Flat flexible tube for conveying fluid

Abstract

A flat flexible tube for conveying a fluid such as water, which is easily movable between a non-operating position and an operating position, in which non-operating position the flexible tube is substantially flat, and in which operating position the flexible tube radially expands under the pressure of the fluid. The tube comprises a first inner layer defining an axis (X), a second covering layer, and a reinforcing textile layer (4) inserted between the first inner layer and the second outer layer. The first inner layer and the second outer layer are made of a first and a second thermoplastic elastomer material respectively, and the first and second thermoplastic elastomer materials are compatible in such a way as to adhere to each other. The reinforcing textile layer (4) consists of rigid textile yarns which at least partially have respective first and second predetermined inclinations (α, β) relative to the axis (X) and opposite to each other, such that the length of the tube remains unchanged in both the non-operating position and the operating position. The reinforcing textile layer (4) is a knitted layer with a chain stitch (6) of the warp knitting type having stitch rows (8) and stitch columns (7), and the stitch rows and stitch columns are composed of the chain stitch (6).

Description

Technical Field

[0001] The present invention relates to the technical field of flexible tubes, such as irrigation tubes, and more particularly, the present invention relates to a flat flexible tube for transporting fluids, and a method for manufacturing the flat flexible tube.

[0002] Definition

[0003] In this document, the expression "textile yarn" or its derivatives is used to indicate an elongate yarn-like element of any shape and made of any material, provided that the dimension of the length is much greater than the other dimensions. For example, the textile yarn can be a polymer yarn, which can have a single structure or which can in turn be composed of the joining of several base yarns or textile tapes of any shape.

[0004] In this text, unless otherwise specified, the expression "rigid textile yarn" or its derivatives is used to indicate a textile yarn having an elongation at break of less than 10%, and preferably less than 7%, measured according to BISFA (Cap 7).

[0005] In this text, the expression "reinforcing textile layer" or its derivatives is used to indicate a layer composed of at least one textile yarn arranged on a base layer. The "reinforcing textile layer" is arranged on a load-bearing layer so as to leave a part in the load-bearing layer, and this left part is usually square, rectangular or diamond-shaped.

[0006] In this document, the expression "cross-hatched textile layer" or "cross-hatching" or its derivatives is used to indicate a layer composed of at least two yarns or groups of yarns, which are helically wound on a load-bearing layer at opposite inclinations and are superimposed on each other but not connected. Therefore, the cross-hatching consists of two or more superimposed spirals.

[0007] In this text, the expression "helical textile layer" or "helix" or derivatives is used to indicate a layer composed of a single yarn helically wound on a load-bearing layer at a predetermined pitch, or a group or groups of yarns helically wound on a load-bearing layer without being superimposed on each other.

[0008] In this text, the expression "woven textile layer" or "weaving" or derivatives is used to indicate a layer composed of at least two yarns or groups of yarns placed on a load-bearing layer and connected together to form a plurality of chain stitches, i.e., "stitches" of the warp knitting type. The "woven textile layer" is obtained using a circular knitting machine equipped with a plurality of needles of known types.

[0009] In this text, the expression "chain stitches of the warp knitting type" and the like is used to indicate a part of the "woven textile layer" that forms ring-shaped holes that are not necessarily closed. Each "chain stitch of the warp knitting type" is strung to the corresponding previous "chain stitch of the warp knitting type" and to the corresponding subsequent "chain stitch of the warp knitting type".

[0010] In this document, the expression "stitch row" and the like of a braided textile layer with chain stitches of warp knitting type is used to indicate a line defined by "chain stitches of warp knitting type" strung together with each other.

[0011] In this document, the expression "stitch column" and the like of a braided textile layer with chain stitches of warp knitting type is used to indicate a part of a textile yarn (or a set of yarns grouped into a single yarn) that connects two consecutive "chain stitches of warp knitting type" to each other along the same yarn. This part can be linear or instead configured as a "chain stitch of warp knitting type".

[0012] In this document, the expression "compatible materials" or its derivatives is used to indicate materials that are chemically / physically compatible with each other, that is, materials that form a joint suitable for supporting the transmission of tensile or shear forces through the contact surface once coupled. Thus, the greatest compatibility will be observed in the same material or materials with the same substrate matrix.

[0013] In this document, the expression "matrix" or its derivatives is used to indicate a polymeric material capable of providing the molecular structure of a finished product.

