FR3046789A1 - MATERIAL BASED ON PLASTER - Google Patents

Abstract

The present invention relates to a plaster-based material comprising a fixing agent chosen from aminoalcohols, in particular a gypsum board intended for the interior design of residential buildings, as well as its use for reducing the content of volatile organic compounds in the buildings.

Description

BACKGROUND OF THE INVENTION The invention relates to a plaster-based material, in particular plasterboard for the interior design of residential buildings, and to its use for reducing the content of volatile organic compounds. in the buildings.

Volatile organic compounds (VOCs) are chemical substances based on carbon and hydrogen present in the air in the gaseous state. Directive 2010/75 of the European Union of November 24, 2010 defines them as any organic compound with a vapor pressure of 0.01 kPa or more at a temperature of 293.15 K or having a corresponding volatility under the conditions particular use. They include various types of chemical substances such as alkanes, alkenes such as terpenes, alkynes, alcohols, aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, cronotaldehyde, butyraldehyde, benzaldehyde, valeraldehyde and the like. , hexaldehyde or heptanaldehyde, ketones, ethers such as glycol ethers, aromatic hydrocarbons such as benzene and toluene, or halogenated hydrocarbons such as tetrachlorethylene and dichlorobenzene. VOCs are present in most paints, building materials, solvents, detergents, fuels, as well as in resins, varnishes or glues used for furniture or electrical appliances, or in cigarette smoke. These VOCs are found in the ambient air of buildings and, even if their quantity seems low, they can in the long run inconvenience people who are exposed to it or even affect their health. In particular, some VOCs can cause allergic reactions, breathing problems, nausea or headaches.

In recent years, the proportion of VOCs emitted by the aforementioned materials has greatly decreased as a result of stricter regulations. However, alternative materials with low, or no, VOC emissions often exhibit higher cost and lower performance levels.

In parallel with efforts to control VOC emissions, various ways to reduce the amount of VOCs in ambient air have been proposed. Thus, it has been proposed to incorporate scavenger agents into building materials to reduce the amount of VOCs, such as formaldehyde, in indoor air inside buildings. However, fixing agents commonly used in building materials may have certain disadvantages. For example, the introduction of acetoacetamide-type fixing agents or hydrazides into gypsum-based building materials causes discoloration or yellow-brown discoloration on the surface of these materials, which can be troublesome, particularly for applications where the aesthetic appearance of the product is important. This coloration is also likely to affect the appearance of a coating applied to plaster materials (paints, wallpapers or coatings). In addition, depending on the applications, regulatory constraints may limit the use of certain fixing agents.

There therefore remains a need for alternative fixing agents capable of fixing VOCs, in particular aldehydes, which are compatible with plaster-based materials and which do not have the abovementioned disadvantages, notably making it possible to avoid or reduce the observed coloration phenomenon. .

Thus, one aspect of the present invention relates to a plaster-based material comprising a fixing agent selected from aminoalcohols. The use of aminoalcohol as a fixing agent in gypsum-based materials makes it possible to effectively capture the VOCs present in the indoor air, in particular the aldehydes, while avoiding a coloration of the material during its aging.

The term "plaster" in the sense of the present invention refers both to the plaster taken, that is to say the calcium sulfate dihydrate (CaSCL, 2H 2 O) that the plaster not taken or calcined gypsum, that is to say that is, calcium sulfate hemihydrate (CaSCL, VH2O). The expression "plaster-based material" refers to a material consisting essentially of plaster, that is to say comprising in particular at least 50%, preferably at least 70%, more preferably at least 80%, by dry weight of plaster, said material may comprise up to 90%, up to 94%, even up to 97%, or even up to 99% by dry weight of plaster, and not including other inorganic hydraulic binders than the plaster. This expression excludes mortars and cementitious materials. Preferably, the gypsum material according to the present invention does not include aggregates, aggregates, sand and / or fillers. Examples of gypsum-based materials include gypsum board, gypsum board and dry (powdered) or wet (paste) mixes, such as powdered or powdered pre-mixes. ready-to-use dough. The fixing agent according to the invention is preferably chosen from primary aminoalcohols of formula R / R 1 -C-NLL, in which R 1, R 2 and R 3 are independently chosen from H, hydroxyl, alkyl and hydroxyalkyl, at least one of R1, R2 and R3 comprising a hydroxyl group.

