Description

Technical Field

[1 ] The invention relates to a bead bundle assembly for tire. The invention also relates to a tire comprising a pair of bead bundle assembly.

Background Art

[2] A radial tire normally comprises a tread, at least one belt layer, at least one carcass layer and a pair of beads, wherein the belt layer and carcass layer are reinforced by steel cords or polyester cords, the bead is reinforced by a bead ring formed by a steel wire or a group of steel wires wound as a bundle.

[3] Every year there are about 1 billion end-of-life tires worldwide. The recycling of the end-of-life tires is meaningful for preserving the environment and natural resources for sustainable development. The rubber of the end-of-life tires can be recycled by being converted into new materials, fuels or recycled rubber; the tire can be re-treaded to be a new tire; the bead wire can be pulled out of the tire for recycling the steel.

[4] CN107553778 discloses a method for pulling the bead wires out of the end-of-life tire. The bead wire is pulled out and thereby wound on a roller, and then the wound bead wire is removed from the roller. The bead wire from the tire is treated as waste steel wire for recycling the steel.

[5] It is still desired to have more recycling ways to optimize the value of an end-of-life tire.

Disclosure of Invention

[6] The primary object of the invention is to provide a new solution for the recycling of the end-of-life tires.

[7] The first object of the invention is to provide a bead bundle assembly available for being recycled.

[8] The second object of the invention is to provide a tire comprising the recyclable bead bundle assembly.

[9] According to a first aspect of the invention a bead bundle assembly for tire is provided, the bead bundle assembly comprises a bead core and a polymer layer covering the bead core, the polymer layer comprises at least a first polymer region and a second polymer region, the first polymer region is upon the partial or the entire of the radially outward side of the bead core, the second polymer region is upon at least the entire of the radially inward side of the bead core, the first polymer region has a thickness of Ti and the second polymer region has a thickness of T2 as observed in a cross section of the bead bundle assembly, both T1 and T2 are expressed in mm, T1 and T2 satisfy: TI <T2.

[10] The polymer layer covering the bead core is beneficial to the recycling of the bead core from an end-of-life tire. Normally a tire has the carcass ply being turned up outward of the bead core. During the air inflation or the running of the tire, the alternating stresses are generated in the carcass ply and the bead core, these make the carcass ply and the bead core shearing and squeezing mutually, thus there is a risk that the steel cord in the carcass ply breaks and thereby the tire busts, or the wire of the bead core is deformed or even breaks, so that the bead core is deformed. With the application of the polymer layer on the bead core, such risk is reduced. In a used tire or an end-of-life tire, the bead core is less deformed due to the protection of the polymer layer, as thus the bead core has an acceptable shape available for being recycled and re-used in a new tire. In addition, when taking out the bead bundle assembly or the bead core for recycling by the waterjet or the cutter, the polymer layer acts as a protection layer to resist the cut force from the waterjet or the cutter, and this reduces the deformation of the bead core. Furthermore, when using waterjet for taking out the bead bundle assembly or bead core for recycling, the polymer layer prevents the entering of water into the bead core, thereby the risk of corrosion of the metal bead wire of the bead core is reduced.

[11] The bead bundle assembly shows a ring shape, since the bead core shows a ring shape as stipulated by tire design.

[12] The polymer layer has at least a first polymer region and a second polymer region, both the first polymer region and the second polymer region are extending along the circumferential direction of the ring shape of the bead bundle assembly, i.e. , the coverage of the first polymer region and the coverage of the second polymer region extend along the circumferential direction of the ring shape of the bead core. The first polymer region has a thickness smaller than the second polymer region. When observing the cross section of the bead bundle assembly, the first polymer region has a thickness Ti , and the second polymer region has a thickness of T2, TI <T2.

