IT201800006881A1 - PROCESS OF PRODUCTION OF A COMPOSITE PRODUCT AND RELATED COMPOSITE PRODUCT - Google Patents

Description

DESCRIPTION

Title: PRODUCTION PROCESS OF A COMPOSITE PRODUCT E

ITS COMPOSITE PRODUCT

Technical field of the invention

The present invention relates to a production process 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 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 glass fiber impregnated with a polyurethane material that partially penetrates the core as well, to fix everything.

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

These composite panels are widely used, for example for sports equipment such as skis or snowboards, or in the automotive sector, for example to create loading floors, overhead racks, box bottoms, etc.

For the realization of sandwich panels, a semi-finished product of the panel is typically made first by assembling the core and the two sheets of glass fiber, and spraying the sheets to impregnate them with a precursor liquid mixture of the polyurethane material (e.g. a mixture of polyol and isocyanate). The semi-finished product is then subjected to a hot compression molding process (for example at 130-140 ° C in the case of polyurethane), in which a mold is used consisting of two half-molds that are pushed against each other with the interposition of the semi-finished product. In this way, the semi-finished product is formed, by conforming the surfaces and cutting its contour, and also the liquid cross-linking mixture to form the solid polyurethane material which fixes the final shape of the sandwich panel.

In some applications, composite products are equipped with inserts to give the product appropriate functionality, for example to allow the product to be fixed (rigidly or with relative degrees of freedom) to other structures, or to allow the attachment of other elements to the product. For example, in the case of loading floors for cars, the sandwich panel is equipped with two inserts that create 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 fastening means.

Summary of the invention

The Applicant has realized that the known production processes of composite products equipped with at least one insert, and the related known composite products, have some drawbacks and / or can be improved in one or more aspects.

The Applicant has observed that fixing the inserts on composite products with screws or the like entails an increase in production costs and / or times, due to the cost of the fixing means themselves and the time required to arrange and tighten the fixing means. .

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

The Applicant has therefore posed the problem of developing a production process for 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 dimensions and / or reduced weight, while ensuring the strength of fixing the insert to the composite product.

According to the Applicant, the problem of achieving one or more of these objects is solved by a production process of a composite product comprising an insert, and a relative composite product comprising an insert, in accordance with the attached claims and / or having the following characteristics .

According to one aspect, the invention relates to a production process 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 with a solid polymeric 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 includes:

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

- provide a mold comprising two half-molds, where a first of said half-molds comprises a housing cavity counter-shaped to the second portion of the insert;

- insert 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-molds 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 mold, thermosetting said liquid mixture to transform it into said polymeric material and thus produce the composite product,

where, during forming and thermosetting, a tight barrier is interposed between the insert and said first half-mold 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 in correspondence with a first face of the core, the first layer comprising a sheet impregnated with solid polymeric 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 mold and of the seal barrier allows the insert to be applied directly during the molding phase of the semi-finished product (including 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 such a mixture flow occurs, part of the mixture or the resulting polymeric material would be in correspondence with the second portion of the insert, instead of completely occupying the interstices around the first portion. In this way, the first portion may not be sufficiently encapsulated by the solid polymeric material, resulting in a loss of firmness of the insert fixing. In other words, the sealed barrier helps direct the liquid mixture towards the interstices around the first portion of the insert, so as to occupy them sufficiently or substantially completely.

Furthermore, the mixture or solid polymeric material flowed out of the semi-finished product could make the insert adhere to the housing cavity, making it difficult to extract, or it could require a cleaning of the housing cavity before a subsequent use, or a cleaning of the housing cavity. second portion of the insert, under penalty of imperfections and / or loss of functionality.

The present invention in one or more of the above aspects may exhibit one or more of the following preferred features.

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

In a preferred embodiment, said seal barrier is fixed to the first half-mold. In this way the insert remains free from constraints deriving from the barrier. Preferably, said sealed barrier is elastically deformable, for example it is made of elastomeric material or elastic polymer. In this way the seal is favored.

Preferably, said seal barrier is a gasket, such as an O's ring. Preferably, said seal barrier has a continuous annular shape and surrounds said insert during forming and thermosetting. In this way the sealing effect is efficient.

