Vehicle tires with noise absorbers and methods for detecting a vehicle tire with noise absorbers and for recycling a vehicle tire with noise absorbers

Description

[0001] The invention relates to a pneumatic tire for vehicles with at least one noise absorber attached to the inner surface opposite the tread. The invention further relates to a method for detecting a pneumatic tire with a noise absorber and a method for recycling a pneumatic tire with a noise absorber.

[0002] It is common practice to equip vehicle tires with noise absorbers to reduce road noise. These absorbers are usually in the form of a foam ring that reduces air vibrations within the tire, thus improving the vehicle's noise levels. The foam ring can be made of open-cell foam and is also referred to as an "internal absorber." For example, the noise absorber might be a polyurethane foam ring, meaning it is made of different materials than the other tire components.

[0003] EP 1 795 377 A2 relates to a pneumatic tire with a damping element which is protected against water and UV radiation by means of a protective film before tire mounting.

[0004] JP 2012-254655 A relates to a pneumatic tire and its manufacture, wherein short fibers with a dye are attached to the inside of the tire for noise reduction, the color of which can change depending on the temperature in order to indicate thermal overload.

[0005] However, several noise absorbers can also be installed, as disclosed in DE 102017210929 A1 or EP 1 510 366 A1.

[0006] When recycling vehicle tires with noise absorbers, the problem arises that material separation is desirable before the usual shredding of the tires, i.e., the noise absorber in particular should be separated.

[0007] Depending on the visual condition of the noise absorber – which may be dark in color and / or dirty – and the lighting conditions, it can be difficult to identify pneumatic tires with noise absorbers. This, in turn, makes it harder to distinguish and separate pneumatic tires with and without noise absorbers, which in turn complicates or slows down the recycling of pneumatic tires with regard to the desired material separation.

[0008] The present invention is therefore based on the objective of providing a vehicle pneumatic tire with at least one noise absorber attached to the inner surface opposite the tread, wherein the noise absorber has a radially inwardly directed surface (vehicle pneumatic tire with noise absorber), which can be more easily recognized as a vehicle pneumatic tire with a noise absorber and can thus be more easily distinguished from vehicle pneumatic tires without a noise absorber.

[0009] The problem is solved by applying at least one colorant as defined in claim 1 to the radially inwardly directed surface of the noise absorber.

[0010] Because pneumatic tires with noise absorbers have at least one colorant on the radially inward-facing surface of the noise absorber, they can be more easily distinguished from pneumatic tires without noise absorbers. In particular, this distinction can be made automatically using a detector, especially a color detector or photodetector, without requiring individual inspection of the tire by an operator.

[0011] Furthermore, an operator can identify such a tire with a noise absorber more quickly and clearly thanks to the dye.

[0012] This significantly simplifies and facilitates the recycling of tires with (and without) noise absorbers.

[0013] Within the scope of the present invention, both the processes of detection by means of a detector and recognition by an operator are referred to as "detection".

[0014] By only applying a colorant to the surface of the noise absorber, the tires can be distinguished from one another without the need to color the entire noise absorber.

[0015] The invention is further explained below, and other advantageous embodiments are described. Unless otherwise stated or technically not feasible, different embodiments can also be combined.

[0016] The term "radially inward directed surface" refers to a position that is not the surface with which the noise absorber adheres to the inside of the tire, but rather, in particular, in the direction of the inside of the tire, in a radial direction away from the tread, on which the noise absorber is located.

[0017] In the case of individual blocks of several noise absorbers, any inward-facing surface not adhering to the inside of the tire is meant.

[0018] It is not necessary for the entire radially inward-facing surface to be covered with the colorant. According to advantageous embodiments of the invention, the colorant covers 50 to 100%, preferably 80 to 100%, and particularly 90 to 100% of the radially inward-facing surface of the noise absorber.

[0019] The larger the proportion of the surface area that is coated with the dye, the more reliable the detection can be.

[0020] However, small gaps are not a disadvantage.

[0021] In advantageous embodiments, the colorant is arranged circumferentially in the form of a stripe, which can be continuous or interrupted. A stripe can be applied circumferentially, either continuously or in sections, in a simple and automated manner.

[0022] In principle, the colorant can have any shade that differs sufficiently from the shade of the noise absorber.

[0023] According to advantageous embodiments, the colorant has a colored or white hue that is easily distinguishable from black hues, such as those according to RAL color codes 1000 to 1037, 2000 to 2013, 3000 to 3033, 4000 to 4012, 5000 to 5026, 6000 to 6038, 7000 to 7048, 8000 to 8029, 9000 to 9003, 9010 or 9016.

