WO2020008486A1

WO2020008486A1 - Method for producing a composite article and composite article obtained thereby

Info

Publication number: WO2020008486A1
Application number: PCT/IT2019/050150
Authority: WO
Inventors: Sergio Battista GASTALDI
Original assignee: Persico S.P.A.
Priority date: 2018-07-03
Filing date: 2019-06-20
Publication date: 2020-01-09
Also published as: IT201800006881A1

Abstract

Composite product and process for the production of a composite product (1), the composite product (1) comprising a core (2), a first layer (3) comprising a sheet impregnated by a polymeric solid material and an insert (10; 11; 12) having a first portion (13) inserted in the first layer (3) and in the core (2), and a second portion (14) protruding from the first layer (3), wherein the process comprises producing a semi-finished product comprising the core (2) and the sheet impregnated by a liquid mixture precursor of the polymeric material, forming the semi-finished product by closing it with pressure between two half-moulds, wherein a first (20) half-mould comprises a housing cavity (34) in which it is inserted the second portion (14) of the insert (10; 11), so that the first portion (14) of the insert (10; 11) penetrates into the semi-finished product, thermosetting the liquid mixture to transform it into the polymeric material, wherein a sealing barrier (39) is interposed between the insert (10; 11) and the first half-mould (20) to prevent the liquid mixture from flowing from the semi-finished product towards the housing cavity (34).

Description

METHOD FOR PRODUCING A COMPOSITE ARTICLE AND COMPOSITE ARTICLE OBTAINED THEREBY

Technical field of the invention

The present invention relates to a process for the production of a composite product comprising at least one insert and a relative composite product comprising at least one insert.

State of the art

It is known to produce composite products, such as typically sandwich panels, comprising a core, typically in honeycomb cardboard or in solid foams, and an upper layer and a lower layer, of reduced thickness, arranged at opposite faces of the core. Each layer is composed of a sheet of fiberglass impregnated with a polyurethane material that partially penetrates the core, to fix the whole.

The structure thus composed has a considerably better static behaviour than the individual parts from which it is made. The lower and upper layers perform the function of distributing the loads in the plane, while the core, which occupies almost the entire thickness, performs the function of increasing the flexural and torsional stiffness of the panel, which depends on the distance of the layers from the middle plane, all against a reduced overall weight.

Such composite panels are widely used, for example for sports equipment such as skis or snowboards, or in the automotive sector, for example to make load decks, hatboxes, containers bottoms, etc.

For the production of the sandwich panels typically a panel semi-finished product is first made by assembling the core and the two fiberglass sheets, and by spraying the sheets to impregnate them with a liquid precursor mixture of the polyurethane material (e.g. a mixture of polyol and isocyanate). The semi-finished product is then subjected to a hot compression moulding process (for example at 130-140°C in the case of polyurethane), in which it is used a mould composed by two half-moulds which are pushed against each other with the interposition of the semi-finished product. In this way the semi-finished product is formed, by conformation of the surfaces and cutting of its contour, and furthermore the liquid mixture crosslinks to make the solid polyurethane material which fixes the final form of the sandwich panel.

In some applications the composite products are equipped with inserts to give the product appropriate functionality, for example to allow the fixing of the product (rigidly or with relative degrees of freedom) to other structures, or to allow the securing of other elements to the product. For example, in the case of car loading decks, the sandwich panel is equipped with two inserts that make a rotation hinge of the panel with respect to the car frame.

Such inserts are usually fixed to the composite product by means of screws or other similar fixing means.

Summary of the invention

The Applicant has realized that the known process for the production of a composite product provided with at least one insert, and the relative known composite products, have some drawbacks and/or can be improved under one or more aspects.

The Applicant has observed that the fixing of the inserts on the composite products by screws or the like entails an increase in the production costs and/or times, due to the cost of the fixing means themselves and to the time necessary for the arrangement and tightening of the fixing means.

Furthermore, the Applicant has observed that the presence of the fixing means requires an oversizing of the inserts themselves, which must offer sufficient material to the fixing means to support the fixing itself. Furthermore, the fixing means must not encumber the space useful to the functionality required by the inserts. All this entails a further increase in the costs of the inserts themselves, as well as greater encumbrances and/or imperfections on the finished product.

