Tyre sealant layer

Abstract

A compound for a tyre sealant layer comprising at least one polymer base consisting of an essentially saturated polymer and a filler, which in turn comprises kraft lignin.

Claims

1. A compound for a tyre sealant layer comprising at least one polymer base consisting of an essentially saturated polymer and a filler; wherein said filler comprises kraft lignin; said essentially saturated polymer being a polymer produced with less than 15% in moles of diene monomers and is a halobutyl and/or butyl rubber.

2. A compound for a sealant layer according to claim 1, comprising 0.5 to 40 phr of kraft lignin.

3. A compound for a sealant layer according to claim 2, comprising at least 5 phr of kraft lignin.

4. A compound for a sealant layer according to claim 1, wherein the filler comprises carbon black.

5. A compound for a sealant layer according to claim 1, wherein said kraft lignin makes up 0.5 to 100% by weight of the whole filler.

6. A compound for a sealant layer according to claim 5, wherein said kraft lignin makes up at least 10% by weight of the whole filler.

7. A tyre sealant layer produced with the compound according to claim 1.

8. A tyre comprising a sealant layer according to claim 7.

Description

BEST MODE FOR CARRYING OUT THE INVENTION

(1) Some embodiment examples are given below for purely illustrative non-limiting purposes.

(2) Three compounds were prepared (A-C), the first two of which (A and B) constitute two comparison examples, and the third (C) constitutes an example of a compound produced according to the precepts of the present invention.

(3) In particular, the comparison compound A is relative to a compound currently used to prepare sealant layers, while the comparison compound B differs from the comparison compound A due to the fact that part of the carbon black has been replaced with sulfonate lignin.

(4) The compound of the invention C differs from the comparison compound A due to the fact that part of the carbon black has been replaced with kraft lignin.

(5) Basically the comparison compound B and the compound of the invention C differ only due to the type of lignin used.

(6) Table I shows the compositions in phr of the three compounds.

(7) TABLE-US-00001 TABLE I A B C Br-IIR 100 Liquid p-butene 350 Carbon black 20 10 10 Sulfonate lignin 10 Kraft lignin 10 Br-IIR stands for bromobutyl rubber.

(8) The sulfonate lignin used in the examples is sold under the trade name Borresperse NA by the company Borregaard.

(9) The kraft lignin used in the examples is sold under the trade name Indulin AT by the company WestVaco.

(10) The mixing step production process is described below.

(11) Mixing Step

(12) The ingredients indicated in Table I were mixed together and kept under stirring at a temperature of 100 C. for 10 min.

(13) From each of the compounds produced as described above a sealant layer was produced, which was subjected to a pressure retention test following puncturing of the tyre on which it was applied. The pressure retention test was performed on the sealant layers both before and after they had undergone an ageing process which entailed keeping them in a stove at 100 C. for three days according to the ISO 188 standard.

(14) In particular, the test was performed on tyres on which a respective sealant layer produced with a respective compound A-C was applied, in the same conditions. Specifically, the sealant layer is extruded directly on the surface of the inner cavity of the tyre.

(15) The tyres, after being inflated with the same internal pressure, were subjected to the same puncturing conditions with subsequent removal of the object used for the puncturing. For each of the tyres that underwent the test, retention of the pressure after 24 h from puncturing (and subsequent removal of the object) was evaluated.

(16) Table II shows the evaluations of the air retention expressed in a form indexed to the result obtained with the sealant layer produced with the compound A before undergoing the ageing process. The higher the indexed value, the better the pressure retention.

(17) TABLE-US-00002 TABLE II A B C Pressure retention 100 95 100 Pressure retention after ageing 80 85 95

(18) From the results of Table II it can be clearly seen that the presence of kraft lignin in the sealant layer (layer relative to the compound of the invention C) not only provides sealing properties comparable to those of the sealant layer commonly used but, at the same time, guarantees the maintenance of said properties also after a period of ageing.

(19) From a comparison between the results for the layer produced with compound B with the results for the layer produced with compound C, it can be seen that it is not the lignin in itself that guarantees the advantages of the present invention; said advantages derive from the exclusive use of kraft lignin, which contributes to giving the present invention the required originality.