[13] The first polymer region with relatively thinner polymer layer is upon the partial or the entire of the radially outward side of the bead core, and the second polymer region is upon at least the entire of the radially inward side of the bead core, and this means the first polymer region is not upon the radially inward side of the bead core, so that the first polymer region is able to match with the bead filler of the tire. The surface of the bead core is deemed to have two equal sides divided by the imaginary central axis plane, i.e. the radially outward side and the radially inward side. The first polymer region is upon the partial of the radially outward side of the bead core, or, the first polymer region is upon the entire of the radially outward side of the bead core. There is no overlap between the first polymer region and the second polymer region. The first polymer region with a relatively thinner polymer layer is for matching with the bead filler of the tire. It is found that, during the air inflation or the running of the tire, the carcass ply and the bead core shear and squeeze mutually, however, there is less shearing and squeezing between the bead filler and the bead core. The present invention makes the region of the polymer layer which is for matching with the bead filler being relatively thinner. The usage of polymer is thereby reduced, and the weight of the tire is reduced, while the advantages of the application of the polymer layer are maintained.

[14] More preferably, the first polymer region is upon at least 2/3 of the radially outward side of the bead core. The second polymer region is upon the entire of the radially inward side of the bead core and at most 1/3 of the radially outward side of the bead core. The coverage of the first polymer region and the second polymer region can be detected by observing the cross section of the bead bundle assembly or the tire having the bead bundle assembly. [15] Preferably, Ti and T2 satisfy: T2-T1 >0.05. More preferably, T1 and T2 satisfy: T2-T1 >0.1. Most preferably, T1 and T2 satisfy: T2-T1 >0.2. most preferably T2-T1 <4.5.

[16] Preferably, T1 is 0.1 -3mm.

[17] Preferably, T2 is 0.2-5mm.

[18] As observed in a cross section of the bead bundle assembly, the first polymer region has a substantially uniform thickness, and the second polymer region has a substantially uniform thickness. Alternatively, the first polymer region has an uneven thickness, and the second polymer region has an uneven thickness, for example, the first polymer region has a thickness showing gradient change, or the second polymer region has a thickness showing gradient change.

[19] According to the invention, the polymer layer is made of thermoset polymer or thermoset polymer base composite. Thermoset polymer or thermoset polymer base composite brings sufficient strength for reducing the impact of the force from the sidewalls of the tire to the bead core. Preferably, the thermoset polymer or the thermoset polymer base composite comprises one or more polymers selected from melamineformaldehyde resin, epoxy resin, organic silicone resin, polyester resin, furan resin, polyurethane resin, phenolic resin, urea formaldehyde resin, vinyl esters, bismaleimide resin, polyimide, cyanate ester, polybutadiene resin.

[20] The bead core comprises a bead ring with or without a fabric cover upon the bead ring. The fabric cover is applied for fixing and stabilizing the shape of the bead ring.

[21 ] The bead ring can be any type of the existing bead ring of a bundle of metal wires made by any of existing technologies. Normally the metal wire for bead is coated with bronze, zinc or brass for the adhesion with rubber. The metal wire may be further coated with a resin coating for adhesion with rubber and corrosion resistance. Optionally, a thin rubber layer is coated upon the resin coating or the metal wire for the position fixing of the metal wire within the bead ring. [22] The cross section of the bead core shows a round, square, rectangular, quadrilateral or hexagon shape, accordingly, the cross section of the bead bundle assembly shows a round, square, rectangular, quadrilateral or hexagon shape.

[23] According to a second aspect of the invention a tire is provided, the tire comprises a first and a second bead bundle assembly according to the invention, the first and second bead bundle assembly are coaxially to one another, the tire comprises a first and a second bead filler, the first bead bundle assembly is matching with the first bead filler via at least part of the first polymer region of the first bead bundle assembly, the second bead bundle assembly is matching with the second bead filler via at least part of the first polymer region of the second bead bundle assembly.

[24] The portion of the bead bundle assembly which is matching with the bead filler is one part of or the entire of the first polymer region.

[25] Preferably the first bead bundle assembly is matching with the first bead filler via the entire of the first polymer region of the first bead bundle assembly, the second bead bundle assembly is matching with the second bead filler via the entire of the first polymer region of the second bead bundle assembly. This defines the extent or the coverage and the position of the first polymer region on the bead bundle assembly. This provides a better balance between the strength and the weight/cost brought from the polymer layer.

