Method for moulding seat tops or the like having a gel coating layer

Abstract: The present invention relates to a method for providing elements such as seat tops or the like having a coating layer of a viscoelastic or thermoplastic material, in particular gel, comprising the following steps: placing a layer of a first uniformly thick material into a uniformly deep mould (10) being larger than the shape of the product to be provided; applying a sheet of a flexible plastic material (13) to this layer of a first uniformly thick material; when catalyzation has been completely or almost completely carried out, removing said layer of a first uniformly thick material (12) joined to said sheet of a flexible plastic material (13); placing said layer of a first uniformly thick material into the mould (14) used to provide the requested product and fastening said plastic sheet along its edges at a certain distance from the mould edge; deforming said layer of a first uniformly thick material by suction from the mould bottom, so that said layer of a first uniformly thick material perfectly fits in with the mould shape covering also the mould side edges; closing the mould by means of a head cup (16) to which a shell (17) of a rigid material can be applied; injecting a foam material (18) into the gap between said layer of a first uniformly thick material and said head cup.

Description: The present invention relates to a method for providing moulded elements, e.g. seat tops, wristrests, lying cushions or the like, having at least one coating layer of a compressible viscoelastic material or any other thermoplastic material, in particular gel, wherein said layer covers not only the element surface, but also the element edges. The object of the present invention is to permit to use less gel than other known systems, thus providing a considerable saving of quite expensive material as well as a remarkably even colour on the whole element surface, independently of the element configuration. This object is achieved by the method as defined in claim 1. The following description will specifically relate to a method for providing gel coated seat tops, but obviously the same method can be validly applied also to other elements, such as cushions, wristrests or the like, being coated with other materials, without thereby departing from the scope of the invention. Some elements, in particular seat tops or backs, bicycle saddles or the like have been recently presented on the market, said elements having a gel coating layer. This material is highly appreciated for its peculiar softness and elasticity, which make it suitable for these specific uses, due to aesthetic reasons and because it provides good and cheap products. The current methods employed to provide these elements, e.g. seat tops, comprise the steps of pouring gel directly into the final mould and then completing the process by injecting an expandable foam which gets bound on one side to the gel and on the other side to a possible shell or a rigid support. A method for providing saddles with a gel layer is described in the Italian Patent No. 1.270.728. An example of a known method used to provide seat tops is illustrated with reference to figures from 1 to 5, in which figures from 1 to 4 are sectional views of a mould for providing a seat during the various process steps, whereas figure 5 is a perspective view of a seat top provided according to this known method. In the drawings numeral 1 indicates the mould body in which a cavity 2 is provided the shape of which corresponds to the external upper surface of the finished product. As known, a sheet 3 of a plastic material (figure 2) is placed on this mould and fastened by a frame 4 which runs along the periphery of the mould cavity; a certain amount of vacuum is applied through the mould bottom to deform the sheet so that the sheet perfectly fits in with the cavity shape. At this point (figure 3) a gel layer 5 is poured, after which the mould upper cover, to which a stiffening shell 7 is applied, is closed and a certain amount of expandable material 8, e.g. a polyurethane foam, is injected into the gap between the gel layer 5 and the head cup 6. When polymerization has been completed, it is possible to take out the piece which looks as shown in figure 5, with a clean-cut boundary line between the gel layer and the layer of expanded material. However, this system has some drawbacks, or at least it can be further improved. As a matter of fact, pouring the gel directly into the final mould causes a considerable waste of material, since if for example the mould bottom is corrugated a gel layer is provided which is thicker adjacent to the mould cavity, which compels to use a larger amount of gel, which is much more expensive than the foam material. Further, due to the different thickness of this gel layer also the element colour changes along the element surface, which is not always appreciated. Finally, the separation layer between the gel and the foam material can be clearly seen on the edges, therefore a shell must be used which has raised edges to cover and hold the element along the sides. All these drawbacks are now overcome by the method of the invention, which provides a finished element with a uniformly thick gel layer extending also along the edges. An element is thus provided in which less gel is used, the coating colour is even along the whole surface and the gel layer covers also the element edges, thus avoiding the need of a shell with raised edges. The present invention will now be described in detail, by way of non restrictive example, with reference to the accompanying drawings from 6 to 10 in which: figure 6 is a sectional view of a mould used to provide an initial manufactured article which is then used to provide a seat top; figure 7 is a sectional view of the manufactured article provided in this way; figures 8 and 9 are sectional views of a mould used to provide a top seat according to the invention during the two subsequent process steps; figure 10 is a perspective view of a seat top provided with the method of the invention. With reference to the above mentioned drawings, in the first place the method of the invention provides a gel layer having a substantially uniform thickness, said layer being provided by pouring gel into a mould 10 having a uniformly deep cavity 11 and being larger than the finished element to be provided. Preferably a thin plastic film 13 will be applied to this gel layer 12. Once the gel has been fully polymerized, it can be taken out of the mould thus providing a gel layer 12 having a substantially uniform thickness and being provided with a sheet 13 of a thin and deformable plastic material, as shown in figure 7. During the following step this gel layer 12 is placed into the final mould 14, having a cavity 24 the shape of which corresponds to the final shape of the seat to be provided. The gel layer is held in its place by a frame 15 which is tightened around the edge of the plastic sheet 13, preferably at a certain distance from the cavity 24, to facilitate the subsequent deformation of the gel layer 12, said deformation being always carried out by drawing air in from the mould bottom so that the air pressure on the upper surface leads the layer 12 to fit exactly in with the surface of the mould bottom. The fact that the layer 12 is larger than the mould 14 causes gel to be placed also along the mould side edges, so that the foam layer which is later injected is completely held inside gel. During the following process step the mould is closed by a head cup 16 to which a stiffening shell 17 is applied and the foam material 18 is subsequently injected. Once the layer 18 has hardened the mould can be opened and the finished product 19 of figure 10 is provided, said product having an even gel layer on the whole of its upper surface and its side edges. Thus, as stated above, a seat top is provided having a gel coating which covers the whole seat top and edge, wherein this gel has a uniform thickness and, thence, also the seat colour on the whole of the seat surface is uniform. Instead of gel, viscoelastic materials, thermoplastic materials or the like can be used. Those skilled in the art can then provide several modifications and variations, all of which, however, fall within the scope of the present invention.

