WO2002006180A1

WO2002006180A1 - Composition for gypsum plaster base board, method for preparing same and for making gypsum plaster base boards

Info

Publication number: WO2002006180A1
Application number: PCT/FR2001/002125
Authority: WO
Inventors: Claude Leclercq
Original assignee: Lafarge Platres
Priority date: 2000-07-18
Filing date: 2001-07-03
Publication date: 2002-01-24
Also published as: EP1303462A1; PL359092A1; AU2001272612A1; MXPA02012831A; BR0112993A; CA2418235A1; FR2811980A1; KR20030022863A; US20030138614A1; FR2811980B1; ZA200210272B; JP2004504252A; CN1443146A

Abstract

The invention concerns a gypsum plaster base board composition comprising: 55 to 92 % of calcium sulphate capable of being hydrated; 0.1 to 5 % of mineral and/or refractory fibres: 3 to 25 % of a mineral additive; 1 to 5 % of non-exfoliated vermiculite; 3 to 15 % of hydrated alumina. The invention also concerns a method for preparing said composition and a method for making gypsum plaster base boards. Said gypsum plaster base boards have improved fire resistance.

Description

COMPOSITION FOR PLASTERBOARD,

PREPARATION OF THIS COMPOSITION AND

MANUFACTURE OF PLASTERBOARDS

The present invention relates to a composition for plasterboard, a process for the preparation of this composition as well as a process for manufacturing plasterboard having a greatly improved fire resistance.

It is well known to use plasterboard to make partitions, coverings for vertical or inclined elements or to make suspended or unsuspended ceilings.

These plates generally consist of a core essentially of plaster, covered on each of its faces by a sheet serving both as reinforcement and facing and which can be made of cardboard or mats of mineral fibers.

American patent n ° US 3,616,173 describes a fire-resistant plate, of low density (between 0.64 and 0.8 g / cm ³ ), the heart of which is based on plaster, glass fibers, a mixture or not of clay, colloidal silica and / or colloidal aluminum oxide, and optionally unexpanded vermiculite. In this patent, it is specified that the oxides of silicon and aluminum, in the form of dry powder, are difficult to disperse and moreover, expensive. For this reason in particular, this patent recommends the use of clays. The plasterboard according to this patent has a shrinkage at high temperature which is quite low but its resistance to fire is limited. Such a plate therefore does not have the properties necessary to constitute good protection against fire.

European Patent Application No. 0 470 914 to the Applicant disclosed in 1992 a plasterboard intended for fire protection, the faces of which are covered with a reinforcing material based on threads and / or fibers. mineral and / or refractory material. The heart of this plate includes: - 55 to 94% plaster,

0.1 to 5% of mineral and / or refractory fibers, 2 to 25% of silica, 1 to 15% of talc and / or mica, - and optionally aluminum hydroxide and / or expanded vermiculite . Since then, the Applicant has continued its work in the field of plasterboard, with a view to improving, at the same time, the mechanical strength when hot, the kinetics of shrinkage and the thermal transfer of its plasterboard.

It has now achieved its objectives by developing a composition for plasterboard comprising: from 55 to 92% hydratable calcium sulphate; from 0.1 to 5% of mineral and / or refractory fibers; from 3 to 25% of a mineral additive; from 1 to 5% unexpanded vermiculite; 3 to 15% hydrated alumina.

According to a preferred embodiment of the invention, the nature and the quantity of mineral additive are chosen so that the composition for plasterboard contains at most 2% of crystalline silica, and / or at most 1% of alveolar crystalline silica, that is to say having crystals of less than 5 microns. Such a composition then has the advantage of having a content of crystalline silica, in particular alveolar, in accordance with the recommendations of the International Agency for Research on Cancer, according to which the use of alveolar crystalline silica should be reduced as much as possible. this compound is presumed to have maximum toxicity. A second object of the invention is also a process for preparing a composition for plasterboard, in which the constituents of the composition for plasterboard defined above are mixed in any order.

