FR2811980A1 - COMPOSITION FOR PLASTER PLATE, PREPARATION OF THIS COMPOSITION AND MANUFACTURE OF PLASTER PLATES - Google Patents

Abstract

The present invention relates to a composition for plasterboard comprising: - 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% of unexpanded vermiculite; - from 3 to 15% of hydrated alumina. The invention also relates to a process for the preparation of this composition as well as a manufacturing process for plasterboard.These plasterboards have an improved fire resistance.

Description

l 2811980

COMPOSITION FOR PLASTER PLATE,

PREPARATION OF THIS COMPOSITION AND

MANUFACTURE OF PLASTER PLATES

  The present invention relates to a composition for plasterboard, a process for the preparation of this composition and a method of manufacturing plasterboard having

  a greatly improved fire resistance.

  It is well known to use plaster plaster to make partitions, vertical element cladding or

  sloping or to achieve suspended ceilings or not.

  These plates generally consist of a substantially plaster core, covered on each of its faces by a sheet serving both as reinforcement and facing and which may be made of cardboard or mineral fiber mats. US Pat. No. 3,616,173 discloses a low density fireproof plate (between 0.64 and 0.8 g / cm3) whose core is based on plaster, glass fibers, a mixture of clay, colloidal silica and / or colloidal aluminum oxide, and possibly

unexpanded vermiculite.

  According to Lbrevet, silica and aluminum oxides, in dry powder form, 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 high temperature shrinkage which! is quite weak but its fire resistance is limited Such a plate does not have the properties necessary for

  provide good fire protection.

  European Patent Application No. 0 470 914 of the Applicant disclosed in 1992 a plasterboard for fire protection whose faces are covered with a reinforcing material based on son and / or fiber material mineral and / or refractory. The heart of this plate includes:

1/58, 17/07 / '00 1/17

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  55 to 94% of 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 of hydroxide of aluminum and / or

expanded vermiculite.

  Since then, the Applicant has continued its work in the field of drywall, with a view to improving, at the same time, the mechanical resistance to heat, the kinetics of withdrawal and the

  thermal transfer of its plasterboard.

  It has now achieved its objectives by developing 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;

from 3 to 15% of hydrated alumina.

  According to a preferred embodiment of the invention, the nature and the quantity of the mineral additive are chosen so that the composition for plasterboard contains at most 2% of crystalline silica, and / or at most 1% of silica. crystalline alveolar, that is to say having crystals less than 5 microns. Such a composition then has the advantage of having a content of crystalline silica, in particular alveolar silica, in accordance with the recommendations of the International Agency for Research on Cancer, according to which it is advisable to minimize the use of crystalline alveolar silica,

  because this compound is presumed to have maximum toxicity.

  The subject of the invention is also a process for the preparation of a composition for plasterboard, in which the constituents of the composition for

  gypsum board defined above in any order.

  Finally, the third object of the invention is a method of continuously manufacturing plasterboard, essentially comprising the following steps:

? \ '7, / 07/00 2 /'

  preparing a paste by mixing the various constituents of the composition with water in a mixer; depositing the dough thus prepared on the veiling material, the upper part of the dough using a second material of reinforcements; where appropriate, forming the edges of the previously obtained plate by molding the fresh plate on profiled strips, this forming consisting in particular of thinning the edges of the plate; hydrates calcium sulfate hydraulically on a manufacturing line while the hydratable calcium sulfate plate ribbon travels on a treadmill; cutting the ribbon at the end of the line, according to determined lengths; and

drying of the obtained plates.

  Other features and advantages of the invention will now be described in detail in the following description, which is given with reference to the drawings, in which: FIG. 1 represents the evolution of the shrinkage as a function of time for the Witness plates, A and B; Figure 2 shows the change in shrinkage over time for the Control, B, C and D plates in another test; - Figure 3 shows the increase in temperature in the unexposed face of the plasterboards Control, A and B; Figure 4 shows the temperature increase in the unexposed face of the control plasterboards, B, and C, in another test; and FIG. 5 shows the temperature increase in the unexposed face of the control plates D and D at

during another trial.

  The subject of the invention is therefore a composition for plasterboard making it possible to manufacture a plasterboard having

17583-17 / 07 / 00-3 / 17

  a greatly improved fire resistance.

  This composition comprises (in% relative to the entire dry mixture): from 55 to 92% of hydratable calcium sulfate 3 to 25% of an inorganic additive - 1 ml of unexpanded vermiculite

from 3 to 15% hydrated alumina.

  By "hydratable calcium sulfate" is meant herein an anhydrous calcium sulphate (anhydrite II or IIi) or a calcium sulphate semihydrate CaSO.sub.1, 1HO} in its crystalline form (u or J3. 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, we use

  glass fibers having a single length of 13 mm +/- 5 mm.