Claims: Method for providing moulded elements having a viscoelastic or thermoplastic coating layer constituted by a gel coating layer (12), characterised in that it comprises the following steps: placing said gel coating layer (12) of a first uniformly thickness into a first mould (10), said first mould (10) having a surface which is larger than the surface of the moulded element to be provided; when polymerisation of the gel has been fully carried out, removing said gel coating layer (12) of a first uniformly thickness; placing said gel coating layer (12) of a first uniformly thickness into a second mould (14) having a surface which corresponds to the surface of the moulded element to be provided; deforming said gel coating layer (12), so that the gel coating layer (12) perfectly fits in with the shape of said second mould (14); closing said second mould (14) by means of a head cup (16); injecting a filling foam material (18) in the gap between said gel coating layer (12) and said head cup (16) . Method for providing moulded elements as claimed in claim 1, characterised in that said first mould (10) has a uniformly deep cavity (11), in which said gel coating layer (12) is placed. Method for providing moulded elements as claimed in claim 1, characterised in that , after having placed the gel coating layer (12) into said first mould (10), a thin plastic film (13) is applied to said gel coating layer (12). Method for providing moulded elements as claimed in claim 3, characterised in that , after having placed said gel coating layer (12) into said second mould (14), said plastic film (13) is fastened along its edges at a prefixed distance from the edge of the second mould (14) . Method for providing moulded elements as claimed in claim 1, characterised in that said deformation of the gel coating layer (12) is carried out by drawing air from the bottom of said second mould (14). Method for providing moulded elements as claimed in claim 1, characterised in that a stiffening shell (17) is applied to said head cup (16) of the second mould (14) . Moulded elements such as seat tops or the like having a gel coating layer (12) and being provided by the method according to claim 1.

Inventors: PROMPICAI GIOVANNI GIOSUE, PROMPICAI, GIOVANNI GIOSUE, Prompicai, Giovanni Giosuè
Applicants: DINICTA S R L, DINICTA S.R.L.
Application year: 2000
Main classification: B29C44
IPC codes: A47C27, B29C44, A47C7