For the purposes of the present invention, the term "alkyl" means any linear or branched alkyl group, in particular alkyl groups containing 1 to 6 carbon atoms, in particular methyl, ethyl, n-propyl, isopropyl or isobutyl groups.

The term "hydroxyalkyl", for the purposes of the present invention, denotes any alkyl group containing in particular 1 to 6 carbon atoms, substituted with at least one hydroxyl group, preferably with a hydroxyl group. Examples of hydroxyalkyl groups include hydroxymethyl and hydroxylethyl groups.

The aminoalcohols according to the invention preferably comprise at least two hydroxyl groups, more preferably three hydroxyl groups. The fixing agent may for example be chosen from 2-amino-2-methyl-1,3-propanediol, 2-amino-2 (hydroxy methyl) propane-1,3-diol (also called tris (hydroxymethyl) aminomethane), 2-amino-2-methyl-1,3-propanol and 2-amino-2-ethyl-1,3-propanediol. Preferably, the fixing agent is 2-amino-2 (hydroxymethyl) propane-1,3-diol which comprises three hydroxyl groups.

The amount of aminoalcohol in the plaster-based material is generally 0.01 to 2%, preferably 0.05 to 1% by dry weight based on the dry weight of plaster.

The gypsum based material according to the invention may comprise processability additives for adapting the properties of the mixes depending on the manufacturing conditions as well as other functional agents for modifying the final properties of the material. The processability additives well known to those skilled in the art can be in particular adhesion agents, setting accelerators, set retarders, fluidifying agents, thickening agents or antifoaming agents. Functional agents also well known to those skilled in the art may be foaming agents, biocides, water repellents, fire retardants or reinforcing agents. The plaster-based material comprises in particular up to 50%, preferably up to 30%, more preferably up to 20%, by dry weight of additives. By way of example, the plaster-based material can typically comprise, for 100 parts by weight of plaster: 0 to 15 parts of an adhesion agent, for example a polyvinyl acetate, a polyalcohol vinyl), a starch, in particular previously treated with an acid or pre-gelatinized, a dextrin or a vegetable meal, in particular wheat or maize; 0 to 10 parts of a biocide, for example carbamates, such as 3-iodoprop-2-yn-1-yl butylcarbamate, or pyrothione complexes; 0 to 10 parts of at least one water-repellent agent, for example a siloxane, a polysiloxane or a wax; 0 to 20 parts of at least one anti-fire agent, for example vermiculite, silica, in particular of micrometric size or a clay; and / or 0 to 20 parts of at least one reinforcing agent, for example polymer fibers, mineral fibers, especially glass fibers, or vegetable fibers.

The gypsum material may also include adsorbents. The adsorbents are typically porous materials such as activated carbon or zeolites. Adsorbents are generally capable of capturing a broad spectrum of VOCs but their adsorption capacity is not identical for all VOCs. On the contrary, although the fixing agents, such as the aminoalcohols according to the invention, are generally more specific to a particular type of VOC, they have the advantage of fixing them permanently. The plaster based material according to the invention typically comprises from 0.01 to 2%, preferably from 0.05 to 1% by weight of adsorbent based on the dry weight of plaster.

In a particular embodiment, the plaster based material according to the invention is a plasterboard. Plasterboards are panels comprising a layer of plaster between two facing sheets generally made of cardboard or fiberglass. Industrially, plasterboard is formed in a continuous process comprising three main steps: shaping, setting and drying. During the step of shaping the plasterboard, a batch is continuously made in a mixer from calcined powdered gypsum, water and specific additives to adapt the properties of the batch and / or of the final product as mentioned above. It is particularly known to add foaming agents or foam directly to reduce the density of drywall. The mix is then poured continuously onto a first facing sheet driven by a conveyor belt to an extruder to form the plate. After folding the edges of the first facing sheet, a second facing sheet is fed to the extruder. The extruder plates the second facing sheet on the mix, smoothes the surfaces and reduces the thickness of the gypsum board to the desired value. To improve the mechanical properties of plasterboard, it is also known to form a layer of plaster denser on one side and possibly on the edges of the plasterboard. For this purpose, a first, denser, layer of coating, called a roller coating layer, is poured and formed on the first facing sheet, upstream of the spill of the main mix, which then forms a second layer called the body of the plasterboard. The roller coating layer generally has a small thickness, typically less than 2 mm, for example about 1 mm. The gypsum strip obtained at the exit of the extruder is conveyed continuously by a conveyor for a distance sufficient to allow it to be taken and to reach a level of hardening sufficient to be able to be cut into plates to the desired size. The plates are then dried in an oven to remove excess water.

