Method of making a solvent-free polymer-based tire sealant
The invention relates to a method for the production of a tire sealant (C) with a polymeric base. A highly viscous first sealant component (A) (including a natural rubber component that is undiluted or diluted with at least one additional natural rubber component and mixture ingredients that are free of a solvent and an activator) is mixed with at least one second sealant component (B) (comprising a separately produced medium with low viscosity containing at least one activator), to combine to the tire sealant (C), wherein a cross linking occurs associated with the subsequent application of the tire sealant (C) to the inside of the tire. Appropriate method steps are disclosed.
1. A method of making a polymer-based tire sealant (C), the method comprising the steps of:
providing a high viscosity first sealant component (A) comprising:
(a) a rubber component, which is unblended or has been blended with at least one further rubber component; and,
(b) mixture ingredients which are free from any solvent and from any activator;
providing a second sealant component (B) comprising a separately produced low-viscosity medium comprising at least one activator;
mixing said first sealing component (A) with said second sealing component (B) to form said tire sealant (C) and causing crosslinking to occur; and,
introducing said tire sealant (C) into the inner side of a tire;
wherein the first sealant component (A) is prepared with a twin-screw extruder.
2. The method of claim 1 , comprising the further steps of:
preparing the first sealant component (A) in a mixing device optimized for mixing high viscosities;
separately producing the second sealant component (B) in a stirrer;
pumping the first sealant component (A) and the second sealant component (B) separately to a metering apparatus;
then mixing the high-viscosity first sealant component (A) with the low-viscosity second sealant component (B) in a mixing device to form the tire sealant (C);
introducing the tire sealant (C) into the inner side of the tire; and, allowing the tire sealant (C) to solidify.
3. The method of claim 2 , wherein a diaphragm-based metering device is used for the pumping and metering of the first sealant component (A), the second sealant component (B), or both.
4. The method of claim 3 , wherein a hydraulic system is used for the pumping and metering to generate a uniform volume flow rate.
5. The method of claim 2 , wherein, with respect to the first sealant component (A) and/or with respect to the second sealant component (B), the pumping process takes place first and then the metering process takes place.
6. The method of claim 5 , wherein, with respect to the second sealant component (B), a gearwheel-based metering process takes place.
7. The method of claim 5 , wherein, with respect to the first sealant component (A) and/or with respect to the second sealant component (B), a piston-based metering process takes place.
8. The method of claim 7 , wherein the piston-based metering process takes place for the second sealant component (B).
9. The method of claim 1 , wherein the mixing of the first sealant component (A) with the second sealant component (B) to form the tire sealant (C) takes place in a static mixer.
10. The method of claim 1 , wherein the mixing of the first sealant component (A) with the second sealant component (B) takes place in a dynamic mixer.
11. The method of claim 1 , wherein the tire is preheated prior to contact thereof with the tire sealant (C), accelerating the crosslinking process and thus the completion of the reaction of the tire sealant.
12. The method of claim 11 , wherein the tire is preheated at a temperature from 40° C. to 100° C.
13. The method of claim 11 , wherein the tire is preheated at a temperature from 50° C. to 70° C.
14. The method of claim 1 , wherein the tire sealant (C) is inserted into a rotating tire.
15. The method of claim 1 , wherein the method of introduction of the tire sealant (C) is such that a continuous bead is placed in the tire and, using a winding pattern, covers the area to be covered on the inner side of the tire.
16. The method of claim 15 , wherein a nozzle with a non-circular or non-square geometry is used for a metering outlet, thus placing a wide bead in the tire.
17. The method of claim 16 , wherein the winding pattern is achieved in a single pass.
18. The method of claim 1 , wherein the rubber component used for the first sealant component (A) comprises natural rubber (NR), butadiene rubber (BR), isoprene rubber (IR), styrene-butadiene rubber (SBR), polychloroprene (CR), butyl rubber (IIR), bromobutyl rubber (BIIR), or chlorobutyl rubber (CIIR), or a blend of the above-mentioned types of rubber.
19. The method of claim 1 , wherein, for the first sealant component (A), mixture ingredients are used encompassing a filler and/or a processing aid and/or a plasticizer and/or an antioxidant, and also, optionally, further additives, where these exclude the activator.
20. The method of claim 1 , wherein the first sealant component (A) encompasses a crosslinking agent.
21. The method of claim 1 , wherein the first sealant component (A) uses mixture ingredients which are free from any crosslinking agent.
22. The method of claim 21 , wherein the crosslinking agent, which forms a crosslinking agent system with the activator, is admixed with the second sealant component (B).
23. The method of claim 20 , wherein a crosslinking agent from the quinones class is used.
24. The method of claim 23 , wherein the crosslinking agent used comprises a quinone dioxime (QDO).
25. The method of claim 1 , wherein the second sealant component (B) comprises a peroxidic activator.
26. The method of claim 1 , wherein the total quantitative proportion of mixture ingredients used, inclusive of the crosslinking agent system, is from 5 to 200 phr.
27. The method of claim 26 , wherein the total quantitative proportion of mixture ingredients used is from 20 to 100 phr.
28. The method of claim 1 , wherein the second sealant component (B) comprises a medium that has the consistency of a paste or of an oil.