[26] Preferably, as observed in a cross section of the bead bundle assembly of the tire, the first polymer region has a substantially uniform thickness, and the second polymer region has a substantially uniform thickness. Or as observed in a cross section of the bead bundle assembly of the tire, the first polymer region has a thickness showing gradient change, or the second polymer region has a thickness showing gradient change.

Brief Description of Figures in the Drawings

[27] Figures 1a-1b describe a bead core.

[28] Figures 2a-2c describe a first embodiment of the invention bead bundle assembly. [29] Figure 3 describes a second embodiment of the invention bead bundle assembly.

[30] Figure 4 describes a third embodiment of the invention bead bundle assembly.

[31 ] Figure 5 describes an embodiment of the invention tire.

[32] Figures 6 describes the fourth embodiment of the invention bead bundle assembly.

[33] Figures 7 describes the fifth embodiment of the invention bead bundle assembly.

[34] Figures 8 describes the sixth embodiment of the invention bead bundle assembly.

Mode(s) for Carrying Out the Invention

[35] The bead bundle assembly is made starting from a bead wire. The bead wire is a metal wire with a metal coating, such as bronze, zinc or brass coating, for the adhesion with the rubber. The metal wire has a cross section has a round shape or polygonal shape including flat, rectangular or square shape. The angles of the polygonal shape of the bead wire present a smooth curve but not a sharp angle due to the manufacturing reality. The metal bead wire may have a resin coating upon the metal coating for the adhesion with rubber. In some cases, the metal bead wire has a thin rubber layer upon the resin coating, or the metal bead wire has a thin rubber layer directly upon the metal coating. This is known in the art.

[36] And then a bead ring is made by any of the existing methods, and the bead ring has a cross section showing a desired shape such as round, square, rectangular, quadrilateral or hexagon. Due to the inevitable manufacturing errors, the shape of the bead ring is not a perfect or classic round, square, rectangular, quadrangular or hexagon but with an acceptable deformation. Optionally a fabric cover is applied upon the bead ring for fixing and stabilizing the shape of the bead ring, i.e. the fabric cover wrapping around the bead ring. Consequently, a bead core is prepared.

[37] And then a polymer layer is applied upon the bead core with a first polymer region and second polymer region by extrusion. The thickness of the polymer layer including the thin first polymer region and the thick second polymer region is reached by adjusting the design of the extrusion die. The first polymer region has a substantially uniform thickness, the second polymer region has a substantially uniform thickness. There can be a small connection region between the first polymer region and the second polymer region for smooth thickness variation from thin to thick, and it is also possible such a connection region is not existing. Alternatively, the first polymer region has a thickness showing gradient change, or the second polymer region has a thickness showing gradient change.

[38] Figure 1 a shows the front view of one existing bead core. Figure 1 b shows the cross-sectional view of the bead core. The bead core 100 is formed by a bead ring covered by a fabric cover 120, the bead ring has the wires 115 wound around one big core wire. The bead core 100 has a ring shape as shown in Figure 1a, as thus the surface of the bead core 100 has a radially outward side 105 and a radially inward side 110 divided by the imaginary central axial plane referred by the dot line A.

[39] Figure 2a shows the front view of first embodiment of the invention bead bundle assembly. Figure 2b shows the cross section of the bead bundle assembly. Figure 2c is the cross-sectional view of the bead bundle assembly. The bead bundle assembly 200 is formed by a bead core 100 covered with a polymer layer, the polymer layer has a first polymer region 205 and a second polymer region 210. The bead core 100 has a cross section showing a round shape as shown in Figure 2b. The first polymer region 205 is on the radially outward side of the bead core 100, and the second polymer region 210 is covering the radially inward side of the bead core 100 and extending to the radially outward side of the bead core 100, the second polymer region 210 and the first polymer region 205 are integrated. Both the first polymer region 205 and the second polymer region 210 are extending along the circumferential direction of the ring shape of the bead bundle assembly 200 as shown in Figure 2a. Both the first polymer region 205 and the second polymer region 210 have a substantial uniform thickness. The first polymer region 205 has a thickness of Ti of 0. 20mm, and the second polymer region 210 has a thickness of T2 of 0.40mm.

