WO2011161576A1

WO2011161576A1 - Flexible braided garden hose

Info

Publication number: WO2011161576A1
Application number: PCT/IB2011/052469
Authority: WO
Inventors: Alessandro Mezzalira; Valentino Vigolo
Original assignee: Fitt S.P.A.
Priority date: 2010-06-23
Filing date: 2011-06-07
Publication date: 2011-12-29
Also published as: BR112012030437A2; CA2708484A1

Abstract

A flexible garden hose comprising at least one inner first layer (2) made of a first thermoplastic polymer material, at least one reinforcing braided layer ( 3 ) and at least one outer second layer (4) made of a second thermoplastic polymer material. The at least one reinforcing braided layer consists of a first plurality of textile yarns (5) superimposed to a second plurality of textile yarns (6). At least one of the first and second plurality of textile yarns (5,6) comprises at least one first yarn (7,7') consisting of a fiber having an elongation at break of less than 5% at ambient temperature as measured according to DIN EN ISO 2062 and at least one second yarn (8) consisting of a polyester fiber. A process for manufacturing such hose..

Description

FLEXIBLE BRAIDED GARDEN HOSE

DESCRIPTION

Field of the invention

The present invention generally relates to the technical field of the flexible hoses, and particularly concerns a reinforced flexible braided garden hose and its manufacturing process.

Background of the invention

It is known that flexible garden hoses, i.e. those hoses which are designed for irrigation purposes, include one or more inner layers, one or more reinforcing layers and one or more outer layers.

The inner and outer layers are usually made of an extruded polymer thermoplastic material, such as PVC, while the reinforcing layers are made of polyester yarns.

Generally speaking, two kinds of reinforcing layers are known for garden hoses, the knitted one and the braided one. As known, these two different kinds of reinforcing layers give to the hose unique properties.

In fact, while the knitted hoses have high quality and great flexibility and resistance to deflections, the braided hoses are preferable for cost-effectiveness and resistance to internal pressure.

A braided reinforcing layer usually consist of a first plurality of textile yarns superimposed to a second plurality of textile yarns.

In order to form the reinforcing layer, a braiding machine is used which has two consecutive counter-rotating braiding units. During the braiding process, the first braiding unit winds the first plurality of textile yarns around the bearing layer in a spiral-like manner with a predetermined first inclination with respect to the axis of the hose, while the subsequent braiding unit winds the second plurality of textile yarns onto the first plurality with an inclination which is opposite to the first inclination.

One of the problem of the known flexible hoses is the so-called "swelling" under internal pressure. This is mainly due to the nature of the materials used both for the inner and outer layers and for the reinforcing layers. The swelling of the hose unavoidably negatively affects also the burst pressure.

Although in general the braided hose is less subject to this problem with respect to the knitted hose, for certain applications it is desirable to minimize as much as possible or even completely overcome the swelling problem, as well as to improve the burst pressure.

To date, the known solutions to this problem are unacceptably expensive for the market of braided hoses.

In fact, hoses are known having one or more reinforcing layers fully consisting of high tenacity fibers, such as Kevlar ®, carbon fibers and the like. From EP-A- 0074747 is known an example of these hoses.

[As it is apparent, although these solutions can completely obviate to the swelling problem, they are designed for applications different from the irrigation. In fact, the reinforcing layers are netted on the bearing layer, in such a manner to completely cover it. As a result, these solutions are unacceptably expensive for the market of the braided garden hose.

An other alternative solution to this problem is to superimpose to the first braided layer at least one second reinforcing polyester layer. From FR-A-2762376 is known an example of these hoses.

This solution cannot completely obviate to the swelling problem, because of the nature of the materials used. Moreover, it again increases the production costs of the hose. As it is apparent, a high production cost means also a high environmental impact of the hose.

Another solution to the problem of the swelling known in the art of hose manufacturing is to increase the thickness of the outer PVC layer, in such a manner that it cooperate with the reinforcing layer to contrast the internal pressure.

