PNEUMATIC TYRE COMPRISING A FOAM MATERIAL FOR SOUND ABSORPTION

Abstract

A pneumatic tyre comprising an impermeable layer that is suitable for guaranteeing the pressure tightness of the air contained within the internal cavity of the casing and a layer of sound-insulating material housed within said internal cavity and made, in turn, with polyols deriving from CNSL.

Claims

1. Pneumatic tyre comprising an impermeable layer that is suitable for guaranteeing the pressure tightness of the air contained within the internal cavity of the casing and a layer of sound-insulating material housed within said internal cavity; said pneumatic tyre being characterized in that said sound-insulating material is a polyurethane foam made with polyols deriving from CNSL.

2. Pneumatic tyre according to claim 1, characterized in that said polyurethane foam has an apparent density of between 5 and 100 kg/m.sup.3 (between 5 and 100 g/dm.sup.3).

3. Pneumatic tyre according to claim 1, characterized in that said polyurethane foam has an apparent density of between 10 and 30 kg/m.sup.3 (between 10 and 30 g/dm.sup.3).

4. Pneumatic tyre according to claim 1, characterized in that the layer of sound-insulating material occupies a volume of between 0.1 and 100% of the volume of the internal cavity.

5. Use of a polyurethane foam made with polyols deriving from CNSL as a sound-insulating material housed within the cavity of a pneumatic tyre.

6. Use according to claim 5, characterized in that said polyurethane foam has an apparent density of between 5 and 100 kg/m.sup.3 (between 5 and 100 g/dm.sup.3).

7. Use according to claim 5, characterized in that said polyurethane foam has an apparent density of between 10 and 30 kg/m.sup.3 (between 10 and 30 g/dm.sup.3).

Description

[0020] Reported below are examples of non-limiting embodiments given purely by way of illustration with the aid of the attached FIGURE, which is a graph relating to a comparison between the sound absorption of the polyurethane foam which is commonly of fossil origin and the polyurethane foam utilized in the present invention.

[0021] Reported below, in terms of sound absorption and water absorption, is a comparison between a polyurethane foam that is commonly used as a sound-insulating material in pneumatic tyres (PU-comp.) and deriving from fossil resources, and a polyurethane foam obtained using polyols deriving from CNSL (PU-inv.) according to the present invention.

[0022] The polyurethane foam of the prior art utilized for comparison, is marketed under the trade name Metzonor 023 and is produced by Metzler Schaum GMBH.

[0023] The polyurethane foam utilized in this invention is made according to example 3 reported within the patent application EP1930355A2.

[0024] The polyurethane foam used for comparison (PU-comp.) and the polyurethane foam used as an example for the present invention (PU-inv.) have the same apparent density.

[0025] Reported in the FIGURE is the sound absorption coefficient of both of the polyurethanes described above as a function of frequency. From the FIGURE, within the frequency range that characterizes the noise observed within the vehicle, it can clearly be seen that the polyurethane made with the polyols deriving from CNSL has a sound absorption coefficient that is progressively greater than that of the comparison polyurethane.

[0026] The sound absorption test was performed according to the ISO 10534-2 standard at a frequency of between 180 and 300 Hz.

[0027] The water absorption test was performed by measuring the variation in weight of the polyurethane foam after the same was exposed to air at a controlled temperature and humidity for a period of 7 days and, successively, after the same had been maintained within a vacuum oven at 70 C. for a period of 24 hours. The water absorption index is expressed as a variation in weight which is normalized in relation to the dry weight of the foam (the lower the index, the lower the water absorption.)

[0028] The results of the above tests are reported in Table I in indexed form with respect to the respective results obtained with the comparison polyurethane foam (PU-comp.).

[0029] For a correct assessment of the results reported in Table I, it should be specified that the greater the relevant absorption coefficient and the lower the water absorption index the better the sound-insulating material.

TABLE-US-00001 TABLE I PU-comp. Pu-inv. Sound absorption 100 150 Water Absorption 100 60

[0030] From the values reported in Table I it is evident that the polyurethane foam used in the present invention guarantees, in relation to the polyurethane foam of the prior art, both a greater sound absorption coefficient and a lower water absorption index.

[0031] To summarize, the polyurethane foam utilized according to the present invention does not only offer the great advantage of being made with material emanating from a renewable source but, at the same, it guarantees, in relation to polyurethane foam of fossil origin and indeed of the prior art, advantages in terms of sound absorption and water absorption.

[0032] Finally, it is the opinion of the inventors that the polyurethane foam according to the invention, by virtue of the low water absorption and the differing chemical composition, is able to guarantee greater aging stability in relation to the polyurethane foam of the prior art.