RUBBER-BASED PUNCTURE SEALING AGENT FOR TIRES

Abstract

A puncture sealing agent is disclosed which comprises a rubber latex, a carbohydrate, an additional polymer, and an antifreeze agent. The sealing agent can be used for repairing or preventing punctures in tubeless tires as well as tires having an inner tube, in particular in bicycle tires and e-scooter tires.

Claims

1. A puncture sealing agent, comprising a rubber latex, a carbohydrate, an additional polymer, and an antifreeze agent, wherein the rubber latex is present in an amount of 10 to 35 weight % per 100 weight % of the puncture sealing agent, and the carbohydrate is a monosaccharide and/or a disaccharide and/or an oligosaccharide.

2. The puncture sealing agent according to claim 1, wherein the rubber latex is a natural rubber latex, which is free of ammonia.

3. The puncture sealing agent according to claim 1, wherein the carbohydrate is present in an amount of 0.1 to 15 weight % per 100 weight % of the puncture sealing agent.

4. The puncture sealing agent according to claim 1, wherein the additional polymer is a polysaccharide which is different from the carbohydrate.

5. The puncture sealing agent according to claim 4, wherein the polysaccharide is cellulose and/or a cellulose derivative.

6. The puncture sealing agent according to claim 1, wherein the puncture sealing agent further comprises a biomass-derived polymeric material which is different from the additional polymer, the carbohydrate and the rubber latex.

7. The puncture sealing agent according to claim 6, wherein the biomass-derived polymeric material, which is different from the additional polymer, the carbohydrate and the rubber latex, is present in an amount of 0.1 to 10 weight % per 100 weight % of the puncture sealing agent.

8. The puncture sealing agent according to claim 6, wherein a weight ratio of the amount of the biomass-derived polymeric material present in the puncture sealing agent to the amount of the additional polymer in the puncture sealing agent is in the range of 1:10 to 25:1.

9. The puncture sealing agent according to claim 1, wherein the puncture sealing agent comprises the additional polymer, which is a water-soluble polysaccharide.

10. The puncture sealing agent according to claim 9, wherein the water-soluble polysaccharide is a water-soluble cellulose ether.

11. The puncture sealing agent according to claim 9, wherein the puncture sealing agent comprises the water-soluble additional polymer in an amount of 0.10 to 2.5 weight % of the puncture sealing agent.

12. The puncture sealing agent according to claim 9, wherein the water-soluble additional polymer has a water solubility of at least 5 g/L at 20° C.

13. The puncture sealing agent according to claim 1, wherein the puncture sealing agent is a bicycle tire puncture sealing agent.

14. A method comprising using the puncture sealing agent according to claim 1 to repair punctured tubeless tires.

15. A method comprising using the puncture sealing agent according to claim 1 to repair punctured tires having an inner tube, wherein the punctured tires having the inner tube are bicycle tires or e-scooter tires.

16. A method comprising using the puncture sealing agent according to claim 1 to-prevent punctures in tubeless tires.

17. A method comprising using the puncture sealing agent according to claim 1 to prevent punctures in tires having an inner tube.

18. A puncture sealing agent, comprising a rubber latex, a carbohydrate, an additional polymer, and an antifreeze agent, wherein the carbohydrate is a monosaccharide and/or a disaccharide and/or an oligosaccharide, the additional polymer is a polysaccharide which is different from the carbohydrate, and the polysaccharide is cellulose and/or a cellulose derivative.

19. The puncture sealing agent according to claim 18, wherein the polysaccharide is microcrystalline cellulose, a cellulose ether containing a hydroxyethyl group, a cellulose ether containing a hydroxypropyl group, or a mixture thereof.

20. A puncture sealing agent, comprising a rubber latex, a carbohydrate, an additional polymer, and an antifreeze agent, wherein the carbohydrate is a monosaccharide and/or a disaccharide and/or an oligosaccharide, and the additional polymer is present in an amount of 0.55 to 5 weight % per 100 weight % of the puncture sealing sealant.

Description

EXAMPLE 1

[0082] A puncture sealing agent according to the present invention was prepared by mixing a rubber latex (ammonia-free natural rubber latex), a carbohydrate (sucrose), an additional polymer (hydroxyethyl methyl cellulose), an antifreeze agent (glycerol) water and a coloring agent (chlorophyllin) according to the formulation given in Table 1 above.

[0083] In order to check the injectability of the above formulation, it was injected into a tubeless bicycle tire through the valve of the tire at varying temperatures with the aid of a manually operated bicycle air pump, without using a compressor. It was found that, over a temperature range from −20° C. to +50° C., the material could be injected into the tire without clogging the valve.

