US3518730A - Monoform shoelace - Google Patents

Description

July 7, 1970 J. A. cuPLER MONOFORM SHOELACE Filed Jan. 22. 1968 INVENTOR JOHN A. CUPLER 1I ATTORNEYS.

om Q oN @N4/7 United States Patent O 3,518,730 MONOFORM SHOELACE John A. Cupler Il, Cupler Drive-LaVale, Cumberland, Md. 21502 Filed Jan. 22, 1968, Ser. No. 699,637 Int. Cl. A43c 9/ 00 U.S. Cl. 24-143 14 Claims ABSTRACT OF THE DISCLOSURE The disclosure is directed to an improved extensible shoelace that is virtually indestructible in normal usage, does not require a tip and is formed in such a manner that, when knotted, it will not slip and when cut, it will not fray.

The lace consists of a minute central core surrounded by oppositely wound filamentary strands embedded in a cured settable resin Whose internal bonding strength is greater than the bonding strength between the resin and strands.

In a preferred form of the invention, the core is formed frcm one to about ten parallel extensible strands that are surrounded by oppositely wound strands having a lesser linear extensibility than the core strands. The wound strands are embedded in the resin which holds the strands firmly in place dispensing with the need for end tips. Additionally, a granular abrasive of any desired type, such as a grit, may be incorporated with the resin to provide a roughened surface on the lace so that, once knotted, it will not slip.

CROSS REFERENCE TO RELATED APPLICATION This application is relatedto copending application Ser. No. 699,683 filed Jan. 22, 1968, entitled Endless Monoform Belt. This application and the aforesaid copending application are commonly owned.

BACKGROUND OF THE INVENTION The invention relates to extensible shoelaces generally Vof the type disclosed in U,S. Pats. 1,767,732; 1,948,844;

and 2,869,205.

Conventional shoelaces are, necessarily, tipped 1n order -to preclude the ends from becoming frayed and, addit tionally, the lifetime of conventional laces is normally less than that of a shoe. Another shortcoming of conventional laces is the fact that impregnated laces, of the general type herein disclosed, are quite firm as opposed to cloth type laces and tend to come untied.v Shoelaces are presently manufactured and sold in various lengths which must be specified by the purchaser depending on -to proper length by clipping off the end.

SUMMARY OF THE INVENTION It is a primary object of the invention to provide a shoelace that is virtually indestructible in usage, does not require a tip and is formed in such manner that, when knotted, it will not slip and when cut, it will not fray.

It is a further object of the invention to provide an extensible shoelace that may be cut to any desired length thereby dispensing With the necessity of attempting to match lace lengths with various types of shoes.

The foregoing objects are achieved by forming, about a minute core, an extensible lace body having an excellent elastic memory and consisting of oppositely wound strands embedded in an elasto-polymeric binder preferably of the ambient setting type, such as Du Ponts Adiprene and incorporating with the binder an abrasive substance, such as a grit. Alternatively, a binder which, when set, exhibits a dull or generally retentive surface may be used to preclude relative slipping between engaged portions of the lace.

The shoelace of this invention is of monoform character, i.e. the lamentary strands forming a portion of the lace body are embedded in and bonded to the binder so that there is no possibility of the lace ends becoming frayed. The presence of the abrasive grit within the binder gives a roughened surface finish to the lace which, in contrast to previously known resin impregnated laces, provides engaging roughened surfaces when the lace is knotted which prevents the engaging portions from undergoing relative movement and becoming unknotted. Any fine granular grit, such as emery, fine sand or the like may be incorporated in the binder material prior to its application during the manufacturing process to impart the roughened surface characteristics above referred to.

A critical factor contributing to the attainment of the foregoing advantages is the fact that the diameter of the lace core is extremely small as compared to the diameter of the finished shoelace. In actual practice the core may consist of from one to about ten parallel strands of denier polypropylene. The purpose of the core is merely to provide a form on which the oppositely wound strands and settable material may be applied. In view of the foregoing it will be apparent that fit is quite feasible to use a single minute filamentary strand to provide the desired form though, in some cases, it may be desirable to form the core from several strands, such as three or four, to make the same more readily visible to an operator to facilitate certain manufacturing operations that may be performed manually.