This solution also cannot completely obviate to the swelling problem, because of the nature of the materials used, and again involves unacceptably high production costs and environmental impact. Moreover, as it is apparent, a thick outer layer reduces the flexibility and the so-called "malleability" of the hose.

Summary of the invention

Main object of the present invention is, therefore, to provide a braided garden hose, as well as a manufacturing process thereof, that minimizes or even completely eliminates the problem of swelling under pressure in an economical and simple manner.

An other object of the present invention is to provide a braided garden hose having an improved burst pressure.

Another object of the present invention is to provide a cost-effective braided garden hose. A further object of the present invention is to provide a braided garden hose that has the lowest possible environmental impact.

Another object of the present invention is to provide a process for manufacturing a braided garden hose in a simple and economical manner.

These objects, as well as others that will be more apparent hereinafter, are fulfilled by a flexible hose having one or more of the features herein described and/or claimed.

The hose of the invention may comprise one or more inner first layers made of a first thermoplastic polymer material, preferably plasticized PVC; one or more reinforcing braided layers and one or more outer second layers made of a second thermoplastic polymer material, preferably plasticized PVC.

The first polymer material may have a Shore A hardness higher than the hardness of the second polymer material.

In particular, the Shore A hardness of the first polymer material may be of 40 to 95, and preferably of 70 to 80, while the Shore A hardness of the second polymer material may be of 40 to 95, and preferably of 60 to 70.

As used herein, the term "braided layer" or derivatives thereof is intended as a layer formed by a first plurality of textile yarns superimposed to a second plurality of textile yarns.

The yarns of the first and second plurality are not knitted, netted nor otherwise connected each other.

The yarns of the first and second plurality do not completely cover the bearing layer on which they are wound.

In particular, each yarn of the first and second plurality has a predetermined pitch, i.e. the distance between two points of the same yarn taken along an axis parallel to the axis of the hose, and a predetermined distance from the preceding and subsequent yarn of the same plurality.

The first plurality and/or the second plurality of yarns of at least one of the braided layers of the hose comprises one or more first yarns consisting of fibers having an elongation at break of less than 5%, and preferably less than 3%, at ambient temperature as measured according to DIN EN ISO 2062 and one or more second yarns consisting of polyester fibers.

Thanks to these features, the one or more first yarns having low tensile elongation, which are spiral-like wound around the hose for the entire length thereof, act as "barrier" against the pressure internal to the hose, in such a manner to minimize or even completely overcome the problem of swelling.

At the same time, the fact that the braided reinforcing layer comprise both low tensile elongation and polyester fibers results in an important cost-effectiveness of the hose, which also means a low environmental impact.

In fact, as it is apparent, the hose according to the invention is very economical if compared with the netted hoses of the prior art, such as the above cited EP-A-0074747.

Moreover, the hose according to the invention is easier to manufacture, and therefore more economical, with respect to the double layered hoses of the prior art such as FR-A-2762376, because only one layer is to be manufactured instead of two. As a result, less energy is to be spent for manufacturing the hose of the invention with respect to the hoses of the prior art.

Further, the hose of the present invention may have thinner outer layers with respect to the prior art solutions, because its braided layer need not to cooperate with the outer layer to contrast the swelling.

Advantageously, the first yarns having low tensile elongation, which may pertain to the first and/or the second plurality of textile yarn of the braided layers, may also have high tenacity.

In particular, the first yarns may have a tenacity of at least 1500 mN/tex at ambient temperature as measured according to DIN EN ISO 2062, preferably of at least 2000 mN/tex and more preferably of at least 2500 mN/tex.

Suitably, the first yarns may be chosen among the group consisting of aramid fibers, particularly Kevlar®, Nomex® or Twaron®, high modulus polyethylene fibers, poly-ether-ether-ketone fibers, metallic fibers, carbon fibers, basalt fibers, Rayon® fibers or hybrid fibers obtainable by coupling two or more thereof.