[0024] This makes it significantly easier and more reliable to identify tires, especially those with dark or black noise absorbers.

[0025] The colorant is preferably selected from inorganic and organic colorants.

[0026] This provides a wide range of coloring substances, so that suitable colors can be used via the colorant(s) that are adapted to the respective detector or are particularly easy to detect using a color detector under the given light conditions.

[0027] Even "white" can be detected using a color detector.

[0028] According to advantageous embodiments of the invention, the colorant comprises at least one conjugated π-electron system (pi-electron system). Numerous such organic colorants exist, so a suitable colorant can be selected which, particularly under the given lighting conditions, is especially well detectable by a color detector.

[0029] Furthermore, such colorants can be used in a particularly material-saving manner.

[0030] The colorant(s) are applied via a liquid phase, especially as a dispersion or solution.

[0031] The organic colorant having at least one conjugated π-electron system can in principle be any molecule which is preferentially colored due to conjugation.

[0032] According to preferred embodiments of the invention, the organic pigment is selected from the group comprising, for example, 1-[(2-chloro-4-nitrophenyl) azo]2-naphthol (Pigment Red 4; CAS No.: 2814-77-9), 4,4'-[(3,3'-Dichloro[1,1'-biphenyl]-4,4'-diyl)bis(azo)]bis[2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one] (Pigment Orange 13; CAS No.: 3520-72-7), 1-amino-2-methyl-9,10-anthracenedione (CAS No.: 82-28-0), Permanent Violet RL (CAS No.: 6358-30-1), pigment yellow 155 (CAS No.: 68516-73-4), disperse blue 1 (CAS No.: 2475-45-8), methyl orange (CAS No.: 547-58-0).

[0033] Preferably, a non-carcinogenic and non-toxic colorant is used.

[0034] According to advantageous embodiments of the invention, the colorant comprises at least one metal atom or metal ion. Such colorants are particularly stable and retain their color for a longer period of time and are washed out relatively slowly by water ingress, such as after rain.

[0035] The colorant containing at least one metal atom or metal ion can in principle be any substance that is colored, such as metal complexes with organic ligands or inorganic pigments.

[0036] According to preferred embodiments of the invention, the colorant comprises at least one metal atom or metal ion selected from the group, for example, containing, particularly preferably, the following: Pigment Blue 27 (CAS No.: 12240-15-2), Barium Chromate (CAS No.: 10294-40-3), Aureolin (CAS No.: 13782-01-9), Egyptian Blue (CaCu[Si 4 O 10 ], CAS No. 15843-33-1).

[0037] According to further advantageous embodiments, the colouring agent comprises at least one white pigment, such as in particular kaolin, titanium dioxide (TiO 2 ), barium sulfate (BaSO 4 ), or calcium carbonate (CaCO 3 ), in particular chalk.

[0038] It is also conceivable that colored chalk is used.

[0039] The following describes various embodiments for applying the colorant to the noise-absorbing surface. All embodiments can be combined with the described possible arrangements and the resulting surface coverage of the noise absorber.

[0040] According to advantageous embodiments of the invention, the colorant is applied to the surface of the noise absorber by means of a dispersion, in particular a suspension or emulsion, wherein the dispersion contains 1 to 80 wt.%, preferably 5 to 50 wt.%, particularly preferably 10 to 30 wt.%, and most preferably 20 to 30 wt.%, colorants.

[0041] The percentage by weight refers to the total mass of the dispersion before drying.

[0042] According to advantageous embodiments, the dispersion contains at least one binder, such as polystyrene or polymethyl methacrylate or styrene-acrylate copolymer or polyvinyl acetate.

[0043] Preferably, the dispersion is a suspension. According to this embodiment, the colorant(s) are suspended in a liquid.

[0044] The percentage given by weight refers to the total mass of the suspension before drying.

[0045] A suspension can be applied easily and with minimal material usage.

[0046] The liquid of the suspension can be any conceivable liquid that is compatible with the respective noise absorber. According to advantageous embodiments of the invention, it is an aqueous suspension, which is particularly environmentally friendly.

[0047] According to further advantageous embodiments of the invention, the colorant is applied to the surface of the noise absorber by means of a solution, wherein the solution contains at least a solvent and 1 to 80 wt.%, preferably 5 to 50 wt.%, particularly preferably 10 to 30 wt.%, most preferably 20 to 30 wt.%, of colorants.

[0048] According to this embodiment, the colorants are dissolved in a liquid.

