LU86796A1 - METHOD AND INSTALLATION FOR FORMING A SOLID LAYER OF INTUMESCENT MATERIAL, AND SOLID LAYER OF INTUMESCENT MATERIAL - Google Patents

Description

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A i GRAND ni (. 1E Di- LUXEMBOURG

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ÿMister the Minister of 27 .feb J 987 of the Economy and Classes Mo \ ennes * IX ^ rAisi

Intellectual Property Service

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., · Application for Patent of invention 'Url · .............................. — ....... ..........................................-....... ..__............................................... ..-................, · -------------—.....-....... (1) I. Application

The company ..... anonymous GLAVERBEL, 166 ...... chaussée.de ....... la..Hu] pe, .BJ 17Û Bruxel 1 es (2) represented, by MM, .. ..... Freyl i nger Ernes t l ...... & ..... Meyers ..Ernest, .ing. cons. in .propr.ind., ...... 46. rue ..... du ..... Cimetière., ...... Luxembourg. "________________________________________________, ......

acting in ..... capacity ..... of ..... agents ___________________________________________________________________________.... (3) remove! nt) cc ...... V ingt-sept ..... f..é.v..ri er ..... mi.l.-D.euf ...- cent .... .quatr.ery..i.ngt-sept .................................. (4) to ............ 3.00 p.m., at the Ministry of the Economy and the Middle Classes, in Luxembourg: 1. this request for obtaining a patent of invention concerning: ... " ...... Process ..... and Jnstal lation ...... to — form ...... a ..... a layer ...... solid ..... of. ..material .........-...... (5) ............. intumescent., ... and ..... layer .. ... solid ...... of ..... intumescent material ............................... ............................

2. description in French .................... language ....................... .................... of the invention in triplicate; 3 ..................................] .............. ........... drawing boards, in triplicate; 4. the receipt of the taxes paid to the Luxembourg Registration Office, on February 27, i987: 5. the delegation of power, dated Bruxel 16S ............ ......................... February 25! 987 .............; 6. the successor document (authorization); declares (s) assuming responsibility for this declaration, that P (es) inventors) is (are): (61 - Marcel DE BQEL, rue ..... de Brabant 184 a ...... B - 6070 Châtelet ............................................

- Pierre GOELFF, rue Grand Douze Bois 31 ,. B - 6290 Na 1 innate ______________ _______________________________ claim) for the above patent application the priority of one (or more) applicants (7) ..................... ....................................... · ../ / ...... .................................................. ............. filed in (8) ............................. .................................................. ................

on (9) ..... ......................................... .............................. .................... .................................................. ................................................-- ---------------------------------------........... ......- under the N ° (10) .............. // .................... .................................................. ............... ........ ........................... .................................. ................ ................................

on behalf of (11) _______________ // ......................................... ........................................... ....... .................................................. ................... .....................—. -..........

elect! elect) domicile for him / her and, if designated, for his / her representative, in Luxembourg -------------------------— --- ------------------------ 46 ..... rue du Cimetière ................. .................................................. .................................................. ..............._.................................. . (12) sollpatpat) the grant of a patent for the invention for the subject described and represented in the abovementioned appendices, with postponement of this grant to ................. .......... dïx-hui________________________________________________________________________ month. (13)

The depositor / agent: _____________________....______________________________________________________________________________________ (14) MEYERS ^ ErneS t Minutes of Deposit

The above-mentioned request for a brevej ^ PiffêeiUion has been filed with the Ministry of the Economy and the Middle Classes, Service of Property Intdl ^ fceDe'a'fe ^ embourg, dated: 27 févrî ΘΓ 1987 /> v \, ' - - | ^ 1 Pr. The Minister of the Economy and the Middle Classes, 4 to ............ 3.00 p.m. 4 ^ 1 p. I.

^ J The head of the Intellectual Property Department.

A68D07_ _ / / _ / A; EXPLANATION OF THE DEPOSIT FORM. * y [, î (1) if applicable "Request to certify addition to the main patent, to main patent application No ........... of ....... ..... "- (2 nscnrt the last name, first name, profession address of the applicant, when it is a private individual or the corporate name, legal form, address of the registered office, when the operator is: · a legal person - ( 5 · register lf "c name tvrénnm arlmctp rtu mnnirâmri" ηστ £ /> mn ^ pil en ητηηή ^ Γ ^ inrinctrielle. Muni H'nn nmjVrttr snAîial β'Π va îiVur ** rcnréw? Nlè? Î5r _...... .. as Mandate-iire "BL-4005 / vdw» *

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DESCRIPTIVE MEMORY filed in support of a PATENT INVENTION APPLICATION in Luxembourg for "Method and installation for forming a solid layer of intumescent material, and solid layer of intumescent material"

GLAVERBEL

166 chaussée de la Hulpe B - 1170 Brussels ^ Λ 1.

