Tire fabric comprising tousled weft reinforcing elements with low moisture absorption content

Abstract

A weft fabric (T) for tires (10) comprises several textile warp reinforcing elements (44) and several weft reinforcing elements (50), wherein the moisture regain MR of the weft reinforcing elements (50) is less than or equal to 2.0%, the moisture regain being determined according to standard ASTM D 885/D 885MA of January 2010 the weft reinforcing elements (50) interweave the warp reinforcing elements (44), and the weft reinforcing elements (50) are hairy.

Claims

1. A weft fabric for tires comprising several textile warp reinforcing elements and several weft reinforcing elements, wherein a moisture regain MR of the weft reinforcing elements is less than or equal to 2.0%, the moisture regain MR being determined according to standard ASTM D 885/D 885MA of January 2010, wherein the weft reinforcing elements interweave the warp reinforcing elements, and wherein the weft reinforcing elements are hairy.

2. The weft fabric according to claim 1, wherein the weft reinforcing elements are such that a number of threadlike elements protruding from a diameter of each weft reinforcing element is greater than or equal to 1250 threadlike elements per 100 meters of weft reinforcing elements, the number of protruding threadlike elements being determined according to a first method of measuring hairiness in which any threadlike element crossing a line perpendicular to a tangent to an external diameter of each weft reinforcing element in a direction of a length of each weft reinforcing element is counted.

3. The weft fabric according to claim 1, wherein the weft reinforcing elements are such that a number of 1 to 2 mm threadlike elements protruding from a diameter of each weft reinforcing element is greater than or equal to 5000 threadlike elements per 100 meters of weft reinforcing elements, the number of protruding threadlike elements being determined according to a second method of measuring hairiness in which a number of threadlike elements protruding from the diameter of each weft reinforcing element which have a size of between 1 and 2 mm if a line is plotted perpendicular to a tangent to an external diameter of each weft reinforcing element in a direction of a length of each weft reinforcing element are measured.

4. The weft fabric according to claim 1, wherein the warp reinforcing elements are substantially parallel to one another and extend in a general warp direction and the weft reinforcing elements are substantially parallel to one another and extend in a general weft direction different from the general warp direction.

5. The weft fabric according to claim 1, wherein each textile warp reinforcing element comprises several multifilament strands.

6. The weft fabric according to claim 5, wherein each warp reinforcing element comprises an assembly consisting of two multifilament strands, the two strands being wound in a helix around one another.

7. The weft fabric according to claim 1, wherein each weft reinforcing element comprises, for at least 50% of its weight, one or more textile filaments and/or several textile fibers.

8. The weft fabric according to claim 1, wherein each weft reinforcing element comprises at least one strand comprising a core and a layer coating the core, the core comprising at least one filament and the layer comprising several protruding short fibers.

9. The weft fabric according to claim 8, wherein the core comprises several synthetic organic polymeric filaments and the layer comprises several synthetic organic polymeric fibers.

10. The weft fabric according to claim 9, wherein each filament and/or each fiber is selected from polyester filaments and fibers, polyamide filaments and fibers, polyketone filaments and fibers, polyurethane filaments and fibers, acrylic filaments and fibers, polyolefin filaments and fibers, polyether ether ketone filaments and fibers and assemblies thereof.

11. The weft fabric according to claim 1, wherein a diameter of each weft reinforcing element is strictly less than 0.50 mm.

12. The weft fabric according to claim 1, wherein a density of the weft reinforcing elements ranges from 3.0 to 8.0 weft reinforcing elements per dm of fabric.

13. An elastomer composite for tires comprising at least one weft fabric according to claim 1 embedded in an elastomer composition.

14. A tire comprising a hoop reinforcement comprising at least one hooping ply, wherein the at least one hooping ply comprises the elastomer composite according to claim 13.