[0014] In this document, the expression "provide" or its derivatives is used to indicate the preparation of the elements of interest for the process steps of interest, and thus includes any preventive treatment for the optimal execution of the steps of interest, from simple collection and potential storage to heating and / or chemical and / or physical pretreatment and the like. Background Art

[0015] Flat flexible tubes for transporting fluids, specifically liquids, are known. Such tubes are used, for example, in agriculture or horticulture, and they are typically made of plasticized PVC with polyester cross-hatching.

[0016] Due to the presence of cross-hatching, the first drawback of such flexible tubes is the presence of points prone to cracking at the folds of the flat tubes.

[0017] Due to the different mechanical behaviors of the polymer material and the cross-hatching, another drawback lies in the change in the response of the tube to widening and flattening cycles.

[0018] Therefore, such tubes have a limited duration over time.

[0019] Another drawback of such flexible tubes lies in their greater impact on the environment in terms of the materials used in production and in terms of the handling of the finished products. Summary of the Invention

[0020] An object of the present invention is to overcome the drawbacks described above by providing a flat tube with excellent mechanical properties.

[0021] Another object of the present invention is to provide a particularly strong and flexible flat tube.

[0022] Another object of the present invention is to provide a flat flexible tube that has a constant response to the widening and flattening cycles.

[0023] Another object of the present invention is to provide a flat flexible tube that is particularly resistant to wear.

[0024] Another object of the present invention is to provide a flat flexible tube with low environmental impact.

[0025] These and other objects, which will become more apparent hereinafter, are achieved by a flat tube made of a thermoplastic elastomer and a method for manufacturing it as described and / or claimed herein.

[0026] The flat flexible tube can be used to convey any fluid. The flat flexible tube may include:

[0027] - at least one first inner layer defining an axis;

[0028] - at least one second layer;

[0029] - at least one reinforcing textile layer inserted between the at least one first layer and the at least one second layer.

[0030] The at least one first and one second layer and the at least one reinforcing textile layer may cooperate with each other such that the flexible tube is easily movable between a non-operating position and an operating position. In the non-operating position, the flexible tube is generally flat-shaped, and in the operating position, the flexible tube radially expands to assume a generally cylindrical shape. The tube moves from the non-operating position to the operating position under the pressure of the fluid being conveyed, and moves from the operating position to the non-operating position when the pressure of the fluid disappears.

[0031] The at least one first and one second layer may be made of first and second thermoformable polymer materials that are mutually compatible with each other.

[0032] The at least one reinforcing textile layer may be composed of rigid textile yarns that at least partially have respective first and second predetermined inclination angles relative to the axis and opposite to each other.

[0033] The at least one reinforcing textile layer may be a knitted layer with a chain stitch of the warp knitting type in stitch rows and stitch columns, and at least one of the stitch rows and stitch columns is composed of the chain stitch.

[0034] Advantageously, both the stitch rows and the stitch columns may be composed of the chain stitch of the warp knitting type.

[0035] Suitably, the flexible tube may include a single reinforcing textile layer consisting of the braided layer having a chain stitch of the warp-knit type.

[0036] Preferably, the flexible tube may be free of at least one reinforcing textile layer that is cross-hatched and / or helical.

[0037] Advantageously, the first and second polymer materials may have an elastic behavior both in the non-operating position and the operating position of the tube.

[0038] In a preferred but non-exclusive embodiment, the first and second polymer materials may be selected from the group consisting of: thermoplastic polymer materials, elastomers, thermoplastic elastomers.

[0039] Suitably, the at least one second outer layer may be easy to grip by the user, and according to ASTM D 2240 measurement, the Shore A hardness of the at least one second outer layer is greater than the Shore A hardness of the at least one first inner layer.

[0040] Advantageously, according to ASTM D 2240 measurement, the Shore A hardness of the at least one second outer layer may be between 70 ShA and 90 ShA, and preferably between 75 ShA and 85 ShA.

[0041] Preferably, according to ASTM D 2240 measurement, the Shore A hardness of the at least one first inner layer may be between 60 ShA and 80 ShA, and preferably between 65 ShA and 75 ShA.