In a further aspect, the present invention relates to a process for manufacturing the above braided garden hose, which comprises the steps of: a) extruding a first thermoplastic polymer material for manufacturing at least one inner first layer; b) braiding externally to said at least one inner first layer at least one reinforcing layer for manufacturing a semi-finished hose and c) extruding externally to the semi-finished hose a second thermoplastic polymer material for manufacturing at least one outer second layer.

The braiding step b) comprises a first step b') of deposition externally to the at least one inner first layer of the second plurality of textile yarns and a second step b") of deposition onto the second plurality of the first plurality of textile yarns to form the reinforcing layer.

Suitably, the above process may further comprise a step d) of heating the semi-finished hose after the second deposition step b") for heat shrinking the polyester yarns.

This is particularly advantageous if the first plurality of the braided layer fully consist of polyester fibers, while the second plurality comprise both low elongation and polyester fibers. In this case, the polyester fibers of the first plurality heat shrink over the low tensile elongation fibers of the second plurality, in such a manner to stabilize it onto the bearing layer.

In fact, the polyester fiber is a high-heat shrinkable fiber, while the low elongation fibers are generally not or very few heat shrinkable.

Therefore, thanks to the heating step, the low elongation fibers perfectly adhere to the bearing layer, thus improving the mechanical properties and the performances of the hose.

Advantageous embodiment of the invention are defined in accordance with the dependent claims.

Brief description of the drawings

Further features and advantages of the invention will become more apparent from the detailed description of a few preferred, non exclusive embodiments of the invention, presented by way of illustrating and non-limiting examples in connection with the accompanying drawings in which:

FIGS. 1 and 2 are schematic views of a first and second embodiment of the hose according to the invention;

FIGS. 3 and 4 are schematic views of a third and fourth embodiment of the hose according to the invention;

FIGS. 5 and 6 are schematic views of a fifth and sixth embodiment of the hose according to the invention;

FIG. 7 is a schematic view of a production line of the hose according to the invention.

Detailed description of some preferred embodiments of the invention

With reference to the above cited drawings, a flexible garden hose 1 is described which comprises an inner first layer 2 made of a first thermoplastic polymer material, e.g. plasticized PVC, a reinforcing braided layer 3 and an outer second layer 4, made of a second thermoplastic polymer material, e.g. plasticized PVC.

The hose 1 may comprise other polymer layers, both internally and externally to the inner and outer layers 2 and 4, as well as other reinforcing layers. However, preferably, the hose 1 will comprise only one braided layer 3.

The braided layer 3, which consists of a first plurality 5 of textile yarns superimposed to a second plurality 6 of textile yarns, may comprise both yarns consisting of polyester fibers and one or more yarns consisting of a fiber having a tensile elongation of less than 5%, preferably less than 3%, at ambient temperature as measured according to DIN EN ISO 2062 and a tenacity of at least 1500 mN/tex at ambient temperature as measured according to DIN EN ISO 2062, preferably of at least 2000 mN/tex and more preferably of at least 2500 mN/tex.

The latter fibers may be, as a non limiting example, Kevlar® or Carbon fibers having a linear density of 1 100 or 2200 dtex. In fact, the Kevlar fiber has a tenacity of 2000 - 2500 mN/tex and an elongation at break of 2 - 4%, while the carbon fiber has a tenacity of 1500 - 2000 mN/tex and an elongation at break of 1 - 3%.

By way of comparison, the polyester fibers having a linear density of 550 or 1 100 dtex have an elongation at break of about 10 - 15% and a tenacity of about 800 mN/tex.

In the FIGS. 1 to 6 several embodiments of the invention are shown, which differ each other in the configuration of the braided reinforcing layer 3. In these drawings, the Kevlar® or Carbon fibers have been outlined in solid black, while the polyester fibers are in white. In each drawing, the working direction by which the hose moves along the production line is indicated by V.

The FIG. 1 shows a first embodiment of the hose according to the invention, in which the yarns of the first plurality 5 of the braided layer 3 consist only of polyester fibers, while in the second plurality 6 one first yarn 7 consists of a Kevlar® or Carbon fiber and the remaining second yarns 8 consist of polyester fibers.