The present invention relates to a method and an installation for forming a solid layer of intumescent material on a support by drying an aqueous solution of said material, and to a solid layer of transparent intumescent material consisting of a hydrated alkali metal salt.

Layers of intumescent material are frequently used in the field of fire panels. In this case, one or more layers of intumescent material 10 are associated with a rigid sheet, for example this or these layers are sandwiched between two sheets, ün case of frequent and important application lies in the production of fire-resistant glazing transparencies in which one or more layers of intumescent material are sandwiched between transparent sheets. It is then imperative that the or each layer of intumescent material has a high transparency and suitable optical qualities to be incorporated into a glazing.

The layers of intumescent material are generally formed from an aqueous solution, containing for example at least 50% water, or from a suspension of the intumescent material, poured onto a support, from which causes or allows water to evaporate to form a solid layer. Intumescent materials generally consist of hydrated metal salts and especially hydrated salts of aluminum or an alkali metal.

A problem encountered when forming layers of intumescent material from a solution is the appearance of microbubbles in the layer. These microbubbles 30 appear during drying and their population tends to increase over time, even after the layer has hardened. These microbubbles tend to collect and merge so that the resulting larger bubbles become visible to the naked eye. It is clear that, if this does not in any way harm the intumescent and fire-resistant properties of the layer, it is unacceptable in a layer which must have high optical qualities.

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Precautions can be taken to reduce this formation of microbubbles during the drying operation, for example by boiling the solution before pouring it onto its support to form a layer. A certain improvement has been obtained without however succeeding in completely suppressing the appearance of the microbubbles after the drying operation.

Another problem encountered when drying layers of intumescent material is the appearance of waves or undulations on the surface of the layer. These waves can significantly deteriorate the quality of the finished product or at least make it more delicate to assemble, if necessary, with a sheet of glass.

When using layers of intu-mescente material in glazing, there is also sometimes a rapid aging of these layers over time. It results in particular in the appearance of a veil which disturbs the transparency of the glazing provided with this layer. This deterioration in the appearance of the glazing over time is obviously detrimental to its use.

The studies carried out have generally shown that the conditions under which the drying operation is carried out, mainly the characteristics of the surrounding atmosphere, have a primary importance on the quality, in particular optical quality, of the layers formed.

Obtaining a transparent hard layer · of intumescent material having good optical qualities, by drying a liquid is a delicate operation which must be carried out under good conditions. The temperature must be sufficiently high, for example close to 100 ° C. at normal atmospheric pressure in the case of hydrated solutions, to allow a relatively rapid hardening, but not too high to avoid premature intumescence of the material constituting the layer. . It is often preferable that the humidity of the atmosphere is high enough to prevent the surface from w J * * 3.

dries too quickly which could lead to cracking. In addition, in some cases, the atmosphere may have a particular composition. It is generally necessary to properly control all of these operating conditions.

An obvious concern in the case of the manufacture of fire panels is the obtaining of a layer with high fire performance. This is a point to which it is necessary to be attentive 10 in order to avoid certain improvements in the optical qualities of the layer being made at the expense of its fire performance.

One of the main objects of the present invention is to improve the optical quality of the layers of intumescent material and in particular to reduce or eliminate the formation of microbubbles while providing them with good fire resistance properties.

The present invention relates to a method for forming a solid layer of intumescent material on a support by drying an aqueous solution of said material, characterized in that a layer of said solution is deposited on the support, reduces its water content during a first drying step, and then distributes, during at least one subsequent step taking place at a temperature below the maximum temperature of said first step and above room temperature, the water content of said layer uniformly throughout the volume of the layer.

The Applicant has found that by carefully choosing the operating conditions, the method according to the invention makes it possible to significantly improve the qualities of the resulting solid layer, in particular its surface state and its optical qualities while ensuring good fire resistance. The Applicant has found, for example, that the invention thus leads to a substantial reduction in the formation of microbubbles inside the mass of the layer.

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it is believed that these interesting results are mainly due to the uniformity of the residual water content in the layer produced during the said subsequent step or steps.

5 Variations in residual humidity may exist, for example, between the core of the layer and the surface areas. Indeed, the water contained on the surface of the layer can evaporate easily while the water contained inside the layer must first migrate to the surface 10 before it can evaporate. Local variations in the residual moisture can also appear between different places on the surface of the layer such as for example between the center and the marginal zones of the layer. These variations may be due to the immediate environment of the layer at the time of the drying operation, which may be slightly different from one place to another following the operating conditions. Indeed, the concentration of water in the atmosphere above the layer and the movements of this atmosphere can vary from one place to another, following for example the ventilation generated by a system of regulation of the atmosphere if the case occurs. These variations may also be due to slight differences in the thickness of the layer.