[0049] The percentage given by weight refers to the total mass of the solution before drying.

[0050] According to advantageous embodiments, the solution also contains at least one binder, such as polystyrene or polymethyl methacrylate or styrene-acrylate copolymer or polyvinyl acetate.

[0051] The solution is easy to apply.

[0052] The solvent(s) can be any conceivable liquid that is compatible with the respective noise absorber.

[0053] According to advantageous embodiments of the invention, it is an aqueous solution which is particularly environmentally friendly and non-flammable.

[0054] According to further advantageous embodiments of the invention, the solvent is at least one organic solvent. In principle, the organic solvent can be any suitable solvent known to those skilled in the art, such as alcohols (simple or polyalcohols), ketones, esters, aldehydes, aromatics, alkanes such as hexane, or ethers such as petroleum ether.

[0055] According to preferred embodiments, the organic solvent is selected from solvents that are compatible with the noise absorber and the other tire components, or that do not cause them to swell or dissolve the components, such as, in particular, simple alcohols like ethanol or isopropanol. These are also comparatively environmentally friendly, and most water-insoluble dyes are readily soluble in them.

[0056] According to further embodiments, which are not according to the invention, the colorant is applied as a solid, in particular in powder form.

[0057] The powder can be applied by air atomization, for example using a gun, or electrostatically.

[0058] Depending on the type of noise absorber, it may be advantageous to apply an adhesive layer before applying the solid, especially powder.

[0059] According to further embodiments (not according to the invention), the colorant is applied as a component of a film to the radially inwardly directed surface of the noise absorber. A film can also be applied simply and with minimal material usage, and in particular with a constant layer thickness.

[0060] According to advantageous embodiments, the colorant is applied with a layer thickness (measured in the radial direction (rR) perpendicular to the axial direction (aR) of the vehicle tire) of 1 µm (micrometer) to 1000 µm.

[0061] A layer thickness of 2 to 400 µm (micrometers), and especially preferably 5 µm to 100 µm, is particularly preferred.

[0062] This allows the noise absorber to be color-coded in a way that saves material, without adding too much mass to the vehicle's pneumatic tire, which would result in disadvantages in terms of rolling resistance.

[0063] According to advantageous embodiments of the invention, the noise absorber is black or nearly black. This means that the noise absorber has, for example, a color tone according to the RAL color codes 9004 to 9007, 9011, 9017 to 9023.

[0064] The sound absorber can also be brown or grey.

[0065] The noise absorber of the vehicle pneumatic tire according to the invention can, in principle, be any element or combination of elements that can be attached to the inner surface of a vehicle pneumatic tire by means of adhesion and that reduces the noise emission of the tire during driving, wherein the at least one noise absorber is at least a porous damping element. Porous materials have the particular advantage that, in addition to noise absorption, they also introduce a not excessive weight into the tire, so that the rolling resistance properties of the tire are not unnecessarily impaired.

[0066] The porous material from which the damping element is formed is selected, for example, from the group consisting of polyurethane, in particular polyurethane foams on a polyether base and / or polyurethane foams on a polyester base with a density of 18 to 300 kg / m³, preferably 30 to 35 kg / m³, and a hardness of 6.5 kilopascals; polyester with a density of 18 to 300 kg / m³, preferably 30 to 35 kg / m³, and a hardness of 6.5 kilopascals; polyether; and any porous, sound-absorbing material mixtures, such as glass or rock wool, loop pile or high-pile or non-woven materials, or cork. Other possible porous materials suitable for use as a damping element include, for example, melamine resin foam or construction foam.

[0067] Preferably, the noise absorber contains at least one polyurethane. Polyurethane is particularly suitable due to its specific density, other material properties, and availability.

[0068] According to a particularly advantageous embodiment, the porous damping element is a sound-absorbing foam ring that is either closed or open in the circumferential direction. This ensures uniform sound absorption, and the tire retains its uniformity. The ring can be closed in the circumferential direction or open, forming a strip, with the ends of the strip optionally touching or overlapping.

[0069] The foam used in the foam ring is preferably an open-cell foam, as this is best suited to absorbing sound.

[0070] A particularly preferred sound absorber is a closed sound-absorbing foam ring made of polyurethane, preferably a polyurethane foam based on polyether.

[0071] Such foams are known to experts.

[0072] Furthermore, the noise absorber(s) can have any shape, such as individual elements in the form of blocks, strips or similar, which can be combined with each other as desired.