[0084] To test the sealing performance of the above composition in an emergency situation, a puncture tool was used to create a hole having a diameter of 4 mm in the tread portion of a tubeless bicycle tire. After pulling out the puncture tool, the puncture sealing agent according to the formulation above was injected through the tire valve using a manually operated bicycle air pump, and driving was simulated by spinning the wheel. After one minute of spinning, there was no more air leakage and the tire presented a tight status, i.e. no bubbling effect was observed after spraying water in the vicinity of the puncture hole.

[0085] To test the sealing performance of the above composition when it is used preventively, the formulation was injected into a tubeless bicycle tire through an air valve while the tire was still intact, using a manually operated bicycle air pump. Then, a puncture tool was used to create a hole having a diameter of 4 mm in the tread portion of the tire. After pulling out the puncture tool, driving was simulated by spinning the wheel. After one minute of spinning, there was no more air leakage and the tire presented a tight status, i.e. no bubbling effect was observed after spraying water in the vicinity of the puncture hole. Re-pumping of the tire was not required.

[0086] The composition was then subjected to sealing performance tests in a bicycle tire having an inner tube. To test the sealing performance in tires having an inner tube in an emergency situation, a puncture tool was used to create holes in two inner tubes for bicycle tires, one hole having a diameter of 2 mm and being situated in the tread portion of one inner tube, and the other hole having a diameter of 2 mm and being situated in the side section of another inner tube. After pulling out the puncture tool and placing each tube within a tire and on a wheel, the puncture sealing agent according to the formulation above was injected through the tire valve using a manually operated bicycle air pump, and driving was simulated by spinning the wheel. As shown in Table 2, the puncture holes were sealed within ten minutes of spinning.

[0087] To test the sealing performance of the above composition when it is used preventively in a tire with an inner tube, the formulation was injected into two tires having an inner tube through an air valve while the tires and inner tubes were still intact, using a manually operated bicycle air pump. Then, a puncture tool was used to create holes in the two bicycle tires, one hole having a diameter of 2 mm and being situated in the tread portion of one tire, and the other hole having a diameter of 2 mm and being situated in the side section of the other tire. After pulling out the puncture tool, driving was simulated by spinning the wheel. As shown in Table 2, the puncture holes were sealed within ten minutes of spinning. Re-pumping of the tires was required.

[0088] To evaluate the storage properties, stability tests were performed causing the original state of the dispersion to change or at least to be stressed. The aging experiments with respect to preventive use were carried out as follows: The sealant was pumped inside an intact tire, as when used preventively. The tire together with the wheel rim and the sealant was then subjected to repeated +60/−25° C. cycles for 6 hours. Subsequently, the tire was stored for twenty days at room temperature (20° C.). Throughout this period, the sealing agent remained liquid and did not coagulate. Accordingly, it was found that the formulation can be stored between −25° C. and +60° C. With respect to emergency applications, the shelf-life of the above-described formulation when not removed from its original bottle was determined as follows: Aging tests were performed using a LUMiSizer (available from LUM GmbH, Berlin, Germany) by analyzing particle and droplet velocity distributions for creaming and sedimentation phenomena and determining particle size (in conformity with ISO 13318-2:2007). After running a simulation using the LUMiSizer, the shelf life of the sealant within the bottle was estimated to be six years (in conformity with ISO/TR 13097:2013). With respect to preventative applications, the period during which the formulation remains liquid when placed within the tire was estimated to be six months.

EXAMPLE 2

[0089] A puncture sealing agent according to the present invention was prepared as described above in Example 1, except that hydroxy ethyl methyl cellulose was replaced with the same amount of microcrystalline cellulose (CAS 9004-34-6). Injectability, sealing performance and storage properties were evaluated using the same methods as described above in Example 1 and were found to be equal to those observed with the composition containing hydroxyethyl methyl cellulose.

EXAMPLE 3

[0090] A puncture sealing agent according to the present invention was prepared as described above in Example 1, except that ammonia-free natural rubber latex was replaced with the same amount of a high-ammonia natural rubber latex (0.6% ammonia, approx. 60% solid content). Injectability, sealing performance and storage properties were evaluated using the same methods as described above in Example 1 and were found to be equal to those observed with the composition containing ammonia-free natural rubber latex.