The uniform distribution of the residual water content of the layer also improves its fire resistance properties. Indeed, under the action of fire, the intumescence of the layer will be more regular and will thus constitute a screen against heat which will be more effective.

When distributing the water content in the layer, the overall content may have already reached its final value. This distribution of the residual water content is then carried out without loss of water in the layer.

Preferably, however, advantage is taken of the step or steps for distributing the water content of the layer in order to continue reducing this water content. This allows an easier and more uniform distribution of the humidity level of the layer. This also makes it easier ▼ 5.

* ¥ obtaining an optimum quality layer. In fact, by avoiding reducing the water content to its final value during the first step, the risk of forming, during this step, certain defects, such as cracks, which is difficult to remove, is reduced. in a later step.

Or can very quickly carry out the first stage of drying the layer, for example by means of a microwave oven, and then eliminate the humidity gradients by distributing the water content uniformly in the 'entire layer volume to improve its fire and optical qualities.

Preferably, however, said first drying step, during which most of the quantity of water to be removed is evaporated from the layer, extends over at least one hour at a temperature above 50 ° C. and is followed by at least one said step of distributing the degree of humidity having a total duration at least as long as the duration of said first step; these different steps 20 take place in an atmosphere whose humidity level is greater than 50%, The spreading of the first drying step, during which most of what has to be removed is evaporated, over a minimum of one hour under conditions of temperature of at least 50 ° C. and in an atmosphere of which the humidity degree is greater than 50% provides conditions favorable to hardening which, without being too slow, reduces the risk of deteriorating the qualities of the layer irreparably.

The time allowed in the successive stages is largely compensated by an important advantage of the invention, since it allows a simple and easy obtaining of a high quality layer, even in large series, on an industrial scale. It should also be noted that, if the first step 35 takes place at a higher temperature than the subsequent step or steps, as it is during this step that the major part of the quantity of water to be eliminated is evaporated, the f i 6.

total treatment time is significantly less than if all treatment was carried out at a constant lower temperature.

To obtain a layer having good optical and fire-resistant qualities, the curing cannot be too rapid, this is why the duration of this first step is preferably at least one hour. The stage (s). subsequent distribution, meanwhile, further enhance these qualities of the layer. The method 10 according to the invention therefore offers a good compromise between obtaining a layer having good qualities and a treatment time which is not too high.

Advantageously, during the first stage, the water loss is on average greater than 0.6% per hour, by weight relative to the quantity of starting water, while it is on average less than 0, 3% per hour, by weight relative to this same starting quantity, during the subsequent stage or stages. This makes it possible to optimize the compromise between the processing time and the quality of the layer.

Preferably, the subsequent distribution step or steps are carried out at a temperature below 80 ° C. A temperature of the order of 70 ° C to 75 ° C may for example be suitable. It has been found in fact that a prolonged stay of the layers at high temperature has a detrimental influence on the optical quality of the layers and particularly on the transparency of the layer after aging.

In this context, the average temperature of the first stage of drying can be situated at around 75 ° C. for example, while the subsequent stage or stages are carried out at a temperature of the order of 65 to 70 ° C. But advantageously, a better compromise is obtained between the quality of the layer and the duration of the treatment if, during the first drying step, the average temperature -3b is not more than 80 ° C. while the subsequent step or steps of distribution takes place at a temperature below 65 ° C.

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To allow the temperature and humidity to be easily adjusted and controlled, it is preferable that the layers to be formed are placed in an enclosure such as an air-conditioned room, for example 5 closed chamber in which the temperature and humidity of the atmosphere are controlled and regulated by an adequate servo system. The successive stages of treatment for a given series of layers can take place in the same enclosure.

Preferably, however, said first step on the one hand and the subsequent step or steps on the other hand, take place in separate enclosures inside which the humidity of the atmosphere is controlled. If desired, one or each of the drying chambers 15 may consist of an autoclave for drying under high pressures, but it is simpler and more economical, and therefore preferred, for the chambers to be maintained at atmospheric pressure. or near-atmospheric. The atmosphere of the enclosures can also, if desired, be constituted or contain a gas less soluble than oxygen in the intumescent material such as SF6, CH4, N2 or cyclohexane for example. But it is obvious that the use of such atmospheres increases the production costs and that is why it is generally preferred that the atmosphere consists of air and water vapor for controlling the ambient humidity. . The different enclosures will preferably be air-conditioned rooms.

The Applicant has unexpectedly found that the fact of dividing the operation of forming the layer 30 into at least two stages each taking place in separate chambers not only makes it possible to obtain a layer having good optical quality but also makes it possible to '' improve the utilization rate of drying chambers.