[0073] The noise absorber(s) are preferably attached to the inside of the tire by means of an adhesive. Examples of adhesives and combinations of adhesives include: adhesive tape and / or a silicone-based adhesive and / or a two-component adhesive and / or a construction adhesive and / or a polyurethane adhesive and / or a rubber-based adhesive and / or a tire repair adhesive and / or a cyanoacrylate-based adhesive and / or an adhesive based on a water-based acrylic system with a polyethylene terephthalate structure and / or based on acrylonitrile butadiene rubber in combination with a formaldehyde resin dissolved in acetone and / or based on a silane polyether and / or based on polybutene cross-linked with butyl rubber and / or based on an alkoxy silicone.

[0074] These types of adhesives have the particular advantage that they can be applied in such a small quantity that they harden after adhesion. This means that after the noise absorber is removed and before the tires are shredded during recycling, they are not sticky, allowing the tires to be shredded in the usual way without the noise absorber.

[0075] The noise absorber is applied to the inside of the tire using methods and devices known to those skilled in the art.

[0076] Depending on its type, the colorant is applied to the radially inward-facing surface of the sound absorber. In particular, it can be applied as a suspension, emulsion, or solution.

[0077] A further object of the invention is a method for detecting a vehicle pneumatic tire with at least one noise absorber attached to the inner surface opposite the tread inside the tire, wherein the noise absorber has a radially inwardly directed surface, and at least one colorant is applied to the radially inwardly directed surface of the noise absorber to distinguish vehicle pneumatic tires having a noise absorber from vehicle pneumatic tires without a noise absorber.

[0078] In the method according to the invention, the noise absorber is detected by an operator or by means of a detector due to the colorant.

[0079] The detector can be a photodetector or a color detector. A color detector programmed to detect specific colors, for example according to the RAL system, is preferred.

[0080] Suitable detectors are known to experts and are usually computer-aided.

[0081] It can also be a handheld device or a detector used in an automated process via a robot.

[0082] A further object of the invention is a method for recycling vehicle pneumatic tires with at least one noise absorber attached to the inner surface opposite the tread inside the tire, wherein the noise absorber has a radially inwardly directed surface, and at least one colorant is applied to the radially inwardly directed surface of the noise absorber, the method comprising at least the following process steps: A) Provision of the vehicle tire to be recycled; B) Detection of the noise absorber based on the dye; C) Separation of the noise absorber from the vehicle tire; D) Subsequent shredding of the vehicle tire without the noise absorber.

[0083] According to advantageous embodiments, process steps A) to D) are automated.

[0084] Another object of the invention is a method for recycling vehicle pneumatic tires comprising at least the following process steps: a) Provision of vehicle tires to be recycled; b) Implementation of the inventive method for detecting a vehicle tire in order to distinguish vehicle tires with a noise absorber from vehicle tires without a noise absorber; c) Spatial separation of vehicle tires having a noise absorber from vehicle tires without a noise absorber; d) Recycling of vehicle tires without a noise absorber comprising the shredding of the vehicle tires; e) Transfer of vehicle tires having a noise absorber to a separate recycling process comprising the removal of the noise absorber and only then the subsequent shredding of the vehicle tires.

[0085] According to advantageous embodiments, process steps a) to e) are automated. According to an advantageous embodiment of the invention, step c) is automated in conjunction with step b).

[0086] Further details of the invention will be provided with reference to the Figure 1 , which is a schematic representation of an exemplary embodiment, explained in more detail.

[0087] The invention will now be explained in more detail using an exemplary embodiment. An example of a vehicle pneumatic tire according to the invention is shown in Figure 1 shown in a schematic representation.

[0088] In Fig. 1Figure 1 shows a cross-section of a passenger car radial tire, which has a profiled tread 1, sidewalls 2, bead areas 3, bead cores 4, a multi-layer belt 5, and a carcass ply 6. The inner surface of the tire is covered with an inner layer 7 made of an airtight rubber compound. On the inner surface of the inner layer 7 opposite the tread 1, a sound-absorbing foam ring 9 is subsequently (on the finished tire) bonded to the tire by means of an adhesive 8, for example, a polyurethane-based adhesive 8.

[0089] The sound-absorbing foam ring is tuned to the tire cavity frequency with regard to its sound-absorbing properties. For example, the noise absorber 9, in the form of a foam ring, has an approximately elongated triangular cross-section that is symmetrical with respect to the tire equator.

[0090] The foam used in the foam ring is an open-cell foam, as this type is particularly well-suited for sound absorption. The foam contains materials such as polyurethane.

[0091] The noise absorber 9 has a radially inwardly directed surface 9a.

