Fire-resistant fastening device and method of manufacture

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a flame and elevated temperature resistant separable fastening device of the type having two fastening members each provided with a very large number of 'θ closely spaced interengageable hooking elements of the hook and loop type, one of said members comprising hooks and the other of said members comprising loops. The fastening members are characterized by the property that opposed surfaces of the two can be pressed together in face-to-face relation so ⁵that a large number of hooks on one of the members will engage a large umber of loops on the other member for several cycles of repeated engagement and disengagement without permanently deforming the hooks or loops and without sub- _ stantially crushing the loops. The invention also relates to a method of making these fastening devices.

2. Description of the Prior Art

U.S. Pat. Nos. 3,009,235 and 3,083,737 and 3,154,837 disclose various forms of separable pile-fastening devices, i.e., a fastener comprised of two separate fastening tapes having interengageable piles which contain loop elements and loop-engaging hook elements. The fastening devices described in these patents are recited as preferably being constructed from synthetic polymer materials such as nylon (polyamide fiber ₃₀manufactured by the Du Pont Company). For some applications these apes may be fabricated from natural textile material with an interwoven pile of synthetic material.

Engageable pile fasteners have found widespread use where ease of opening and closing is desired such as use in clothing, footwear, belts, curtains, tapestry, and for a variety of uses in commercial aviation. However, because of the flammable nature of the polymeric materials utilized in the manufacture of the interengageable pile elements, such fasteners, when used on commercial aircraft, must necessarily be resistant to flame and elevated temperatures and must meet he United States Federal Aviation Agency standards in this respect. It has generally been found that fasteners of the type referred to herein, when produced from a standard polyamide fiber such as the nylon monofilament produced by the Du Pont Com- 45 pany, ill bun when tested under the conditions specified in certain standard “bum tests such as that disclosed in United

States Test CCC-T 1916, method 5902, dated May 15, 1951. Accordingly, it is an object of his invention to provide a separable fastening device which will function satisfactorily as such and yet be resistant to flame nd elevated temperatures.

SUMMARY OF THE INVENTION

Broadly stated, the invention relates to a separable fastening device, resistant to flame and high temperatures, having two fastening members each provided with a very large number of closely spaced hooking elements of the hook and loop type such that pressing opposed surfaces of two fastening members together in face-to-face relation will engage a large number of hooks and loops.

The hook tape member is manufactured, in the warp and filling ground weave, from a high-temperature nylon, and, for the hook element, from a standard nylon monofilament. The pile loop fastening member is manufactured from high-temperature nylon in both the warp and filling ground weave and also for the pile loops. By “high temperature nylon,” there is meant a synthetic polyamide fiber having good dimensional stability and excellent heat and flame resistance. A high-temperature nylon such as Nomex (a nylon manufactured by the

Du Pont Company) which, at temperatures above 700° F. (371° C.) degrades to a friable char at a rate proportional to the intensity of the heat source and in which any flame produced during oxidation is self-extinguishing when the fiber is withdrawn from the source of heat, is particularly suitable for use in commercial aircraft.

A major drawback, to date, with respect to the use of hightemperature nylon in producing the separable fastening device described herein is its unavailability in a filament greater than 2 denier in size which is much too weak a filament for the production of satisfactory loop elements. It has been found that a 20-denier standard nylon is sufficient to produce a satisfactory pile loop fastening member. The loops themselves must have sufficient strength and body to withstand repeated engagements with the hook elements, which is not possible with a weak filament. However, the exceptional flame-resistant properties of high temperature nylon makes highly desirable its adaptation for use in the separable fastening device.

For the purpose of enhancing the firmness of engagement and strength of flame resistant separable fastening device, the present invention provides a method for weaving he fastening member which comprises he pile loops from mutifilament yarns of the light-denier high-temperature nylon. The hightemperature nylon, which is a 2-denier filament, may, of course, be twisted to form yarns of greater denier size. Such yarns, however, are unsatisfactory for producing the loops because of their tendency to twist upon themselves and “close” after their formation during weaving thus preventing engagement with the hooking element.