The FIG. 2 shows a second embodiment of the hose according to the invention, in which the first plurality 5 of the braided layer 3 consists only of polyester fibers, while in the second plurality 6 two first yarns 7, T consist of Kevlar® or Carbon fibers and the remaining second yarns 8 consist of polyester fibers.

The FIG. 3 shows a third embodiment of the hose according to the invention, in which the second plurality 6 of the braided layer 3 consists only of polyester fibers, while in the first plurality 5 one first yarn 7 consists of a Kevlar® or Carbon fiber and the remaining second yarns 8 consist of polyester fibers.

The FIG. 4 shows a fourth embodiment of the hose according to the invention, in which the second plurality 6 of the braided layer 3 consists only of polyester fibers, while in the first plurality 5 two first yarns 7, T consist of Kevlar® or Carbon fibers and the remaining second yarns 8 consist of polyester fibers.

The FIG. 5 shows a fifth embodiment of the hose according to the invention, in which the first plurality 5 of the braided layer 3 comprises one first yarn 7 consisting of a Kevlar® or Carbon fiber and the remaining second yarns 8 consisting of polyester fibers, while the second plurality 6 comprises third yarns 9 consisting of polyester fibers and one fourth yarn 10 consisting of a Kevlar® or Carbon fiber.

The FIG. 6 shows a sixth embodiment of the hose according to the invention, in which the first plurality 5 of the braided layer 3 comprises two first yarns 7, T consisting of Kevlar® or Carbon fibers and the remaining second yarns 8 consisting of polyester fibers, while the second plurality 6 comprises third yarns 9 consisting of polyester fibers and two fourth yarns 10, 10' consisting of Kevlar® or Carbon fibers.

Anyway, it is understood that the number of polyester and Kevlar® or Carbon fibers may vary in the first and/or the second plurality of the braided layer 3 according to needs, without departing from the scope or spirit of the invention.

The hose of the invention may be manufactured by the production line 20 shown in FIG. 7. In this drawing, the direction in which the hose advances trough the production line is indicated by V.

In the first extruder 21 a first thermoplastic polymer material, e.g. plasticized PVC, is extruded for manufacturing the inner first layer 2.

In the subsequent braiding machine 22 the reinforcing layer 3 is braided onto the inner layer 2. In particular, the braiding machine 22 comprises a first braiding unit 23 for winding the first plurality of textile yarns 5 around the bearing layer 2 and a subsequent second braiding unit 23' for winding the second plurality of textile yarns 6 onto the first plurality 5. As a result, a semi-finished hose is manufactured comprising the inner layer 2 and the braided layer 3.

In the second extruder 24 a second thermoplastic polymer material, e.g. plasticized PVC, is extruded to cover the semi-finished hose by the outer layer 4.

According to the exemplary embodiments shown in the FIGS. 1 to 6, each braiding unit 23, 23' comprises six yarn reels, in such a manner that both first and second plurality 5 and 6 consist of six yarns.

In particular, the first embodiment of FIG. 1 may be manufactured by a braiding machine 22 having the first braiding unit 23 comprising a single reel of the first yarn 7 consisting of a Kevlar® or Carbon fiber and the remaining five reels of second yarns 8 consisting of polyester fibers, while the second braiding unit 23' comprises six reels of polyester yarns.

The second embodiment of FIG. 2 may be manufactured by a braiding machine 22 having the first braiding unit 23 comprising two reel of the first yarns 7, 7' consisting of a Kevlar® or Carbon fibers and the remaining four reels of second yarns 8 consisting of polyester fibers, while the second braiding unit 23' comprises six reels of polyester yarns.

The third embodiment of FIG. 3 may be manufactured by a braiding machine 22 having the first braiding unit 23 comprising six reels of polyester yarns, while the second braiding unit 23' comprises a single reel of the first yarn 7 consisting of a Kevlar® or Carbon fiber and the remaining five reels of second yarns 8 consisting of polyester fibers.