Preferably said first half-mold or said insert comprises a housing groove counter-shaped at least partially to the sealing barrier, where during forming and thermosetting said sealing barrier is inserted in said housing groove. In this way the barrier is kept in position during molding. Preferably a housing section of said housing groove is smaller than a section of the sealed barrier. In this way, part of the barrier protrudes from the groove, interposing itself between the mold and the insert. Preferably, said housing groove has a width at a free surface of said first mold half or, respectively, of said insert, smaller than a maximum width along a depth of the housing groove. This prevents the barrier from coming out when the half-molds are separated.

Preferably said first mold half comprises said housing groove. Preferably, said housing groove develops in correspondence with a free surface of the first half-mold along a closed path around said housing cavity.

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

Preferably, said first half-mold comprises at one of its free surfaces 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 make the housing groove by milling, inserting the tip of the cutter into the cavity with an axial movement and then moving the tip of the cutter orthogonally so as to make said connecting groove. Once in position, the tip of the cutter can travel the closed path and come out again from the connection groove.

Preferably, said insert is in a 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 arranged, in the composite product, at said first layer of the composite product.

Preferably said first portion of the insert comprises an end plate, in a 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 said surface plate. In this way, a space is defined around the connecting section between the two plates which, once filled with the polymeric material, resists the extraction efforts 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 are arranged on opposite sides of the second portion. In this way the insert can be retained in the housing cavity by gripping said seats, which do not have a function in the finished product.

Preferably said plurality of seats includes at least three seats, and more preferably no more than three seats (in order to keep the insert aligned).

Preferably, said seats have a spherical cap shape (in this way a respective ball can be used to hold the insert).

Preferably, said first half-mold comprises an insert retention system arranged inside the housing cavity and structured to retain the insert inside said housing cavity. In this way the insert does not come out of the first half of the mold and also the holding system does not interfere with the conformation surface of the mold.

Preferably, the holding system comprises for each seat of the insert a respective holding element (for example a ball) counter-shaped to the seat, and a thrust element (for example a spring) to keep the holding 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 and the respective retaining elements compensates for the need to use a pin inserted removably in the space inside the C, which would make the mold more complex and expensive.

Preferably, said first half-mold comprises a body having a surface for the conformation of the composite product and a system of cutting blades.

Preferably, said first half-mold 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 retention system. Preferably, said insert-holder element is removably fixed to a body of the first mold half, for example by means of screws. This simplifies the production of the first half-mold, which is versatile when the type of insert 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 with said solid polymeric material. In this way the mechanical resistance of the product increases.

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

Preferably said sheet is made of glass, carbon or Kevlar fiber, or natural fibers, more preferably of glass fiber (advantageously cheap).

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 nucleus.

Preferably, said solid polymeric 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 (due to its wide availability and cheapness).

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

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

Preferably, during forming and thermosetting, said seal barrier is located near a perimeter edge of a free face of said insert facing said first half-mold. 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 system of blades. Preferably thermosetting the liquid mixture comprises keeping the semi-finished product inside the mold at a determined temperature, more preferably greater than 120 °, even more preferably greater than or equal to 130 ° C, for a determined time interval.

Brief description of the drawings

The characteristics 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 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-mold according to the present invention

Figure 5 shows a perspective view of an insert-holder element of the half-mold 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-mold of figure 4;

figure 9 shows a central sectional view of the insert-holder element of figure 8. Detailed description of some embodiments of the invention

In Figure 1, the reference number 1 shows a finished composite product according to the present invention. For example, the composite product 1 shown is a loading surface of a trunk of a car.

The composite product 1 by way of example comprises, in correspondence with a lower face (visible in Figure 1), a pair of first inserts 10 which are identical and aligned with each other, a second insert 11 and a third insert 12.

Each insert 10, 11 and 12 is rigid and in a single piece, typically made of polymeric material.

For example, the first inserts 10 are used to hook the loading surface to a pair of pins integral with the rest of the car (not shown), creating two hinged couplings to allow the rotation (lifting) of the loading surface. For example, the second insert 11 serves to hook the loading surface to the rest of the vehicle with a snap hook. For example, the third insert 12, comprising a pair of holes, serves to ensure the correct positioning of the loading surface in the hooking position.

For example, 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 the first face 4. The core 2 and the layers 3 and 5 have a laminar development. The first and second layers 3, 5 consist (not shown) of a respective sheet of glass fiber impregnated with a solid polyurethane material, which in Figure 2 is schematically represented by the dots. For example, 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 layers 3, 5 have been deliberately exaggerated to improve visibility.

