| CLAIMS 1. A watertight zip fastener comprising an elastic element (100) consisting of a pair of opposite seals (2) destined to receive respective series of engagement elements (20) which can be brought into mutual engagement by means of a slider (31) and a pair of membranes (3) suitable for connecting said seals (2) to the article to which the zip fastener (1) is applied, characterized in that each of said membranes (3) is an element separated from the corresponding seal (2) and presents at one longitudinal edge thereof, a series of holes (30) in alignment with a corresponding series of through cavities (13) provided in an alveolar rib (14) of each seal (2) and destined to receive and to elastically retain said engagement elements (20), such that the membrane (3) is interposed and tightly retained between the seal (2) and said series of engagement elements (20). 2. A zip fastener according to claim 1, characterized in that said membrane (3) is a strip of waterproofed fabric with barrier effect. 3. A zip fastener according to claim 1 or 2, characterized in that each of said seals (2) has a substantially U-shaped section, the base side of which presents said alveolar rib (14) and the branches of which form a double lip (10) with watertight end contact surfaces (1 1). 4. A zip fastener according to any one of the preceding claims, characterized in that each series of engagement elements is carried by a respective cord (21). 5. A method of producing a waterproof zip fastener according to any one of the preceding claims, comprising the following steps: - producing through extrusion an elastic element (100) comprising a specular pair of seals (2) with U-shaped section; - forming a series of through cavities (13) in each of said seals (2) to produce an alveolar rib (14); - forming a series of holes (30) in proximity of a longitudinal edge of a pair of membranes (3); - positioning said series of holes (30) of each membrane (3) in alignment with the corresponding series of cavities (13) of a respective seal; - forced inserting said engagement elements (20) in said series of aligned cavities (13) and holes (30); - mounting a slider (31) on said seals (2) for the mutual engagement of said engagement elements (20). 6. A method according to claim 5, characterized in that said through cavities (13) in said seals (2) and said holes (30) in said membranes (3) are produced by means of a single stepped perforation operation, with a prior fastening of the membranes (3) to the seals (2) by means of welding, structural bonding or vulcanization. 7. A method according to claim 5 or 6, characterized in that said engagement elements (20) are secured along a carrying cord (21) prior to the forced insertion in said aligned cavities (13) and holes (30). |
DESCRIPTION
The present invention relates to a watertight zip fastener with barrier effect, particularly suitable for civilian and military uses, principally in those cases where specific high characterstics of resistance to highly aggressive chemical pollutants are required.
In particular the invention sets out to improve the watertight zip fastener of European patent EP 933036 in the name of the same applicant.
The zip fastener forming the subject matter of the cited document comprises a profile of elastic material produced by means fo a single extrusion operation, forming two half- chains each consisting of a double-lipped seal having a substantially U-shaped section, the base of which consists of an alveolar rib in which cavities are formed to house the teeth of engagement elements that can be brought into mutual engagement by means of a suitable slider which tends to bring the two half-chains together, placing them in mutual forced opposition.
Integrally with said elastic profile, and thus at the two sides of the U-shaped seals, there extends a flat membrane which forms, without breaks in continuity, the final fixing tape of the fastener with respect to the item to which it is applied.
This characteristic, namely the provision of the fixing tape of the zip fastener in a single body with the elastic profile, though proving useful and advantageous in various applications, can, however, constitute a considerable limit in other applications, for example in those cases in which high, specific properties of resistance to highly aggressive chemical pollutants are required.
In fact, whilst the thickness of the sealing profiles is in the order of a few millimetres, the thickness of the fixing tape is normally less than one millimetre. Therefore, a given elastomer material may prove sufficient with respect to the expected performance if used for the thicknesses of the sealing profiles, but not sufficient in the flattened area of the fixing tape.
On the other hand, since the fixing tape is integral with the sealing profile, one is tied to the material of the latter, which is often not compatibile with particular materials (generally textiles) used in special applications, with which they do not join firmly to create an optimal seal.
An object of the present invention is to eliminate the drawbacks encountered in the zip fastener according to patent EP 933036.