The finished shoelace, in accordance with a preferred form of the invention, includes an extensible core of extremely small diameter lying along the central axis of the shoelace; at least two oppositely wound strands whose winding bias imparts extensibility to the same along the axis of the core; and an elasto-polymeric binder encasing the wound strands and core whose coefficient of extensibility is different from that of the wound strands. The internal bonding strength of the binder is greater than the bond between the strands and elasto-polymer. The inherent elasticity of the binder coupled with the winding bias of the wound strands provides a number of advantageous results not previously attainable with conventional shoelaces. Firstly, the bond between the strands and binder is suflciently strong that under moderate lace elongation there is little if any relative movement between the component parts of the lace. When, however, unusual stress conditions are present as in the case of maximum overall stretching the bond between the binder and wound strands may be broken at points of unusual stress permitting relative movement between the same whereby the strands may more readily accommodate the stress condition. Secondly, when a large tension stress is introduced uniformly along the length of the lace all portions of the wound strands may move relative to the binder to, in effect, decrease their helical wrap angle which adds to the restoring force resulting from elongation of the binder. Thirdly, both lace strength and extensibility are derived from the binder and helically wrapped strands which permits the core to serve a completely different function than in the case of conventional structures of the type under consideration, i.e. it serves merely as a winding form. Once the shoelace is formed, the core serves no substantial function and even if it should be broken, as by forming the same of a strand whose linear extensibility is substantially less than that of the finished lace, the function of the lace would not be impaired. In actual practice, the core has a greater extensibility than the finished lace and the same does not rupture in usage. The fact that the core has such a minimal cross-sectional dimension in comparison to the finished lace permits the lace to have a uniform diameter throughout which is substantially wholly composed of the wound strands and binder. It will also be apparent that where, say for example, three strands of 160 denier polypropylene are used as a core that the cross-sectional area of such core will be negligible when compared to the cross-sectional area of the finished lace having a diameter of, for example, 1/16 of an inch.

In actual practice it has been found that nylon is particularly advantageous for use as the wrapping strands while du Ponts Adiprene is the preferred elasto-polymeric binder. Although polypropylene, nylon and Adripene have been mentioned for use as the core material, winding strands and binder, respectively, it is obvious that many other materials could be used to impart desired characteristics to the shoelace. For example, it has been found that when using Dacron for the winding strands, the wear resistance of the lace is increased although its strength is decreased.

The characteristics of the shoelace may also be altered, as desired, by varying the pitch of the helically wrapped strands. The extensibility of the lace is increased by increasing the number of wound turns per inch while the strength of the lace is decreased and, conversely, the strength is increased and extensibility decreased by decreasing the number of turns per inch.

The winding strands themselves may be inherently linearly extensible or nextensible as desired. Thus when using nextensible winding strands, the extensibility of these strands in relation to the lace will be derived solely from their winding bias and when using linearly extensible strands, their inherent extensibilty will supplement that imparted thereto by the winding bias.

The shoelace according to the invention may be manufactured as an endless loop or lace in the manner described in connection with an endless belt in the aforementioned copending application after which time the same may be cut to desired lengths either prior to packaging for sale or by the consumer himself. In one form of the invention, the grit is added to the binder material before it is applied to the lace during the manufacturing process such as by adding the same to the binder in the fountain applicator as disclosed in the aforesaid copending application.

In the case of extensible shoelaces, it is particularly desirable to use wrapping strands which are relatively non-porous and Whose surface exhibits a slick or smooth finish. Nylon is representative of strands of this type and these characteristics facilitate the relative movement between the strands and binder.