The Applicant has therefore faced the problem of developing a process for the production of a composite product comprising an insert, and a relative composite product comprising an insert, which requires reduced times and/or costs and which allows the use of inserts of reduced dimensions and/or weight, while ensuring the strength of the fixing of the insert to the composite product.

According to the Applicant the problem of realizing one or more of these objects is solved by a process for the production of a composite product comprising an insert, and a relative composite product comprising an insert, according to the attached claims and/or having the following features.

According to an aspect the invention relates to a process for the production of a composite product.

The composite product (when finished) comprises a core, at least a first layer at a first face of the core, the first layer comprising a sheet impregnated by a polymeric solid material, and an insert comprising a first portion inserted in the first layer and in the core, and a second portion protruding from the first layer.

Preferably the process comprises:

- producing a semi-finished product comprising said core and, at the first face, said sheet impregnated by a liquid mixture precursor of said polymeric material;

- providing a mould comprising two half-moulds, wherein a first of said half-moulds comprises a housing cavity counter-shaped to the second portion of the insert;

- inserting the second portion of the insert into the housing cavity;

- forming the semi-finished product by closing said semi-finished product between said two half-moulds pressed against each other, so that said first portion of the insert penetrates into said sheet and into said core of the semi-finished product;

- with the semi-finished product in the mould, thermosetting said liquid mixture to transform it into said polymeric material and thus producing the composite product, wherein during forming and thermosetting a sealing barrier is interposed between the insert and said first half-mould to prevent the liquid mixture from flowing from the semi- finished product towards the housing cavity.

According to a further aspect the invention relates to a composite product comprising a core, at least a first layer at a first face of the core, the first layer comprising a sheet impregnated by polymeric solid material, and an insert comprising a first portion inserted in the first layer and in the core and at least partially encapsulated in said polymeric material, and a second portion protruding from the first layer.

According to the Applicant, the presence of the housing cavity in the mould and of the sealing barrier allows the application of the insert directly during the moulding step of the semi-finished product (comprising forming and thermosetting), without the use of any fixing means, at the same time avoiding that the mixture (when still in the fluid state) invades the housing cavity flowing from the semi-finished product. If this mixture flow occurs, part of the mixture or of the resulting polymeric material would be at the second portion of the insert, instead of to completely occupy the interstices around the first portion. In this way the first portion may not be sufficiently encapsulated by the polymeric solid material, with consequent loss of firmness of the fixing of the insert. In other words, the sealing barrier helps to direct the liquid mixture towards the interstices around the first portion of the insert, in order to occupy them sufficiently or substantially completely.

Furthermore, the mixture or the polymeric solid material flowed outside the semi- finished product may cause the insert to stick to the housing cavity, making the extraction difficult, or it may require a cleaning of the housing cavity before a subsequent use, or a cleaning of the second portion of the insert, under penalty of imperfections and/or of loss of functionality.

The present invention in one or more of the aforesaid aspects can have one or more of the following preferred features.

In one embodiment said sealing barrier is fixed to the insert, for example integral with the insert (i.e. in single piece). In this way the mould is structurally simple.

In a preferred embodiment said sealing barrier is fixed to the first half-mould. In this way the insert is free from constraints deriving from the barrier.

Preferably said sealing barrier is elastically deformable, for example it is made of elastomeric material or of elastic polymer. In this way it is favoured the tightness. Preferably said sealing barrier is a gasket, as for example an O-ring.

Preferably said sealing barrier has continuous annular shape and during forming and thermosetting surrounds said insert. In this way the sealing effect is efficient.

Preferably said first half-mould or said insert comprises a housing groove at least partially counter-shaped to the sealing barrier, wherein during forming and thermosetting said sealing barrier is inserted in said housing groove. In this way it is maintained the barrier in position during the moulding. Preferably a housing section of said housing groove is smaller than a section of the sealing barrier. In this way part of the barrier protrudes from the groove, interposing between mould and insert.