35 This result is surprising because the interruption of the hardening process to allow the manipulation necessary for the passage from one enclosure to another should have 8.

obviously lead to the opposite result. Indeed, the reestablishment of ordinary ambient conditions in the enclosures to effect transfers, manipulations and return to drying conditions are operations which require a certain amount of time and this amount of time is lost for the operation proper drying. In addition, the upheavals of the thermal and hygrometric regimes that this provokes should obviously have increased the risks of deterioration of the optical qualities of the layer.

Most of the amount of water to be removed is preferably evaporated during the first step. It is also the delicate moment when the viscosity of the diaper increases rapidly. This step must therefore preferably be carried out in a very specific primary enclosure. This primary enclosure is relatively sophisticated to allow effective control of its atmosphere, particularly with regard to temperature and humidity. It will generally be subjected to severe corrosion conditions given the high temperature and humidity, which therefore represents a high investment. On the other hand, the evaporation of a relatively large amount of water at the start of drying requires a fairly large free space above each layer. The space occupied by a small number of layers to be dried is large, which means that the rate of use of said primary enclosure is low.

The fact of interrupting the manufacture of the layer to complete it during at least one subsequent step 30 carried out in a secondary enclosure makes it possible to release said primary enclosure so that it can be used for the first drying step of a new series of layers. This secondary enclosure can be much less sophisticated because the control of the atmosphere is generally less critical and the corrosion conditions are less severe, in particular due to the fact that the temperature is lower. The invention therefore allows better profitability * 9.

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the various enclosures by developing and making the most of their specialization.

Before the drying operation begins, the layer of intumescent material is relatively fluid since it contains a large amount of water. It is therefore necessary to maintain the support in a horizontal position to prevent the layer from flowing out of the support and to maintain an even thickness of the layer. This position can also be adopted for the subsequent step or steps.

Preferably, however, during the first drying step, the support is placed in a horizontal position while during the subsequent step or steps, the support is placed in a position clearly distinct from the horizontal hori-15. The most suitable position for this or these subsequent steps is the vertical or quasi-vertical position. It is obvious that to place the support in a strongly inclined position, the layer must at least be hard enough not to creep. This way of proceeding makes it possible to store the supports, provided with their partially hardened layers, vertically next to each other by separating them using a simple interlayer during the subsequent step or steps and to superimpose pl \ i-several rows of supports thus arranged.

25 This arrangement promotes a significant saving of space compared to the space occupied by the same number of supports during the first drying step. Indeed, in the case of a horizontal arrangement, the separation between the different layers, required to allow the water to pass from the layers to the environment and to avoid damaging the layers, requires, for each layer support , a sufficiently rigid supporting structure such as shelves for example. In the vertical position, on the other hand, a single rigid supporting structure can support a large stack of supports provided with their layer. The number of supports carrying a layer of intumescent material in the process of drying can thus be greatly increased for a 10.

, the location on the ground given. The yield, and therefore also the cost price, during mass production can thus be significantly improved.

An appreciable advantage which is deduced from the consequences of this manner of proceeding is the possible increase in the time devoted to the subsequent step (s) without delaying the start of the first drying step of the following volumes and without too much clutter at ground. This extension of the time of the subsequent step or steps is very beneficial for obtaining a high quality layer free of microbubbles.

The first step can be stopped when only a small amount of water remains to be removed from the layer. In the case of a change in the position of the support, the second step can be started at any time after the layer is sufficiently hard. However, the greatest benefit will be obtained if the first drying step is stopped as soon as the layer is viscous enough to no longer flow by gravity. This viscosity is such that it allows or facilitates the uniformity of the degree of humidity during the subsequent step or steps. In the case of a change in the position of the support, one can also make the most of the advantage obtained thanks to the substantially vertical position of the volumes treated. For example, for layers based on hydrated sodium silicate, the first drying step is preferably stopped when the layer contains between 35% and 40% of water. This range of water concentrations has been found to be the most favorable for terminating the first step and starting the subsequent step (s). This water concentration is low enough to allow handling without risking the creep of the layer and still high enough to derive maximum benefit from the separation of the treatment in several stages.

35 By the expression "so as not to flow by gravity", is meant, in the present specification, the fact that the layer is not subjected, during the whole time of the treatment, Μ 11.

no significant deformation due to its strongly inclined position.

The duration of the treatment depends of course partly on the thickness of the coat to be formed. For the most common intumescent layers 5, the thickness of which, once the layers are hard, is around one millimeter, the first step may take just under 12 hours and the distribution step may be extend over a dozen hours to make a total cycle of 24 hours for example. Advantageously, however, the total duration of the subsequent step or steps is at least three times as long as the duration of the first drying step. This period of time allows reorganization by diffusion of moisture into the layer after the first stage has dried faster. In the case of the use of separate speakers, this clearly militates for improving the performance of the speakers, because the primary enclosure in which the first stage takes place is thus occupied for a minimum of time with the same series of layers to be form, which makes it possible to best use the specificity of the different speakers.