15. A process for manufacturing a weft fabric comprising the steps of: in an unwinding step, unwinding several warp reinforcing elements from a creel on an air-jet loom; in a separation step, separating the warp reinforcing elements into a first and a second ply of warp reinforcing elements; in an interweaving step, alternately interweaving at least one weft reinforcing element with warp reinforcing elements of the first ply of warp reinforcing elements, then of the second ply of warp reinforcing elements; and in a winding step, winding the weft fabric on a storage reel, wherein a moisture regain MR of the weft reinforcing elements is less than or equal to 2.0%, wherein the moisture regain MR is determined according to standard ASTM D 885/D 885MA of January 2010, and wherein the weft reinforcing elements are hairy.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The invention will be better understood from reading the following description, given solely by way of non-limiting example and with reference to the drawings in which:

(2) FIG. 1 is a view, in a meridian section plane, of a tyre 10 according to the invention;

(3) FIG. 2 illustrates a composite C for obtaining a hooping ply of the tyre of FIG. 1;

(4) FIG. 3 illustrates a cross-sectional view along the plane III-III of the composite C of FIG. 2;

(5) FIG. 4 an enlargement of the composite C according to the invention;

(6) FIG. 5 is a detail view of a fabric according to the invention;

(7) FIG. 6 is an enlargement of a weft reinforcing element 50 according to the invention;

(8) FIG. 7 is an illustration of a weaving process according to the invention; and

(9) FIG. 8 illustrates curves of capillary action of the weft reinforcing element 50 of the weft fabric T and of the weft reinforcing element of the fabric TEDT.

(10) When using the term radial, a distinction should be made between several different uses of the word by a person skilled in the art. Firstly, the expression refers to a radius of the tyre. It is in that sense that a point A is said to be

(11) radially inside a point B (or radially on the inside of the point B) if it is closer to the axis of rotation of the tyre than is the point B. Conversely, a point C is said to be radially outside a point D (or radially on the outside of the point D) if it is further from the axis of rotation of the tyre than is the point D. Progress radially inwards (or outwards) will mean progress towards smaller (or larger) radii. This sense of the term also applies when it is a matter of radial distances.

(12) A radial cross section or radial section is understood herein to be a cross section or a section in a plane that contains the axis of rotation of the tyre.

(13) The median circumferential plane M of the tyre is the plane that is normal to the axis of rotation of the tyre and which is situated equidistantly from the annular reinforcing structures of each bead.

(14) The median tangential plane TT of the tyre is the plane which is perpendicular to the median circumferential plane M.

(15) An axial direction is a direction parallel to the axis of rotation of the tyre.

(16) A circumferential direction is a direction that is perpendicular both to a radius of the tyre and to the axial direction.

(17) Example of a Tyre According to the Invention

(18) A frame of reference X, Y, Z corresponding to the usual respectively axial (X), radial (Y) and circumferential (Z) directions of a tyre is shown in the figures.

(19) FIG. 1 schematically depicts a view in radial section of a tyre according to a first embodiment of the invention and denoted by the general reference 10. The tyre 10 substantially exhibits revolution about an axis substantially parallel to the axial direction X. The tyre 10 is in this case intended for a passenger vehicle.

(20) The tyre 10 comprises a crown 12 comprising a crown reinforcement 14 comprising a working reinforcement 15 comprising two working plies 16, 18 of working reinforcing elements and a hoop reinforcement 17 comprising a hooping ply 19 of hooping reinforcing elements. The crown reinforcement 14 is surmounted by a tread 20 arranged radially on the outside of the crown reinforcement 14. In this case, the hoop reinforcement 17, the hooping ply 19, is radially interposed between the working reinforcement 15 and the tread 20.

(21) The tyre also comprises two sidewalls 22 extending the crown 12 radially inwards. The tyre 10 also has two beads 24 radially on the inside of the sidewalls 22, each having an annular reinforcing structure 26, in this case a bead wire 28, surmounted by a mass of filling rubber 30 on the bead wire, and also a radial carcass reinforcement 32.

(22) The carcass reinforcement 32 comprises at least one carcass ply comprising several reinforcing elements, the ply being anchored in each of the beads 24 by a turn-up around the bead wire 28, so as to form, in each bead 24, a main strand 38 extending from the beads through the sidewalls towards the crown 12, and a turn-up strand 40, the radially outer end 42 of the turn-up strand 40 being radially on the outside of the annular reinforcing structure 26. The carcass reinforcement 32 thus extends from the beads 24 through the sidewalls 22 and into the crown 12. The carcass reinforcement 32 is arranged radially on the inside of the crown reinforcement 14 and of the hoop reinforcement 17. The carcass reinforcement 32 comprises a single carcass ply 34.