[0042] On the other hand, a method for manufacturing a flat flexible tube may be provided, which sequentially includes the following steps:

[0043] - Providing a tubular semi-finished product, which includes:

[0044] - At least one first inner layer defining an axis;

[0045] - At least one second outer layer;

[0046] - At least one reinforcing textile layer, which is inserted between the at least one first layer and the at least one second layer;

[0047] wherein the at least one first and one second layer are respectively made of first and second thermoformable polymer materials that are mutually compatible with each other;

[0048] wherein the at least one reinforcing textile layer consists of rigid textile yarns, and the rigid textile yarns at least partially have corresponding first and second predetermined inclinations relative to each other with respect to the axis;

[0049] Wherein the at least one reinforcing textile layer is a woven layer with a warp knitting type chain stitch in the form of stitch rows and stitch columns, and at least one of the stitch rows and stitch columns is composed of the chain stitch; wherein the tubular semi-finished product is at a first predetermined thermoforming temperature;

[0050] - Extrude the semi-finished product to obtain a flat flexible tube;

[0051] - Cool the flat flexible tube for the first time.

[0052] The dependent claims describe advantageous embodiments of the present invention. Description of the Drawings

[0053] Other features and advantages of the present invention will become more apparent from the following detailed description of some preferred but non-exclusive embodiments of the present invention, which are illustrated by way of non-limiting examples with reference to the accompanying drawings, in which:

[0054] Figure 1A is a schematic view of the semi-finished product 5, wherein both the stitch row 8 and the stitch column 7 are composed of the chain stitch 6;

[0055] Figure 1B is a schematic view of the semi-finished product 5, wherein the stitch row 7 is composed of the chain stitch 6;

[0056] Figure 2 is a schematic view of the flat flexible tube 1;

[0057] Figure 3 is a legend showing the degree of wear evaluated for the wear test on the tube 1;

[0058] Figure 4A and 4B show the sample tubes WX2 and WX3 that have undergone the wear test after being dragged for 4 hours, respectively;

[0059] Figure 4C and 4D show the sample tubes WX2 and WX3 that have undergone the wear test after being dragged for 8 hours, respectively;

[0060] Figure 5A 、 5B and 5C show the stress-strain curves related to the average results detected for each sample WX1, WX2, WX3;

[0061] Figure 6 is a schematic view of the production line of the flat flexible tube 1, highlighting the section of the object 5 and the gradually obtained tube 1. Detailed Description of the Embodiments

[0062] With reference to the foregoing drawings, a flat flexible tube 1 for transporting fluids is described herein.

[0063] For example, the flexible tube 1 can be a garden hose or an irrigation hose for transporting water, specifically drinking water.

[0064] The tube 1 can move between a non-operating position and an operating position. In the non-operating position, the flexible tube is generally flat-shaped. In the operating position, the flexible tube is radially expanded under the action of the pressure exerted by the fluid, thus taking on a conventional tubular cylindrical shape. When the pressure in the tube disappears, for example when the faucet is closed, the tube can return to the non-operating position.

[0065] Therefore, when there is no fluid flowing in the flexible tube, the flexible tube is in a generally flat shape, as Figure 2 shown. This ensures the minimum overall size of the flexible tube while ensuring the same flow rate as that of a "conventional" flexible tube.

[0066] In a preferred but non-exclusive embodiment, the flexible tube 1 can be composed of an inner layer 2, an outer covering layer 3, and one or more reinforcing textile layers 4 inserted therebetween. The inner layer can be made of a thermoplastic elastomer, the outer covering layer can also be made of a thermoplastic elastomer, and the reinforcing textile layer can be made of, for example, polyester yarn (PET).

[0067] Obviously, the reinforcing layer 4 can be arranged on the inner layer 2 so as to leave several parts in the inner layer 2, and these parts are, for example, square, rectangular or diamond-shaped. In this way, the overlying layer, such as the covering layer 3, can be coupled to the underlying layer mainly by gluing or melting materials at such vacated parts.

[0068] Preferably, the thermoplastic elastomers of the layers 2 and 3 can thus be compatible materials.

[0069] Suitably, the inner layer 2 can define an axis X, that is, the axis of the tube 1.

[0070] Such a layer 2 can be designated to be in contact with the liquid to be transferred, while the outer covering layer 3 can be designated to be grasped by the user.

[0071] However, without departing from the scope of protection of the appended claims, other textile or polymer layers can be provided between, below or above the foregoing layers 2, 3 and 4.

[0072] For example, another inner layer can be provided and inserted between the layer 2 and the textile layer 4, such as a membrane suitable for preventing the formation of algae in the tube.

