SLIDE FASTENER AND A METHOD FOR ITS MANUFACTURE

Abstract

A slide fastener and a method for its manufacture A slide fastener (1) has a pair of opposed tapes (2), each including a strip (6) made of a flexible material, in particular natural or artificial skin or leather. Each strip (6) is folded on itself around an elongate core member (8) so as to form a teeth-carrying edge onto which a respective row of coupling teeth (3) is fastened. A layer (7) of a reinforcing sheet material is applied by means of an adhesive to the inner surface or face (6a) of said flexible material (6), and a layer of adhesive is applied onto the reinforcing material (7), and a strip of the thus obtained composite material is folded on itself around the core (8).

Description

The present invention relates to a slide fastener having a pair of opposed tapes, each including a strip made of a flexible material folded on itself around an elongate core member, in particular a flexible cord, so as to form a teeth-carrying edge onto which a respective row of coupling teeth is fastened.

The invention also relates to a method for the manufacture of such a slide fastener.

Slide fasteners of that type are disclosed for instance in U.S. Pat. No. 1,933,290 and EP-1 384 412 A1.

The manufacture of slide fasteners having stringer tapes made of a flexible material, in particular thin soft natural or artificial skin or leather, faces the problem that with said materials it is very difficult, if not almost impossible, to obtain tapes having the required strength and dimensional stability. Tapes made of such materials are in fact relatively weak and prone to yield under stress. Difficulties can thus be involved in maintainining the correct relative positions of the coupling teeth which are affixed thereto, which is a necessary condition for the proper functioning of a slide fastener.

An object of the present invention is to provide an improved slide fastener and a method for the manufacture thereof, which allows to overcome the above-outlined inconveniences of the prior art.

This and other objects are achieved according to the invention by a slide fastener and a method according to claim 1 and claim 8, respectively.

The stringer tapes of a slide fastener manufactured in accordance with the present invention exhibit a superior strength and an optimal dimensional stability, allowing to reliably maintain the correct relative positions of the coupling teeth affixed thereto.

Further features and advantages of the invention will become apparent from the detailed description which follows, provided purely by way of a non-limiting example, with reference to the accompanying drawings, in which:

FIG. 1 is a partial front view of a slide fastener manufactured in accordance with the present invention;

FIG. 2 is a partial top plan view showing a phase of the manufacture of a stringer tape for a slide fastener according to the invention;

FIG. 3 is a cross-sectional view along the line III-III of FIG. 1; and

FIG. 4 is a cross-sectional view along the line IV-IV of FIG. 1.

Referring to the embodiment illustrated in FIG. 1, a slide fastener generally designated by the reference numeral 1 comprises a pair of oppositely disposed stringer tapes 2, each carrying a respect row of discrete fastener elements or coupling teeth 3. Said fastener elements or coupling teeth 3 are affixed to a longitudinal edge of each of said tapes 2, and are disposed so as to be taken into and out of engagement by a slider 4 which is manually operable by means of a pull-tab 5.

Each stringer tape 2 includes a strip 6 (FIG. 2) made of a flexible material, such as a woven or non-woven or knitted material. The strips 2 can be in particular made of natural or artificial skin or leather, having a thickness comprised between 0.20 and 0.35 mm, preferably between 0.25 and 0.30 mm.

As shown in FIG. 2, onto the inner surface or face 6a of the strip 6 there is applied a correspondingly shaped strip 7 of a reinforcing sheet material. The reinforcing strip 7 is conveniently made of a plastic material (preferably nylon) or metal or woven or non-woven or knitted film or tape, having a thickness of preferably between 0.05 and 0.15 mm, and very preferably of 0.10 mm, and is applied to the strip 6 by means of an adhesive, such as a glue or mastic.

After the reinforcing strip 7 has been applied to the strip 6, a layer of adhesive, preferably the same interposed between said strips, is applied onto the reinforcing strip 7. Thereafter, the thus obtained composite strip is folded on itself, around an elongate core member 8, such as a flexible cord, and is pressed for a predetermined period of time, for instance by passing through a rolling guide.