Finally, the third object of the invention is a process for the continuous production of plasterboard, essentially comprising the following steps: - Preparation of a paste by mixing the different constituents of the composition with water, in a mixer; depositing the dough thus prepared on the reinforcement material, followed by the forming and coating of the upper face of the dough with a second reinforcement material; where appropriate, forming the edges of the plate obtained previously by molding the fresh plate on profiled strips, this forming consisting in particular in thinning the edges of the plate;

- hydraulic intake of hydratable calcium sulphate on a production line while the ribbon of hydratable calcium sulphate plate travels on a conveyor belt; cutting the ribbon at the end of the line, according to determined lengths; and drying the plates obtained.

Other characteristics and advantages of the invention will now be described in detail in the description which follows and which is given with reference to the drawings, in which: Figure 1 represents the evolution of shrinkage as a function of time for the plates Witness, A and B; - Figure 2 shows the evolution of the shrinkage as a function of time for the control plates, B, C and D, during another test;

- Figure 3 shows the temperature increase on the unexposed side of the witness plasterboards, A and B; - Figure 4 shows the temperature increase on the unexposed face of the witness plasterboards, B and C, during another test; and

- Figure 5 shows the temperature increase on the unexposed face of the control plasterboards and D, during another test.

The subject of the invention is therefore a composition for plasterboard making it possible to manufacture a plasterboard having greatly improved fire resistance.

This composition comprises (in% relative to the whole of the dry mixture): from 55 to 92% of hydratable calcium sulphate; - from 0.1 to 5% of mineral and / or refractory fibers; from 3 to 25% of a mineral additive; from 1 to 5% unexpanded vermiculite; 3 to 15% hydrated alumina. By "hydratable calcium sulphate" is meant, in the present description, an anhydrous calcium sulphate (anhydrite II or III) or a semi-hydrated calcium sulphate (CaS0,% H ₂ 0) in its crystalline form α or β. Such compounds are well known to those skilled in the art and are generally obtained by baking a gypsum. The mineral and / or refractory fibers are preferably glass fibers. They can be short (3 to 6 mm on average) or long (10 to 24 mm on average) or of intermediate dimensions. Preferably, glass fibers having a single length of 13 mm +/- 5 mm are used. In particular, fibers from type E glass are used, which can come in two forms, one called "roving" and designating strands of glass supplied in coils and cut before introduction into the usual circuit for mixing calcium sulphate hydratable with water or alternatively in the form of precut strands which are dosed before mixing the calcium sulphate hydratable with water.

Preferably, fibers having a length of about 13 mm (+/- 5 mm) and a diameter of about 13 microns (+/- 5 μm) are used. The essential function of glass fibers is to impart mechanical resistance at high temperature, which helps maintain the cohesion of calcined plaster.

As a mineral additive, many clays can be used. The advantages provided by clays are, on the one hand, the fact that they release the water of which they consist (water of constitution) when they are brought to a temperature between 100 and 600 ° C and on the other go, the fact that they compensate for the shrinkage of the plaster thanks to their ability to exfoliate.

Preferably, the nature and the quantity of the mineral additive are chosen so that the plaster composition contains a maximum of 2% of crystalline silica and / or a maximum of 1% of alveolar crystalline silica.

An inorganic additive is therefore advantageously used, comprising at most 7.5% of cellular crystalline silica.

As a mineral additive, a mineral additive can be used which essentially comprises a clay material, the amount of crystalline silica of which is at most equal to approximately 15% by weight of the mineral additive, and an inert mineral supplement, compatible with the clay material and dispersible. in the hardened plaster substrate. For example, it is possible to use a mineral additive comprising, as clay material, kaolin, illite, quartz and, as mineral supplement for dolomite. In particular, a mineral additive having the following composition is used (in percentages by weight relative to the total mass of mineral additive):

25% kaolin;

- 10% illite; 15% quartz; 50% dolomite. The calcined chemical composition of this additive is as follows (in%):

- Si0 ₂ : 43

- Ti0 ₂ : 1, 1

- A1 ₂ 0 ₃ : 15 - Fe ₂ 0 ₃ : 1, 6

- K ₂ 0: 1, 2

- CaO: 23

- MgO: 14

Its particle size is expressed by a refusal at 63 μm of less than 15%.

