LU83075A1 - PROCESS AND DEVICE FOR ACCELERATING THE ADHESIVE TAKING OF A COMPOSITE MATERIAL COMPRISING AT LEAST TWO LAMELLAR LAYERS GLUED TO BOTH - Google Patents

Description

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The present invention relates generally to composite materials comprising at least two lamellar layers bonded to one another, which, after assembly, is to ensure the setting of the bonding planes, taken commonly known as drying. , even when, the adhesive used being constituted by an organic polymeric material, such a setting does not imply the elimination of any volatile component.

It relates more particularly, but not exclusively, to construction panels with a sandwich structure, such as those marketed for example under the designation "PLACOPAN", used for the production of partitions and / or insulation coatings.

Such a panel usually comprises, on both sides. 15 be of an intermediate cellular cardboard layer, two outer layers each formed by a plasterboard coated on both sides with a sheet of cardboard.

For joining these layers, two bonding planes are used, one between the intermediate layer and one of the plasterboards, the other between this intermediate layer and the other of these plasterboards.

It is from these two collage planes that it is necessary to ensure the taking.

To date, two separate techniques have been used for this purpose.

According to the first, the adhesive used is a vinyl adhesive, capable of setting cold.

The panels concerned are therefore subjected to pressing means long enough for the setting 30 of such an adhesive to have time to intervene.

In addition to the fact that the adhesive used is relatively expensive, such a technique involves prolonged, and therefore expensive, immobilization of the pressing means used, as well as, in practice, a discontinuous manufacturing process.

According to the other technique concurrently implemented with the previous one, and, in practice, more widespread than the latter, the adhesive used is a urea-formaldehyde adhesive, which is of lower cost than that of vinyl adhesives with setting cold,

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2 and mistletoe, capable of accelerated setting when subjected to this effect to an appropriate treatment source, allows for the panels concerned, a faster manufacturing process than that authorized by vinyl adhesives.

5 In practice, to date, the source of treatment used to accelerate the setting of bonding of such a urea-formaldehyde adhesive is a source of heat: the panels to be treated are, for this, stacked alternately with hot plates, the assembly being subjected jointly to 10 pressing means suitable for expelling the parasitic air knives, for holding the laminated layers glued against the panels concerned, and for calibrating the these.

Although such a technique has given and can still give satisfaction, it has various drawbacks, which are as follows.

First of all, the transmission of heat towards the bonding planes whose setting is to be accelerated takes place through a material, namely plaster, which by nature is a poor conductor of heat, in particular if it is lightened by air bubbles, which in practice can lead to prolonged treatment times.

In addition, and by reason of this poor thermal conductivity of the plaster, a large temperature gradient is established within each plaster plate, so that, in order to have at the corresponding bonding plane a sufficient temperature when it is taken, on the first side of such a plasterboard, the other side of it must be overheated, at the risk of untimely dehydration of the plaster on this side, which, in practice, it is necessary to comply with very strict temperature limits, to the detriment, therefore, as before, of the processing speed.

These difficulties are not without slowing down the evolution towards a lower weight and / or a lower cost of the panels concerned, since any increase in the density of air bubbles in the plaster used and any reduction in 1 thickness or grammage of cardboard sheets enclosing such plaster can only increase them.

If, moreover, it is intended, to improve the contact between the hot plates used and the panels to be treated, and thus, to accelerate the heat transmission between these plates and these panels, to increase the force of pressing to which the assembly is subjected, the intermediate honeycomb cardboard layer 5 that each of these panels has a tendency to crush, by buckling, so that, here too, a pressure limit must imperatively be respected.

Finally, and as before, such a technique involves, for the panels concerned, a discontinuous manufacturing process.

The present invention generally has for its objects a method and a device which, suitable for accelerating the bonding of a composite material comprising at least two lamellar layers glued one by one 'other, overcome the shortcomings briefly outlined above.

According to the invention, as regards the use of a processing source suitable for the acceleration of setting of the desired bonding and pressing means suitable for holding the affected layers against one another, a radiation source is chosen for the treatment source, and the composite material to be treated is scrolled directly above the action zone of this radiation source.

25 It is thus possible to ensure bonding> sought without the use of any heat source, and, by the movement of the composite material to be treated, it is advantageously possible to make it benefit in a uniform manner , and therefore optimal, of the energy delivered by the radiation source used in substitution for such a heat source; it can be a source of high frequency waves or a source of microwaves.

