RUBBER COMPOUND TO PRODUCE TYRES

Abstract

A rubber compound comprising a polymer base with a cross-linkable unsaturated chain, a filler, and a vulcanization system. The vulcanization system comprises at least sulphur, one or more vulcanization accelerators, and one or more vulcanization activators. The vulcanization system comprises a vulcanization activator consisting of Zn.sub.2SiO.sub.4.

Claims

1. A rubber compound comprising a polymer base with a cross-linkable unsaturated chain, a filler, and a vulcanization system; said vulcanization system comprising at least sulphur, one or more vulcanization accelerators, and one or more vulcanization activators; wherein said vulcanization system comprises a vulcanization activator consisting of Zn.sub.2SiO.sub.4.

2. A rubber compound according to claim 1, wherein said vulcanization activator consisting of Zn.sub.2SiO.sub.4 is present in the compound in a quantity ranging from 0.01 to 2.5 phr.

3. A rubber compound according to claim 1, wherein said vulcanization activator consisting of Zn.sub.2SiO.sub.4 is present in the compound in a quantity ranging from 0.01 to 1.5 phr.

4. A rubber compound according to claim 1, wherein said vulcanization activator consisting of Zn.sub.2SiO.sub.4 is the only vulcanization activator in said vulcanization system.

5. A rubber compound according to claim 1, wherein Zn.sub.2SiO.sub.4 is the only source of Zn in the compound.

6. A tyre portion manufactured with a compound according to claim 1.

7. A tyre comprising a portion according to claim 6.

8. A use of Zn.sub.2SiO.sub.4 as a vulcanization activator in rubber compounds.

9. A use according to claim 8, wherein said vulcanization activator consisting of Zn.sub.2SiO.sub.4 is present in the compound in a quantity ranging from 0.01 to 2.5 phr.

10. A use according to claim 8, wherein said vulcanization activator consisting of Zn.sub.2SiO.sub.4 is present in the compound in a quantity ranging from 0.01 to 1.5 phr.

Description

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] Examples are given below for illustrative non-limiting purposes for a better understanding of the present invention.

Examples

[0015] —Vulcanization Tests—

[0016] To test the capacities of Zn.sub.2SiO.sub.4 as a vulcanization activator compared to ZnO, an experimental method was formulated based on the vulcanization reaction of a model molecule in the presence of a vulcanization system comprising alternatively ZnO or Zn.sub.2SiO.sub.4 and squalene as a molecule representative of the polymer base. Occurrence of the vulcanization was monitored by means of the HPLC analysis technique.

[0017] Tables I-V show the compositions in phr of the 10 reaction mixtures (A-J) used for the vulcanization tests.

TABLE-US-00001 TABLE I A B Squalene 100 CBS 1.2 Sulphur 2 Stearic acid 2 ZnO 0.5 — Zn.sub.2SiO.sub.4 — 0.5

TABLE-US-00002 TABLE II C D Squalene 100 CBS 1.2 Sulphur 2 Stearic acid 2 ZnO 1.5 — Zn.sub.2SiO.sub.4 — 1.5

TABLE-US-00003 TABLE III E F Squalene 100 CBS 1.2 Sulphur 2 Stearic acid 2 ZnO 2.5 — Zn.sub.2SiO.sub.4 — 2.5

TABLE-US-00004 TABLE IV G H Squalene 100 CBS 1.2 Sulphur 2 Stearic acid 2 ZnO 3.0 — Zn.sub.2SiO.sub.4 — 3.0

TABLE-US-00005 TABLE V I J Squalene 100 CBS 1.2 Sulphur 2 Stearic acid 2 ZnO 5.0 — Zn.sub.2SiO.sub.4 — 5.0

[0018] For each of the above reaction mixtures, the degree of vulcanization of the squalene was determined by the HPLC analysis technique referring to the chromatographic signals typical of the cross-linking products. The results are reported in Tables VI and VII in an indexed form with respect to the value found for the compounds with ZnO at the same concentration of phr (0.5; 1.5; 2.5; 3.0; 5.0).

TABLE-US-00006 TABLE VI A B C D E F Vulcanization 100 333 100 250 100 167 index Moles of Zn 0.006 0.004 0.018 0.013 0.031 0.022

TABLE-US-00007 TABLE VII G H I J Vulcanization 100 50 100 63 index Moles of Zn 0.037 0.027 0.061 0.045

[0019] From the values of Tables VI and VII it is clear that Zn.sub.2SiO.sub.4 at low concentrations has an effectiveness in terms of vulcanization activation significantly higher than that of the ZnO.

[0020] In particular, from the values of Tables VI and VII it can be seen that Zn.sub.2SiO.sub.4 is more effective than the ZnO when used in concentrations below 3 phr (values of Table VI), while it is less effective than the ZnO when used in concentrations above 3 phr (values of Table VII).

[0021] For a better understanding of the advantages of the present invention, Tables VI and VII also show the number of moles of Zn present in each of the compounds A-J. In said regard, the values of Tables VI and VII show that it is possible to drastically reduce the presence of Zn in the compound while maintaining the vulcanization capacities of the compound unchanged.

[0022] In fact, the possibility of obtaining a high degree of vulcanization using low quantities of Zn.sub.2SiO.sub.4 is necessarily reflected in a significant reduction of the overall quantity of Zn in the compound.