Its loss on ignition at 900 ° C is 26.5%. The composition according to the invention comprises unexpanded vermiculite, which is an alumina, iron and magnesium silicate in the form of flakes which expand at a temperature above 200 ° C., which makes it possible to compensate removing the plaster. In addition, unexpanded vermiculite improves the thermal resistance of the plaster.

Preferably, a micronized unexpanded vermiculite, that is to say of which all the grains are less than 1 mm, is used. This has the advantage of making possible a better distribution of the vermiculite within the plaster and of avoiding a sudden expansion generating structural disorders.

Hydrated alumina (or aluminum trihydroxide) is preferably used in fine particle size (median diameter of about 10 microns). Its effect is to give rise to an endothermic reaction complementary to that of gypsum, in particular by a water content of crystallization of approximately 35%, releasable between 200 and 400 ° C. (gypsum containing approximately 20% of water releasable at approximately 140 ° C). The composition according to the invention can also optionally comprise up to 4%, in particular from 1 to 4%, of boric acid, since this product advantageously loses its water of constitution from 100 ° C., which contributes to the fire resistance of plasterboard. On the other hand, boric acid modifies the crystal structure of hydrated calcium sulphate, in a favorable manner at the level of shrinkage on fire.

The composition according to the invention can be prepared by mixing, per 100 parts by weight of composition: from 55 to 92 parts by weight of hydratable calcium sulphate;

- from 0.1 to 5 parts by weight of mineral and / or refractory fibers;

- from 3 to 25 parts by weight of a mineral additive;

- from 1 to 5 parts by weight of unexpanded vermiculite; - from 3 to 15 parts by weight of hydrated alumina.

The manufacture of plasterboard can be carried out essentially according to the following stages: preparation of a paste by mixing the various constituents of the composition with water; depositing the dough thus prepared on the reinforcing material, followed by the forming and coating of the upper face of the dough with a second reinforcing material; if necessary, forming the edges of the plate obtained previously by molding the fresh plate on profiled strips; - hydraulic intake of hydratable calcium sulphate on a production line while the ribbon of hydratable calcium sulphate plate travels on a conveyor belt; cutting the ribbon at the end of the line, according to determined lengths; and drying the plates obtained. After this treatment, the plasterboards are ready for use.

According to one embodiment, the density of the cured composition forming the core of the plates is between 800 and 1000 kg / m ³ .

The reinforcing material may be based on mineral or refractory fibers. It can be in the form of a veil, a fabric or a mast of mineral fibers, preferably glass fibers. The veil, fabric or mast can be combined with a web of tangled continuous threads, grids of mineral and / or refractory threads or in other forms.

The reinforcing material can also be made of cardboard. Preferably, a reinforcing material made of glass fibers or yarns is used.

The plasterboard according to the invention has the following advantages: - the composition can be easily formulated in the form of a fluid paste which is then transformed, advantageously continuously, into plasterboard, in conventional installations used for this type of manufacturing; thanks to the presence of an external reinforcing material, the edges of the plasterboard can be advantageously formed, in particular thinned, during the manufacture of the plate; it constitutes effective protection against fire; thus plates according to the invention, with a thickness of around 12.5 mm and a density of around 0.88 g / cm ^3, guarantee fire resistance greater than 2 hours; thanks to their -good dimensional stability, 1-es plates according to the invention retain after the fire resistance test a good general appearance without deep crack and have a mechanical resistance (this behavior is important for applications in very high fire protection , such as the ventilation and smoke extraction air ducts, where sealing for hot gases under high pressure is required); the results of the reaction to fire tests of the plasterboards according to the invention are very good: when these plates are subjected to the action of a radiating source and / or of a specific burner under defined conditions (for 20 minutes ), liable to cause ignition of the gases released and propagation of combustion, no ignition was observed and the deterioration of these plates is only superficial; at the end of this test, the plasterboards according to the invention are therefore still able to stop the spread of a fire; thanks to its lightness and its ability to be worked (cut, nailed, screwed, stapled, screwed / glued, etc.) it is very easy to set up; advantageously, it has tapered edges, with which reliable joints can be made between the plates using sealants for plasterboard, for example of the type used for plates coated in cardboard, and preferably resistant joint plasters fire ; also, the possibilities of finishing the construction elements produced with plates according to the invention are varied and include painting, wallpaper, etc. ; - it has the characteristics of use required in the construction field: such as bending stiffness, mechanical resistance to heavy shocks, resistance to humidity, and the absence of creep in the presence of moisture or under its own weight when mounted on the ceiling; finally, since it can be manufactured according to a simple and well-known process in the field of plasterboard and, moreover, the raw materials which constitute it are fairly inexpensive, the plasterboard according to the invention presents the advantage of being of a moderate cost price.