Preferably said housing groove has a width at a free surface of said first half-mould or, respectively, of said insert, smaller than a maximum width along a depth of the housing groove. In this way it is avoided the exit of the barrier when the half-moulds are separated.

Preferably said first half-mould comprises said housing groove. Preferably said housing groove extends at a free surface of the first half-mould along a closed path around said housing cavity.

In one alternative embodiment, said insert comprises said housing groove.

Preferably said first half-mould comprises at a free surface thereof a connecting groove which connects said housing groove with said housing cavity. Preferably a section of said connecting groove is equal to a housing section of said housing groove. In this way it is possible to obtain the housing groove by milling, inserting the tip of the cutter in the cavity with an axial movement and then moving orthogonally the tip of the cutter to obtain said connecting groove. Once in position, the tip of the cutter can complete the closed path and exit again from the connecting groove.

Preferably said insert is in single piece. Preferably said insert is made of rigid material, such as a polymeric material.

Preferably said first portion of the insert comprises a surface plate placed, in the composite product, at said first layer of the composite product.

Preferably said first portion of the insert comprises an end plate, in distal position with respect to said second portion of the insert, and a connecting portion between the end plate and the surface plate, having a section smaller than a section of said end plate and of said surface plate. In this way it is defined a space around the connecting section between the two plates which, once filled by the polymeric material, opposes a resistance to the extraction stresses of the end plate.

In one embodiment said second portion of the insert comprises a C-shaped wall. In this way the insert lends itself to a hinged coupling.

Preferably said second portion of the insert comprises at least one seat, more preferably a plurality of seats at least two of which placed on opposite sides of the second portion. In this way the insert can be retained in the housing cavity by gripping on said seats, which do not have a function in the finished product.

Preferably said plurality of seats comprises at least three seats, and more preferably no more than three seats (for maintaining the insert aligned).

Preferably said seats have a spherical cap shape (in this way it is possible to use a respective bead for retaining the insert).

Preferably said first half-mould comprises a retaining system of the insert arranged inside the housing cavity and structured to retain the insert inside said housing cavity. In this way the insert does not exit from the first half-mold and moreover the retaining system does not interfere with the conformation surface of the mould.

Preferably the retaining system comprises for each seat of the insert a respective retaining element (for example a bead) counter-shaped to the seat, and a thrust element (for example a spring) to keep the retaining element pushed against the seat. In this way the insert is retained in the housing cavity in a particularly effective and simple way. In particular, when the second portion of the insert is a C-shaped wall, the presence of the seats of the respective retaining element make up the necessity of using a pin removably inserted into the inner space of the C, which would make more complex and expensive the mould.

Preferably said first half-mould comprises a body having a conformation surface of the composite product and a cutting blade system.

Preferably said first half-mould comprises an insert-holder element comprising said housing cavity and/or said sealing barrier and/or said housing groove and/or said connecting groove and/or said free surface and/or said retaining system. Preferably said insert-holder element is removably fixed to a body of the first half-mould, for example by means of screws. In this way it is simplified the production of the first half- mould, which is versatile as the type of the inserts varies.

Typically said composite product (when finished) comprises a second layer at a second face of the core opposite to the first face, the second layer comprising a respective sheet impregnated by said polymeric solid material. In this way it is enhanced the mechanical resistance of the product.

Preferably said core and/or said first and/or second layer have substantially laminar extension.

Preferably said sheet is made of glass fibre, or carbon fibre or Kevlar fibre, or natural fibres, more preferably of glass fibre (advantageously economic).

Preferably said core comprises (or consists of) a honeycomb paperboard or a solid foam (with open or closed cells), more preferably a honeycomb cardboard having cells with development perpendicular to said first face of the core.

Preferably said polymeric solid material is a polyurethane material, more preferably based on diphenylmethane diisocyanate (MDI), even more preferably 4-4’- diphenylmethane diisocyanate (4-4’-MDI), also known as rigid polyurethane foam. Preferably said liquid mixture is a mixture of polyol and isocyanate, more preferably MDI, even more preferably 4-4’-MDI (for its wide availability and economy).

Preferably producing said semi-finished product comprises spraying said sheet with said liquid mixture.