Preferably, the total duration of the subsequent step or steps is at least 30 hours. This favors obtaining good homogeneity of the residual moisture in the layers. One can, for example, organize the production so that the subsequent step spans 48 hours while the first step spans 24 hours. One could thus carry out a cycle during which a primary enclosure intended for the first stages of drying would supply two secondary enclosures specialized for the 30 stages of distribution.

Advantageously, the total duration of the subsequent step or steps is at least 72 hours.

The Applicant has found that this significant elongation of the subsequent step makes it possible to improve the optical quality of the layer and in particular to significantly reduce the formation of microbubbles inside the mass of the layer. It is believed that the extension of time by 12.

treatment towards the end of the process, i.e. at a time when the viscosity of the layer slows down the migration of water inside the mass, promotes the homogenization of moisture throughout the mass by tending towards the establishment of equilibrium conditions. Equilibrium conditions prevent the further development of microbubbles. This fairly long treatment time during the subsequent stage favors the gradual establishment of a uniform degree of humidity in the layer which makes it not very sensitive to storage conditions pending the mounting in the panels. fire stop for example.

This extension of the treatment time surprisingly departs from the usual drying techniques in this area. In fact, research efforts are generally focused on reducing the drying time of the intumescent layers in order to reduce the cost prices.

Advantageously, the subsequent step or steps take place at a temperature maintained between 35 ° C and 55 ° C, and preferably between 40 ° C and 50 ° C, and in an atmosphere 20 whose hygrometric degree is maintained between 55% and 90 % relative humidity. These humidity and temperature conditions favor a good end of the drying operation if necessary as well as a good homogenization of the hygrometric degree of the layer. These conditions are also very advantageous for avoiding the appearance of waves on the surface of the layer during the end of the treatment due to rewetting of the surface layers. On the other hand, these temperature and humidity conditions, less severe from a corrosion point of view than the usual conditions for drying this type of layer, allow the use of enclosures whose cost is lower.

Ideally, a first part of the subsequent step or steps takes place in an atmosphere in which the relative humidity is maintained at least 77% relative humidity, and the relative humidity is then reduced to a value less than 77%. These conditions make it possible to establish a gradient of chemical potential at the start of second 13.

, a step which is favorable to standardization and therefore to obtaining good optical qualities, and to approach normal atmospheric conditions and thermodynamic equilibrium conditions at the end of treatment.

The flat support on which the layer to be dried is applied may consist of a smooth sheet of plastic material for example. This support could be a temporary support, that is to say that once sufficiently cured, the e layer would be removed from the support to be used while the support would receive a new layer to be cured. However, it is obvious that this operation is delicate to guarantee the integrity of fragile layers. It is therefore preferable that said flat support is not separated from the formed layer and enters into the composition of the finished product, and preferably, the flat support comprises at least one sheet of glassy material. After the drying operation, the glass sheet provided with the hardened layer is thus ready to be assembled with another glass sheet for example to constitute a fire-resistant glazing.

The present invention can be applied to the drying of different intumescent materials and particularly materials comprising a hydrated metal salt, especially a hydrated salt of aluminum or an alkali metal. Examples of suitable salts are: aluminates p. ex. lead sodium or potassium aluminate p. ex. sodium or potassium leadate

Stannates p. ex. sodium or potassium stannate alum p. ex. double sodium and aluminum sulphate or double potassium and aluminum sulphate borates p. ex. sodium borate phosphates p. ex. sodium orthophosphate, potassium phage orthophos and aluminum phosphate.

Preferably, however, the layer of intumescent material to be dried contains hydrated alkali silicate.

Such materials exhibit excellent performance.

fire mances. They are in many cases capable of forming light transmitting layers which have good adhesion to glass or to a glass-crystal material. If this material is subjected to sufficient heating, for example in the event of a fire, the water combined therewith boils and the layer begins to foam, so that the hydrated salt is converted into an opaque porous mass which constitutes a good thermal insulator while adhering to glass or vitrocrystalline material. This phenomenon is particularly important, since even if all the sheets of a panel are cracked or broken by thermal shock, the panel can retain its effectiveness as a screen against heat, as well as against fumes, because the leaf fragments remain in place, maintained by the transformed metal salt.

Preferably, the intumescent material to be dried contains hydrated sodium silicate. Sodium silicate has the additional advantage of being relatively inexpensive and of making it possible to produce a layer 20 very similar, from a visual point of view, to ordinary glass.

The invention extends to a solid layer of transparent intumescent material formed according to a method as described above.