Preferably, the area of action of such a radiation source on the composite material to be treated is limited to a portion of the surface thereof, and for example to one or more elongated strips parallel to the direction of travel. of this material.

It is thus advantageously possible to best limit the energy used, while ensuring a solida-

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4 immediate localization of the bonded layers concerned, sufficient for these layers to then be able to join over their entire surface without risk of any deformation for the whole.

5 A particularly advantageous compromise is thus found between the cost of the energy to be used, on the one hand, and the effectiveness of the bonding to be provided, on the other hand.

According to a preferred form of implementation of the invention, the pressing means used consist of boxes generating air cushions, so that the pressure applied to the treated panels can be modulated so as to avoid any deterioration by buckling thereof, the advance means used to jointly ensure the movement of such a panel being in this case dis-15 tincts of these pressing means.

As a variant, the pressing means used comprise for example endless conveyors forming by themselves the associated advancing means.

Anyway, the treatment of the panel concerned, or, more generally, of any composite material comprising at least two lamellar layers glued to each other, can advantageously and economically be done by continuous, due to the guaranteed scrolling.

The characteristics and advantages of the invention res-25 will also emerge from the description which follows, by way of example, with reference to the appended schematic drawings in which: FIG. 1 is a view, on the side, of a construction panel with a composite structure to which the invention can be applied; Figure 2 shows on a larger scale, and in section, the detail of Figure 1 identified by an insert II thereon; FIG. 3 is a perspective view of a device specific to the implementation of the invention; Figure 4 is, on a larger scale, a cross-sectional view of this device, along the line IV-IV of Figure 3; Figure 5 is a partial view in section along longitudinal "K".

5 dinal, along the line V-V of Figure 4; FIG. 6 is a plan view of the bottom of one of the boxes generating air cushions that this device comprises; Figure 7 is a view similar to that of Figure 5 6, for an alternative embodiment; Figure δ is a schematic perspective view similar to that of Figure 3, for another device specific to the implementation of the invention; FIG. 9 is a diagrammatic end view of this other device, along arrow IX of FIG. 8.

These figures illustrate by way of example the application of the invention to the treatment of a construction panel with a sandwich structure 10, of the type of those marketed under the designation "PLACOPAN".

• 15 Such a panel 10 forms a composite material comprising three successive lamellar layers, namely, on either side of an intermediate layer 11, which is a honeycomb cardboard layer, two front plates 12A, 12B of the type for example those sold under the designation “PLACOPLAERE“. 20 These are, as shown, plates comprising a plaster core 13 flanked on each of its faces by a cardboard covering sheet 14.

Since such a panel 10 is not in itself part of the present invention, it will not, however, be described in all its details here.

It will suffice to specify that, during its assembly, its intermediate layer 11 is glued to the plate 12 by a gluing plane 15A, and that, likewise, it is glued to the plate 12B by a gluing plane 15B, FIG. 2 .

These bonding planes 15A, 15B can for example be produced using urea-formaldehyde glue.

Anyway, it is these bonding planes 15A, 15B for which bonding must be ensured, or, more precisely, the acceleration of this bonding.

35 To this end, it is necessary to jointly submit the panel 10 concerned, on the one hand to a source of treatment suitable for the acceleration of bonding setting sought, and on the other hand to pressing means suitable for maintaining one against the other of the glued layers which constitute it.

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According to the invention, a radiation source is chosen for the treatment source, that is to say a source specific to the emission of waves, and it is scrolled vertically in the area of action of this radiation source the panel 10, 5 or other composite material, to be treated.

In the embodiment of the invention illustrated in FIGS. 1 to 7, the radiation source chosen is a high frequency wave source, that is to say waves whose frequency is of the order of a few tens of mega 10 hertz.

Such a radiation source is well known in itself, and not being part of the present invention, it will not be described in detail here, either in its constitution or in its operation.

It will suffice to specify that these means of action are electrodes of opposite polarities between which an alternating electric field is applied.

In the device 18 for implementing the invention illustrated by FIGS. 3 to 7, the pressing means have 20 air cushions.

They comprise two boxes generating air cushions 20A, 20B defining between them a slot 21 in which the panel 10 to be processed is allowed to pass.