Preferably an amount of said liquid mixture in a portion of the sheet corresponding to the position of said insert in the composite product, is greater than an amount in the prevailing part of the rest of the sheet. In this way the excess mixture will encapsulate the first end of the insert, firmly fixing it in the finished product.

Preferably during forming and thermosetting said sealing barrier is located near a perimetral edge of a free face of said insert facing said first half-mould. In this way the action of conveying the liquid mixture towards the first portion of the insert is particularly effective.

Preferably forming the semi-finished product comprises cutting said semi-finished product at least along a contour line, more preferably by means of said cutting blade system

Preferably thermosetting the liquid mixture comprises keeping the semi-finished product inside the mould at a given temperature, more preferably greater than or equal to 120°, even more preferably greater than or equal to 130°, for a given time interval. Brief description of the drawings

The features and advantages of the present invention will be further clarified by the following detailed description of some embodiments, presented by way of non-limiting example of the present invention, with reference to the attached figures, in which: figure 1 shows a perspective view of a composite product according to an embodiment of the present invention;

figure 2 shows in a schematic form and not to scale a partial section of the composite product of figure 1 ;

figures 3a and 3b show two perspective views of an insert of the composite product of figure 1 ;

figure 4 shows a schematic and partial perspective view of a half-mould according to the present invention

figure 5 shows a perspective view of an insert-holder element of the half-mould of figure

4;

figure 6 shows an exploded view of the insert-holder element of figure 5;

figure 7 shows a central section view along the plane A of the insert-holder element of figure 5;

figure 8 shows a perspective view of a further insert-holder element of the half-mould of figure 4;

figure 9 shows a central section view of the insert-holder element of figure 8.

Detailed description of some embodiments of the invention

In figure 1 with the reference number 1 it is shown a finished composite product according to the present invention. Exemplarily, the shown composite product 1 is a load deck of a car trunk.

The composite product 1 exemplarily comprises, at a lower face (visible in figure 1 ), a pair of first inserts 10 equal and aligned to each other, a second insert 1 1 and a third insert 12.

Each insert 10, 1 1 and 12 is rigid and in single piece, typically made of polymeric material.

Exemplarily the first inserts 10 serve to hook the load deck to a pair of pins integral with the rest of the car (not shown), obtaining two hinge couplings to allow the rotation (lifting) of the load deck.

Exemplarily the second insert 1 1 serves to hook the load deck to the rest of the car with a snap coupling. Exemplarily the third insert 12, comprising a pair of holes, serves to ensure the correct positioning of the load deck in the hooked position.

Exemplarily the composite product 1 is of the sandwich panel type.

As schematically shown in figure 2, the composite product 1 comprises a core 2, a first layer 3 at a first face 4 of the core 2 and a second layer 5 at a second face 6 of the core opposite to the first face 4. The core 2 and the layers 3 and 5 have a laminar extension. The first and second layers 3, 5 are made (not shown) of a respective glass fibre sheet impregnated with a polyurethane solid material, which in figure 2 is schematically represented by the dots. Exemplarily the thickness of the undeformed layers 3 and 5 is equal to about 0.3-0.4 mm, while the thickness of the undeformed core 2 is equal to about 12-20 mm. In figure 2 the thicknesses of the first and second layer 3, 5 have been deliberately exaggerated to improve visibility.

Preferably the core 2 consist of a honeycomb cardboard in which the cells (not shown) are formed by walls with development substantially perpendicular to the first and second faces of the core. Although not shown, the solid polyurethane material typically partially invades also the internal space of the cells near to the first and second faces 4, 5, to firmly fix the first and second layers 3 and 5 to the core 2.

Each insert 10, 1 1 and 12 comprises (shown only for the first insert 10) a first portion 13 completely inserted in the first layer 3 and in the core 2 and encapsulated by the polyurethane material, and a second portion 14 protruding from the first layer 3.

Preferably the first portion 13 of each insert 10, 1 1 and 12 comprises a surface plate 15 placed, in the composite product, at the first layer 3, an end plate 16, distal to the second portion 14 of the insert, and a connecting portion 17 between the end plate and the surface plate, having smaller section than the section of the two plates 15 and 16 to delimit a space 46 interposed between the two plates.