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

Each insert 10, 11 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, 11 and 12 comprises a surface plate 15 arranged, in the composite product, in correspondence with the first layer 3, an end plate 16, in a distal position with respect to the second portion 14 of the insert, and a connecting portion 17 between the end plate and the surface plate, having a smaller section than the section of the two plates 15 and 16 so as 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 attachment to a respective pin.

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

Figure 4 shows by way of example a portion of a first half-mold 20 of a mold used in the process of the present invention. The rest of the mold, including the other half-mold with the respective conformation surface, the thermostating circuits, etc., is not shown as for example of a known type.

Preferably, the first half-mold 20 comprises a body 21 having a conformation surface 22 of the composite product, counter-shaped to the lower face of the composite product from which the inserts 10, 11 and 12 protrude, and a system of blades 60 for cutting the contours of the panel 1 .

Preferably, the first half-mold 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 11 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 which is removably fixed to the body 21 of the first half-mold, 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 obtained 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 extends along a closed path, for example a circle, around the respective housing cavity 34. Preferably the groove of housing 35 has a width l 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 the same as the orthogonal section (i.e. the housing section) of the housing groove 35, since the grooves are made by milling with the same milling tip a, which enters by 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 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 seal barrier (for example the depth d is less than the diameter D of the gasket).

Preferably each insert-holder element 30, 31 and 32 comprises a retaining system 40 of the insert arranged inside the housing cavity 34 and structured to retain the respective insert 10, 11 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 ball housed in a suitable cavity 43 obtained 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 thrust against the seat 19. The cavity 43 has an outlet mouth in correspondence with the smaller sphere of the ball 41 to provide a travel stop for the retaining element 41, when uncoupled from the respective seat 19.

An exemplary production process of the composite product 1 according to the present invention comprises first of all producing a semi-finished product (not shown) by arranging on the first and second faces 4, 6 of the core 2 a respective glass fiber sheet and spraying the glass fiber sheets, until they are completely impregnated with a liquid mixture of polyol and isocyanate, for example from the Elastoflex <®> series marketed by BASF <®> or the Baypreg <®> series marketed by Covestro <®>. The process preferably provides for spraying a greater quantity of mixture in the points of the semi-finished product in correspondence with which the inserts 10, 11 and 12 will be found in the finished product, for example by means of additional passages under the spraying head.

Preliminarily, the inserts 10, 11 and 12 are inserted with their second portions 14 into the respective housing cavity 34 of the first mold half 20, which by way of example is the upper mold half. Thanks to the retention system 40, the inserts do not fall out of the housing cavities. To this end, a recess 29 on the end plate 16 favors the correct positioning of the insert.

The aforementioned semi-finished product is then formed by means of the mold.

To this end, the semi-finished product is closed between the two half-molds pressed against each other, so that thanks to the pressure of the two half-molds the conformation surfaces of the two half-molds conform the respective faces of the panel 1 and the first portion 13 of the insert penetrates in the fiberglass sheet and core. Typically, as shown in figure 2 in a schematic way for illustrative purposes only, the first portion 13 of the insert, more precisely mainly the end plate 16, tends to penetrate the fiberglass sheet by breaking it or tearing it and crushing the core. 2 reducing it in thickness. The space 46 which is located 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 has been sprayed in abundance in this position), thanks also to the interposition of the sealing barrier 39 (shown as an example in broken 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 located (as schematically shown in broken lines in figure 2) near the perimeter edge 44 of the free face 38 of the insert facing the first half-mold (more specifically, the free face 38 faces the free surface 36 of the insert-holder element).

During forming, the system of blades 60 of the half-shell cuts the semi-finished product along the contour line, and by way of example also along a closed path to form an opening for the application of a handle on the finished loading surface.

For example, the pressure exerted on the two half-molds is approximately 300 tons, largely due to the cutting action.

Subsequently, the semi-finished product is kept in the thermostated mold at a temperature of about 140 ° C for a certain time interval, for example one minute, in order to thermoset the liquid mixture to transform it into the solid polyurethane material and thus create 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 (12)

