WO2025017458A1

WO2025017458A1 - Process for obtaining coated pressing pads for the manufacture of structured slabs of ceramic material

Info

Publication number: WO2025017458A1
Application number: PCT/IB2024/056853
Authority: WO
Inventors: Fabio TAROZZI
Original assignee: Siti - B&T Group S.P.A.
Priority date: 2023-07-14
Filing date: 2024-07-15
Publication date: 2025-01-23

Abstract

Process for obtaining coated pressing pads for the manufacture of structured slabs of ceramic material, comprising at least the following phases: - supplying (A) at least one pad to be coated (1) adapted to press the ceramic powder material and provided with a first face (la) to be coated and a second face (lb) opposite the first face (la); - applying (D) at least one coating layer (3) on the first face (la) to obtain a pre-machined pad (4); - grinding of the coating layer (3); - engraving (F) of the coating layer (3) to define on the latter at least one structured surface (3a) adapted to obtain at least one structured slab. Preferably the process comprises also the phases of: abrasion (B) of the first face (la); heating (C) of the pad to be coated (1); consolidation (E) by heating of the coating layer (3) on the first face (la).

Description

PROCESS FOR OBTAINING COATED PRESSING PADS FOR THE MANUFACTURE OF STRUCTURED SLABS OF CERAMIC MATERIAL

Technical Field

The present invention relates to a process for obtaining coated pressing pads for the manufacture of structured slabs of ceramic material, i.e., ceramic slabs the surface of which, instead of being smooth and uniform, has grooves, reliefs, depressions, cuts and/or slots that give it a three-dimensional appearance.

Background Art

As is well known, the manufacture of structured slabs of ceramic material generally involves a phase of deposition of a powder material, which may consist of ceramic materials or of a mixture of mineral compounds in granular form (e.g., marble and granite), glass, quartz powder, etc., as well as resins acting as binders, on a supporting surface, such as a belt or a mold, to form a slab to be compacted, and a subsequent phase of pressing in order to obtain a compacted slab.

Depending on the case, further phases are then provided such as, e.g., firing and subsequent cooling, so as to obtain a product with special mechanical and physical properties.

Thus, the equipment required to carry out these phases comprises at least the presence of a supporting surface, movable along a direction of forward movement, on which the slab to be compacted is deposited, and pressing means for pressing the slab to be compacted to obtain a compacted slab.

The pressing means of known type comprise a fluid- operated cylinder provided with a piston, movable with respect to the main body of the fluid- operated cylinder itself close to/away from the supporting surface(s) and with which a pressing pad is associated.

Specifically, the pressing pad comprises a pressing surface, facing the supporting surface and intended to contact the ceramic material of the slab to be compacted. The current working method involves coating the pressing surface of the pad by bonding with one or more Bakelite layers which allow the slabs to be given the specific three-dimensional appearance sought after as a result of pressing. It has, however, been observed that the Bakelite bonding operation is rather difficult and frequently causes air bubbles to form between the Bakelite layer and the pad, which end up compromising the aesthetic quality of the resulting structured slabs.

It is easy to appreciate how such a drawback can lead to the formation of structured slabs with an appearance that differs from that sought after and, therefore, in need of further machining or even to be discarded, resulting in higher production costs.

Description of the Invention

The main aim of the present invention is to devise a process for obtaining coated pressing pads for the manufacture of structured slabs of ceramic material which allows the pressing pads to be effectively coated while avoiding the defects characterizing the processes used to date, so as to achieve a high aesthetic quality of the structured slabs made.

Another object of the present invention is to devise a process for obtaining coated pressing pads for the manufacture of structured slabs of ceramic material which allows the aforementioned drawbacks of the prior art to be overcome within the framework of a simple, rational, easy and effective to use as well as cost-effective solution.

The aforementioned objects are achieved by this process for obtaining coated pressing pads for the manufacture of structured slabs of ceramic material having the characteristics of claim 1.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become more apparent from the description of a preferred, but not exclusive, embodiment of a process for obtaining coated pressing pads for the manufacture of structured slabs of ceramic material, illustrated by way of an indicative yet non-limiting example in the accompanying tables of drawings in which:

Figure 1 shows the supply phase of the process according to the invention;

Figure 2 shows the abrasion phase of the process according to the invention;

Figure 3 shows the warming phase of the process according to the invention; Figure 4 shows the application phase of the process according to the invention; Figure 5 shows the consolidation phase of the process according to the invention; Figure 6 shows the engraving phase of the process according to the invention;

Figure 7 shows by way of example a machined pad obtained by the process according to the invention.

