FR3127431A3 - Method of manufacturing a plate with a bubble structure comprising a rolling step intended to deform the bubble structure. - Google Patents

Abstract

The invention relates to a method of manufacturing a plate with a bubble structure, comprising a rolling step intended to deform the bubble structure. The manufacturing method implements the following steps: - a step of covering (2) a central sheet (6) delimited by two opposite large faces (4,4A), a large face (4A) of the central sheet comprising protrusions (10) of equal or substantially equal height during the covering step (2) , each large face of the central sheet is covered by an outer sheet (8) so as to form a bubble structure plate (14); then - a rolling step (16) of the bubble structure plate (14); At the end of the rolling step, the maximum height of the protrusions (10), measured between the covering step (2) and the rolling step (16), is reduced by 40% or more. Figure 1

Description

Method of manufacturing a plate with a bubble structure comprising a rolling step intended to deform the bubble structure.

Technical field to which the invention relates

The present invention relates to the technical field of the manufacture of plates of plastic material, intended for the production of storage or transit packaging.

Technology background

It is known from the state of the art to use sheets of plastic material to produce packaging or containers intended for the transport of goods.

In order to give sufficient rigidity to the plates, without significantly increasing their weight, the plates consist of two outer sheets held apart by means of spacers. The spacers are arranged perpendicular to the outer sheets and are parallel to each other. In a known manner, this type of plate is obtained by extruding a thermoplastic material through a die, then passing it between calibration plates to fix its shape.

This type of plate adequately resists mechanical stresses when exerted perpendicular to the outer sheets. Conversely, the mechanical stresses exerted in shear, i.e. parallel to the outer sheets and perpendicular to the spacers, cause the spacers to tilt and therefore the plate to collapse.

In order to overcome this drawback, a new plate structure, called a bubble structure, has been proposed. A bubble structure board is made up of two outer sheets joined together by a central sheet having bosses on its surface. The bosses are dome-shaped and are distributed in a regular pattern on the surface of the central sheet. A method of manufacturing a plate with a bubble structure is in particular described in document WO2005/105436. Advantageously, the cylindrical shape of the bosses confers greater resistance to this type of plate, with respect to the shear stresses mentioned above.

The aim of the invention is to propose a new process for the manufacture of plates with a bubble structure, having better resistance to delamination as well as greater elasticity when they are subjected to a bending stress.

Object of the invention

The invention proposes a method for manufacturing a plate with a bubble structure, implementing the following steps:

- a step of covering a central sheet, the central sheet being delimited by two large opposite faces, a large face of the central sheet comprising protuberances, the protuberances being of equal or substantially equal height during the covering step, each large face of the central sheet is covered by an outer sheet so as to form a plate with a bubble structure; Then

- a rolling step of the bubble structure plate.

The invention is remarkable in that the maximum height of the protrusions, measured between the covering step and the rolling step, is reduced by 40% or more, preferably by 50% or more, preferably by 60% or more, at the end of the rolling step.

In other words, during the rolling step, a mechanical force is exerted perpendicular or substantially perpendicular to the large faces of the outer sheets, so as to crush the protuberances in order to reduce their height. By the term "height" is meant a dimension measured along a direction normal to a large face of the central sheet.

Surprisingly, the inventors have observed that the rolling step described above makes it possible to modify the mechanical properties of the plate with a bubble structure, in particular to increase its resistance to delamination as well as its elastic properties when the plate bubble structure is subjected to mechanical bending stresses.

The manufacturing method according to the invention thus allows the production of plates with a more resistant and more flexible bubble structure, for an equivalent or substantially equivalent grammage.

According to another embodiment of the invention, the central sheet is made from plastic material.

According to another embodiment of the invention, the central sheet is made from polypropylene.

According to another embodiment of the invention, the outer sheets are formed from the same material as the central sheet. By the term “external sheets”, we mean the sheets in contact with the external environment.

It should be noted that the invention is not limited to a particular number of sheets for producing the plate with a bubble structure. For example, one or more intermediate sheets can be stored between the central sheet and an outer sheet. The intermediate sheet(s) may be identical in nature to the central sheet or identical in nature to the outer sheet.

According to another embodiment of the invention, the temperature of the central sheet, during the rolling step, is between 80°C and 160°C, preferably between 100°C and 130°C. Advantageously, in the temperature ranges mentioned above, the protuberances present on the surface of the central sheet can be deformed more easily and in a non-reversible manner. In other words, in the temperature ranges mentioned above, the central sheet is more easily malleable and retains its shape after the rolling step. The plate structure becomes stable or substantially stable when its temperature is below 50°C and no mechanical stress is exerted on it.

According to another advantage, in the temperature ranges mentioned above, during lamination of the sheet with a bubble structure, stronger adhesion is favored between the central sheet and the outer layers.