The fourth embodiment of FIG. 4 may be manufactured by a braiding machine 22 having the first braiding unit 23 comprising six reels of polyester yarns, while the second braiding unit 23' comprises two reels of the first yarns 7, 7' consisting of a Kevlar® or Carbon fibers and the remaining four reels of second yarns 8 consisting of polyester fibers.

The fifth embodiment of FIG. 5 may be manufactured by a braiding machine 22 having both the first and second braiding units 23, 23' which comprise a single reel of Kevlar® or Carbon fiber and the remaining five reels of polyester fibers. In particular, the first braiding unit 23 comprises a single reel of the fourth yarn 10 consisting of a Kevlar® or Carbon fiber and the remaining five reels of third yarns 9 consisting of polyester fibers, while the second braiding unit 23' comprises a single reel of the first yarn 7 consisting of a Kevlar® or Carbon fiber and the remaining five reels of second yarns 8 consisting of polyester fibers.

The sixth embodiment of FIG. 6 may be manufactured by a braiding machine

22 having both the first and second braiding units 23, 23' which comprise two reels of

Kevlar® or Carbon fiber and the remaining four reels of polyester fibers. In particular, the first braiding unit 23 comprises two reels of the fourth yarns 10, 10' consisting of

Kevlar® or Carbon fibers and the remaining four reels of third yarns 9 consisting of polyester fibers, while the second braiding unit 23' comprises two reels of the first yarns 7, 7' consisting of a Kevlar® or Carbon fibers and the remaining four reels of second yarns 8 consisting of polyester fibers.

Advantageously, the semi-finished hose may be heated in a suitable heating device 25, e.g. an oven, interposed between the braiding machine 22 and the second extruder 24, in order to heat shrunk the polyester fibers.

Thanks to this feature, the layers comprising polyester fibers heat shrink over the layers below. This is particularly advantageous in case of the embodiment of the invention shown in the FIGS. 1 and 2, because the first plurality of polyester fibers heat shrink over the second plurality comprising the Carbon or Kevlar® fiber, i.e. a not-heat shrinkable material, in such a manner to stabilizing thereof on the inner layer 2.

By way of comparison, while the polyester fibers at 180 °C heat-shrink by about 10 - 15% as measured according to DIN 53866, the Kevlar ® or Carbon fibers at 400 °C only heat-shrink by 0,1 - 2 %.

The temperature of the heating device 25 may be comprised between 160 and 200 °C, preferably close to 180 °C.

Suitably, cooling tanks 26, 27 may be provided downstream the first and second extruders 21 , 24 for cooling the extruded layers. Further, hauling-off machines 28, 29 and 30 may be provided along the line 20.

The hose of this invention is susceptible of a number of changes and variants. All the components thereof may be replaced by other technically equivalent compounds without departure from the spirit or scope of the invention. The present embodiment, therefore, are to be considered in all respects as illustrative and not restrictive of the invention.

Claims

1 . A flexible hose comprising:

- at least one inner first layer (2) made of a first thermoplastic polymer material;

- at least one reinforcing braided layer (3);

- at least one outer second layer (4) made of a second thermoplastic polymer material;

wherein said at least one reinforcing braided layer (3) consists of a first plurality of textile yarns (5) superimposed to a second plurality of textile yarns (6), wherein at least one of said first and second plurality of textile yarns (5, 6) comprises at least one first yarn (7, 7') consisting of a fiber having an elongation at break of less than 5% at ambient temperature as measured according to DIN EN ISO 2062, said at least one of said first and second plurality of textile yarns (5, 6) further comprising at least one second yarn (8) consisting of a polyester fiber.

2. Hose according to claim 1 , wherein said at least one first yarn (7, 7') is chosen among the group consisting of aramid fibers, high modulus polyethylene fibers, poly-ether-ether-ketone fibers, metallic fibers, carbon fibers, basalt fibers, Rayon® or hybrid fibers obtainable by coupling two or more thereof.

3. Hose according to claim 2, wherein said aramid fibers are chosen among the group consisting of Kevlar®, Nomex® or Twaron®.