(23) The tyre 10 also comprises an airtight inner liner 43, preferably made of butyl, axially on the inside of the sidewalls 22 and radially on the inside of the crown reinforcement 14 and extending between the two beads 24.

(24) Each working ply 16, 18, hooping ply 19 and carcass ply 34 comprises a polymeric composition, in which reinforcing elements of the corresponding ply are embedded. Each polymer composition, here an elastomer composition, of the working plies 16, 18, hooping ply 19 and carcass ply 34 is made from a conventional composition for the skim coating of reinforcing elements conventionally comprising a diene elastomer, for example natural rubber, a reinforcing filler, for example carbon black and/or silica, a crosslinking system, for example a vulcanization system, preferably comprising sulfur, stearic acid and zinc oxide, and possibly a vulcanization accelerator and/or retarder and/or various additives.

(25) Example of a Composite According to the Invention

(26) A composite from which the hooping ply 19 is obtained will now be described with reference to FIGS. 2, 3 and 4.

(27) The composite comprises a fabric T comprising textile warp reinforcing elements 44 and weft reinforcing elements 50 embedded in an elastomer composition. The warp reinforcing elements 44 are substantially parallel to one another and extend in a general warp direction Dwp and the weft reinforcing elements 50 are substantially parallel to one another and extend in a general direction referred to as weft direction Dwt different from the general warp direction Dwp. The general weft direction Dwt and the general warp direction Dwp forming an angle greater than or equal to 45, preferably ranging from 80 to 110 and here equal to 90.

(28) Example of a Fabric According to the Invention

(29) The fabric T will be described below with reference to FIG. 5.

(30) The weft reinforcing elements 50 interweave the warp reinforcing elements 44.

(31) The moisture regain of the weft reinforcing elements 50 is less than or equal to 2.0%. In this case, it is 1.8%.

(32) The weft reinforcing elements 50 are hairy as shown in FIG. 6. The weft reinforcing elements 50 are such that the number of threadlike elements protruding from the diameter of the weft reinforcing element 50 is greater than or equal to 1250 threadlike elements per 100 metres of weft reinforcement, preferably greater than or equal to 5000 threadlike elements per 100 metres of weft reinforcing elements and more preferentially greater than or equal to 7500 threadlike elements per 100 metres of weft reinforcing elements. In this case, it is 8750 threadlike elements per 100 metres of weft reinforcing elements 50.

(33) The warp and weft reinforcing elements will be described below.

(34) Nature of the Strands of Each Warp and Weft Reinforcing Element

(35) As depicted schematically in FIG. 3, each warp reinforcing element 44 comprises several multifilament strands and comprises an assembly consisting of two multifilament strands made of aromatic polyamide, the two strands being wound in a helix around one another. In this case, the aliphatic polyamide is Nylon 6,6. Each warp reinforcing element is twist-balanced. For the sake of the accuracy of the description, FIG. 4 is a cross-sectional view of the warp reinforcing element 44, in which the filaments of each of the strands can be seen.

(36) Each weft reinforcing element 50 comprises, for at least 50% of its weight, one or more textile filaments and/or several textile fibres and preferably consists of one or more textile filaments and/or several textile fibres. As depicted in FIG. 6, each weft reinforcing element 50 comprises at least one strand comprising a core and a layer coating the core, the core comprising at least one filament and the layer comprising several protruding short fibres. In this case, each weft reinforcing element consists of an assembly of two strands comprising a core and a layer coating the core, the core comprising at least one filament and the layer comprising several short fibres that protrude and go back in.

(37) The core comprises several synthetic organic polymeric filaments and the layer comprises several synthetic organic polymeric fibres. Here, each filament and each fibre are chosen from polyester filaments and fibres.

(38) Count of Each Warp and Weft Reinforcing Element

(39) The count of the aliphatic polyamide multifilament strand of the warp reinforcing element ranges from 80 to 120 tex, preferably from 90 to 110 tex, and more preferentially from 90 to 100 tex. In this case, the count of each aliphatic polyimide multifilament strand of the warp reinforcing element is 94 tex.

(40) the sum of the counts of the strands of weft reinforcing elements 50 is strictly less than 40 tex, preferably less than or equal to 30 tex and is greater than or equal to 2 tex and preferably greater than or equal to 4 tex. In this case, the sum of the counts of the strands of the weft reinforcing elements 50 is equal to 22 tex.