Embodiments of the Invention

With particular reference to these figures, reference numeral 1 globally denotes a pad to be coated by means of the process according to the invention.

The process for obtaining coated pressing pads for the manufacture of structured slabs of ceramic material comprises, first of all, at least one phase of supplying A at least one pad to be coated 1 adapted to press the ceramic powder material. Specifically, the pad to be coated 1 is provided with a first face la to be coated and with a second face lb opposite the first face la.

Specifically, the first face la faces, in use, the ceramic material to be compacted. Advantageously, a phase of grinding is carried out on the first face la of the pad to be coated 1.

Preferably, the process then comprises at least one phase of abrasion B of the first face la (see Figure 2). More specifically, the phase of abrasion is carried out subsequently to the phase of grinding of the first face la.

In the present case, the phase of abrasion B comprises at least one sanding step B of the first face la.

This expedient allows the surface of the first face la to be cleaned and eroded, thus adequately preparing the latter for the next steps of the process shortly described.

That said, it cannot be ruled out that the phase of abrasion B may comprise, in combination with or instead of the sanding step B, one or more additional machining steps of the first face la such as, e.g., a blasting step or the like.

Advantageously, the process comprises at least one phase of heating C the pad to be coated 1 shown by way of example in Figure 3.

Specifically, the phase of heating C is carried out by means of special heating means 2 (shown by way of example in Figure 3) of the type of a ceramic kiln or other functionally similar devices known to the branch engineer.

Conveniently, the phase of heating C is carried out subsequently to the phase of abrasion B.

Providing for a phase of heating C following sanding B proves particularly useful since it induces thermo-relaxation of the first face la, thus allowing the removal of residual stresses in the same and improves the adhesion quality of any coating layers on the latter.

According to the invention, the process comprises at least one phase of application D, shown by way of example in Figure 4, of at least one coating layer 3 on the first face la to obtain a pre-machined pad 4. In this sense, it is worth noting that providing a sanding step B allows advantageously increasing the roughness of the first face la and, therefore, promotes the adhesion of the coating layer 3 on the latter during the phase of application D.

Preferably, the coating layer 3 is made of a polymeric material, e.g. rubber, resin or the like.

Advantageously, the phase of application D is carried out by casting a liquid mixture on the first face la.

Specifically, the phase of application D is carried out subsequently to the phase of abrasion B and to the phase of heating C.

Appropriately, the process comprises, then, at least one phase of consolidation E of the coating layer 3 on the first face la.

Precisely, the phase of consolidation E, shown for illustration purposes only in Figure 5, comprises at least one step of heating E the pre-machined pad 4.

Again, the step of heating E is carried out by special consolidation means 5 of the type of a heating machine such as a ceramic kiln or other functionally similar devices known to the branch engineer. Specifically, the pre-machined pad 4 obtained as a result of the application of the coating layer 3 is placed inside the heating machine in order to carry out the consolidation of the coating layer itself. The phase of consolidation E allows the mixture cast on the first face la to solidify and to further increase the adhesion of the coating layer 3 to the pad to be coated 1. According to the invention, the process comprises at least one phase of grinding the coating layer 3 aimed at increasing the degree of surface finish of the coating layer itself.

Specifically, the phase of grinding is carried out subsequently to the phase of consolidation E.

The phase of grinding, therefore, makes it possible to reduce the roughness and surface imperfections of the coating layer 3, making it easier to carry out the subsequent work phases.

In this sense, the process comprises at least one phase of engraving F of the coating layer 3 (Figure 6) to define thereon at least one structured surface 3 a adapted to obtain at least one structured slab.

Specifically, the phase of engraving allows for a structured surface 3a having grooves, reliefs, depressions, cuts and/or slots that allow it to give the structured slab its characteristic three-dimensional appearance.

Conveniently, the phase of engraving F is carried out subsequently to the grinding of the coating layer 3.