The second portion 14 of the first insert 10 comprises a C-shaped wall 18, for hooking to a respective pin.

Exemplarily the second portion 14 of the first insert 10 comprises three seats 19, with spherical cap shape, arranged one on one side and two on the opposite side of the second portion 14.

Figure 4 shows exemplarily a portion of a first half-mould 20 of a mould used in the process of the present invention. The rest of the mould, including the other half-mould with the respective conformation surface, the thermostatting circuits, etc., is not shown since for example of a known type.

Preferably the first half-mould 20 comprises a body 21 having a conformation surface 22 for conforming the composite product, counter-shaped to the lower face of the composite product from which the inserts 10, 1 1 and 12 protrude, and a cutting blade system 60 for cutting the contour of the panel 1 .

Preferably the first half-mould 20 comprises a respective first insert-holder element 30 for each first insert 10 of the finished product, a second insert-holder element 31 for the second insert 1 1 and a third insert-holder element 32 for the third insert 12.

Each insert-holder element 30, 31 and 32 comprises a main body 45 removably fixed to the body 21 of the first half-mould, for example by means of screws 33 passing through respective holes in the main body 45.

One or more of the insert-holder elements (in the example the insert-holder elements 30 and 31 ) comprises a housing cavity 34 counter-shaped to the second portion 14 of the respective insert and formed in the respective main body 45.

Each insert-holder element 30, 31 and 32 comprises a housing groove 35 formed on a free surface 36 of the main body 45 and which develops along a closed path, exemplarily a circle, around the respective housing cavity 34. Preferably the housing groove 35 has a width I at the free surface 36 of the main body 45 smaller than the maximum width L along the depth of the housing groove 35.

Preferably, a connecting groove 37 is formed on the free surface 36 of the main body 45 and connects the housing groove 35 with the housing cavity 34. Preferably the orthogonal section of the connecting groove 37 (visible in particular in figures 7 and 9) is equal to the orthogonal section (i.e. the housing section) of the housing groove 35, since the grooves are made by milling with the same cutter tip, which enters exploiting the housing cavity 34 as explained above.

Each insert-holder element 30, 31 and 32 comprises a sealing barrier 39 housed in the housing groove 35.

Preferably the sealing barrier 39 is a gasket, for example an O-ring made of elastomeric material, as exemplarily shown in the figures.

Preferably the housing groove 35 has a housing section smaller than the section of the sealing barrier (for example the depth d is smaller than the diameter D of the gasket). Preferably each insert-holder element 30, 31 and 32 comprises a retaining system 40 for retaining the insert arranged inside the housing cavity 34 and structured to hold the respective insert 10, 1 1 and 12 inside the housing cavity. Preferably the retaining system 40 of each first insert-holder element 30 comprises for each seat 19 of the first insert 10 a respective retaining element 41 (for example a small bead housed in a suitable cavity 43 formed in the main body 45) counter-shaped to the seat 19 of the insert, and a thrust element 42 (for example a spring housed in the aforementioned cavity 43) to keep the retaining element pushed against the seat 19. The cavity 43 has an outlet mouth at the bead of smaller dimension than the bead 41 for making a stroke end for the retaining element 41 , when decoupled from the respective seat 19.

An exemplary process for the production of a composite product 1 according to the present invention comprises, first of all, producing a semi-finished product (not shown) by placing on the first and second face 4, 6 of the core 2 a respective glass fibre sheet and spraying the glass fibre sheets, up to completely impregnate them, with a liquid mixture of polyol and isocyanate, for example of the Elastoflex^® series marketed by BASF^® or of the Baypreg^® series marketed by Covestro^®. The process preferably provides spraying a greater quantity of mixture in the points of the semi-finished product at which the inserts 10, 1 1 and 12 will be located in the finished product, for example through additional passages under the spraying head.