CLAIMS 1. Production process 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 a insert (10; 11; 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), where the first layer (3 ) comprises a sheet impregnated with a solid polymeric material, where the process includes: - producing a semi-finished product comprising said core (2) and, in correspondence with the first face (4), said sheet impregnated with a liquid precursor mixture of said polymeric material; - provide a mold comprising two half-molds, where a first (20) of said half-molds includes a housing cavity (34) counter-shaped to the second portion (14) of the insert (10; 11); - insert the second portion (14) of the insert (10; 11) into the housing cavity (34); - form the semi-finished product by closing said semi-finished product between said two half-molds pressed against each other, so that said first portion (14) of the insert (10; 11) penetrates said sheet and said core (2) of the semi-finished product; - with the semi-finished product in the mold, thermosetting said liquid mixture to transform it into said polymeric material and thus obtain the composite product (1), where during forming and thermosetting a tight barrier (39) is interposed between the insert (10; 11) and said first half-mold (20) to prevent the liquid mixture from flowing from the semi-finished product towards the housing cavity (34). Process according to claim 1, where said sealing barrier (39) is an elastically deformable gasket, where said sealing barrier (39) has a continuous annular shape and during forming and thermosetting surrounds said insert (10; 11), where said first half-mold (20) or said insert (10; 11) comprises a housing groove (35) counter-shaped at least partially to the sealing barrier (39), where during forming and thermosetting said sealing barrier (39) is inserted in said housing groove (35), where a housing section of said housing groove (35) is smaller than a section of the sealing barrier (39) and where said housing groove (35) has a width (l) at a free surface (36) of said first mold half (20) or, respectively, of said insert (10; 11), smaller than a maximum width (L) along a depth of the housing groove (35). Process according to claim 2, wherein said first mold half (20) comprises said housing groove (35), where said housing groove (35) extends at a free surface (36) of the first mold half (20) along a closed path around said housing cavity (34) and where said first mold half (20) comprises at said free surface (36) a connecting groove (37) which connects said housing groove (35) with said housing cavity housing (34), where a section of said fitting groove (37) is equal to a housing section of said housing groove (35). 4. Process according to any one of the preceding claims, where said insert (10; 11; 12) is in a single piece and made of rigid material, where said first portion (13) of the insert (10; 11; 12) comprises a surface (15) arranged, in the composite product (1), in correspondence with said first layer (3), where said first portion (13) of the insert comprises an end plate (16), in a distal position with respect to said second portion (14) of the insert (10; 11; 12), and a connecting portion (17) between the end plate (16) and the surface plate (15), having a section smaller than a section of said plate end (16) and of said surface plate (15). Process according to any one of the preceding 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 are arranged on opposite sides of the second portion (14), preferably said plurality of seats (19) comprises at least three seats, and where said seats (19) have a spherical cap shape. Process according to any one of the preceding claims, wherein said first half-mold (20) comprises a retaining system (40) of the insert arranged inside the housing cavity (34) and structured to retain the insert (10; 11) at the 'inside of said housing cavity (34), and where the retention system (40) comprises for each seat (19) of the insert (10) a respective retention element (41) counter-shaped to the seat (19), and a thrust element (42) to keep the holding element (41) thrust against the seat (19). Process according to any one of the preceding claims, wherein said first mold half (20) comprises a body (21) having a conformation surface (22) of the composite product and a system of cutting blades (60), wherein said first mold half ( 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 retention system (40) and / or said free surface (36), and where said insert-holder element (30; 31; 32) is removably fixed to a body (21) of the first half-mold ( 20). Process according to any one of the preceding claims, wherein said composite product (1) comprises a second layer (5) in correspondence with a second face (6) of the core opposite to the first face (4), the second layer (5) comprising a respective sheet impregnated with said solid polymeric material, where said core and / or said first and / or second layer have a substantially laminar development, where said sheet is made of glass, carbon or Kevlar fiber, or natural fibers, where said core comprises a honeycomb cardboard or a solid foam, where said solid polymeric material is a polyurethane material, and where said liquid mixture is a mixture of polyol and isocyanate, preferably diphenylmethane diisocyanate (MDI). Process according to any one of the preceding claims, where a quantity 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 the prevailing part of the rest of the sheet. Process according to any one of the preceding claims, where during forming and thermosetting said barrier (39) is located in proximity to a perimeter edge (44) of a free face (38) of said insert (10; 11; 12) facing said first half-mold (20). Process according to any one of the preceding claims, where producing said semi-finished product comprises spraying said sheet with said liquid mixture, where forming the semi-finished product comprises cutting said semi-finished product at least along a contour line and where thermosetting the liquid mixture comprises keeping the semi-finished product inside the mold at a determined temperature, preferably greater than or equal to 120 °, for a determined time interval. 12. Composite product (1) comprising a core (2), at least a first layer (3) in correspondence with a first face (4) of the core (2), the first layer (3) comprising a sheet impregnated with solid polymeric 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).