[0073] In addition, without departing from the scope of protection of the appended claims, another polymer layer that can be grasped by the user can be fixed on the covering layer 3.

[0074] The thermoplastic elastomers of layers 2 and 3 can optionally be selected from the group consisting of: EPDM or NBR vulcanized thermoplastic elastomers (TPE-V), thermoplastic silicone polymers (TPSiV), SEBS or SEPS thermoplastic elastomers (TPE-S), thermoplastic olefin elastomers (TPO), thermoplastic polyamide elastomers (TPE-A), thermoplastic polyurethane elastomers (TPU), thermoplastic polyester elastomers (TPE-E).

[0075] According to a preferred but non-exclusive embodiment, both layers 2 and 3 can be made of EPDM vulcanized thermoplastic elastomer (TPE-V), such as 201-64 and 201-73 respectively. Suitably, layers 2 and 3 can be the only polymer layers of the tube.

[0076] Preferably, the inner layer 2 can be made of a material suitable for contact with food or food liquids.

[0077] Obviously, without departing from the scope of protection of the appended claims, the materials of the inner layer 2 and the covering layer 3 can be the same or different.

[0078] Suitably, as measured according to the ASTM D 2240 standard, the Shore A hardness of the material of the covering layer 3 can be included in the range between 70 ShA and 90 ShA, and preferably between 75 ShA and 85 ShA, in order to maximize the abrasion resistance of the tube 1 after a period of time while providing a soft touch.

[0079] In addition, as measured according to the ASTM D 2240 standard, the Shore A hardness of the material of the inner layer 2 can be between 60 ShA and 80 ShA, and preferably between 65 ShA and 75 ShA, that is, lower than the Shore A hardness of the covering layer 3.

[0080] In this way, specifically, layer 2 can be light and at the same time it may be able to reduce and compensate for the traction force generated by the reinforcing layer 4 during the progressive expansion cycle of the tube 1.

[0081] In another embodiment, layers 2 and 3 can be made of an elastic material or a thermoplastic material such as plasticized PVC.

[0082] In any case, the polymeric materials of layers 2 and 3 can have elastic behavior both in the non-operating position and the operating position of the flexible tube, so as to allow the flexible tube to automatically move between the non-operating position and the operating position in response to the action or absence of the internal pressure of the tube.

[0083] In addition, the polymeric materials of layers 2 and 3 can be of the thermoformable type, so as to allow the tube to be in a flat shape during production, as described better below.

[0084] To prevent rupture zones from occurring due to the relatively small elastic response of layer 3 mainly with respect to the rigid textile yarns of reinforcement layer 4 when the tube 1 is radially expanded under fluid pressure, the reinforcement layer 4 can be a woven layer with a chain stitch 6 of the warp knitting type.

[0085] The woven layer can be obtained, for example, according to the disclosure of patent EP0623776, as Figure 1B shown.

[0086] However, the stitch rows 8 and stitch columns 7 can consist of chain stitches, as Figure 1A specially shown in.

[0087] In this way, the reinforcement layer 4 configured in this manner can expand when fluid flows through the tube 1, thus preventing the formation of typical local traction points such as cross-hatching, and therefore distributing the traction force over the entire woven layer 4.

[0088] Therefore, the flexible tube 1 can be without cross-hatching and / or a helical reinforcement layer.

[0089] In addition, the flexible tube 1 can include, for example, a single reinforcement layer 4 configured as described above.

[0090] Suitably, such a reinforcement layer 4 can consist of rigid textile yarns having respective first and second predetermined inclination angles α, β relative to each other with respect to the axis X, such that the length of the tube 1 remains unchanged in both the non-operating position and the operating position.

[0091] Additionally, the radial expansion of the tube 1 can be controlled in order to prevent it from bursting when subjected to the pressure of the fluid.

[0092] More precisely, in order to avoid excessive deformation of the tube 1 due to the pressure of the fluid in the operating position, the values of the inclination angles α, β relative to the axis X can be between 42° and 53°.

[0093] In fact, such values will allow the reinforcement layer 4 to resist deformation due to the internal pressure in both the axial and radial directions.

[0094] In fact, in the absence of a reinforcement layer 4 configured as described above, in the operating position, due to the elasticity of the material used, the tube 1 will tend to deform axially and radially.

