TECHNICAL FIELD

The present invention is related to a puncture sealing agent having an excellent sealing performance for use in a puncture repair system.

BACKGROUND ART

In tire puncture repair systems a puncture sealing agent is used for sealing punctures in pneumatic tires. The puncture sealing agent is a liquid comprising a solid dispersion and is injected into a damaged tire. The tire is then filled with air with the aid of a compressor and can be used to travel in that condition. When traveling, the puncture sealing agent is shaken within the tire, and as a result, the solid content of the dispersion is deposited to cover the puncture hole.

In recent years the required level of performance for puncture sealing agents has increased. Most of the efforts have been put into improving the sealant performance, injectability, and/or the injectability in low-temperature environments while maintaining ideal storage performance.

Puncture sealing agents contain usually synthetic components for improving the sealing performance, injectability and/or the injectability in low-temperature environments while maintaining ideal storage performance. However, using synthetic components is not resource saving and environmentally friendly. In addition, there is room for improving the sealing properties of puncture sealing agents having sufficient low temperature injectabilities.

A puncture sealant agent is described in Patent Literature 1, wherein natural rubber is contained in an amount such that the solid content derived from natural rubber is 25 wt %, based on the total weight of the puncture sealant agent together with a rosin resin having a softening point of 90° C. and propane-1,3-diol. In Patent Literature 2, a further puncture sealing agent is described which contains a rubber latex, propane-1,3-diol and a resin emulsion as tackifier, such as a terpene resin. However, there remains room for improvement with regard to low temperature injectability and seal retention performance.

CITATION LIST

Patent Literature

Patent Literature 1: JP 2015-98538 A

Patent Literature 2: US 2015/0175862 A1

SUMMARY OF INVENTION

Technical Problem

In view of the above, the object underlying the present invention is to provide a puncture sealing agent, which is resource saving, environmentally friendly and has a sealing performance, injectability, and injectability in low-temperature environments comparable to conventionally used puncture sealing agents based on synthetic components.

Solution to Problem

In accordance with the present invention, this object is solved by a puncture sealing agent according to claim1.

The puncture sealing agent according to the present invention comprises natural rubber latex, an aqueous solution of an adhesive and an antifreezing agent. The adhesive is a carbohydrate and the puncture sealing agent comprises a solid content resulting from the natural rubber latex in an amount of 21 wt % or less, based on the total weight of the puncture sealing agent.

This solution bases on the surprising finding that by combining in a puncture sealing agent a solid content derived from natural rubber latex of 21 wt % or less, based on 100 wt % of the puncture sealing agent, an aqueous solution of a carbohydrate as an adhesive and an antifreezing agent, a puncture sealing agent can be obtained which is at least primarily based on natural components and therefor resource saving and environmentally friendly. It was found that such a puncture sealing agent provides excellent sealing performance, injectability and injectability in low-temperature environments. In addition, by using carbohydrates as adhesives, it is possible to significantly reduce the costs for the puncture sealing agent, since the use of synthetic resins can be reduced or completely avoided. Accordingly, it is possible to reduce or even avoid the use of dangerous compounds and additives. Moreover, disposal of the puncture sealing agent according to the invention after expiry is easy and non-dangerous.

Another aspect of the present invention is a puncture repair system comprising a puncture sealing agent according to the present invention.

The present invention concerns also a method of producing a puncture sealing agent by mixing natural rubber latex, an aqueous solution of an adhesive and an antifreezing agent, wherein the adhesive is a carbohydrate and the puncture sealing agent comprises a solid content resulting from the natural rubber latex in an amount of 21 wt % or less, based on the total weight of the puncture sealing agent.

Preferred embodiments of the present invention are the subject-matter of dependent claims and described subsequently along with further preferred embodiments which are not expressly mentioned in the dependent claims.