  In particular, fibers originating from a type E glass are used, which can take two forms, one called "roving" and designating glass strands supplied in coils and cut before introduction into the usual mixing circuit of the calcium sulphate hydratable with water or in the form of pre-cut strands which are dosed before mixing

  aut su. mc cacv cm r ', yortaOaLe with water.

  Fibers having a length of about 13 mm (+/- 5 mm) and a diameter of about 13 microns are used as reference.

(+/- 5 / um).

  The essential function of glass fibers is to confer mechanical strength at high temperature, which allows

  to preserve the cohesion of calcined plaster.

  As a mineral additive, many arg-ies can be used. The advantages provided by the clays are, on the one hand, the fact that they release the water of which they are constituted (water of constitution) when they are brought to a temperature comprised between 100 and 600 C and secondly The fact that they compensate for the fire removal of the plaster by means of

their ability to exfoliate.

  Preferably, the nature and quantity of the mineral additive are chosen so that the plaster composition contains at most 2% crystalline silica and / or at most

  he crystalline silica alveolar.

  It is therefore advantageous to use a mineral additive

  with not more than 7.5% of respirable crystalline silica.

  As mineral additive, it is possible to use a mineral additive comprising essentially a clay material the amount of crystalline silica of which is at most equal to about 15% by weight of the mineral additive, and an inert mineral complement, compatible with the clay and dispersible material

in the hardened plaster substrate.

  For example, it is possible to use a mineral additive comprising, as clay material, kaolin, illite, quartz and, as a mineral complement of dolomite. In particular, a mineral additive is used before the following composition (in percentages by weight relative to the total mass of mineral additive): 25% of kaolin; - 10% illite; - 15% quartz;

- 50% dolomite.

  The calcined chemical composition of this additive is: - SiO: 43 - TiO 1,1 - Al2,0: 15 - Fe-O: 1,6

- KO: 1,2

  - CaO: 23 -MgO: 14z Its granulometry is expressed by a refusal to 63 Mm

less than 15%.

  Its 900% loss on ignition is 26.5%.

6 2811980

  The composition according to the invention comprises unexpanded vermiculite, which is a silicate of alumina, iron and magnesium which is in the form of flakes which expose at a temperature greater than 200 ° C., which makes it possible to compensate the removal of plaster. In addition, unexpanded vermiculite improves the thermal resistance of the plaster. Preferably, micronized unexpanded vermiculite is used, that is to say all grains are less than 1 mm. This has the advantage of making possible a better distribution of the vermiculite within the plaster and to avoid

  a brutal expansion generating structural disorders.

  Hydrated alumina (or aluminum trihydroxide) is preferably used in fine particle size (median diameter of about 10 microns). It has the effect of giving rise to an endothermic reaction complementary to that of gypsum, in particular by a water content of crystallization of about 35%, releasable between 200 and 400 C. (the gypsum containing

  about 20% releasable water at about 140 ° C).

  The composition according to the invention may also optionally comprise up to 4%, in particular from 1 to 4%, boric acid, since this product advantageously loses its water of constitution from 100 C, which contributes to the resistance at the fire of the plasterboard. On the other hand, boric acid modifies the crystal structure of calcium sulphate

  hydrated, favorably at the level of fire shrinkage.

  The composition according to the invention can be prepared by mixing, for 100 parts by weight of composition: from 55 to 92 parts by weight of calcium sulphate, which is hydratable; 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 gypsum boards can be carried out essentially in the following steps: - 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 forming and coating the upper face of the dough with a second reinforcing material; - Where appropriate, closing the edges of the previously obtained plate by molding the fresh plate on profiled strips; hydraulically taking up hydratable calcium sulfate on a manufacturing line while the hydratable calcium sulfate slab runs on a treadmill; cutting the ribbon at the end of the line, according to determined lengths; and

drying of the obtained plates.

  After this treatment, the plasterboard is ready to

1 job.

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

  The reinforcing material may also be cardboard.

  Preferably, a reinforcing material made of

glass threads or fibers.