The structure of such an air cushion generator box 20A, 20B is within the skill of the art, and, not being part of the present invention per se, it will not be described in detail here. .

It will suffice to specify that such an air cushion generator box 20A, 20B generally comprises a chassis 22, 30 which is provided with a nozzle 23 suitable for supplying it with pressurized air, according to the arrows Fl, and which is closed by a bottom 24 assigned to a network of perforations 25 suitable for allowing diffusion of this air under pressure, according to the arrows F2.

Preferably, and as shown, at least one of the air cushion generating boxes 20A, 20B is mounted floating, for example, as shown, under the control of pneumatic cylinders 27.

It is, in the embodiment shown,

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7 * of the box 20A intended to act on the upper face of the panel 10 to be treated, while the box 20B intended to act on the underside of the latter is rigidly connected to the frame of the assembly (not shown).

5 However, a reverse arrangement could be adopted, and / or each of the boxes 20A, 20B be mounted floating, under the control of pneumatic cylinders or other return means, such as springs for example.

Anyway, the air diffused according to the arrows 10 F2 by these boxes 20A, 20B forms two air cushions, one upper, the other lower, which, on the one hand, provide the -. maintenance of the panel 10 to be treated in a medium position between these boxes, in the slot 21 provided for this purpose between them, and which, on the other hand, apply to this panel 10 a pressure force sufficient to properly maintain the contact with one another the different layers glued to each other which constitute such a panel 10.

These air cushions have a constant thickness, depending on the air supply pressure entering the cais-20 sounds concerned, chosen accordingly *} and, as it is easy to understand, the floating mounting of the at least one of these boxes makes it possible to ensure that the pressure applied to one and the other of the faces of the panel 10 to be treated also remains constant, whatever the possible variations in positions thereof. -to these boxes.

In addition to the two pressing means thus formed, the device according to the invention comprises, in combination, on the one hand, as mentioned above, a course of high frequency radiation, detailed below, and on the other hand, 30 means of advance suitable for ensuring the scrolling of the panel 10 to be treated directly above the area of action of this radiation source, and therefore, in practice, a scrolling of this panel 10 between boxes 20A, 20B.

In the example of implementation illustrated by the fi-35 gures 3 to 7, these advance means are distinct from the pressing means that constitute the boxes 20A, 20B.

They comprise lateral rollers 29, capable of acting on the edges of the panel 10 to be treated parallel to the direction of travel of the latter; it is therefore, in the embodiment shown »8 embodiment, rollers with vertical axes.

These rollers 29 are correctly driven (not shown in the figures).

Preferably, and as shown, the means of action which comprises the radiation source used are associated with the perforated bottom 24 of the air cushion generator boxes 20A, 20B, and, as shown, can even be incorporated into such a background, being perforated like this.

10 According to one aspect of the invention, these means of action are divided transversely with respect to the direction of travel of the panel 10 to be treated, identified by an arrow F3 in FIGS. 3 and 5, and are extended parallel to this. scroll direction.

As the radiation source is a high frequency source, these means of action are, as mentioned above, made up of electrodes of opposite polarities 17, 17 ′ elongated in strips parallel to the direction of travel of the panel 10 to be treated.

20 In the implementation example illustrated by FIGS. 4 to 6, the electrodes 17 of the same polarity are incorporated into the bottom 24 of the same air cushion generator box, in practice the box 20Ά, while the electrodes 17 'of opposite polarity are incorporated into the bottom 24 of the other box, in practice the box 20B.

Such electrodes thus act in the manner of capacitor plates, and develop between them an electric field which crosses the panel 10 to be treated throughout its thickness, perpendicular thereto.

Preferably, but not necessarily, the length of such electrodes is chosen to be equal to the wavelength of the corresponding radiation, or to a multiple of this wavelength.

However, taking into account their arrangement, depending on which they are elongated parallel to the direction of travel of this panel 10, no particular precaution is to be taken despite their functioning as an antenna inevitably creates an alternation of bellies and nodes for the electric field which they develop between them; in fact, by virtue of the scrolling according to the invention of the panel 10 to be treated, the latter benefits uniformly over its entire length from the optimal energy corresponding to such bellies.

