for the parts 60, 70 and 80 of fasteners made from strip material according to the present invention which strip material can also be made by the method illustrated in Fig. 6 with the addition of one method step. The added method step is that of varying the position of the guide 37 transversely of the path for the strip 26. Such variation can for example be done by cam arrangements in a sinusoidal pattern to produce fastener parts with heads disposed in rows arranged as illustrated in Fig. 8, or in a saw tooth pattern to produce heads disposed in rows as illustrated in Fig.

9. Alternatively, as illustrated in Fig. 10, such variation can be in a random pattern. In any event it is desirable that the variation shift the stems 1 4b, 1 4c or 1 4d of successive rows of U-shaped monofilaments 1 3b, 1 3c or 1 3d by about one half the width of the spacing between the U-shaped monofilaments 1 3b, 1 3c or 1 3d in a direction normal to the edges 1 9b, 1 9c or 1 9d. This insures that there is no uninterrupted path between the stems 1 4b, 1 4c or 1 4d in a direction parallel to the edges 19b, 19e or 19d.

Like the parts 10 and 50, the parts 60, 70 and 80 each comprise a backing 1 2b, 1 2c or 1 2d having parallel edges 1 9b, 1 9c or 1 9d.

In a bonding layer of the backing are bonded a multiplicity of flexible resilient generally Ushaped monofilaments 1 3b, 1 3c or 1 3d of longitudinally oriented polymeric material.

Each monofilament 1 3b, 1 3c or 1 3d includes a central bight portion 1 7b, 1 7c or 1 7d, and two projecting stem portions 1 4b, 1 4c or 1 4d each terminating in a head 1 8b, 1 8c or 1 8d defining an outer cam surface 20b, 20c or 20d. Also, like the parts 11 and 50, the bight portions 1 7b, 1 7c or 1 7d of the U-shaped monofilaments 1 3b, 1 3c or 1 3d are disposed generally parallel to each other, and a plurality of groups of the bight portions 1 7b, 1 7c or 1 7d are disposed generally side by side to form a plurality of generally parallel straight rows of U-shaped monofilaments 1 3b, 1 3c or 1 3d and heads 1 8b, 1 8c or 1 8d disposed at generally a right angle with the parallel edges 1 9b, 1 9c or 1 9d.In each of the parts 60, 70 or 80 it will be noted that the U-shaped monofilaments 1 3b, 1 3c or 1 3d in successive rows are not aligned in a direction parallel with the edges 1 9b, 1 9c or 1 9d which im proves the shear strength of fasteners made from two of the parts 60, 70 or 80 should the rows of U-shaped monofilaments 1 3b, 1 3c or 1 3d be aligned during engagement.

Fig. 11 illustrates an alternate embodiment of a fastener 90 according to the present invention in which a part 92 (similar in all respects to the part 10 of Fig. 1 and having similar parts similarly numbered with the addition of the suffix "e") is engaged with projecting fiber loops 94 projecting from the woven backing 96 of a part 98 comprising a length of commercially available material such as that designated "Scotch mate" brand nylon woven loop No. SJ3401 available from Minnesota Mining and Manufacturing Company, St. Paul, Minnesota. As illustrated the part 92 includes a plurality of U-shaped monofilaments 1 3e having bight portions 1 7e bonded in a non-fibrous polymeric bonding layer 1 sue of a backing 1 2e for the part 92.The Ushaped monofilaments 1 3e also include stem portions 1 4e projecting from the bonding layer 1 sue. The stem portions 1 4e support heads 1 8e with outer cam surfaces 20e adapted to deflect the resilient fiber loops 94 of the part 98 upon engagement therebetween so that the loops 94 releasably catch on latching surfaces 20e of the heads 1 8e. As illustrated, the headed U-shaped monofilaments 1 3e are positioned and spaced as were the U-shaped monofilaments 1 3 of the part 11. Such positioning and spacing is not required to afford proper engagement between the headed stems 1 4e and loops 94, however. Any position of the U-shaped monofilaments is suitable so long as the number of monofilaments is suitable to provide a desired degree of engagement therebetween.The spacing schemes illustrated in Figs. 7, 8, 9 and 10 are of no advantage, since shear is not a problem between the loops 94 of the part 98 and the headed stem portions 1 4 of the part 92.