4. Hose according to claim 1 , 2 or 3, wherein said second plurality of textile yarns (6) comprise both said at least one first and second yarn (7, 7'; 8), said first plurality of textile yarns (5) comprising at least one third yarn (9) consisting of polyester fiber.

5. Hose according to claim 4, wherein said first plurality of textile yarns (5) consists of polyester fibers.

6. Hose according to claim 4, wherein said first plurality of textile yarns (5) comprise at least one fourth yarn (10, 10') consisting of a fiber having substantially the same elongation at break of said at least one first yarn (7, 7').

7. Hose according to claim 1 , 2 or 3, wherein said first plurality of textile yarns (5) comprises both said at least one first and second yarn (7, 7'; 8), said second plurality of textile yarns (6) consisting of polyester fibers.

8. Hose according to one or more of the preceding claims, wherein said at least one first yarn (7, 7') has a tenacity of at least 1500 mN/tex at ambient temperature as measured according to DIN EN ISO 2062.

9. Hose according to one or more of the preceding claims, wherein said at least one first yarn (7, 7') has a tenacity of at least 2000 mN/tex at ambient temperature as measured according to DIN EN ISO 2062.

10. Hose according to one or more of the preceding claims, wherein said at least one first yarn (7, 7') has a tenacity of at least 2500 mN/tex at ambient temperature as measured according to DIN EN ISO 2062.

1 1 . Hose according to one or more of the preceding claims, wherein said at least one first yarn (7, 7') has an elongation at break of less than 3% at ambient temperature as measured according to DIN EN ISO 2062.

12. A process for manufacturing a flexible hose, comprising the steps of:

a) extruding a first thermoplastic polymer material for manufacturing at least one inner first layer (2);

b) braiding externally to said at least one inner first layer (2) at least one reinforcing layer (3) for manufacturing a semi-finished hose;

c) extruding externally to said semi-finished hose a second thermoplastic polymer material for manufacturing at least one outer second layer (4);

wherein said braiding step b) comprises a first step b') of deposition externally to said at least one inner first layer (2) of a second plurality of textile yarns (6) and a second step b") of deposition on said second plurality of textile yarns (6) of a first plurality of textile yarns (5) to form said at least one reinforcing layer (4),

wherein at least one of said first and second plurality of textile yarns (5, 6) comprises at least one first yarn (7, 7') having an elongation at break of less than 5% at ambient temperature as measured according to DIN EN ISO 2062, said at least one of said first and second plurality of textile yarns (5, 6) further comprising at least one second yarn (8) consisting of a polyester fiber.

13. Process according to claim 12, wherein said at least one first yarn (7, 7') is chosen among the group consisting of aramid fibers, high modulus polyethylene fibers, poly-ether-ether-ketone fibers, metallic fibers, carbon fibers, basalt fibers, Rayon® fibers or hybrid fibers obtainable by coupling two or more thereof.

14. Process according to claim 13, wherein said aramid fibers are chosen among the group consisting of Kevlar®, Nomex® or Twaron®.

15. Process according to claim 12, 13 or 14, wherein said second plurality of textile yarns (6) comprise both said at least one first and second yarn (7, 7'; 8), said first plurality of textile yarns (5) comprising at least one third yarn (9) consisting of polyester fiber.

16. Process according to claim 15, wherein said first plurality of textile yarns (5) consists of polyester fibers.

17. Process according to claim 15, wherein said first plurality of textile yarns (5) comprise at least one fourth yarn (10, 10') consisting of a fiber having substantially the same elongation at break of said at least one first yarn (7, 7').

18. Process according to claim 15, further comprising a step d) of heating said semi-finished hose after said second deposition step b") for heat shrinking said at least one third yarn (9) of said first plurality (5) over said at least one first yarn (7, 7') of said second plurality (6).

19. Process according to claim 18, wherein said heating step d) is carried out by passing said semi-finished hose through a heating device at a temperature comprised between 160 °C and 200 °C.

20. Process according to claim 15, wherein said first plurality of textile yarns (5) comprise both said at least one first and second yarn (7, 7'; 8), said second plurality of textile yarns (6) consisting of polyester fibers.