EXAMPLE 4

[0091] A puncture sealing agent according to the present invention was prepared by mixing a rubber latex (ammonia-free natural rubber latex), a carbohydrate (sucrose), an additional polymer (hydroxyethyl methyl cellulose), a biomass-derived polymeric material (cork powder), an antifreeze agent (glycerol), water and a coloring agent (chlorophyllin) according to the formulation given in Table 1 above. Sealing performance was evaluated using the same methods as described above in Example 1, except that the sealing agent was injected after removing the valve, and the results are shown in Table 2. The sealant does not come out of the tube, which results in two advantages: First, the hole is sealed fast, and secondly, no dirt is generated by sealant in the wheel rim or at the valve position.

EXAMPLE 5

[0092] A comparative puncture sealing agent outside the scope of the present invention was prepared by mixing a rubber latex (ammonia-free natural rubber latex), a carbohydrate (sucrose), an antifreeze agent (glycerol), water and a coloring agent (chlorophyllin) according to the formulation given in Table 1 above. Injectability and sealing performance were evaluated using the same methods as described above in Example 1, and the results are shown in Table 2. This composition, which contained neither an additional polymer (such as cellulose) nor a biomass-derived polymeric material (such as cork powder), displayed poor aging properties as it coagulated within the tire during storage. No sealing effect at all was observed in tires with an inner tube. Sealing performance in tubeless tires was lower than in the examples containing the additional polymer and/or the biomass-derived polymeric material.

TABLE-US-00002 TABLE 2 Performance of sealing compositions according to Examples 1, 4 and 5 Road Test Aging.sup.(1) Tubeless Tires with Seal Storage Sealant tires inner tube Retention Properties Tip Top.sup.(2) B − − n.d. milKit.sup.(2) A B.sup.− + n.d. Slime.sup.(2) B − − n.d. Example 1 AA B.sup.− + L Example 4 AA AA + L Example 5 A − + C .sup.(1)Aging test conditions were as described above in Example 1, i.e. sealant was pumped inside an intact tire, and the tire together with the wheel rim and the sealant was subjected to repeated +60/−25° C. cycles for 6 hours. Subsequently, the tire was stored for twenty days at room temperature (20° C.). .sup.(2)Commercial puncture sealing agents available from REMA TIP TOP AG, Poing, Germany (“Tip Top”), SPORT COMPONENTS AG, Zurich, Switzerland (“milKit”), and ITW Global Tire Repair Inc., San Luis Obispo, USA (“Slime”), respectively. Legend: −: Negative result. AA: Sealed within the first minute of rotation. No repumping required. A: Sealed within the first two minutes of rotation. No repumping required. B: Sealed within the first five minutes of rotation. Repumping may be required. B.sup.−: Sealed within the first ten minutes of rotation. Repumping is required. L: Liquid. C: Coagulated. n.d. not determined.

TABLE-US-00003 TABLE 3 Physical properties of sealing compositions according to Ex. 1 and 4 Viscosity at 20° C. Viscosity at −10° C. Sealant Density (g/mL) (mPa .Math. s) (mPa .Math. s) Example 1 1.065 220 700 Example 4 0.957 600 900

[0093] Viscosity was measured in accordance with DIN EN ISO 2555:2018 using a Brookfield viscosimeter with stainless steel spindle LV-3 at 20-60 rpm at 20° C. and at −10° C. The density was measured by using an areometer at 20° C. according to DIN 12791-1:2011-01.

[0094] Examples 1 to 4 show that an environmentally friendly, resource-saving puncture sealing agent based on natural compounds according to the present invention can be injected into tubeless tires over a broad temperature range from −20° C. to +50° C. to seal punctures having a size of up to 4 mm in both emergency and preventative applications. In each example, the puncture sealing agent can be injected using a manually operated air pump, such as a bicycle pump, without any need for a compressor, which is important in emergency situations. Moreover, the puncture sealing agent of Examples 1 to 4 is stable during storage, resulting in a long estimated shelf life of 6 years. Examples 1 and 3 demonstrate that ammonia-free and ammonia-containing natural rubber latex can be used interchangeably in the puncture sealing agent without negatively affecting performance. Similarly, Examples 1 and 2 demonstrate that hydroxyethyl methyl cellulose and microcrystalline cellulose can be used interchangeably in the puncture sealing agent without negatively affecting performance. Example 4 shows that the presence of a biomass-derived polymeric material such as cork powder surprisingly leads to a strong increase in viscosity and greatly enhances sealing performance in tires having an inner tube. From Example 5, which is not according to the present invention, it becomes evident that the presence of the additional polymer is important for both aging performance and sealing performance.