As will be apparent from the foregoing, it is also within the contemplation of the invention to construct nextensible laces by using an inelastic binder which is tightly bonded to the wrapped strands. In this latter case, where wearability rather than extensibility is the desired objective, a strand material such as Dacron exhibiting a porous dull surface may be used which permits a much stronger bond between the binder and strands to resist relative movement.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of an endless lace member prior to the time the same is cut to form individual shoelaces;

FIG. 2 is an individual shoelace cut from the lace member of FIG. 1;

4 FIG. 3 is a greatly enlarged fragmentary illustration of one end of a shoelace having portions thereof broken away; and

FIG. 4 is a greatly enlarged cross-sectional view taken along the line 4-4 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The completed shoelace 10 shown in FIG. 2 may be initially formed as an endless member 12 in the manner described in detail in the aforementioned copending application with the single exception that a granular abrasive is added to the binder prior to its application in the coating process therein described. After the endless member is formed it may be cut to desired lengths as along the cut lines 14 of FIG. 1 to provide the shoelace herein described having minute core 16 and oppositely helically wound strands 18, 20 embedded in elastopolymer 22 that is impregnated with a granular abrasive 24. Although three strands 26 have been illustrated as comprising the core 16 it will be apparent that a single strand or a larger number of strands may be used consistent with the requirement that the core be extremely small as compared to the finished lace.

The presence of the granular abrasive provides a roughened outer surface on the finished lace which affords an excellent gripping action between the engaged portions of a knot. This gripping action coupled with the inherent resiliency of the lace which tends to return to its normal unstressed state after release of the stress applied thereto during a knotting operation, provides for a very secure knot that will not tend to slip or become unknotted. Inasmuch as the abrasive is embedded uniformly throughout the binder, any of the abrasive that is worn off in use will expose underlying abrasive particles and the non-slip characteristic of the lace will not be impaired.

If the appearance of a lace tip is desirable for cosmetic purposes, the same may be readily formed on the ends of the monoform lace merely by heating and compressing the end portions thereof. In other instances such treatment of the lace ends may be desirable to render the same relatively rigid although the cut ends of a lace constructed in the manner described wherein the same is merely cut to length exhibits suicient rigidity that lacing operations are not impaired.

I claim:

1. An untipped lace of substantially uniform diameter comprising; a central core surrounded by at least one sheath of oppositely wound alternately wrapped filamentary strands embedded within a plastic binder for movement relative thereto.

2. The lace of claim 1 wherein said core consists of not more than ten parallel strands.

3. The lace of claim 2 wherein the diameter of each of said strands forming said core does not exceed that of a denier polypropylene strand.

4. The lace of claim 2 wherein said binder is an elasto-polymer.

5. The lace of claim 4 wherein said wound strands are linearly extensible.

6. The lace of claim 5 wherein said binder has a greater coefficient of extensibility than said wound strands.

7. The lace of claim 5 wherein said core has a greater coeicient of extensibility than -said binder.

8. The lace of claim 2 wherein said parallel strands are polypropylene.

9. The lace of claim 1 wherein said binder has a relatively retentive surface.

10. The lace of claim 1 wherein the outer surface of said shoelace is roughened.

11. The lace of claim 10 wherein an abrasive grit is mbedded in said binder to provide said roughened surace.

12. The lace of claim 11 wherein said grit is embedded substantially uniformly throughout said binder.

13. The lace of claim 1 wherein said alternately wrapped strands in said at least one sheath have diametrically opposite portions extending equidistantly from the axis of said core.

14. An untipped lace of substantially uniform diameter comprising; a central core surrounded by oppositely wound lamentary strands embedded within a plastic binder for movement relative thereto, said core consisting of not more than ten parallel strands, and wherein a `bond is formed between said strands and binder that is of lesser strength than the internal bonding strength of said binder whereby under stress conditions portions of the bond between the binder and strands may be broken to facilitate said relative movement.

References Cited UNITED STATES PATENTS 1,767,732 6/1930 Breadon 24-143 1,948,844 2/1934 Dawes 24--143 2,760,330 8/1956 Lowney 57-152 XR 3,131,530 5/1964 Dietz 57-149 3,323,301 6/1967 Jackson 57-152 XR FOREIGN PATENTS 557,418 8/1932 Germany.

DONALD A. GRIFFIN, Primary Examiner

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