Conventionally, the mixture comprises calcium sulfate hemihydrate (calcined gypsum) and any additives described above. The calcined gypsum undergoes a hydration reaction in the presence of water and transforms into calcium sulphate dihydrate (gypsum) causing the setting, or hardening, of the plasterboard. The composition of the mix may vary depending on the nature of the gypsum board to be manufactured. The batch typically comprises, for 100 parts by weight of plaster, 40 to 200, preferably 50 to 150 parts of water, 2 to 10 parts of foam obtained from a mixture of water and a foaming agent, for example an alkyl sulphate optionally in admixture with an alkyl ether sulphate, and 0.1 to 1 part of setting accelerator, for example hydrated calcium sulphate or potassium sulphate.

The plasterboard generally has a thickness of 6 to 25 mm, preferably 10 to 15 mm. The fixing agent can be introduced into the plasterboard in various ways.

According to a first embodiment, the fixing agent is added to the mix before it is deposited on the first facing sheet. The addition of the fixing agent can be done during the manufacture of the batch, for example by simultaneously or successively introducing the calcined gypsum and the aforementioned compounds into the mixer, or after the batch has been obtained, for example at the outlet of the mixer or in a secondary mixer. The simultaneous addition of constituents is advantageous because easier to implement. This embodiment makes it possible to have a homogeneous distribution of the fixing agent in the plasterboard.

According to a second embodiment, the fixing agent is introduced into the one layer of roller coating. For this, the fixing agent is introduced into a mixture used for the formation of the roller coating layer, the main batch intended for the formation of the body of the plate being generally free of the fixing agent. This embodiment makes it possible to concentrate the fixing agent only on one face of the plasterboard and only on a part of its thickness.

In another particular embodiment, the plaster based material according to the invention is a plaster tile. Plaster tiles are generally obtained by molding. For this, a mixture is prepared in a kneader. After obtaining a homogeneous mix, it is poured into molds and trimmed to the height of the molds to eliminate the surplus of tempered. After a sufficient setting of the plaster tiles for handling, they are removed by extrusion and then dried in an oven to eliminate excess water.

Conventionally, the mixture comprises calcium sulfate hemihydrate (calcined gypsum) and any additives described above. The composition of the mix may vary depending on the nature of the gypsum tiles to be manufactured. The batch typically comprises, for 100 parts by weight of plaster, 40 to 200, preferably 50 to 150 parts of water, 0.1 to 1 part of setting accelerator, for example calcium sulfate hydrate or sodium sulfate. potassium, 0.1 to 2 parts of plasticizer, 0 to 1 part of retardant, and 0 to 10 parts of water-repellent agent.

Plaster tiles generally have a thickness of 30 to 200 mm, preferably 50 to 150 mm. The fixing agent can be introduced into the plaster tiles during the preparation of the batch.

In another particular embodiment, the plaster-based material according to the invention is a dry or wet mixture (ready for use). The dry mixtures are obtained by addition, sequenced or simultaneous, of each of the constituents in a dry mixer. Since the fixing agent is in powder form, it can be added to the mixture in the same way as the other constituents. The wet mixtures can be obtained by adding, sequenced or simultaneous, each of the constituents in a mixer in the presence of water, or by mixing a dry premix, the fixing agent can be introduced during the preparation of the pre -mixed dry or at the moment of mixing.