Example The following is a specific non-limiting example of a part of the type shown in Figs. 1 through 5 produced by the method described with reference to Fig. 6, and test results relating to that part.

The part was made from 0.38 millimeter (0.015 inch) diameter polypropylene monofilament applied to a 25.4 millimeter (1 inch) wide backing comprising a polypropylene surface layer having a thickness of about 0.76 millimeter (0.030 inch). Fifteen of the monofilaments were applied over the central 1 9 millimeter (3/4 inch) of the strip width to provide a spacing of about 1.3 millimeter (0.05 inch) center to center between the stems along the rows of U-shaped filaments.

Each U-shaped filament was formed to have a center to center width between its projecting stems of about 1.3 millimeter (0.05 inch), and the adjacent stems of adjacent U-shaped monofilaments in a direction normal to the rows of U-shaped filaments were spaced at about 1.4 millimeter (0.056 inch). The hemispherical heads of the monofilaments were in the range of about 0.9 to 1.0 millimeter (0.035 to 0.040 inch) in diameter and the stems had a length of about 2.3 to 2.8 millimeters (0.030 to 0.110 inch) between the surface layer and the heads.

Two such parts were firmly adhered to a rigid planar member on a testing device that would simultaneously engage and disengage the heads in repetitive cycles. It was found that 1000 engagement-disengagement cycles reduced the force required to disengage the heads from 1 2.3 to 7.75 kilograms (27.3 to 17.1 pounds), and the force to engage the heads from 14.1-10.7 kilograms (31 to 23.6 pounds). Also after the cycling force required to separate the engaged parts by sliding them relative to each other in the planes of their backing strips was still about 14 kilograms (31 pounds) when the rows of U-shaped monofilaments were disposed at 90 degrees to each other, and between about 5 kilograms (12 pounds) when the rows of U-shaped monofilaments were disposed parallel to each other. After the testing it was noted that none of the U-shaped monofilaments had pulled free of the backing.

Claims (7)

1. A method for forming a strip material adapted to be cut into lengths that provide parts of a fastener, wherein said method comprises the steps of moving two non-fibrous polymeric strips from generally opposite directions around parallel arcuate spaced guides and away from the guides in the same direction along parallel paths; feeding spaced parallel lines of flexible, resilient polymeric monofilaments between the spaced guides from the sides thereof opposite said parallel paths and in a direction generally parallel to said parallel paths; alternately pressing U-shaped lengths of the flexible monofilaments into engagement with one of the strips and then pressing U-shaped lengths of the monofilaments spaced therefrom into engagement with the other strip while bonding the U-shaped segments of the monofilaments to the strips in the positions that they are pressed into engagement therewith so that lengths of the monofilaments between the U-shaped segments extend generally normally between the strips as the the strips move along the parallel paths; severing the monofilaments midway between the strips to form two brush-like halves; and heating the newly severed terminal ends of the monofilaments projecting from the strips to form heads having arcuate surfaces opposite the strips.

2. A method according to claim 1 wherein said feeding step includes the step of varying the positions of said monofilaments transversely of said parallel paths.

3. A method according to claim 1 wherein the polymeric strips are heat softenable and said bonding comprises the steps of heating the strips to their softening temperature prior to said pressing step so that said pressing step presses the U-shaped lengths of the monofilaments into the strips.

4. A method substantially as herein described for forming a strip material adapted to be cut into lengths to provide parts of a fastener.

5. Products made by the method of any preceding claim.

6. Products substantially as herein described with reference to the accompanying drawings.

7. Any novel compound, composition, process or product herein described, irrespective of whether the present claim is within the scope of or relates to the same invention as, any of the preceding claims.