As shown by way of example in Figure 6, the phase of engraving F is preferably carried out by laser engraving means, but different methodologies, known to the branch technician, cannot be ruled out to achieve the structured surface 3 a. Finally, the process comprises at least one phase of heat treatment of the resulting structured surface 3 a.

Specifically, the phase of heat treatment is carried out subsequently to the phase of engraving F and involves placing the pre-machined pad 4 within a heating machine.

Advantageously, at least one of either the phase of consolidation E or the phase of heat treatment is carried out at a reference temperature of between 50 °C and 120 °C. Preferably, the reference temperature is of between 70 °C and 100 °C. Indeed, this temperature range allows the pre-machined pad 4 to be consolidated and the structured surface 3 a to be stabilized very effectively while minimizing energy expenditure.

Thus, the process just outlined makes it possible to obtain a machined pad 6, shown in Figure 7 by way of example, which is not subject to the formation of internal air bubbles and which is, for this reason, profitably employable to form structured slabs distinguished by a remarkable aesthetic quality.

It has in practice been ascertained that the described invention achieves the intended objects.

In particular, the fact is emphasized that the process according to the invention allows the pressing pads to be effectively coated, thus avoiding the defects that characterize the processes used to date, allowing for a high aesthetic quality of the structured slabs made. Specifically, the process according to the invention ensures obtaining a coated pad that is not subject to the problem of air bubble formation and, therefore, particularly suitable for the formation of structured slabs.

In this sense, the pad obtained by the process of this invention enables the structured slabs to be given the precise aesthetic appearance desired and, therefore, causes them to undergo no further treatment or machining following pressing, with a clear and advantageous reduction in overall production costs.

Claims

CLAIMS 1) Process for obtaining coated pressing pads for the manufacture of structured slabs of ceramic material, characterized by the fact that it comprises at least the following phases: supplying (A) at least one pad to be coated (1) adapted to press the ceramic powder material and provided with a first face (la) to be coated and a second face (lb) opposite said first face (la); applying (D) at least one coating layer (3) on said first face (la) to obtain a pre-machined pad (4); grinding of said coating layer (3); engraving (F) of said coating layer (3) to define on the latter at least one structured surface (3a) adapted to obtain at least one structured slab. 2) Process according to claim 1, characterized by the fact that it comprises at least one phase of grinding of said pad to be coated (1) carried out prior to said application (D). 3) Process according to claim 1, characterized by the fact that it comprises at least one phase of abrasion (B) of said first face (la) carried out prior to said application (D). 4) Process according to claims 2 and 3, characterized by the fact that said abrasion (B) is carried out subsequently to said grinding of the pad to be coated (D- 5) Process according to claim 3 or 4, characterized by the fact that said phase of abrasion (B) comprises at least one sanding step (B) of said first face (la). 6) Process according to one or more of the preceding claims, characterized by the fact that it comprises at least one phase of heating (C) said pad to be coated

(1) carried out prior to said application (D).

7) Process according to claim 6, characterized by the fact that said phase of heating (C) is carried out subsequently to said abrasion (B).

8) Process according to one or more of the preceding claims, characterized by the fact that said application (D) is carried out by means of casting the coating layer (3) in liquid form. 9) Process according to one or more of the preceding claims, characterized by the fact that said coating layer (3) is made of a polymeric material.

10) Process according to one or more of the preceding claims, characterized by the fact that it comprises at least one phase of consolidation (E) of said coating layer (3) on said first face (la).

11) Process according to claim 10, characterized by the fact that said consolidation (E) comprises at least one step of heating (E) said pre-machined pad (4).

12) Process according to claim 10 or 11, characterized by the fact that said grinding of the coating layer (3) is carried out subsequently to said consolidation (E) and prior to said engraving (F).

13) Process according to one or more of the preceding claims, characterized by the fact that said engraving (F) is carried out by means of laser engraving means.

14) Process according to one or more of the preceding claims, characterized by the fact that it comprises at least one phase of heat treatment of said structured surface (3a) carried out subsequently to said engraving (F).

15) Process according to one or more of the preceding claims, characterized by the fact that at least one of either said heating step (E) or said phase of heat treatment is carried out at a reference temperature comprised between 50 °C and 120 °C.