[0095] More precisely, the inclination angles α, β described above will be able to obtain a tube 1 whose length can increase by a maximum of 1.1 times, preferably a maximum of 1.05 times, relative to its initial length under an operating pressure of 2 bar, the initial length being the length when no fluid is flowing through it.

[0096] Furthermore, the inclination angles α, β described above will make it possible to obtain a tube 1, the maximum inner diameter of which can increase by a factor of 1.1, preferably by a factor of at most 1.05, relative to the initial inner diameter under an operating pressure of 2 bar.

[0097] In a preferred but non-exclusive embodiment, the inner layer 2 may have a thickness s2, while the covering layer 3 may have a thickness s3, the ratio of which is between 1.05:1 and 1.5:1, and preferably between 1.1:1 and 1.4:1.

[0098] For example, the thickness s2 of the inner layer 2 may be between 1 mm and 1.1 mm, while the thickness s3 of the covering layer 3 may be between 0.8 mm and 0.9 mm.

[0099] This will make it possible to obtain a tube 1 with a total thickness between 1.8 mm and 2 mm, which is particularly strong and resistant to bursting.

[0100] From a manufacturing point of view, as is particularly shown in Figure 6 the tube 1 can be made by means of a production line 100 by extruding a first thermoplastic elastomer in a first extruder 10 to form the inner layer 2, by forming a reinforcing layer 4 above the inner layer by means of a braiding machine 20, and by extruding a second thermoplastic elastomer above the reinforcing layer by means of a second extruder 30 to form the covering layer 3.

[0101] The tubular semi-finished product 5 will then be cooled for a period of time by immersion in a relatively short tank 40 filled with water at a temperature between 12 °C and 20 °C, more preferably between 15 °C and 17 °C, for example 16 °C, the tank 40 being, for example, measured between 20 cm and 40 cm, the period of time preferably being equal to about 0.5 s to 1.5 s, and even more preferably 1 s. More precisely, the length of the tank 40 may be such that the tube section instantaneously immersed therein is about 30 cm.

[0102] Preferably, the tank 40 can be arranged in sequence at a minimum distance from the extruder relative to the extruder 30.

[0103] In this way, the semi-finished product 5 will transition from a first extrusion temperature, i.e. the thermoforming temperature, equal to about 170 °C to 190 °C, for example 180 °C, to a second operating temperature equal to about 90 °C to 110 °C, for example 100 °C. More precisely, such temperatures may relate to the outer surface of the semi-finished product 5.

[0104] Subsequently, the tubular semi-finished product 5 having such a second temperature is extruded into a device 50 for extruding the tube to obtain the flat flexible tube 1.

[0105] Suitably, such a device 50 may include one or more series of rollers 51, 52 facing each other and arranged at a distance from each other so as to minimize the presence of air inside the tube 1. Ideally, the distance between the rollers 51, 52 may be twice the thickness of the wall of the tube 1.

[0106] Suitably, at least one outer layer 53 of a relatively soft material, such as a coating or strip made of rubber, preferably natural rubber with a Shore A hardness between 50 and 70 (e.g., 60), may be arranged outside each roller 51, 52 so as to maintain the structural integrity of the tube during extrusion.

[0107] A relatively long box 60 may be arranged, for example, at a distance of 1 m to 1.5 m relative to the rollers 51, 52 in sequence, such that the tube is instantaneously cooled when using water at a temperature of 12 °C to 20 °C, more preferably 15 °C to 17 °C, e.g., 16 °C, for a period of time equal to 100 s to 120 s.

[0108] The length of the box 60 may be such that the tube section instantaneously immersed therein is about 30 m to 35 m.

[0109] In this way, the tube 1 will reach a third temperature substantially equal to the ambient temperature, for example, in the range of 12 °C to 30 °C, more preferably 15 °C to 25 °C.

[0110] In this way, the production line 100 will allow the obtaining of a flat flexible tube 1 that is particularly durable and has a constant response to the widening and flattening cycles.

[0111] However, obviously, it will be possible to directly obtain the flat flexible tube 1 from the tubular semi-finished product 5 with the aforementioned characteristics by extruding and cooling it.

[0112] The above will be described in more detail with reference to the following examples, which in any case should not be considered as limiting the scope of protection of the present invention.

[0113] Example

[0114] Sample:

[0115] For each type of test, several tests (3 or 5) were carried out on each sample (WX1, WX2, WX3), and all samples were obtained by means of the aforementioned method.

