The invention relates to a viscoelastic plastic interlayer intended to be incorporated between two sheets of glass to form laminated glazing with vibroacoustic damping properties, intended especially for locomotive machines, in particular a motor vehicle.
Among all the qualities contributing to comfort in modern transportation means such as trains and motor vehicles, silence has become a determining factor.
Acoustic comfort has been improved over several years now, by treating noise, such as noise from the engine, rolling or suspension noise, either at their source or during their propagation through the air or through solids, by means, for example, of absorbent coatings or elastomeric connecting pieces.
The shapes of vehicles have also been modified to improve the penetration in air and to reduce the turbulence, which are themselves sources of noise.
In recent years, attention has been focused on the role that glazing might play in improving acoustic comfort, in particular laminated glazing comprising plastic interlayer films. Laminated glazing also has other advantages, such as elimination of the risk of projection of fragments in the event of sudden breakage, constituting an effraction retarder.
It has been demonstrated that the use of standard plastic films in laminated glazing is unsuitable for improving acoustic comfort. Specific plastic films were then developed, which had damping properties that allow an improvement in the acoustic comfort.
Moreover, in the existing windscreens, the thickness of the glass sheet intended to be turned facing the exterior of the vehicle is generally 2.1 mm and the thickness of the glass sheet intended to be turned facing the interior of the vehicle is generally 1.6 mm. However, the tendency is towards lightening motor vehicles in order to reduce their consumption and the induced discharge of CO2. One means is to propose lighter motor vehicle glazing. One solution for reducing the weight of glazing is to reduce the thickness of the glass sheets. However, this reduction of thickness results in a degradation of the acoustic properties of the laminated glazing.
Moreover, it is also important to provide intimacy to persons inside a vehicle or to protect the driver of a vehicle from being dazzled by sunlight or simply to afford an aesthetic effect.
There is thus a need for a viscoelastic plastic interlayer intended to be incorporated between two glass sheets to form a laminated glazing with vibro-acoustic damping properties, which allows a reduction of the thickness of the glass sheets without degradation of the vibro-acoustic damping properties, while at the same time providing intimacy to persons inside a vehicle or protecting the driver of a vehicle from being dazzled by sunlight or simply to afford an aesthetic effect.