According to another embodiment of the invention, prior to the covering step, the central sheet undergoes a thermoforming step, so as to produce a multitude of protuberances on the surface of a large face of the central sheet, possibly on the surface of the two large opposite faces of the central sheet.

According to another embodiment of the invention, the maximum height of the protrusions is between 0.5 mm and 5 mm, preferably between 1 mm and 3 mm, between the covering step and the rolling step.

According to another embodiment of the invention, the walls delimiting the protrusions have a thickness of between 0.05 mm and 0.5 mm, preferably between 0.08 mm and 0.15 mm, between the step of covering and the rolling step.

According to another embodiment of the invention, the protrusions are cylindrical and/or dome-shaped, between the covering step and the rolling step.

According to another embodiment of the invention, the largest diameter of the protrusions is between 2 mm and 9 mm, preferably between 3 mm and 5 mm or between 7 mm and 9 mm.

According to another embodiment of the invention, the protrusions are distributed homogeneously or substantially homogeneously on the surface of the central sheet.

According to another embodiment of the invention, at the end of the rolling step, the basis weight of the sheet with a bubble structure is between 200 g/m ² and 1500 g/m ² , preferably between 250 g/m ² and 400 g/m ² or between 800 g/m² and 1200 g/m².

According to another embodiment of the invention, at the end of the rolling step, the thickness of the plate, measured in a direction perpendicular to an outer sheet, is between 0.4 mm and 34 mm, from preferably between 0.7 mm and 5 mm, preferably between 0.7 mm and 3 mm.

According to a variant embodiment, the manufacturing process may comprise one or more intermediate steps, between the covering step and the rolling step.

Of course, the different characteristics, variants and embodiments mentioned above can be associated with each other in various combinations, insofar as they are not incompatible or exclusive of each other.

The invention also relates to any plate with a bubble structure, produced using a method described above.

Description of figures

The invention will be better understood, thanks to the description below, which relates to preferred embodiments, given by way of non-limiting examples, and explained with reference to the appended diagrammatic drawings, in which:

illustrates an example of a process for manufacturing a plate with a bubble structure according to the invention.

Claims (13)

Process for manufacturing a plate with a bubble structure implementing the following steps:

• a step of covering (2) a central sheet (6), the central sheet being delimited by two opposite large faces (4, 4A), a large face (4A) of the central sheet comprising protrusions (10), the protuberances being of equal or substantially equal height during the covering step (2), each large face of the central sheet is covered by an outer sheet (8) so as to form a plate with a bubble structure (14); Then
• a rolling step (16) of the bubble structure plate (14);

characterized in that at the end of the rolling step, the maximum height of the protrusions (10), measured between the covering step (2) and the rolling step (16), is reduced by 40% or more, preferably 50% or more. Method of manufacturing a plate with a bubble structure according to claim 1, characterized in that the central sheet (6) is made from plastic material. Method of manufacturing a plate with a bubble structure according to claim 2, characterized in that the central sheet (6) is made from polypropylene. A method of manufacturing a bubble structure plate according to claim 2 or 3, characterized in that the outer sheets (8) are formed from the same material as the central sheet (6). Method of manufacturing a plate with a bubble structure according to claim 4, characterized in that the temperature of the central sheet (6), during the rolling step (16), is between 80°C and 160°C . Method of manufacturing a sheet with a bubble structure according to one of Claims 1 to 5, characterized in that, prior to the covering step (2), the central sheet (6) undergoes a thermoforming step, so to produce a multitude of protrusions on the surface of a large face of the central sheet (6). Method of manufacturing a plate with a bubble structure according to one of Claims 1 to 6, characterized in that the maximum height of the protrusions (10) is between 0.5 mm and 5 mm, preferably between 1 mm and 3 mm, between the covering stage (2) and the rolling stage (16). Method of manufacturing a plate with a bubble structure according to one of Claims 1 to 7, characterized in that the walls delimiting the protrusions (10) have a thickness of between 0.05 mm and 0.5 mm. Method of manufacturing a plate with a bubble structure according to one of Claims 1 to 8, characterized in that the protuberances (10) are cylindrical in shape and/or in the shape of a dome, between the covering step (2 ) and the rolling step (16). Method of manufacturing a plate with a bubble structure according to claim 9, characterized in that the largest diameter of the protrusions is between 2 mm and 9 mm. Method of manufacturing a plate with a bubble structure according to one of Claims 1 to 10, characterized in that the protuberances (10) are distributed in a homogeneous or substantially homogeneous manner on the surface of the central sheet (6). Method of manufacturing a plate with a bubble structure according to one of Claims 1 to 11, characterized in that at the end of the rolling step (16), the basis weight of the plate with a bubble structure ( 14) is between 200 g/m ² and 1500 g/m ² . Method of manufacturing a plate with a bubble structure according to one of Claims 1 to 11, characterized in that at the end of the rolling step, the thickness of the plate is between between 0.4 mm and 34mm.