In the present invention a twisted yam of high-denier hightemperature nylon is produced and is then reverse plied with another such twisted yarn to produce a dead yarn which has sufficient strength and body to produce a pile loop that may be fixed and stabilized and which will retain its shape. A separable fastening device produced in accordance with this invention will be flame and high-temperature resistant and will comprise a pile loop member which affords increased probability of engagement of the hooks with the loops so that a major percentage, if not all, of the hooks bn the hook-carrying member will become engaged with a loop on the loop-carrying member.

BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 is a perspective view of a pile loop tape member of the fastening device of the invention showing pile loop elementsextending from one surface thereof;

FIG. 2 is an enlarged fragmentary perspective of the pile loop element in a fastening device of the invention;

FIG. 3 is an enlarged fragmentary perspective of a hook element in a fastening device of the invention; and

FIG. 4 is a side elevation of two tape members forming a fastening device in opposed face-to-face relationship but spacedapart.

With reference to FIG. 2, the pile loop fastening member is manufactured by forming a base fabric which comprises a number of weft threads 12 and warp threads 14. The loop 16 of said fabric very formed as supplementary warp threads 55 which are passed over metal lancets during the weaving operation, in a loom generally employed in weaving velvet ribbon. Said supplementary warp threads which form the loops, as well as said weft threads 12 and warp threads 14 in the ground weave, are manufactured from Du Pont Nomex nylon yarn 60 which is resistant to flame and high temperature. Because the Nomex nylon cannot be made in the larger denier size required for satisfactory use in the regular pile loop element (20 denier), it is necessary to take a large number of the very fine Nomex nylon filaments (2 denier) and apply twist to them 65 to produce a yarn of sufficiently high denier and then to take two such ends (strands) and ply them in a reverse twist. The reverse twist is necessary to produce what is known as dead yam having sufficient strength and body to produce satisfactory loops.

To produce the loops 16 shown in FIG. 2, the Nomex nylon was prepared by twisting 100 filaments of 2-denier Nomex in

2½ turns per inch S. Two ends each of the 200-denier multifilament yarn thus produced were then reverse plied together in 2½ turns per inch Z. The Nomex yarn thus plied has been found to be quite satisfactory for use in producing the loop

3,594,873 elements; it resists breaking, and is sufficiently stabilized so as to be easily engageable, in repeated use, with the hook element. The loops themselves are fanned out during manufacture and remain so because of the stabilization imparted to the yarn by the reverse twisting and plying of the filaments. The pile loop member thus formed is shown in FIG. 1, and, when said loop element is placed in face-to-face relation with the hooking member as shown in FIG. 4, they may be pressed together to fasten them to each other, and progressively peeled apart when it is desired to separate the two members.

The ground weave fabric or base material, into which the pile loops are woven, is also manufactured from Nomex nylon which has the following yam characteristics: The ground warp yarn used is a 200-denier Nomex nylon having 100 filaments per thread twisted 20 turns per inch in the S direction; the filling yam or weft yarn is a 200-denier Nomex nylon having 100 filaments per thread twisted five turns per inch in the Z direction.

The hooking member, shown in FIG. 3, is manufactured from Du Pont Nomex yarn in the warp 14 and filling ground weave 12 and standard Du Pont nylon monofilament as the hooks 17. The hook element is manufactured from the standard nylon monofilament because of its ability to be thermoset and to retain its shape, necessary factors for satisfactory engagement of the hooks and loops. The danger of flammability of the hooks is negligible because of the smothering effect of the pile loop member when the hooks are in engagement therewith.

The loops are preferably woven with considerable firmness into the base fabric 10, which is formed from warp yarns 14 and weft yarns 12 as shown in FIG. 2. After the weaving operation has been completed, the loops 16 formed from multifilament Nomex nylon yarns may be fastened or stabilized so that they retain their shape or position. This may be effected by heat setting, by impregnation of the fabric by adhesive products, by a heat-settable resin capable of withstanding such temperatures as are likely to be encountered in normal usage, or by a combination thereof. It must be remembered, however, that the adhesive to be used must conform to the standards of the “burn test” referred to herein when the material is to be used under conditions where those standards will apply. In this manner, a very large number of durable and firmly anchored loops are provided.