(41) The count of each strand of weft reinforcing element 50 ranges from 1 to 20 tex and preferably from 10 to 15 tex. Here, it is 11 tex.

(42) Twist of Each Warp and Weft Reinforcing Element

(43) The twist of each warp reinforcing element 44 ranges from 100 to 500 turns per metre, preferably from 250 to 390 turns per metre and even more preferentially from 250 to 380 turns per metre. In this case, it is equal to 320 turns per metre.

(44) The warp reinforcing elements 44 comprise an assembly consisting of two aliphatic polyamide strands, the two strands being wound in a helix around one another with a twist of 320 turns per metre and the reinforcing element is twist-balanced.

(45) The twist of each weft reinforcing element 50 ranges from 250 to 1500 turns per metre, preferably from 500 to 1300 turns per metre, more preferentially from 900 to 1200 turns per metre. In this case, the twist of each weft reinforcing element 50 is 1100 turns per metre.

(46) The weft reinforcing elements 50 comprise an assembly consisting of two strands of 11 tex wound in a helix around one another with a twist of 1100 turns per metre and the weft reinforcing element 50 is twist-balanced.

(47) Density of the Weft Reinforcing Elements in the Fabric

(48) The density of the weft reinforcing elements 50 ranges from 3.0 to 8.0 weft reinforcing elements per dm of fabric T, preferably from 3.0 to 6.0 weft reinforcing elements per dm of fabric T and more preferentially from 3.0 to 5.5 weft reinforcing elements per dm of fabric T. In this case, the density of the weft reinforcing elements 50 is equal to 5.0 weft reinforcing elements per dm of fabric T.

(49) Diameter of the Weft Reinforcing Elements

(50) The diameter of the weft reinforcing elements 50 is strictly less than 0.50 mm and preferably less than or equal to 0.23 mm. In this case it is 0.19 mm.

(51) Process for Manufacturing the Fabric According to the Invention

(52) The process for manufacturing the weft fabric T will now be described with reference to FIG. 7. In an unwinding step 100, several warp reinforcing elements 44 are unwound on an air-jet loom; in a separation step 110, the warp reinforcing elements 44 are separated into a first and a second ply of warp reinforcing elements, in an interweaving step 120, the weft reinforcing elements 50 are alternately interwoven with the warp reinforcing elements 44 of the first ply of warp reinforcing elements then of the second ply of warp reinforcing elements and in a winding step 130, the weft fabric T is wound on a storage reel; wherein the moisture regain of the weft reinforcing elements 50 is 1.8% and wherein the weft reinforcing elements 50 are hairy.

(53) In this case, the air-jet loom used is a Dornier A1 air-jet machine.

(54) In a step 140, the weft fabric T is impregnated with an adhesive composition, for example, an adhesive composition of the RFL (Resorcinol-Formaldehyde-Latex) type, and the fabric T undergoes heat treatment steps in order to at least partially crosslink the adhesive composition.

(55) Process for Manufacturing the Composite According to the Invention

(56) Each composite C is manufactured by embedding the fabric T in the elastomer composition, for example by skim coating. During such a skim coating step, which is well known to those skilled in the art, the fabric T is moved along, and two strips made of an elastomer composition, and referred to as skims, are brought in, one on each side of the reinforcing elements, so that the reinforcing elements are sandwiched between the two skims. The fabric is thus embedded in the elastomer composition.

(57) Process for Manufacturing the Tyre According to the Invention

(58) The method for manufacturing the tyre is the one conventionally used by those skilled in the art. During this process and as already previously described, various plies and composites are successively laid, during a first series of assembly steps. The blank thus obtained is then shaped. Next, other plies and composites intended to form the crown 12 of the tyre 10 are laid, including the composite according to the invention intended to form the hooping ply 19 of the tyre 10. Finally, the blank thus obtained is vulcanized in order to obtain the tyre 10.

(59) Measurements and Comparative Tests

(60) Table 1 summarizes the characteristics and the process for manufacturing a fabric from the prior art, comparative fabrics TC1 and TC2 and a fabric T and T according to the invention. The measurement of the hairiness according to the first method is indicated in the Hairiness method 1 table and the measurement of the hairiness according to the second method is indicated in the Hairiness method 2 table.