The invention also relates to a solid layer of transparent intumescent material consisting of a hydrated alkali metal salt characterized in that its water content is distributed substantially uniformly throughout the entire volume of the layer, as well as to a solid layer of transparent intumescent material consisting of a hydrated alkali metal salt characterized in that it is substantially free of stresses. One can in particular verify this state of stress by means of a polarizer according to techniques known in the art.

During the drying operation, the surface of the layer naturally tends to be drier than the inside. This humidity gradient tends to generate 15.

mechanical stresses so that the surface is put in tension. These constraints may possibly be such that there is the appearance of cracks on the surface. A layer whose residual water content is uniformly distributed or which is free from stresses has increased stability. This is an important advantage in particular by the fact that storage or subsequent handling is less likely to deteriorate its optical properties for example. The Applicant has found that such a layer 10 was less likely to develop microbubbles.

The invention also extends to a transparent fire-resistant glazing comprising at least one such solid layer of intumescent material associated with at least one sheet of glass.

lb The invention also relates to an installation for forming a solid layer of intumescent material on a support by drying an aqueous solution of said material, characterized in that it comprises at least one primary enclosure comprising one or more load-bearing structures intended to receive said supports in a horizontal position and at least one secondary enclosure intended to receive said supports in a strongly inclined position relative to the floor of the enclosure, and in that the temperature and humidity of the atmosphere of each of the 25 said speakers are adjustable.

This installation is advantageous in that the speakers can thus be specialized. The primary enclosure receives said supports, in a horizontal position on load-bearing structures such as shelves or suspended shelves, carrying a relatively fluid layer with a lot of water to be evacuated. Its construction and its accessories may be more particularly able to cope with the processing conditions of this layer. The secondary enclosure receives the supports in an inclined position 35 when the layer is already hard enough to no longer creep. The treatment conditions may therefore be different from the treatment conditions in the enclosure ”16.

primary and this secondary enclosure can be more particularly adapted to it, in particular as regards the system for regulating the atmosphere and the constitution of the walls of the enclosure. In addition, the space saving per unit 5 of floor space in this enclosure. secondary, due to the almost vertical position of the supports, increases the rate of use of the speakers. The secondary enclosure can be filled by a series of carriages carrying the supports provided with their layer in an almost vertical position.

Preferably, the or each secondary enclosure delimits a surface on the ground which is at most equal to half of the surface on the ground delimited by the or each primary enclosure. This arrangement allows a significant gain in the location on the ground occupied by the same number of 15 layers in formation without disturbing the atmosphere surrounding a series of layers in treatment.

This installation is particularly advantageous for implementing the method according to the invention. The step of distributing the water content of the layer, as soon as the latter is sufficiently hardened to no longer flow by gravity, can be carried out in said secondary enclosure.

Preferred embodiments of the invention will now be described by way of example only, with reference to the accompanying schematic figures in which:

Figure 1 shows a schematic sectional view of a primary enclosure for drying layers of intumescent material.

FIG. 2 shows a schematic sectional view 30 of a secondary enclosure in which the water content of layers of intumescent material is distributed.

Example 1. (fig.l)

Supports constituted by sheets (1) of soda-lime glass of ordinary composition having a thickness of 3 mm are placed on shelves (2) inside an air-conditioned chamber constituting a primary enclosure (3). Particular care will be taken to ensure that these 17.

sheets are arranged as horizontally as possible. An adhesive border (4) or any similar means is arranged at the periphery of each glass sheet so as to. make a kind of container. A solution (5) of sodium sili-cate having the proportion by weight SiC> 2 / Na 2 O of 3.4 and containing 64% of water, to which 2% of glycerine has been added, is poured onto the upper face. of each glass sheet in the container delimited by the adhesive. The thickness of the deposited solution is 2.8 mm to obtain a layer of 1.2 mm after curing. The free spaces above each layer and between a support and its neighbors are left large enough to allow easy evaporation and unhindered circulation of the surrounding atmosphere.

The chamber is then closed to begin the drying process. The temperature inside this chamber is gradually raised to 95 ° C in about 3 hours. The regulation system (6) of the atmosphere of the chamber also controls an injection of water vapor 20 so that the relative humidity is gradually brought there from 50% to 80%. This first drying step is extended for a period of 8 hours. It is thus a relatively rapid drying for this type of layer. Without opening the chamber, the temperature is then gradually reduced to 75 ° C in order to begin the next step of distributing the degree of humidity in the layer. This temperature drop is achieved in 2 hours and during this time, the humidity of the chamber is gradually increased to around 85%. At this time, the layer contains 30 between 35 and 40% water. The total duration of the second stage is 40 hours. The humidity of the chamber is maintained at around 85% for 25 hours then is gradually reduced to conditions closer to normal conditions, that is to say around 75%. When the 35 layers are removed from the chamber, they contain just under 30% water.