Preliminarily the inserts 10, 1 1 and 12 are inserted with their second portions 14 in the respective housing cavity 34 of the first half-mould 20, which is exemplarily the upper half-mold. Thanks to the retaining system 40, the inserts do not fall out from the housing cavities. For this purpose, a recess 29 on the end plate 16 favours the correct positioning of the insert. The aforesaid semi-finished product is then formed by means of the mould.

For this purpose, the semi-finished product is closed between the two half-moulds pressed one against the other, so that thanks to the pressure of the two half-moulds the conformation surfaces of the two half-moulds conform the respective faces of the panel 1 and the first portion 13 of the insert penetrates in the glass fibre sheet and in the core. Typically, as schematically shown in figure 2 for illustrative purposes only, the first portion 13 of the insert, more precisely mainly the end plate 16, tends to penetrate the glass fibre sheet, pulping and crumbling it, and to crush the core 2 reducing its thickness. The space 46 which is placed between the two plates 15 and 16 and possibly the space 47 which is created following the crushing of the core 2 is occupied by the liquid mixture (which was sprayed in abundance in this position), thanks also to the interposition of the sealing barrier 39 (shown exemplarily in dashed lines in figure 2) which helps to convey the mixture towards the spaces 36 and 37. For this purpose, during forming and thermosetting the sealing barrier 39 is (as schematically shown in dashed lines in figure 2) near the perimetral edge 44 of the free face 38 of the insert facing to the first half-mould (more specifically, the free face 38 is faced towards the free surface 36 of the insert-holder element).

During forming the cutting blade system 60 of the half-shell cuts the semi-finished product along the contour line, and exemplarily also along a closed path to form an opening for the application of a handle on the finished load deck.

Exemplarily the pressure exerted on the two half-moulds is approximately 300 tons, largely due to the cutting action.

Subsequently, the semi-finished product is kept in the mould thermostated at a temperature of about 140°C for a given time interval, for example one minute, in order to thermoset the liquid mixture to transform it into the polyurethane solid material and thus make the composite product 1. The mixture which is located in the spaces 46 and 47, once hardened to form the polyurethane material, firmly fixes the insert 10, 11 and 12 to the panel structure.

Claims

1 . Process for the production of a composite product (1 ), the composite product (1 ) comprising a core (2), at least a first layer (3) at a first face (4) of the core (2), and an insert (10; 1 1 ; 12) comprising a first portion (13) inserted in the first layer (3) and in the core (2), and a second portion (14) protruding from the first layer (3), wherein the first layer (3) comprises a sheet impregnated by a polymeric solid material,

wherein the process comprises:

- producing a semi-finished product comprising said core (2) and, at the first face (4), said sheet impregnated by a liquid mixture precursor of said polymeric material;

- providing a mould comprising two half-moulds, wherein a first (20) of said half-moulds comprises a housing cavity (34) counter-shaped to the second portion (14) of the insert (10; 1 1 );

- inserting the second portion (14) of the insert (10; 1 1 ) into the housing cavity (34);

- forming the semi-finished product by closing said semi-finished product between said two half-moulds pressed against each other, so that said first portion (14) of the insert (10; 1 1 ) penetrates into said sheet and into said core (2) of the semi-finished product;

- with the semi-finished product in the mould, thermosetting said liquid mixture to transform it into said polymeric material and thus producing the composite product (1 ), wherein during forming and thermosetting a sealing barrier (39) is interposed between the insert (10; 1 1 ) and said first half-mould (20) to prevent the liquid mixture from flowing from the semi-finished product towards the housing cavity (34).

2. Process according to claim 1 , wherein said sealing barrier (39) is an elastically deformable seal, wherein said sealing barrier (39) has a continuous annular shape and during forming and thermosetting surrounds said insert (10; 1 1 ), wherein said first half- mould (20) or said insert (10; 1 1 ) comprises a housing groove (35) at least partially counter-shaped to the sealing barrier (39), wherein during said forming and thermosetting said sealing barrier (39) is inserted in said housing groove (35), wherein a housing section of said housing groove (35) is smaller than a section of the sealing barrier (39) and wherein said housing groove (35) has a width (I) at a free surface (36) of said first half-mould (20) or, respectively, of said insert (10; 1 1 ), smaller than a maximum width (L) along a depth of the housing groove (35).