[0116] Configuration of WX1 sample test:

[0117] Inner layer: Plasticized PVC K70 62ShA;

[0118] Cover layer: Plasticized PVC K70 62ShA;

[0119] Textile reinforcement layer: PET - 38 knots.

[0120] Configuration of WX2 sample test:

[0121] Inner layer: Plasticized PVC S100 48ShA;

[0122] Cover layer: Plasticized PVC S100 48ShA;

[0123] Textile reinforcement layer: PET - 39 knots.

[0124] Configuration of WX3 sample test:

[0125] Inner layer: 201 - 64, 69ShA;

[0126] Cover layer: 201 - 73, 78ShA;

[0127] Textile reinforcement layer: PET - 37 knots.

[0128] The plasticized PVC compositions of samples WX1 and WX2 belong to the standard type in the field of flexible tubes and can be composed of a PVC matrix of the aforementioned type, plasticized with dioctyl terephthalate (DOTP) in an amount such that the aforementioned hardness is obtained, 1 wt% of a CaZn stabilizer, and 0.5 wt% of an epoxidized soybean oil co - stabilizer.

[0129] Example 1: Burst under pressure at room temperature (23 °C)

[0130] The aforementioned samples were subjected to a pressure burst test, i.e., the tubes were inflated at room temperature (23 °C). For each sample, the average results of three tests are reported in Table 1, showing a good response for sample WX3, which, although made of a thermoplastic elastomer, exhibits behavior comparable to the average of the results obtained with samples WX1 and WX2 made of PVC, which have more rigid properties themselves.

[0131] Table 1

[0132] Sample Burst pressure (bar) WX1 42.97 WX2 32.33 WX3 38.5

[0133] It should be noted that the values reported in this first example may refer to the embodiment of sample WX3, which contains a row of stitches 8 and a column of stitches 7, all composed of chain stitches 6.

[0134] Example 2: Shrinkage percentage level

[0135] The aforementioned samples were subjected to a shrinkage percentage level assessment test.

[0136] Specifically, the initial length L of each sample was evaluated i, and then it was introduced into a forced ventilation oven of type M250-VF sold by ATS FAAR Industrie S.p.A. at 80 °C for 168 hours.

[0137] Then, the final length L of each sample was evaluated after leaving the oven. f .

[0138] Therefore, for each sample, the percentage of longitudinal shrinkage was calculated using the following formula:

[0139]

[0140] Where:

[0141] -L i is the length of the sample before being introduced into the oven;

[0142] -L f is the length of the sample after being introduced into the oven.

[0143] Then, the average value of the values detected for each sample in three different tests was calculated, as shown in Table 2, which shows the good mechanical behavior of the WX3 sample made of a polymer elastomer and the subsequent constant behavior of the sample during the widening and flattening cycles.

[0144] Table 2

[0145]

[0146] Example 3: Wear test

[0147] Also shown are the results related to the abrasion test carried out on a tube about 1 m long, filled with water and with an internal pressure of 3 bar.

[0148] Such tubes were dragged on the outdoor ground at a room temperature of 23 °C.

[0149] Specifically, the dragging speed was 2000 m / h, the weight of each meter of the water-filled tube was equal to 160 g / m, and the dragging distance covered after 4 hours was equal to 8000 m and the dragging distance covered after 8 hours was equal to 16000 m.

[0150] Then, the samples were visually inspected by comparing the degree of abrasion with the degree of abrasion shown in the legend of Figure 3 , where the acceptance limit identified was equal to 4.

[0151] Specifically, Figure 4A and Figure 4B show the sample tubes WX2 and WX3 that underwent the abrasion test after 4 hours of dragging, respectively, while Figure 4C and Figure 4DSamples tubes WX2 and WX3 that have undergone wear tests after 8 hours of dragging are shown respectively.

[0152] These two results show that the wear resistance of sample WX3 is 5, so according to Figure 3 the legend can be defined as "not worn", equal to the wear resistance of samples WX1 and WX2 made of plasticized PVC.

[0153] Example 4: Mechanical strength (stress-strain curve according to ISO 527)

[0154] The aforementioned samples underwent mechanical strength tests. For each of the samples WX1, WX2, WX3, Figure 5A 、 5B 5C shows the average results of the three tests in the form of a stress-strain curve according to the UNIEN ISO 527-1 standard.

