Moulding tray for manufacturing slabs made of agglomerate material, method for realizing such moulding tray and method for manufacturing slabs made of agglomerate material

1 . A moulding tray for manufacturing slabs made of agglomerate material from a mix, the tray comprising a base portion;

wherein the base portion comprises at least one surface layer made of elastomeric material and at least one fabric layer;

wherein said moulding tray comprises a rim portion made of elastomeric material and designed to delimit together with said base portion a cavity for containing the mix, the elastomeric material of the rim portion and the elastomeric material of the at least one surface layer of the base portion comprising a filler containing silicon; and

characterized in that said at least one surface layer of the base portion and said rim portion are independent parts of the moulding tray and that the elastomeric material of the rim portion and the elastomeric material of the at least one surface layer of the base portion are chosen from the group comprising ethylene-propylene rubbers (EPM) and ethylene-propylene-diene monomer rubbers (EPDM).

2 . The tray according to claim 1 , characterized in that said filler is silica (SiO 2 ).

3 . The tray according to claim 2 , characterized in that said filler is pyrogenic silica.

4 . The tray according to claim 2 , characterized in that said filler is silica obtained from rice husk.

5 . The tray according to claim 1 , characterized in that said base portion comprises at least one pair of layers of elastomeric material arranged in between at least one pair of fabric layers.

6 . The tray according to claim 1 , characterized in that said rim portion and the at least one surface layer of said base portion are made of the same elastomeric material.

7 . The tray according to claim 1 , characterized in that the ethylene-propylene rubbers (EPM) or ethylene-propylene-diene monomer rubbers (EPDM) are obtained from renewable plant sources.

8 . The tray according to claim 1 , characterized in that the at least one surface layer of elastomeric material of said base portion forms the bottom of said cavity, said rim portion being joined at its base to the fabric layer situated immediately underneath said at least one surface layer of elastomeric material which forms the bottom of the cavity.

9 . A method for realizing a moulding tray for manufacturing slabs of agglomerate material from a mix according to claim 1 , the method comprising the following steps:

(a) providing a mould comprising a peripheral shaped cavity;

(b) positioning said mould in a press comprising a bottom surface and a top surface, at least one of said surfaces being movable along a vertical direction, one or both said surfaces being heated;

(c) distributing a compound of raw elastomeric material inside the cavity of said mould;

(d) positioning a flexible sandwich above said mould and said compound, said flexible sandwich comprising at least one layer of raw elastomeric material and at least one fabric layer;

(e) moving the movable surface so as to obtain a closed position of the press;

(f) pressing and heating with consequent vulcanization of the raw elastomeric materials of the compound and of the at least one layer of said flexible sandwich;

wherein the raw elastomeric material compound is intended to form the rim portion of said tray and the flexible sandwich is intended to form the base portion of said tray;

characterized in that the raw elastomeric materials of said compound and of the at least one layer of the flexible sandwich comprise a filler containing silicon, that said at least one surface layer of the base portion and the rim portion are independent parts of the moulding tray, and that the elastomeric material of the rim portion and the elastomeric material of the at least one surface layer of the base portion are chosen from the group comprising ethylene-propylene rubbers (EPM) and ethylene-propylene-diene monomer rubbers (EPDM).

10 . The method according to claim 9 , characterized in that said filler is silica (SiO 2 ).

11 . The method according to claim 10 , characterized in that said filler is pyrogenic silica.

12 . The method according to claim 10 , characterized in that said filler is silica obtained from rice husk.

13 . The method according to claim 9 , characterized in that the pressing and heating step (f) is performed in a vacuum environment in order to prevent air bubbles from remaining trapped on the surfaces, between the surfaces of the mould and the compound and between the compound and the flexible sandwich.

14 . The method according to claim 13 , comprising an initial step of arranging and fixing a mould-holder element on the bottom surface of said press, said mould being fixed onto said mould-holder element and said mould-holder element being suitable for creating a vacuum pressing environment before and during said pressing step (f).

15 . The method according to claim 14 , characterized in that said mould-holder element comprises at least one air suction duct intended to be connected to air suction means.

16 . The method according to claim 15 , characterized in that said mould-holder element comprises a frame movable along a vertical direction.

17 . The method according to claim 16 , characterized in that in said closed position said top surface, said mould-holder element and said frame delimit a closed chamber and in that a suction step is envisaged for drawing off the air through the at least one air suction duct in order to create the vacuum inside said chamber before and during the pressing step.

18 . The method according to claim 17 , characterized in that said frame comprises at least one upper seal and said mould-holder element comprises a lateral seal for sealing off the vacuum inside said chamber during said pressing step (f).

19 . The method according to claim 9 , characterized in that said flexible sandwich comprises at least one pair of layers of raw elastomeric material arranged between at least one pair of fabric layers.

20 . The method according to claim 19 , characterized in that said flexible sandwich is positioned in said press with said layer of raw elastomeric material directed towards said mould, there being provided a step for removal of the elastomeric material from said layer in the area intended to come into contact with the elastomeric material compound during the pressing step.

21 . A method for manufacturing slabs of agglomerate material comprising in succession the following steps:

preparing a mix by mixing together granules of stone or stone-like material which have a predetermined particle size with a binder consisting of an organic resin;

distributing said mix on a tray so as to form a layer of mix;

moulding and compacting the mix by means of vacuum compression of the mix in order to obtain a compacted slab;

dielectric preheating of the compacted slab by means of application of electromagnetic radiofrequency waves with a frequency of less than 300 MHz;

heating the compacted slab so as to allow hardening of the mix and catalysis of the organic resin;

characterized in that the tray is of the type according to claim 1 .