A sheet of glass provided with its hardened layer is there 18.

then assembled with another glass sheet also or not provided with a solid layer of intumescent material. This assembly is then subjected to calendering or to a pre-bonding under vacuum according to known techniques, then intro-5 duit in a pressure autoclave to produce a fire-resistant laminated glazing.

In order to quantitatively specify the optical quality of the layer from the point of view of microbubbles, an arbitrary bubble index has been defined such that the lower its value, the better the quality of the layer. We delimit four triangular surfaces of 1/4 cm ^ and we count the bubbles corresponding to the diametral classes of 0-25μ; 2b-50p; 50 ~ 75μ and 75-100μ. A number of points is allocated proportional to their visibility, 15 respectively 1; 4; 9 and 16. I / bubble index considered is the arithmetic mean of the numbers of total points corresponding to the four ranges considered, reduced to cm ^ by multiplying by 4. For ease, the comparison is made, with a few standard samples whose value of the bubble index was previously calculated.

After an accelerated aging of 5 days at 80 ° C., it was found that the optical qualities of the layer were very good and in particular that very few microbubbles developed and that the transparency of the layer was not impaired, while the fire performance was very high. The bubble index was less than 150.

By way of comparison, a layer of the same composition and of the same thickness was subjected to a single drying step according to the prior art for 18 hours at 95 ° C. and at 80% relative humidity to bring the layer directly to a residual water capacity of approximately 30%. In this case, we have already observed the appearance of a few microbubbles in the layer after treatment and these have developed during aging to lead to a fairly large population downgrading the quality of the glazing produced. The bubble index was above 800. In addition, there was also a slight tarnishing of the 19.

layer. The fire performance was similar to that of the glazing according to Example 1.

Example 2. (Fig. 1 and 2)

In this example, the supports (1) are placed on 5 of the shelves (2) inside an air-conditioned chamber constituting the primary enclosure (3) and the layers (5) are prepared for hardening on these supports (1 ) in the same way as for example 1 above, except that 4 l / m ^ of liquid are poured in order to obtain a hard layer of 1.7 mm.

The chamber (3) is then closed to start the drying process. The temperature inside this primary enclosure (3) is gradually raised to 95 ° C and the relative humidity is gradually increased from 50% to 80%, thanks to the regulation system (6). This first drying step is extended for a total period of 17 hours. Before the end of this period, the temperature is gradually brought back to room temperature and the humidity is gradually lowered to 55%. At this time, most of the amount of water to be removed is evaporated and the layer is sufficiently cured that the support can be placed in an upright position. However, it still contains around 38% water.

The chamber (3) is then opened and the glass sheets provided with their pre-dried layer are evacuated from the chamber to make room for a new series of layers to be dried. They are transported, using trolleys (8), to a smaller secondary enclosure (7) (fig. 2). In this secondary enclosure (7), the sheets 30 (1) provided with their layer (9) are placed almost vertically on trolleys (8) so that the assembly occupies less space compared to the place occupied in the 'primary enclosure (3, fig.l). The small free space around the layers is possible at this point in the drying cycle since most of the amount of water which must be removed from the layer during the entire drying operation is already evaporated. In FIG. 2, only 20 has been shown.

3 sheets with their layer per cart; it is obvious that in practice this number of leaves will be greater.

Using the regulation system (10), the temperature of this secondary enclosure (7) is gradually raised to 50 ° C. and its relative humidity is gradually brought to 85%. This high humidity value is maintained for 24 hours and it is then gradually reduced to approximately 75% r which corresponds to an equilibrium value of the residual water content in the layer (9) situated around 30% in weight. This latter value of relative humidity is also maintained for 24 hours. Over the past few hours, the temperature has gradually returned to room temperature. The 15 glass sheets (1) provided with their layer (9) are then removed from the secondary enclosure (7).

During this time, the primary enclosure (3) could carry out the first stage of drying for at least two series of layers. The first series having supplied a second secondary enclosure, the second series can in turn be introduced into the present secondary enclosure (7). It is thus seen that the output of each specialized enclosure can be increased.

The location on the ground required by this secondary enclosure (7) for the same number of volumes is significantly lower than that required by the primary enclosure (3). It is therefore possible to process a larger number of volumes for the same location.

As in Example 1, fire-resistant laminated glazing 30 was produced from the glass sheets provided with their layer of intumescent material thus formed.

After accelerated aging, a bubble index of between 150 and 300 was noted, while the fire performance was even better than for Example 1 above, in particular because of the higher thickness of the layer. . The transparency of the layer was also very good.

21.

In the case of a single drying step, of an identical layer, according to the prior art of 26 hours at 95 ° C and under 80% relative humidity, the appearance of microbubbles has already been observed at the end of treatment and these have grown significantly during aging. The bubble index was incalculable as there were so many. In addition, an appreciable tarnishing of the layer was also observed. The fire performance was quite similar, however.