For such an embodiment of the electrodes 17, 5 17 ′ constituting the means of action of the high frequency radiation source used, the two bonding planes 15A, 15B of the panel 10 to be treated are jointly interested in the waves emitted by this radiation source.

As a variant, in FIG. 7, the electrodes 17, 17 ′ are, in a known manner, in the general shape of a comb, and are overlapped two by two within the bottom 24 of each of the cays. 20A, 20B.

In such a case, the electrodes 17, 17 'of the box 20A only concern the single bonding plane 15A, while the 15 electrodes 17, 17' of the box 20B only concern the only bonding plane 15B, the fields electric then being parallel to these bonding planes, and not perpendicular to them.

In both cases, a reduced number of bands 20 d1 electrode17, 17 'is thus provided, equal to three for each air cushion generator box 20A, 20B in the embodiment shown.

Thus divided, the area of action of the radiation source used on the panel 10 to be treated is limited to a portion of the surface of the latter.

In practice, this portion can be between 20 and 30% of the total area of such a panel, and, for example, be close to 25%.

The corresponding energy saving is therefore significant.

In the embodiment shown, the three electrode strips used extend, for one, in the axis of the panel 10 to be treated, and for the other, at a slight distance from the corresponding lateral edges of this panel.

In addition, in this embodiment, they extend over the entire length of the air cushion generator boxes 20A, 20B concerned; but, alternatively, this is not necessarily so.

In the device thus constituted, in the exemplary embodiment shown, there is associated on the one hand a feed conveyor 31, and on the other hand a discharge conveyor 32, respectively upstream and downstream of this device, for supporting the panel 10 to be treated before taking charge of it-5 by such a device.

These are, for example, and as shown, roller conveyors 53.

After gluing of its plates 12A, 12B on its intermediate layer 11, each panel 10 to be treated is introduced between the light-generating boxes 20A, 20B, its travel between them being ensured by the lateral drive rollers 29.

During such scrolling, the panel 10 concerned is suitably pressed, as described above, and • 15 in line with the electrodes 17, 17 ′, its bonding planes 15A, 15B have their bonding bond accelerated by the effect of high frequency waves passing through them.

Consequently, at the end of the device according to the invention, the plates 12A, 12B of the panel 10 concerned are in-timely secured to the intermediate layer 11 thereof, by strips of the bonding planes 15A, 15B which, current along the entire length of the panel, correspond to the electrodes 17, 17 '.

The rest of the bonding planes 15A, 15B of such a panel 25 can then continue to bond freely, without ♦ it being necessary to jointly ensure any pressing, and without however resulting in any deformation for this panel, the strips already taken from these bonding planes 15A, 15B sufficient to ensure adequate maintenance 30 of the plates 12A, 12B thereof in contact with the intermediate layer 11, for taking the rest of these bonding planes 15A, 15B.

In the variant embodiment shown in FIGS. 8 and 9, the radiation source used is a microwave generator 33, that is to say a generator capable of delivering waves of frequency from the order of a few thousand mega hertz.

Such a microwave generator is well known in itself, and not being in itself the subject of the present * * 11 application, it will not be described in detail here.

As is known, microwaves are particularly directive, and they can easily be channeled by waveguides.

5 In the illustrated implementation example, such a waveguide 34A is provided transversely, for the upper face of the panel 10 to be treated, and, by junction boxes 35A, this waveguide 34A supplies three waveguides 36A, which are directed towards the panel 10 to be treated, 10 and whose outlets in this respect form the means of action on such a panel of the generator 33.

In the embodiment shown, the waveguides 36A extend substantially perpendicular to the direction of travel of the panel 10 to be treated.

• 15 As a variant, they could be oblique with respect to such a direction of travel, in order to increase the surface of the area of action on the panel 10 to be treated of the generator 3 3.

As shown diagrammatically in broken lines in FIG. 9, waveguides 34B and 36B can be provided in a similar manner, from the generator 33, for serving the underside of the panel 10 to be treated, with the intervention of boxes bypass 35B.

The production of such waveguides, and the corresponding junction boxes, is well known in itself, and not being the subject of the present application, it will not be described in detail here.

In the embodiment shown in FIGS. 8 and 9, the pressing means used also jointly form the advance means suitable for ensuring the movement of the panel 10 to be treated.

These are, for example, as schematically shown, endless conveyors 38A, 38B, which alternate with the waveguides 36A, 366B, and between which is pinched the panel 10 to be treated.