  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 converted, advantageously continuously, into plasterboard, in conventional installations used for this type of plasterboard. 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 provides effective fire protection and plates according to the invention, the thickness of the order of 12.5mm and order density O, 88g / cm <guarantee a fire resistance greater than 2 hours - Thanks to their good dimensional stability, the plates according to the invention retain after the test of resistance to óe- a b. general appearance without deep cracks and i0 have a mechanical strength (this behavior is important for applications in very high fire protection, such as air ducts for ventilation and smoke extraction, where it is required to seal the hot gases under high pressure); the results of the fire reaction tests of the plasterboard according to the invention are very good: when these plates are subjected to the action of a radiating source and / or a specific burner under defined conditions (during 20 minutes), which can cause ignition of the gases released and combustion propagation, no ignition has been observed and the deterioration of these plates is only superficial; at the end of this test, the gypsum boards according to the invention are thus still able to stop the propagation of a fire; - thanks to its lightness and ability to be work (cut, nailed, screwed, stapled, screwed / glued, etc.) it is very easy to set up; Advantageously, it is possible to use thinned edges, with which it is possible to produce: reliable joints between the plates by means of gypsum board sealants, for example of the type used for the plates coated in cardboard, and preferably, fireproof joint coatings; also, the possibilities of finishing of the construction elements made with plates according to the invention are varied and are in particular paint, wallpaper, etc .;

17583-17 / 07/00 8/17

  - it has the required characteristics of use in the field of construction: such as flexural stiffness, mechanical resistance to heavy impacts, resistance to moisture, and the absence of creep in the presence of hiumdicate or its own weight when mounted on the ceiling; - Lastly, since it can be manufactured by a simple method and well known in the field of gypsum board and in addition, the raw materials that constitute it are rather cheap, the plasterboard according to the invention has the advantage of being at a cost of

returns moderate.

  The best performances are obtained with plates obtained from the following composition: 70 to 80% of hydratable calcium sulfate semi-hydrate; - 1% glass fiber; 10 to 15% of the clay described above, consisting of 25% of kaolin, 10% of illite, 15% of quartz and 50% of dolomite; 2-4% micronized vermiculite, unexpanded; - 6 to 10% hydrated alumina; and

0 to 2% of boric acid.

  Of course, provided that the proportions attributed 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 usually used to facilitate the use of the other constituents or to give them the crc-, mpositioc additional special properties. By way of examples of such adjuvants, mention may be made of fluidifiers, foaming agents and setting accelerators.

and water repellents.

  3 a Examples The following examples are given only for

  illustrative and have no limiting character.

Example 1

  It has prepared a temolin plate according to the above-mentioned European Patent Application No. EP-A-0470914 and three plates A, B, C and

D according to the invention.

  The composition of the plates is given in the following Table [Composition] (1) Control A B C Plaster 76 76 76 76 74

I- t_ _ _ __ _ --- - - - - -

  Fibers of glass 1 1 1 1 1 Clay - 18 13 10 13 Vermiculite -2 4 3 2 Alumina 10 3 6 10 8 hydrated Boric acid - 2 Quartz 9

Talc 4 -

  The hydratable calcium sulphate used comes from the industrial firing of desulphogypsum (FGD) The clay used consisted of 25% of kaolin,

  10% illite, 15% quartz and 50% dolomite.

  The vermiculite used was micronized unexpanded vermiculite.

Example 2

  The mechanical resistance to heat (also called cohesion of the core at high temperature) of the control plates, A,

  B, C and D prepared in Example 1.

  The test implemented combines a thermal stress exerted on both sides of the test piece by means of a Mecker spout delivering a flame at a constant temperature of 1020 C, with a mechanical tensile stress under

strength of 0.2 kg / cm2.

  , 0n 17/07/00 10/1 / l l 2811980 The recorded parameters are the break time and the

final withdrawal.

  The results are given in the following table: ABCA time> 100> 120> 120 109 93, breaking (min) Retrieving (%) 4.4 2.7 T 2.95 1.5 1, It is noted that the rupture of the test pieces T, A and B is not broken after 2 hours of stressing. Else

  hart, t Dutes the formulas pass the duration of 1 hour 30.

  Fear all the plasterboard test pieces according to the invention, it appears that the combination of unexpanded micronized vermiculite combined with the clay allows

  to lower the final withdrawal to less than 3%.

  Specimen D containing boric acid has the

least important withdrawal.

Example 3

  The kinetics of removal of the control plates, A,

  B, C and D prepared in Example 1.

  The test used consists of simply exerting the same thermal stress as in Example 2, in the absence of

tress contrairte m; carinque.

  The enreqiscré parameter is the withdrawal after 15, 30, 45 and

minutes.

  The results are given in the following table Removing in% of plates Time t mn) _111Temoinr A b C T

3.0 1.3 1.4 0.3 0, 9

_ 3.0 1 1.4 1.1 0.5 1.2

3.2 1.6 1.7 0.8 1.1

3, 6 1.5 2, 5 1.2 0, 7

758 I - 1 / 0.7 / 0

13 2 2811980

  Figure 1 shows the evolution of shrinkage as a function of time for the Control, A and B plates. Figure 2 shows the evolution of the shrinkage over time for the Control, B, C and D plates, in the course of time. The difference between the control and the test pieces according to the invention is very clear, especially in the initial phase (up to 30 minutes). The unexpanded micronized clay / vermiculite couple allows to divide by approximately 2

withdrawal from Witness.