As a variant of this example 2, the second stage has been extended to reach a total duration of 5 days. In this case, the bubble index was almost zero.

In a second variant of Example 2, the average temperature of the first drying step was 60 ° C. and this step lasted 38 hours. Standardization took place in two stages, at 40 ° C, 24 hours each. The first at 80% relative humidity, the second at 70%. The bubble index was around 150 and there was no tarnishing. It should be noted, however, that the processing time in the first chamber in this case was significantly higher.

In another variant of the above examples, potassium aluminate was used as the intumescent material to also obtain good results.

Claims (22)

22. 9 1. A process for forming a solid layer of intumescent material on a support by drying an aqueous solution of said material, characterized in that a layer of said solution is deposited on the support, the content of water is reduced. during a first drying step, and then distributing, during at least one subsequent step taking place at a temperature below the maximum temperature of said first step and above ambient temperature, the water content of said layer evenly throughout the volume of the layer. 2. Method according to claim 1, characterized in that during at least one step of distributing the water content of the layer, one continues to reduce this water content. 3. Method according to one of claims 1 or 2, characterized in that said first drying step, during which the major part of the quantity of water to be removed is evaporated from the layer, extends over at least one hour at a temperature above 50 ° C and is followed by at least one so-called moisture distribution step having a total duration at least as long as the duration of said first step, and in that the various steps take place in an atmosphere with a humidity level greater than 50%. 4. Method according to one of claims there 3, characterized in that during the first step the water loss is on average greater than 0.6% per hour, by weight relative to the amount of water starting point, while it is on average less than 0.3% per hour, by weight relative to this same starting quantity, during the subsequent stage or stages. 5. Method according to one of claims 1 to 4, characterized in that the subsequent distribution step or steps are carried out at a temperature below 80 ° C. 6. Method according to claim 5, characterized in that during the first stage of drying, the average temperature * 23. rature is greater than 80 ° C while the subsequent stage or stages of distribution are carried out at a temperature below 65 ° C. 7. Method according to one of claims there 6, b characterized in that the said first step on the one hand and the subsequent step or steps on the other hand / take place in separate enclosures inside which the hygrometric degree of the atmosphere is controlled. 8. Method according to one of claims there 7, 10 characterized in that during the first drying step, the support is placed in a horizontal position while during the subsequent step or steps, the support is placed in a clearly distinct position from the horizontal. 9. Method according to one of claims 1 to 8, 15 characterized in that the first drying step is stopped as soon as the layer is sufficiently viscous to no longer flow by gravity. 10. Method according to one of claims 1 to 9, characterized in that the total duration of the subsequent step or steps is at least three times as long as the duration of the first drying step. 11. Method according to one of claims 1 to 10, characterized in that the total duration of the subsequent step or steps is at least 30 hours. 12. Method according to one of claims 10 or 11, characterized in that the total duration of the subsequent step or steps is at least 72 hours. 13. Method according to one of claims 1 to 12, characterized in that the subsequent step or steps take place at a temperature maintained between 35 ° C and 55 ° C, and preferably between 40 ° C and 50 ° C , and in an atmosphere where the humidity is maintained between 55% and 90% relative humidity. 14. Method according to one of claims 1 to 13, 35 characterized in that a first part of the subsequent step or steps takes place in an atmosphere whose hygrometric degree is maintained at at least 77% relative humidity i 24. ve, and in that the humidity is then reduced to a value less than 77%. 15. Method according to one of claims 1 to 14, characterized in that the planar support comprises at least one sheet of vitreous material. 16. Method according to one of claims 1 to 15, characterized in that the layer of intumescent material to be dried contains hydrated alkali silicate, and preferably hydrated sodium silicate. 17. Solid layer of transparent intumescent material formed by a process according to one of claims 1 to 16. 18. Solid layer of transparent intumescent material consisting of a hydrated alkali metal salt, characterized in that its water content is distributed substantially uniformly throughout the volume of the layer. 19. Solid layer of transparent intumescent material consisting of a hydrated alkali metal salt, characterized in that it is substantially free of stresses. 20. Transparent fire-resistant glazing comprising at least one solid layer of intumescent material according to one of claims 17 to 19 associated with at least one sheet of glass. 21. Installation for forming a solid layer of intumescent material on a support by drying an aqueous solution of said material, characterized in that it comprises at least one primary enclosure comprising one or more supporting structures intended to receive said materials 30 supports in horizontal position and at least one secondary enclosure intended to receive said supports in a strongly inclined position relative to the floor of the enclosure, and in that the temperature and the humidity of the atmosphere of each of said said enclosures are adjustable . 22. Installation according to claim 21, charac terized in that the or each secondary enclosure delimits a surface on the ground which is at most equal to half of the »25. 4 »*» floor area defined by the or each primary enclosure.