The practical realization of such conveyors, as well as the assembly of these and the microwave radiation source corresponding to the same frame, is within the skill of the art.

It goes without saying, however, that with such a source of * * 12 microwave radiation, pressing means and advancing means of the type of those described with reference to FIGS. 3 to 7 can also be used.

The present invention is moreover not limited to the 5 embodiments succinctly described and shown, but encompasses any variant.

In particular, it is not necessary for the panel 10 to be treated to scroll horizontally; on the contrary, it could just as well scroll vertically, standing on a slice, and for this purpose bear on suitable support means.

The processing of such a panel 10 being done continuously, its length is indifferent.

In the figures, it has been deliberately exaggerated.

The scope of the invention is not limited to either. treatment of only sandwich structure panels of the “PLACOPAN” type mentioned above, but extends more generally to that of the treatment of any composite material comprising at least two lamellar layers glued to each other which it this is to ensure the acceleration of the bonding point of the corresponding bonding planes.

These may for example be simple two-layer panels, or structures carrying a number of layers greater than three.

In all cases, although the arrangement described is suitable for the radiation source used in elongated action zones parallel to the direction of travel of the composite material to be treated, with the advantages mentioned, it would not escape to the field of application of the invention by ensuring that this action zone is elongated transversely with respect to such a direction of travel, assuming that the wavelength is suitable in such a case of the radiation used.

Claims (17)

1. Method for accelerating the bonding of a composite material comprising at least two lamellar layers glued to each other, of the type according to which said composite material is jointly subjected, on the one hand to a source of treatment specific to the acceleration of bonding setting sought and on the other hand to pressing means suitable for holding the glued layers concerned against each other, such a method characterized in that one chooses 10 as a treatment source, a radiation source and in that the composite material to be treated is scrolled vertically above the action zone * of this radiation source. 2. Method according to claim 1, characterized in that the area of action of the radiation source on the composite material to be treated is limited to a portion of the surface thereof. 3. Method according to claim 2, characterized in that the zone of action of the radiation source on the composite material to be treated is limited to one or more strips of surface of this material elongated parallel to its direction of travel. 4. Method according to any one of claims 1 to 3, characterized in that the radiation source is a source of high frequency radiation. 25 5) Method according to any one of claims 1 to 3, characterized in that the radiation source is a microwave source. 6. Method according to any one of claims 1 to 5, characterized in that the pressing means used 3. are air cushions. 7. Method according to claim 6, characterized in that the advance means used to ensure the movement of the composite material to be treated are distinct from the pressing means. 35 8) Method according to any one of claims 1 to 5, characterized in that the pressing means used jointly form advance means suitable for ensuring the movement of the composite material to be treated. 9. Device for accelerating the setting of the adhesive: “* 'V * * 14 läge of a composite material comprising at least two lamellar layers glued to one another, of the kind comprising pressing means suitable for holding the glued layers concerned against each other, characterized in that it further comprises, in combination, a source of radiation suitable for ensuring the desired bonding acceleration sought and means for advancing suitable for ensuring that the composite material to be treated runs in line with the area of action of this radiation source. 10 10) Device according to claim 9, characterized in that transversely with respect to the direction of travel of the composite material to be treated, the area of action of the radiation source is fractionated. 11. Device according to any one of the claims 15 tions 9, 10 characterized in that the pressing means comprise two boxes generating air cushions defining between them a slot in which is allowed to pass the composite material to be treated. 12. Device according to claim 11, caractéri-20 se in that at least one of said boxes is mounted floating for example under the control of jacks. 13. Device according to any one of claims 11, 12, in which the radiation source comprises action means, for example electrodes, characterized in that said action means are associated with the perforated bottom * of the at least one of the air cushion generating boxes. 13 V * * ♦ 14. Device according to claim 13, characterized in that said action means are incorporated in the perforated bottom of at least one of the boxes generating air cushions. 15. Device according to any one of claims 13, 14, characterized in that said action means are divided transversely with respect to the direction of travel of the composite material to be treated. 35 16) Device according to claim 15, character ized in that said means of action are elongated parallel to the direction of travel of the composite material to be treated. 17. Device according to any one of claims 9, 10, characterized in that the pressing means com-40 carry endless conveyors forming by themselves the associated advancing means.