Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-08-16
2001-10-30
Weisberger, Rich (Department: 1774)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S244110, C156S244270, C156S349000, C156S459000, C156S580100, C428S036100, C442S327000, C442S381000
Reexamination Certificate
active
06309499
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and a plant for the production of multi-layer auto vehicles trim panels in thermoplastic material. More particularly, the present invention relates to a method for the production of vehicle interior elements such as, for instance, panels, hatboxes, dashboards, consoles and the like, by thermoforming multi-layer sheets. The vehicle interior elements thus obtained are also an object of the present invention.
BACKGROUND OF THE INVENTION
Thermoformed autovehicles interiors are generally obtained from sheets comprising a support material and an external covering layer for aesthetic purposes. According to a widely known and used technique, the external covering (known as “imitation leather”) is produced separately and thereafter joined to the support previously heated in a press. The press also provides for the shaping of the panel into the required form.
The support material is generally a polyolefin resin with a vegetable filler comprising for the most part wood powder. The imitation leather is generally in PVC and comprises a layer of cotton fabric or other textile material which acts as a mechanical bonding means for the polyolefin support.
This technique has several of drawbacks. In the first place, the cost and weight of the traditional imitation leather in PVC are both quite high. A second problem arises from the costs of the process, which requires many steps—some of which are particularly long—such as the cutting of the imitation leather and its positioning on the support plate. Further problems derive from the anisotropy of the panel as produced, from the fact that to recycle the waste or the panel at the end of its life it is necessary to remove the imitation leather (PVC) from the support layer (PP), and problems arise from the mechanical and hand (touch) characteristics of the product.
It has been proposed to produce the panels and the vehicle interior elements by co-injecting the support material and the external imitation leather material. This solution resolves many of the preceding problems but is suited to some types of panel only. The European Patent Application no. 0668142 discloses a method according to which sheets formed from a support layer and two external covering layers are co-extruded; these sheets are then thermoformed to give trim panels for cars, packing containers and the like. The support comprises polyolefin and an organic filler, particularly cellulose fibers, and the covering layers comprise polyolefin and inorganic fillers such as talc and carbonate. Panels of this type apparently present acceptable mechanical characteristics, but aesthetic and hand characteristics are completely insufficient.
DISCLOSURE OF THE INVENTION
An object of the present invention is to solve the above cited problems by means of a method for producing autovehicles trim panels by thermoforming that is simple, inexpensive and reliable, and that give panels with good mechanical properties and excellent aesthetic and hand properties.
A further object of the invention is to obtain thermoformable multi-layer sheets and finished elements having the above characteristics.
Such objects are achieved through the present invention, which relates to a method for the production of autovehicles interiors and similar products shaped by thermoforming, characterized according to claim
1
.
According to a preferred embodiment of the invention, support and covering layers are co-extruded.
According to another aspect of the invention the support layer is obtained by impregnation of two long-fiber needle-punched layers (natural and/or non-woven fabric) with an extruded polyolefin layer; preferably the covering layer is co-laminated on this support. The invention also relates to a plant to carry out the method, the plant being characterized according to claim
8
.
The method according to the invention presents several advantages compared to known methods in the art. The number of steps and the working time are greatly reduced, as it is no longer necessary to produce the imitation leather layer and the support sheets separately and then to join them in a press by thermoforming. Materials with identical or similar bases can be used, for instance PP or polyolefin in general, for both the imitation leather and the support; in this way it is possible to recycle offcuts and production waste. It is no longer necessary to cut the imitation leather and line it up above the support sheet . The embossing of the imitation leather can take place directly in the thermoforming mould, which eliminates the problems of loss of embossing during the thermoforming step and of producing different embossings in different parts of the panel. Besides, the cost of the material is lower; the cost of a imitation leather in PVC is more than double that of an imitation leather produced according to the invention. Finally, the resulting panel is more isotropic.
REFERENCES:
patent: 42 14 389 (1993-04-01), None
patent: 44 23 883 (1994-01-01), None
patent: 668142 (1995-08-01), None
patent: 0 747 213 (1996-12-01), None
patent: 2 067 135 (1981-07-01), None
patent: WO 98 05489 (1998-02-01), None
Principles of Polymer Processing, John Wiley & Sons, 1979, pp. 3-6.
Mascia Francesco
Puppi Cristiano
Cobrin & Gittes
Johnson Control S.p.A.
Weisberger Rich
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