[40] The radially outward side of the bead core and the radially inward side of the bead core are divided by the imaginary central axial plane. In the actual measurement, the imaginary central axial plane can be obtained by the image processing on the cross-sectional view of the bead bundle assembly (such as shown in figure 2c) or the cross-sectional view of the tire. The coverage or the extent of the first polymer region or the second polymer region can also be measured by the image processing on the cross section of the bead bundle assembly (such as shown in figure 2b) or the cross section of the bead bundle assembly of the tire.

[41 ] The thickness measurement can be done by the optical microscope which has the thickness measurement function. The measurement includes the following steps: firstly, transversely cut the bead bundle assembly or cut the tire to take a small segment to expose the cross section of the bead bundle assembly; and then observe the cross section of the bead bundle assembly; and then identify and determine the central axis referring to the imaginary central axial plane, i.e. the dot line A shown in the figures, normally the central axis is the line through the leftmost and the rightmost; and then draw a central vertical line perpendicular to the central axis and through the middle point between the leftmost and the rightmost, and measure the thickness of the rubber ply along the central vertical line as T1 or T2.

[42] Figure 3 shows the cross-sectional view of the second embodiment of the invention. The bead bundle assembly 300 is formed by a bead core 305 covered with a polymer layer, the polymer layer has a first polymer region 310 and a second polymer region 315. The bead core 305 has a cross section showing a rectangular shape, and it has a bead ring with a fabric cover 320. The first polymer region 310 is on the radially outward side of the bead core 305, and the second polymer region 315 is covering the radially inward side of the bead core 305 and extending to the radially outward side of the bead core 305. Both the first polymer region 310 and the second polymer region 315 have a substantial uniform thickness. There is a small connection region 325 between the first polymer region 310 and the second polymer region 315 for the smooth thickness variation from thin to thick. The first polymer region 310 has a thickness of Ti of 0.35mm, and the second polymer region 315 has a thickness of T2 of 0.75mm.

[43] Figure 4 shows the cross-sectional view of the third embodiment of the invention. The bead bundle assembly 400 is formed by a bead core 405 covered with a polymer layer, the polymer layer has a first polymer region 410 and a second polymer region 415. The bead core 405 has a cross section showing a hexagon shape, and it has a bead ring with a fabric cover 420. The first polymer region 410 is on the radially outward side of the bead core 405, and the second polymer region 415 is covering the radially inward side of the bead core 405 and extending to the radially outward side of the bead core 405. Both the first polymer region 410 and the second polymer region 415 have a substantial uniform thickness. The first polymer region 410 has a thickness of T1 of 1.60mm, and the second polymer region 415 has a thickness of T2 of 1 ,95mm.

[44] Figure 5 shows the cross-sectional view of one embodiment of the invention tire. The tire 500 has a first and second bead bundle assembly 300 being coaxially to one another, and it has a first and a second bead filler 505, the first bead bundle assembly 300 is matching with first bead filler 505 via the first polymer region 310 of the first bead bundle assembly 300, the second bead bundle assembly 300 is matching with the second bead filler 505 via the first polymer region 310 of the second bead bundle assembly 300. The carcass ply 510 is turned up outward of each bead bundle assembly 300.

[45] Figures 6-8 show the cross section of the fourth to sixth embodiments of the invention. In figure 6, the first polymer region 605 is upon the entire of the radially outward side of the bead core 100, and the second polymer region 610 is upon the entire of the radially inward side of the bead core 100, and both the first polymer region 605 and the second polymer region 610 have a thickness showing gradient change. In figure 7, the first polymer region 705 is upon the entire of the radially outward side of the bead core 100, and the second polymer region 710 is upon the entire of the radially inward side of the bead core 100, and the first polymer region 705 has a thickness showing gradient change, and the second polymer region 710 has a substantial uniform thickness. In figure 8, the first polymer region 805 is upon the entire of the radially outward side of the bead core 100, and the second polymer region 810 is upon the entire of the radially inward side of the bead core 100, and the first polymer region

805 has a substantial uniform thickness, and the second polymer region 810 has a thickness showing gradient change.