In particular, an object of the invention is to provide a watertight zip fastener able to impart a barrier effect.
Another object of the invention is to provide a watertight zip fastener able to give the protective article uniformity of the textile materials used.
Yet another object of the invention is to provide such a watertight zip fastener with the desired characteristics of physico-chemical resistance and with improved resistance to lateral traction stresses.
These objects are achieved, according to the invention, with the characterics listed in the appended independent claims.
Preferred embodiments of the invention are apparent from the dependent claims.
Essentially, the watertight zip fastener according to the invention, structurally corresponding to that of patent EP 933036, is characterized in that it provides a strip of waterproofed fabric with a barrier effect, integrally coupled to the seal profile.
A pre-perforated fabric edge is interposed and forced between the mechanical engagement elements and the seal profile.
Further characteristics of the invention will be made clearer by the detailed description that follows, referring to a purely exemplifying and therefore non limiting embodiment thereof, illustrated in the appended drawings, wherein:
Figure 1 is a partial axonometric view of a zip fastener according to the invention, with a slider shown exploded; Figure 2 is a diagrammatic view showing the elements forming the zip fastener of Figure
1 exploded. With reference to said figures, the zip fastener according to the invention, shown partially, has been designated as a whole by reference numeral 1. It comprises two half- chains or seals 2, forming part of a single elastic element 100, or linear profile, obtained by means of a single molding operation, two membranes 3, constrained to the seals in the manner that will be described hereunder, two series of opposed teeth or engagement elements 20 fixed to the seals 2, and a slider 31 which by sliding on the engagement elements 20 causes closure of the two seals 2 of the elastic element 100.
Each seal 2 has a substantially U-shaped section, the branches of which form a double lip 10, each presenting a contact surface 11 that abuts tightly against the contact surface of the opposite lip.
On the base side of each U-shaped seal 2 there is an alveolar rib 14 passed through by a series of through cavities 13, substantially oval in shape, suitable for housing the mechanical engagement elements 20.
The two seals 2 of the elastic element 100 end in a head not shown in the figures, for details of which reference can be made to the cited patent EP 933036.
The series of engagement elements or teeth 20 are carried by respective joining cords 21.
Each tooth 20 comprises a heel 22, a lowered central body 26 and a retaining head 27.
The lowered body 26 is suitably sized with respect to the cavities 13 of the alveolar rib 14, so as to dilate the cavity 13 which receives it until it is stably retained therein.
As previously stated, the structure of the zip fastener according to the invention substantially corresponds to that of patent EP 933036, and therefore will not be further described.
The substantial difference with respect to the solution described in said document, and therefore the essential characteristic of the invention, is represented by the fact that the flexible membranes 3 are separate elements from the seals 2.
Each membrane 3 conveniently consists of a strip of waterproofed fabric with a barrier effect and presents, near its free longitudinal edge, a series of holes 30, able to be disposed in alignment with the series of cavities 13 of the seals 2 and to accommodate the lowered body 26 of the engagement elements 20, so that the membrane 3 remains interposed and firmly held between the engagement elements 20 and the respective seal 2, as shown in Figure 1.
Naturally the membranes 3 can be can be fastened in advance to the seals 2, for example by means of welding, structural bonding or vulcanization, so that the cavities 13 and the holes 30 can be produced by means of a single stepped perforation operation.
Provision of the membranes or strips of fabric 3 separated from the seals 2 makes it possible to obtain various advantages, such as:
- giving the protective article uniformity of the textile materials used;
- allowing a single making up process for the article as far as welding, bonding etc. is concerned;
- greater resistance of the fastener to stresses due to lateral traction;
- the choice of fabric for the membrane 3 in no way conditions that of the elastic material from which the seals 2 are made. It follows that the characteristics of physico-chemical resistance of the zip fastener thus produced can be varied on a case by case basis until the required performance is obtained.
Naturally the invention is not limited to the particular embodiment previously described and illustrated in the appended drawing, but numerous modifications of detail within the reach of a person skilled in the art can be made thereto, without thereby departing from the scope of the invention as set forth in the appended claims.