The present invention also relates to the use of a gypsum material as described above, in particular a gypsum board, a plaster tile or a dry or wet mix, for reducing the amount of VOC, in particular aldehydes, in the air inside buildings. The invention is illustrated with the following non-limiting examples.

EXAMPLE

Reference plates RI and according to the invention II to 13 were manufactured from a base mix comprising 100 parts by weight of plaster (CaSC> 4, V2H2O), 75 parts of water, 3 parts of foam ( obtained from water containing 1% by weight of sodium lauryl sulphate), 5 parts of starch, 3 parts of plasticizer and 0.5 parts of setting accelerator. For the reference plate R1, no fixing agent was added to the basic batch. For plates II to 0.12% by weight of fixing agent according to the invention, respectively 2-amino-2 (hydroxymethyl) propane-1,3-diol (TRIS) 2-amino-2-methyl-1, 3-propanol (AMP) and 2-amino-2-methyl-1,3-propandiol (AMPD) were added to the base batch.

The plates were prepared as follows. The different ingredients are weighed and mixed using a mixer and a de flocculating type blade at 1600 rpm for one minute to obtain a homogeneous paste. The foam is prepared to the desired density and mixed with the pulp obtained in a kneader with a blade at 250 rpm to obtain a main mix. In a mold of dimension 20 x 25 cm and 12.5 mm thick, there is a first sheet of cardboard. The main mix is poured on the first carton and leveled to the thickness of the mold. A second sheet of cardboard is disposed on the main batch and the mold is closed to maintain pressure on the plate. After hardening of the plate, it is demolded and dried in an oven for 24 hours at 40 ° C.

The capacity of each of the plates to trap formaldehyde was evaluated according to ISO 1600-23: 2009 at a temperature of 23 ° C ± 2 ° C and a relative humidity of 50% ± 5% during the test. The plate loading factor is set at 0.4, the air exchange rate at 0.5 vol.h-1 and the formaldehyde concentration at 100 μg.irf.sup.-1. Table 1 shows the percent reduction in formaldehyde content (abatement) for each plate.

Table 1

The plates II to 13 according to the invention has a formaldehyde reduction greater than 55%. Plate II containing TRIS has the highest abatement rate.

After aging, plates II to 13 do not show significant staining. The use of fixing agents chosen from amino alcohols thus makes it possible to reduce the coloration phenomenon observed for other fixing agents, in particular of the acetoacetamide or hydrazide type.

Claims (10)

1. Material based on plaster, characterized in that it comprises a fixing agent chosen from aminoalcohols. 2. Material according to claim 1, characterized in that the fixing agent is preferably selected from primary amino alcohols of formula R'RrR -C-NI-f, wherein R1, R2 and R3 are independently selected from H, hydroxyl , alkyl and hydroxyalkyl, at least one of R1, R2 and R3 comprising a hydroxyl group. 3. Material according to claim 1 or 2, characterized in that the fixing agent is chosen from 2-amino-2-methyl-1,3-propanediol, 2-amino-2 (hydroxymethyl) propane-1,3 diol, 2-amino-2-methyl-1,3-propanol and 2-amino-2-ethyl-1,3-propanediol. 4. Material according to any one of claims 1 to 3, characterized in that said material comprises from 0.01 to 2% by weight of fixing agent relative to the dry weight of plaster. 5. Material according to any one of claims 1 to 4, characterized in that said material comprises an adsorbent. 6. Material according to any one of claims 1 to 5, characterized in that said material comprises at least one additive selected from adhesion agents, setting accelerators, fluidizing agents, thickening agents, antifoam agents, foaming agents, biocides, water repellents, fireproofing agents and reinforcing agents. 7. Material according to any one of claims 1 to 6, characterized in that said material comprises at least 50%, preferably at least 70%, more preferably at least 80% by dry weight of plaster. 8. Material according to any one of claims 1 to 7, characterized in that said material is selected from drywall, gypsum and dry or wet mixtures, preferably, said material is a plasterboard. 9. Use of a material according to any one of claims 1 to 8 for reducing the amount of volatile organic compounds in the indoor air of buildings. 10. Use according to claim 9, characterized in that the volatile organic compounds are aldehydes.