Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Composite article making
Reexamination Certificate
1998-12-18
2001-02-20
Kuhns, Allan R. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Composite article making
C264S046400, C264S046600, C264S255000, C264S257000, C264S302000
Reexamination Certificate
active
06190587
ABSTRACT:
The copending patent application PCT/EP 96/01583 (not yet published) of the present applicant describes a method for forming products such as simulated leather or like products with at least one expanded layer from thermoplastic, thermosetting or elastomer materials, comprising the following stages: forming in a slush-moulding mould a first layer of compact material representing the exposed layer of the finished product, on this first layer forming the second layer of expandable material by further slush-moulding, completing with heat the consolidation of the formed layers by gelling and the expansion of said second layer by suitable means to obtain predetermined thicknesses and shapes in said expanded layer, to the layered material formed in this manner there being coupled a support of rigid material possibly filled with reinforcement fibres, said suitable means for obtaining predetermined thicknesses and shapes of said expanded layer consisting either of a counter-mould or of the actual said support of rigid material.
As explained in the said patent application, the finished products obtained by the method in question are generally appropriate for interior trimmings in particular of motor vehicles, for example for parts such as dash panels, consoles, compartment lids and other similar objects for which an appearance as similar as possible to natural leather is required.
As described in the said patent application, the method in question represents considerable progress in particular compared with the preceding method for obtaining such objects produced by thermoforming calendered sheets possibly laminated with an expanded layer.
In this respect, in this preceding method the presence of stretched parts containing congealed forces gives rise to serious shrinking problems with consequent cracking and breakage under hot conditions, especially in that region which in automobiles is exposed to direct sunlight, such as the upper surface of the dash panel.
The inclination of windscreens at increasingly acute angles in accordance with the latest preferred styles has aggravated this problem by causing the temperature to which these interior parts of the vehicle are exposed to often exceed 100° under solar radiation.
The simulated leather obtained by the method of the aforesaid patent application, which essentially uses a slush-moulding method, avoids this defect.
Notwithstanding the substantial progress represented by this patent application, in the practical implementation of the method it has been found that a defect can sometimes arise in the leather produced by it, due substantially to the circumstance that in said stage involving the control of the thickness and shape of the expanded layer, also known as the surface shaping stage for the expanded layer, a uniform and regular surface cannot always be obtained, so that in the next stage involving adhesion to the support, generally by gluing, discontinuity points or regions can arise between the inner surface of the expanded layer and the support itself, which the layer of glue is unable to compensate. This can occur at either cavities or protuberances in the surface of the expanded layer, so that voids or humps are consequently created at the expanded layer/support interface, which are inevitably transmitted to the exposed outer surface of the simulated leather.
This means that the aesthetic effect sought is completely ruined, because those cavities and protuberances transmitted from the interior of the layered structure to the exposed outer surface of the simulated leather are immediately visible.
An analogous defect can occur if, instead of being present on the expanded layer surface, the imperfections are present on the rigid support itself, or on both surfaces.
The object of the present invention is mainly to solve this problem.
The present invention therefore essentially proposes to improve the method described in patent application PCT/EP 96/01583 of the present applicant.
This object, and other advantages which will be apparent from the ensuing description, are attained according to the invention by a method for forming products such as simulated leather or like products with at least one expanded layer from thermoplastic, thermosetting or elastomer materials, comprising the following stages: forming in a slush-moulding mould a first layer of compact material representing the exposed layer of the finished product, on said first layer forming a second layer of expandable material by further slush-moulding, completing with heat the consolidation of said layers by gelling and the expansion of said second layer, to the layered material formed in this manner there being coupled a support of rigid material possibly filled with reinforcement fibres, characterised by comprising a stage involving the filling of every possible interspace between said rigid material support and said expanded second layer.
According to one embodiment of the present invention, said stage involving the filling of every possible interspace between the rigid material support and the expanded second layer consists of coupling the rigid material support to said thus formed layered material by applying a layer of expandable adhesive to their interface.
A suitable expandable adhesive is a bicomponent polyurethane. It is possible in any event to apply a layer of expandable adhesive compatible with the materials to be coupled. The expandable material adhesive can be used either as such or together with suitable adhesion promoters.
In a different embodiment of the method of the present invention, said stage involving the filling of every possible interspace between the rigid material support and said expanded second layer of the layered material consists of coupling to said thus formed layered material the rigid material support possibly filled with reinforcement fibres predispersed in the material or forming a layer to be inserted into the rigid material, this latter being formed by direct moulding onto the free face of said expanded second layer within a suitable mould, for example by casting or by pressure injection moulding so as not to lose the mechanical properties to the expanded layer.
In this embodiment, once formed, the simulated leather is placed in an injection or casting mould, the mould profile reproducing that of the finished product, the rigid support hence being moulded onto the leather in the mould prepared in this manner, to give the finished product.
The thermoplastic, thermosetting or elastomer materials suitable for slush-moulding simulated leather or the like can be chosen from a wide range of resins in powder or liquid form.
The second layer of expandable material comprises expansion agents as azodicarbonamide, sodium bicarbonate, citric acid and others.
Said first layer can be formed of a single color, or of two or more colors for example by using the methods of patents of the present applicant, namely EP 476,742 or WO 94/12331.
For moulding the rigid support, particularly indicated are expanded or non-expanded rigid or semi-rigid thermosetting materials, such as polyurethanes, polyesters, epoxy resins and the like, possibly reinforced with fillers of glass fibres, carbon fibres, polyaramid fibres or fibres with similar characteristics, possibly forming a layer to be inserted into the material.
In that embodiment of the present invention comprising moulding the support directly onto the leather in a mould, particularly indicated are resins liquid at ambient temperature, and hence injectable or castable cold.
REFERENCES:
patent: 4664864 (1987-05-01), Wersosky
patent: 4810452 (1989-03-01), Taillefert et al.
patent: 5073318 (1991-12-01), Rohrlach et al.
patent: 5234653 (1993-08-01), Buzzoni et al.
patent: 5395578 (1995-03-01), Buzzoni et al.
patent: 5580501 (1996-12-01), Gallagher et al.
patent: 5900196 (1999-05-01), Cittadini et al.
Cittadini Paolo
Luisetti Giuseppe
Industrie Ilpea S.p.A.
Kuhns Allan R.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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