According to an alternative, a strip 7 of reinforcing material is folded and sticked by an adhesive on itself around the core member 8, and thereafter a strip 6 of a flexible material, such as a natural or artificial skin or leather, is wrapped around and sticked by an adhesive to the thus obtained semifinished product.

In either case, a thus manufactured stringer tape 2 has a cross-sectional shape such as that shown in FIG. 3.

The core member 8 and the fold of the stringer tape 2 form a teeth-carrying bead or edge, onto which a respective row of fastener elements or coupling teeth 3 can be reliably affixed.

As shown in FIG. 4, for each tooth 3 a hole 9 can be stamped or punched in the corresponding tape 2, and the tooth 3 has an anchoring portion 3a extending through said hole 9. The teeth 3 can be formed for instance by injection moulding a plastic material, or crimping metal elements.

In the manufacture, the composite strips 6, 7 described above can be obtained by cutting into strips a composite sheet obtained by applying a relatively large sheet of reinforcing material to a corresponding sheet of flexible material, with an interposed adhesive. As an alternative, the said composite strips can be obtained by applying a previously cut strip 7 of reinforcing material to a previously cut strip 6 of flexible material, with an interposed adhesive.

The stringer tapes of a slide fastener manufactured in accordance with the present invention exhibit a superior strength and an improved dimensional stability, even though the material forming the strips 6 is inherently weak.

Obviously, without modifying the principle of the invention, the embodiments and the constructional details may be widely varied with respect to what has been described and illustrated purely by way of a non-limiting example, without thereby departing from the scope of the invention as defined in the accompanying claims.

Claims

1. A slide fastener having a pair of opposed tapes, each including a strip made of a flexible material, said strip being folded on itself around an elongate core member so as to foam a teeth-carrying edge onto which a respective row of coupling teeth is fastened, the slide fastener comprising:

a layer of a reinforcing sheet material is attached by means of an adhesive to the inner surface or face of said strip, and a layer of adhesive is applied onto the reinforcing sheet material, and the strip of the thus obtained composite material is folded on itself around the core.

2. The slide fastener of claim 1, wherein each said strip is made of a knitted, or woven or non-woven material.

3. The slide fastener of claim 1, wherein each said strip is made of a natural or artificial skin or leather.

4. The slide fastener of claim 1, wherein the reinforcing layer is made of a plastic or metal or woven or non-woven or knitted film or tape.

5. The slide fastener of claim 4, wherein the reinforcing layer is made of a polyamide material.

6. The slide fastener of claim 1, wherein each strip of said flexible material has a thickness comprised between 0.20 and 0.35 mm, preferably between 0.25 and 0.30 mm, and the reinforcing layer has a thickness of between 0.05 and 0.15 mm, and preferably of about 0.10 mm.

7. The slide fastener of claim 1, wherein each coupling tooth extends through an aperture or hole provided in the respective tape.

8. A method for the manufacture of a slide fastener having a pair of opposed tapes, each including a strip made of a flexible material, said strip being folded on itself around an elongate core member so as to form a teeth-carrying edge onto which a respective row of coupling teeth is fastened, the method comprising:

coupling a reinforcing sheet material is coupled by means of an adhesive to the inner surface or face of said strip, said reinforcing sheet material being folded and sticked by an adhesive on itself around the core.

9. The method of claim 8, wherein the reinforcing sheet material is folded and sticked around the core before being coupled to said strip.

10. The method of claim 8, wherein the reinforcing sheet material is folded and sticked around the core together with said strip after having been coupled to said strip by means of an adhesive.

11. The method of claim 8, wherein each said strip is made of a knitted or woven or non-woven material.

12. The method of claim 8, wherein each said strip is made of a natural or artificial skin or leather.

13. The method of claim 8, wherein the reinforcing layer is made of a plastic or metal or woven or non-woven or knitted film or tape.

14. The method of claim 13, wherein the reinforcing layer is made of a polyamide material.

15. The method according to claim 8, wherein each strip of said flexible material has a thickness comprised between 0.20 and 0.35 mm, preferably between 0.25 and 0.30 mm, and the reinforcing layer has a thickness of between 0.05 and 0.15 mm, and preferably of about 0.10 mm.

16. The method of claim 8, wherein the coupling teeth extend through holes provided in the said tapes.