[0155] According to the quality comparison, it is obvious that in sample WX3, a higher percentage of deformation can be obtained with a reduced applied force, which is a characteristic of thermoplastic elastomers.

[0156] Therefore, the tendency of the tube made of thermoplastic elastomer to produce fracture areas due to the force exerted by the fluid will be lower.

Claims

1. A flat flexible tube for conveying fluids, more precisely a garden hose for conveying water, comprising: - At least one first inner layer defining an axis (X); - At least one second outer layer; - At least one reinforcing textile layer (4) inserted between the at least one first inner layer and the at least one second outer layer; wherein the at least one first inner layer and the at least one second outer layer cooperate with the at least one reinforcing textile layer (4) such that the flexible tube is movable between a non-operating position and an operating position, in the non-operating position the flexible tube being substantially flat, and in the operating position the flexible tube radially expanding to be substantially cylindrical, the tube moving from the non-operating position to the operating position under the pressure of the fluid being conveyed and moving from the operating position to the non-operating position when the pressure of the fluid disappears; wherein the at least one first inner layer and the at least one second outer layer are made of first and second heat-formable polymer materials respectively which are mutually compatible with each other, the first and second polymer materials having an elastic behavior both in the non-operating position and the operating position of the tube; wherein the at least one reinforcing textile layer (4) consists of rigid textile yarns, the rigid textile yarns having respective first and second predetermined inclinations (α, β) relative to the axis (X) at least partially opposite to each other, the rigid textile yarns of the at least one reinforcing textile layer (4) further resisting the radial expansion of the tube in the operating position so as to prevent the tube from bursting when subjected to the pressure of the fluid; characterized in that the at least one reinforcing textile layer (4) is a woven layer having a chain stitch (6) of the warp knitting type with stitch rows (8) and stitch columns (7), at least one of the stitch rows (8) and stitch columns (7) being composed of the chain stitch (6), the tube being free of at least one cross-hatched and / or spiral reinforcing textile layer.

2. The tube according to claim 1, wherein both the stitch rows (8) and the stitch columns (7) are composed of the chain stitches (6) of the warp knitting type.

3. The tube according to claim 1, comprising a single reinforcing textile layer (4) composed of a woven layer having the chain stitches (6) of the warp knitting type.

4. The tube according to claim 1, wherein the length of the tube remains substantially unchanged in both the non-operating position and the operating position.

5. The tube according to claim 1, wherein the first and second polymer materials are selected from the group consisting of: thermoplastic polymer materials, elastomers.

6. The tube according to claim 5, wherein the elastomer includes a thermoplastic elastomer.

7. The tube according to claim 1, wherein the at least one second outer layer is easy for the user to grasp, and the Shore A hardness of the at least one second outer layer is greater than the Shore A hardness of the at least one first inner layer, as measured according to ASTM D2240.

8. A method for manufacturing the flat flexible tube (1) according to claim 1, successively comprising the following steps: - Providing a tubular semi-finished product (5) comprising: - At least one first inner layer defining an axis (X); - At least one second outer layer; - At least one reinforcing textile layer (4) inserted between the at least one first inner layer and the at least one second outer layer; wherein the at least one first inner layer and the at least one second outer layer are made of first and second heat-formable polymer materials respectively which are mutually compatible with each other, the first and second polymer materials having an elastic behavior both in the non-operating position and the operating position of the tube; wherein the at least one reinforcing textile layer (4) consists of rigid textile yarns, the rigid textile yarns having respective first and second predetermined inclinations (α, β) relative to the axis (X) at least partially opposite to each other such that the length of the tube remains substantially unchanged both in the non-operating position and the operating position, the rigid textile yarns of the at least one reinforcing textile layer (4) further resisting the radial expansion of the tube in the operating position so as to prevent the tube from bursting when subjected to the pressure of the fluid; wherein the at least one reinforcing textile layer (4) is a woven layer having a chain stitch (6) of the warp knitting type in stitch rows (8) and stitch columns (7), at least one of the stitch rows (8) and stitch columns (7) being formed by the chain stitch (6), and the tube being free of at least one cross-hatch and / or spiral reinforcing textile layer; wherein the tubular semi-finished product (5) is at a first predetermined thermoforming temperature; extruding the tubular semi-finished product (5) to obtain the flat flexible tube (1); cooling the flat flexible tube (1) for the first time.

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