(61) TABLE-US-00001 TABLE 1 Fabric TEDT TC1 TC2 T T T Nature of the warp Nylon/2 Nylon/2 Nylon/2 Nylon/2 Nylon/2 Nylon/2 strands/number of strands Twist of the warp 250/250 320/320 320/320 320/320 320/320 320/320 strands (t/m) Count of the warp 140/140 94/94 94/94 94/94 94/94 94/94 strands (tex) Nature of the weft Cotton/1 Cotton/1 PET/1 PET/2 PET/1 PET/2 strands/number of strands Twist of the weft 750 750 750 1100/1100 750 750/750 strands (t/m) Count of the weft 30 30 28 11/11 21 10/10 strands (tex) MR (%) 8.0 8.0 0.9 1.8 0.6 0.5 Hairiness method 1 >12500 >12500 0 8750 3800 3882 Hairiness method 2 17756 17756 0 16190 7431 9676 Weft diameter (mm) 0.23 0.23 0.19 0.19 0.18 0.20 Air-jet loom weaving yes yes no yes yes yes Composite CEDT C1 C2 C C C Weft strand density 5.5 5.5 5.0 5.0 5.0 (yarns/dm)

(62) It is noted that the comparative fabric TC2 is not weavable via an air-jet weaving process. Thus no composite can be obtained. The fabrics T, T and T according to the invention are weavable.

(63) The capillary capacity of the weft reinforcing elements coated with an adhesive composition was compared using a tension meter which makes it possible to measure changes in weight over time when the reinforcing element is in contact with a liquid. It is then possible to obtain several pieces of information: measurement of the weight as a function of time on reinforcing elements (capillary action); measurement of the contact angle to determine the affinity of the material of the reinforcing element and a liquid, here water; and measurement of the surface tension of the water.

(64) FIG. 8 shows the curve of the change in weight, in grams, of the reinforcing element sized with an adhesive composition based on phloroglucinol and terephthaldehyde as a function of the time in seconds when the reinforcer is soaked in water. This curve is representative of what happens in the weft fabric when it comes into contact with water. It is observed that the weft reinforcing element 50 made of PET sized with an adhesive composition used in the weft fabric T according to the invention takes up 10 times less water compared with the weft reinforcing element made of cotton used in the weft fabric TEDT. It is also observed that the weft reinforcing element 50 made of PET used in the weft fabric T according to the invention absorbs very little water from the start and that the content thereof increases very little over time.

(65) This test clearly demonstrates the hypothesis of the inventors that by selecting a weft reinforcing element having a low moisture regain, the spread of water in the textile reinforcers is reduced and thus the spread of corrosive agents which oxidize the metal reinforcing elements of the crown reinforcement is reduced.

(66) The behaviour of the weft reinforcing elements sized with an adhesive composition used in the weft fabrics T and T according to the invention soaked in water is identical to that of the reinforcing element 50 of the weft fabric T: they absorb very little water from the start and the content thereof increases very little over time.

(67) Comparison of the Tyres

(68) The tyre 10 according to the invention was compared with tyres PEDT from the prior art and control tyres P1 each respectively comprising a composite C, CEDT and Cl obtained from the fabrics T, TEDT and TC1 respectively.

(69) The tyres and in particular their corrosion resistance were compared using the corrosion test described below: the tyres are run on a stony road in salt water for 5000 kilometres. The total surface area of oxidation pockets on the shoulders of the tyres, i.e. the locations where there is contact between the textile reinforcing elements and the metal cords of the crown ply, and therefore the surface areas where there is corrosion via the spread of water by the hooping ply, is measured.

(70) The results are collated in Table 2 below.

(71) Table 2 shows the corrosion resistances of the tyres tested. A very poor corrosion resistance is indicated by the sign and a poor corrosion resistance is indicated by the sign . A good corrosion resistance is indicated by the sign +. A very good corrosion resistance is indicated by the sign ++.

(72) TABLE-US-00002 TABLE 2 Tyre PEDT P1 10 Corrosion resistance ++

(73) Thus, it is noted that the tyre 10 according to the invention has a corrosion resistance performance better than that of the tyre from the prior art PEDT and the comparative tyre P1.

(74) The invention is not limited to the above-described embodiments.

(75) It will also be possible to combine the features of the various embodiments and alternative embodiments described or contemplated above, provided that these features are compatible with one another.