  It is again noted that the withdrawal is minimal with

  specimen D containing boric acid.

Example 4

  The heat transfer of the control plates, A, was measured

  B, C and D prepared in Example 1.

  The test consists of exerting a thermal stress on one face of the test piece, using 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 Fire and Insulation classification criteria 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 in one point.

  Also, the time for which the temperature is 400 C has been recorded because this time is a value.

  significant heat transfer after dehydration.

  The results are given in the following table: Time (s) to reach the temperature Tetup plates (ature Tmnoin A B i C D

60C 595 525 655 640 570

 C 645 615 710 690 635_

400 C 945 _ 930 _13_ 1020 _

  Figure 3 shows the temperature rise in the unexposed face of the gypsum boards, A and B. Figure 4 shows the temperature increase in: X; I.Explained control plasterboard, B and C, at

or -Sr of another ssai.

  Figure 5 shows the temperature increase in the unexposed face of the control plasterboard and D, during

another try.

  All tests are performed under the same conditions.

  It can be seen that the curves of the curves are similar with a first stage of vaporization towards 100 C, then a

go to L20cC.

  Moreover, thermal transfer through the

  calcined plate is made up to a maximum point at 450 C.

  Test tube A shows results comparable to those

of the test tube.

  All the other test pieces according to the invention have results superior to those of the control plate, especially as regards the duration of the vaporization stage, thereby guaranteeing a fire-resistance criterion over a longer period of time.

  long, that a slowed warm-up in the zone 200 to 400 C.

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Claims (10)

Composite plaster composition comprising: 55 to 924 of hydratable calcium sulfate; from 0.1 to 5% of mineral and / or refractory fibers from 3 to 25% of a mineral additive; - 1 to 5% unexpanded vermiculite - 3 to 15% hydrated alumina.   2. Composition for plasterboard according to claim 1, wherein the mineral additive comprises essentially a clay material whose amount of crystalline silica is at most equal to about 15% by weight of the mineral additive, and an inert mineral supplement , compatible with the material   clay and dispersible in the hardened plaster substrate.   3. Composition for plasterboard according to claim 1 or 2, wherein the nature and quantity of the mineral additive is chosen so that the plaster composition   contains at most 2% crystalline silica.   4. Composition for plasterboard according to claim 1 or 2, wherein the nature and quantity of the mineral additive is chosen so that the plaster composition   contains at most 14 of crystalline alveolar silica.   5. Composition for plasterboard according to one of   preceding claims, characterized in that the additive   3) mineral includes kaolin, illite, quartz and dolomite. 6. Composition for plasterboard according to the preceding claim, wherein the mineral additive comprises, in percentages by weight:% of kaolin; - 10% illite - 1% quartz; 175383-17 / 07 / 00-14 / 17 - 50% dolomite.   7. Composition for plasterboard according to one of   preceding claims, wherein the non-vermiculite expanded is micronized.   8. Composition for plasterboard according to one of   preceding claims, further comprising up to 4% boric acid.   1 (9. Composition for plasterboard according to one of   preceding claims, comprising:   - 70 to 80% hydratable calcium sulfate; - 1% glass fiber; at 15% of the clay described above, consisting of 25% kaolin, 10% illite, 15% quartz and% dolomite; 2-4% micronized vermiculite, unexpanded; - 6 to 10% hydrated alumina; and 0 to 2% of boric acid.   10. Plasterboard consisting of a hardened composition according to   one of the preceding claims.   11. Plasterboard according to the preceding claim, characterized in that at least one of its faces is coated with a reinforcing material based on mineral fibers and / or   refractory, or based on cardboard.   l. Plaster lacquer according to the preceding claim, characterized in that its two faces are each coated   by a reinforcing material based on glass fibers.   13. Process for the preparation of a composition according to one of the   1 to 9, in which the   consticuants of the composition, in any order. 17583-17 / 07 / 00-15 / 1 '/   14. Process for the continuous manufacture of gypsum board, essentially comprising the following steps: preparation of a paste by mixing the various constituents of the composition according to one of the following:   claims 1 to 9 with water;   depositing the dough thus prepared on the reinforcing material, followed by forming and coating the upper face of the dough with a second reinforcing material; - If necessary, forming the edges of the previously obtained plate by molding the fresh plate on profiled strips; - taking hydratable calcium sulphate on a manufacturing line while the hydratable calcium sulphate slab travels on a treadmill; cutting the ribbon at the end of the line, according to determined lengths; and drying of the obtained plates. -F8- 17 / OC '// 00 16 17