The best ^{performances'} are obtained with plates obtained from the following composition: - 70 to 80% calcium sulfate hemi-hydrate hydratable;

1% glass fibers;

10 to 15% of the clay described above, consisting of

25% kaolin, 10% illite, 15% quartz and

50% dolomite; - 2 to 4% of micronized unexpanded vermiculite;

6 to 10% hydrated alumina; and

0 to 2% boric acid.

Of course, provided that the proportions assigned to each of the essential constituents are respected, it is possible to introduce into the composition according to the invention, on a secondary basis, adjuvants commonly used to facilitate the use of the other constituents or to give them to the composition of additional special properties. As examples of such adjuvants, mention may be made of fluidizers, foaming agents, setting accelerators and water repellents. Examples

The following examples are given for illustrative purposes only and are not intended to be limiting.

Example 1

A control plate was prepared according to the aforementioned European patent application No. EP-A-0470914 and four plates A, B, C and D according to the invention.

The composition of the plates is given in the following table:

The hydratable calcium sulphate used comes from industrial desulfogypsum cooking (FGD).

The clay used consisted of 25% kaolin, 10% illite, 15% quartz and 50% dolomite.

The vermiculite used was a micronized unexpanded vermiculite.

Example 2

The mechanical resistance to heat (also called cohesion of the heart at high temperature) of the control plates, A, B, C and D prepared in Example 1 was measured.

The test implemented combines a thermal stress exerted on both sides of the specimen by means of a Mecker nozzle delivering a flame at a constant temperature of 1020 ° C, with mechanical tensile stress under a force of 0.2 kg / cm ² .

The parameters recorded are the break time and the inal shrinkage.

The results are given in the following table:

It is found that the rupture of the Witness, A and B test pieces is not reached after 2 hours of solicitation. On the other hand, all the formulas pass the duration of 1 hour 30 minutes.

For all the plasterboard test pieces according to the invention, it appears that the combination of unexpanded micronized vermiculite combined with the clay makes it possible to lower the final shrinkage to less than 3%.

Test tube D containing boric acid shows the least shrinkage.

Example 3 The kinetics of withdrawal of the control plates, A, B, C and D prepared in Example 1 were measured.

The test implemented consists in simply exerting the same thermal stress as in Example 2, in the absence of any mechanical stress. The saved parameter is the withdrawal after 15, 30, 45 and 60 minutes.

The results are given in the following table:

Figure 1 represents the evolution of the shrinkage as a function of time for the control plates, A and B.

Figure 2 represents the evolution of the shrinkage as a function of time for the control plates, B, C and D, during another test.

The difference between the Witness and the test tubes according to the invention is very clear, in particular in the initial phase (up to 30 minutes). The non-expanded micronized clay / vermiculite couple makes it possible to divide by about 2, the shrinkage compared to the control.

It is again noted that the shrinkage is minimal with the test tube D containing boric acid.

Example 4

The heat transfer of the control plates, A, B, C and D prepared in Example 1 was measured.

The test consists in exerting a thermal stress on one face of the specimen, by means of a Mecker nozzle delivering a flame at a constant temperature of 1020 ° C.

The parameters recorded are the temperature of the unexposed side of the specimen, the time to reach values corresponding to the classification criteria Fireproof and Insulation according to the French Decree of August 99 and the standards EN 1363-1 and EN 13 501-2, in which dt = 140 ° C on average or 180 ° C max at one point.