3. Process according to claim 2, wherein said first half-mould (20) comprises said housing groove (35), wherein said housing groove (35) extends at a free surface (36) of the first half-mould (20) along a closed path around said housing cavity (34) and wherein said first half-mould (20) comprises at said free surface (36) a connecting groove (37) which connects said housing groove (35) with said housing cavity (34), wherein a section of said connecting groove (37) is equal to a housing section of said housing groove (35).

4. Process according to any one of the previous claims, wherein said insert (10; 1 1 ; 12) is in single piece and made of rigid material, wherein said first portion (13) of the insert (10; 1 1 ; 12) comprises a surface plate (15) placed, in the composite product (1 ), at said first layer (3), wherein said first portion (13) of the insert comprises an end plate (16), distal to said second portion (14) of the insert (10; 1 1 ; 12), and a connecting portion (17) connecting the end plate (16) to the surface plate (15) and having a section smaller than a section of said end plate (16) and of said surface plate (15).

5. Process according to any one of the previous claims, wherein said second portion (14) of the insert (10) comprises a C-shaped wall, wherein said second portion (14) of the insert (10) comprises a plurality of seats (19) at least two of which placed on opposite sides of the second portion (14), preferably said plurality of seats (19) comprises at least three seats, and wherein said seats (19) have a spherical cap shape.

6. Process according to any one of the previous claims, wherein said first half-mould (20) comprises a retaining system (40) of the insert arranged inside the housing cavity (34) and structured to retain the insert (10; 1 1 ) inside said housing cavity (34), and wherein the retaining system (40) comprises for each seat (19) of the insert (10) a respective retaining element (41 ) counter-shaped to the seat (19), and a thrust element (42) to keep the retaining element (41 ) pushed against the seat (19).

7. Process according to any one of the previous claims, wherein said first half-mould (20) comprises a body (21 ) having a conformation surface (22) of the composite product and a cutting blade system (60), wherein said first half-mould (20) comprises an insert-holder element (30; 31 ; 32) comprising said housing cavity (34) and/or said sealing barrier (39) and/or said housing groove (35) and/or said connecting groove (37) and/or said retaining system (40) and/or said free surface (36), and wherein said insert-holder element (30; 31 ; 32) is removably fixed to a body (21 ) of the first half- mould (20).

8. Process according to any one of the previous claims, wherein said composite product (1 ) comprises a second layer (5) at a second face (6) of the core opposite to the first face (4), the second layer (5) comprising a respective sheet impregnated by said polymeric solid material, wherein said core and/or said first and/or second layer have substantially laminar extension, wherein said sheet is made of glass fibre, or carbon fibre or Kevlar fibre, or natural fibres, wherein said core comprises a honeycomb cardboard or a solid foam, wherein said polymeric solid material is a polyurethane material, and wherein said liquid mixture is a mixture of polyol and isocyanate, preferably diphenylmethane diisocyanate (MDI).

9. Process according to any one of the previous claims, wherein an amount of said liquid mixture in a portion of the sheet corresponding to the position of said insert (10;

11 ; 12) in the composite product (1 ), is greater than an amount in the prevailing part of the rest of the sheet.

10. Process according to any one of the previous claims, wherein during forming and thermosetting said sealing barrier (39) is located near a perimetral edge (44) of a free face (38) of said insert (10; 11 ; 12) facing said first half-mould (20).

11. Process according to any one of the previous claims, wherein producing said semi- finished product comprises spraying said sheet with said liquid mixture, wherein forming the semi-finished product comprises cutting said semi-finished product at least along a contour line and wherein thermosetting the liquid mixture comprises keeping the semi-finished product inside the mould at a given temperature, preferably greater than or equal to 120°, for a given time interval.

12. Composite product (1 ) comprising a core (2), at least a first layer (3) at a first face (4) of the core (2), the first layer (3) comprising a sheet impregnated by polymeric solid material, and an insert (10; 11 ; 12) comprising a first portion (13) inserted in the first layer (3) and in the core (2) and at least partially encapsulated in said polymeric material, and a second portion (14) protruding from the first layer (3).