[0092] According to the example in Figure 1 At least one colorant 10 is applied to the radially inwardly directed surface 9a of the noise absorber 9.

[0093] For example, the colorant 10 is applied by means of a suspension containing the colorant methyl orange. The noise absorber 9 is thus colored, namely orange, on its inward-facing surface 9a. The liquid in the suspension is, for example, water, and a styrene-acrylate copolymer is also included as a binder.

[0094] The colorant 10, for example, covers the entire (100%) surface 9a of the sound absorber 9.

[0095] The exemplary vehicle tire described above can now be distinguished from vehicle tires without noise absorbers by means of a color detector according to the inventive method. The color detector is specifically programmed to detect orange hues.

[0096] This allows vehicle tires with noise absorbers and vehicle tires without noise absorbers to be distinguished from one another in an, for example, automated process according to the invention, spatially separated, and fed into different recycling processes. In the case of the tire according to the invention, the noise absorber, comprising colorant, is first removed from the tire in an additional step. Reference symbol list (Part of the description)

[0097] 1. Tread strip 2. Sidewall 3. Bead area 4. Bead core 5. Belt bond 6. Carcass insert 7. Inner layer 8. Adhesive 9. Noise absorber 9. Radially inward-facing surface of the noise absorber 10. Dye rRradial direction aRaxial direction URDirection of rotation of the tire

Claims

1. Pneumatic vehicle tyre with at least one sound absorber (9) adhesively attached in its interior to the inner surface opposite the tread (1), wherein the sound absorber (9) has a radially inward-facing surface (9a), wherein the at least one sound absorber (9) is at least one porous damping element, characterized in that the radially inward-facing surface (9a) of the sound absorber (9) has at least one colorant (10) applied to it via a liquid phase.

2. Pneumatic vehicle tyre according to Claim 1, characterized in that the colorant (10) is selected from inorganic and organic colorants and is white or coloured.

3. Pneumatic vehicle tyre according to either of the preceding claims, characterized in that the colorant (10) comprises at least one metal atom or metal ion.

4. Pneumatic vehicle tyre according to any of the preceding claims, characterized in that the colorant (10) has been applied to the surface (9a) of the sound absorber (9) by means of a dispersion, in particular suspension or emulsion, or a solution, wherein the dispersion or the solution contains from 1% to 80% by weight of colorants.

5. Pneumatic vehicle tyre according to any of the preceding claims, characterized in that the colorant (10) covers 50% to 100% of the radially inward-facing surface (9a) of the sound absorber (9).

6. Pneumatic vehicle tyre according to Claim 1, characterized in that the porous damping element is a sound-absorbing foam ring closed or open in the circumferential direction.

7. Pneumatic vehicle tyre according to any of the preceding claims, characterized in that the sound absorber contains at least one polyurethane.

8. Process for detecting a pneumatic vehicle tyre with at least one sound absorber (9) adhesively attached in its interior to the inner surface opposite the tread (1), wherein the sound absorber (9) has a radially inward-facing surface (9a) and the radially inward-facing surface (9a) of the sound absorber (9) has at least one colorant (10) applied to it, wherein the process is for distinguishing pneumatic vehicle tyres comprising the at least one sound absorber (9) from pneumatic vehicle tyres without a sound absorber, wherein the sound absorber (9) is detected by an operator or using a detector as a result of the at least one colorant (10) on the surface (9a).

9. Process for recycling a pneumatic vehicle tyre with at least one sound absorber (9) adhesively attached in its interior to the inner surface opposite the tread (1), wherein the sound absorber (9) has a radially inward-facing surface (9a) and the radially inward-facing surface (9a) of the sound absorber (9) has at least one colorant (10) applied to it, the process comprising at least the following process steps: A) providing the pneumatic vehicle tyre; B) detecting the sound absorber (9) as a result of the colorant (10); C) separating the sound absorber (9) from the pneumatic vehicle tyre; D) subsequently comminuting the pneumatic vehicle tyre without the sound absorber.

10. Process for recycling pneumatic vehicle tyres comprising at least the process steps of: a) providing pneumatic vehicle tyres to be recycled; b) performing the process according to Claim 8; c) spatially separating pneumatic vehicle tyres comprising a sound absorber (9) from pneumatic vehicle tyres without a sound absorber (9); d) recycling pneumatic vehicle tyres without a sound absorber (9) comprising comminution of the pneumatic vehicle tyres; e) transferring pneumatic vehicle tyres comprising a sound absorber (9) to a separate recycling process comprising separation of the sound absorber (9) and comminution of the pneumatic vehicle tyres only subsequently.