In addition, the time for which the temperature is 400 ° C. has also been noted, since this time is a significant value of the heat transfer after dehydration. The results are given in the following table:

Figure 3 shows the temperature increase on the unexposed side of the witness plasterboards, A and B.

FIG. 4 represents the temperature increase on the unexposed face of the control plasterboards, B and C, during another test.

FIG. 5 represents the temperature increase on the unexposed face of the control plasterboards and D, during another test. All tests are carried out under the same conditions.

It can be seen that the shapes of the curves are similar with a first stage of vaporization at around 100 ° C., then another at around 120 ° C.

Furthermore, the heat transfer through the calcined plate takes place up to a maximum point at 450 ° C.

Test tube A presents results comparable to those of the control test tube.

All the other test tubes according to the invention exhibit results superior to those of the control plate, in particular both in terms of the duration of the vaporization plateau, thus guaranteeing a fire-resistance criterion over a longer duration, than a slowed-down heating. in the 200 to 400 ° C zone.

Claims

A plasterboard composition comprising: 55 to 92% hydratable calcium sulfate; from 0.1 to 5% of mineral and / or refractory fibers from 3 to 25% of a mineral additive; from 1 to 5% unexpanded vermiculite; 3 to 15% hydrated alumina.

2. A plasterboard composition according to claim 1, in which the mineral additive essentially comprises a clay material, the amount of crystalline silica of which is at most equal to approximately 15% by weight of the mineral additive, and an inert mineral supplement. , compatible with the clay material and dispersible in the hardened plaster substrate.

3. A plasterboard composition according to claim 1 or 2, in which the nature and the quantity of the mineral additive are chosen so that the plaster composition contains at most 2% of crystalline silica.

4. Composition for plasterboard according to claim 1 or 2, in which the nature and the quantity of the mineral additive are chosen so that the plaster composition contains at most 1% of crystalline alveolar silica.

5. Composition for plasterboard according to one of the preceding claims, characterized in that the mineral additive comprises kaolin, illite, quartz and dolomite.

6. Composition for plasterboard according to the preceding claim, in which the mineral additive comprises, in percentages by mass: 25% of kaolin; - 10% illite; 15% quartz; 50% dolomite.

7. Composition for plasterboard according to one of the preceding claims, in which the unexpanded vermiculite is micronized.

8. Composition for plasterboard according to one of the preceding claims, further comprising up to 4% boric acid.

9. Composition for plasterboard according to one of the preceding claims, comprising: - 70 to 80% hydratable calcium sulphate;

1% glass fibers;

10 to 15% of the clay described above, consisting of 25

% kaolin, 10% illite, 15% quartz and

50% dolomite; - 2 to 4% of micronized unexpanded vermiculite;

6 to 10% hydrated alumina; and

0 to 2% boric acid.

10. Plasterboard consisting of a cured composition according to one of the preceding claims.

11. Plasterboard according to claim 10 or 11, characterized in that the density is between 800 and 1000 kg / m ³ .

12. Plasterboard according to claim 10 or 11, characterized in that at least one of its faces is coated with a reinforcing material based on mineral and / or refractory fibers, or based on cardboard.

13. Plasterboard according to the preceding claim, characterized in that its two faces are each coated with a reinforcing material based on glass fibers.

14. Method for preparing a composition according to one of claims 1 to 9, in which the constituents of the composition are mixed together, in any order.

15. A method of continuously manufacturing plasterboard, essentially comprising the following steps: preparation of a paste by mixing the various constituents of the composition according to one of claims 1 to 9 with water; depositing the dough thus prepared on the reinforcement material, followed by the forming and coating of the upper face of the dough with a second reinforcement material; - If necessary, forming the edges of the plate obtained previously by molding the fresh plate on profiled strips; taking hydratable calcium sulphate on a production line while the ribbon of hydratable calcium sulphate plate travels on a conveyor belt; cutting the ribbon at the end of the line, according to determined lengths; and drying the plates obtained.