Tire having a structural element reinforced with a hybrid yarn
A tire includes at least one structural element which includes at least one reinforcing element which includes at least one hybrid yarn, the at least one hybrid yarn including a plurality of filaments obtained from at least one first multifilament yarn having a first initial tangent modulus and at least one second multifilament yarn having a second initial tangent modulus, the first and the second initial tangent modulus being different from each other, each one of the first and the second multifilament yarn including a plurality of individual filaments, the individual filaments of each one of the first and the second multifilament yarns being at least partially intermixed with each other. The tire may be a high performance or ultra high performance tire, or a tire suitable for being employed in sporting contests such as track motor races, or a tire suitable for sports utility vehicles.
1. A process for manufacturing a hybrid yarn comprising:
feeding at least one first multifilament yarn having a first initial tangent modulus to an air jet device at a conveying speed higher than about 1.0% to about 15% with respect to the take-up speed of the obtained hybrid yarn;
feeding at least one second multifilament yarn having a second initial tangent modulus to an air jet device at a conveying speed higher than about 1.0% to about 20% with respect to the take-up speed of the obtained hybrid yarn;
applying an air pressure of about 3.0 bar to about 10 bar to said air jet device; and
recovering a hybrid yarn so obtained at a take-up speed of about 20 m/min to about 250 m/min.
2. The process for manufacturing a hybrid yarn according to claim 1 , wherein said at least one first multifilament yarn is fed to said air jet device at a conveying speed which is higher than about 1.5% to about 7.0% with respect to the take-up speed of the obtained hybrid yarn.
3. The process for manufacturing a hybrid yarn according to claim 1 , wherein said at least one second multifilament yarn is fed to said air jet device at a conveying speed which is higher than about 5.0% to about 10% with respect to the take-up speed of the obtained hybrid yarn.
4. The process for manufacturing a hybrid yarn according to claim 1 , wherein said air pressure is about 3.5 bar to about 8.0 bar.
5. The process for manufacturing a hybrid yarn according to claim 1 , wherein said take-up speed is about 50 m/min to about 120 m/min.
6. The process for manufacturing a hybrid yarn according to claim 1 , wherein the conveying speed of said at least one first multifilament yarn is lower than the conveying speed of said at least one second multifilament yarn.
7. The process for manufacturing a hybrid yarn according to claim 1 , wherein over delivery of said at least one first multifilament yarn is lower than over delivery of said at least one second multifilament yarn.
8. The process for manufacturing a hybrid yarn according to claim 1 , wherein said first and said second multifilament yarn:
comprise a number of individual filaments of about 50 to about 2000; or
comprise individual filaments having a diameter of about 5 μm to about 100 μm; or
have a diameter of about 0.2 mm to about 1.5 mm; or
have a linear density of about 200 dtex to about 4000 dtex, or
comprise at least one first multifilament yarn having a lower initial tangent modulus and at least one second multifilament yarn having a higher initial tangent modulus; or
comprise at least one first multifilament yarn having an initial tangent modulus of about 200 cN/tex to about 1500 cN/tex; or
comprise at least one second multifilament yarn having an initial tangent modulus of about 600 cN/tex to about 8000 cNitex; or
comprise a hybrid yarn having a transition point of about 0.5% to about 7%; or
comprise at least one first multifilament yarn and at least one second multifilament yarn, which melt at temperatures not lower than about 200° C.; or
comprise at least one first multifilament yarn selected from: aliphatic polyamide fibers, nylon fibers, low initial tangent modulus polyester fibers, low initial tangent modulus cellulosic fibers, or mixtures thereof; or
comprise at least one second multifilament yarn selected from: aromatic polyamide fibers, aramide fibers, high initial tangent modulus polyester fibers, polyketone fibers, polyvinylalcohol fibers, high initial tangent modulus cellulosic fibers, glass fibers, carbon fibers, or mixtures thereof; or
comprise a hybrid yarn which is untwisted or twisted; or
comprise a hybrid yarn which is twisted at a twist of about 50 tpm to about 600 tpm.