MORTAR COMPOSITION FOR AN INTERIOR COATING OR LINING

Abstract

The present invention relates to a mortar composition for interior plaster or coating comprising at least one binder, at least aggregates, sands and/or fillers and at least one additive, characterized in that at least one additive is an agent in powder form capable of scavenging aldehydes and is selected from aminoalcohols.

Claims

1: A dry or pasty mortar composition for interior plaster or coating, the composition comprising: at least one binder, at least an aggregate, sand, and/or a filler and at least one additive, wherein the at least one additive is an agent in powder form capable of scavenging an aldehyde, and wherein the at least one additive is an aminoalcohol.

2: The composition as claimed in claim 1, wherein the agent is a primary aminoalcohol of formula
R.sub.1R.sub.2R.sub.3CNH.sub.2, wherein R.sub.1, R.sub.2 and R.sub.3 are alkyl groups comprising from 1 to 6 carbon atoms, hydrogen atoms or OH hydroxyl groups, and wherein at least one of the R.sub.1, R.sub.2 or R.sub.3 groups comprises a hydroxyl group.

3: The composition as claimed in claim 2, wherein the agent is selected from the group consisting of 2-amino-2-methyl-1,3-propanediol, 2-amino-2(hydroxymethyl)propane 1,3 diol and 2-amino-2-ethyl-1,3-propanediol.

4: The composition as claimed in claim 1, wherein the binder is: a hydraulic binder selected from the group consisting of Portland cements, high-alumina cements, sulfoaluminate cements, belite cements, blast-furnace slags, cements of pozzolanic mixtures optionally comprising fly ash, silica fumes, limestone, calcined schist natural or calcined pozzolans, and any mixture thereof, at least one source of calcium sulfate selected from the group consisting of calcined gypsum or hemihydrate, gypsum and anhydrite, lime, a phosphomagnesium binder, and/or an organic binder which is a polymer dispersion or redispersible powder, and wherein the binder content is between 1% and 95% by weight of the total mixture of the constituents.

5: The composition as claimed in claim 1, further comprising, as at least one further additive: a rheological agent, a water-retaining agent, a thickener, a biocidal protective agent, a dispersant, a mass water-repellent agent, a pigment, an accelerator and/or a retarder, and/or another agent effective for improving the setting, the hardening and/or the stability of the mortar or concrete after application, or effective for adjusting the color, workability, implementation or impermeability thereof, wherein the total content of additives is between 0.001% and 5% by weight relative to the total mixture of the constituents.

6: A process for preparing the dry or pasty mortar composition as claimed in claim 1, the process comprising: directly mixing the agent capable of scavenging the aldehydes with the binder, the aggregates, sands and/or fillers and the at least one additive.

7: An interior coating suitable for floors, walls and/or ceilings obtained from a dry mortar composition mixed with water or a pasty mortar composition as claimed in claim 1, in hardened form.

8: The coating as claimed in claim 7, having a content of between 5 and 50 g/m.sup.2 of aminoalcohol agent capable of scavenging an aldehyde.

9: A method of coating a floor, wall, and/or ceiling with the coating as claimed in claim 7, the method comprising: coating a floor, wall, and/or ceiling with the coating, thereby reducing the amount of aldehydes in the indoor air of a building.

10: The coating of claim 7, wherein a concentration of formaldehyde in a circulated, polluted air above the coating remains below 5 ppbv for 320 hours.

11: The coating of claim 7, wherein the coating comprises plaster and wherein the coating can scavenge at least 0.82 mg of formaldehyde per gram of plaster.

12: The coating of claim 7, wherein an absolute value of a difference between a parameter b* after 40 days and a parameter b* after 1 day is less than 0.42.

13: The coating of claim 7, wherein an absolute value of a difference between a parameter b* after 40 days and a parameter b* after 1 day is 0.17 or less.

14: The coating of claim 7, wherein the coating does not release ammonia when stored in a desiccator for 24 hours.

15: The composition of claim 1, wherein the additive is effective to scavenge formaldehyde, acetaldehyde, propionaldehyde, cronotaldehyde, butyraldehyde, benzaldehyde, valeraldehyde, and/or hexaldehyde.

16: The composition of claim 4, wherein the organic binder is an acrylic and/or vinyl polymer or copolymer, a copolymer of styrene and butadiene, a copolymer of styrene and acrylic acid, a copolymer of vinyl acetate and ethylene, a copolymer of vinyl acetate and vinyl versatate, or a derivative thereof

Description

EXAMPLE 1: CEMENT-BASED INTERIOR PLASTER COMPRISING TRIS(HYDROXYMETHYL)-AMINOMETHANE THAT SCAVENGES FORMALDEHYDES

[0022] 1% by weight of tris(hydroxymethyl)aminomethane is added to a cement-based interior plaster that is commercially available under the name Weber.star 220.

[0023] The performances for eliminating pollutants of formaldehyde type contained in a gas phase with this composition according to the invention are measured and are compared with an interior plaster composition of the same type (Weber.Star 220) without an additive capable of scavenging formaldehydes. An empty test chamber, without a sample of plaster, was also tested, by way of calibration.

[0024] The various samples are tested according to the method described in the ISO 16000-23 standard, with the following conditions and in three test chambers in parallel: [0025] the pollutant is injected at the inlet of each of the chambers comprising each sample, at a concentration of around 90 ppbv (parts per billion, by volume), [0026] the relative humidity of the test chamber is 49%, [0027] the temperature of the test chamber is 23 C., [0028] the flow rate of air comprising the pollutant is 1.6 l/min, [0029] the surface area of each sample is 0.2 m.sup.2 (each chamber comprises two pieces of 380 mm*270 mm each), [0030] the volume of the chamber is 28.2 l.

[0031] Each test consists in placing each of the plaster samples in a chamber, in continuously sending a stream of air polluted by formaldehydes through the chamber, so that the surface of the sample is continuously swept by a stream of polluted air, and in measuring at the outlet of the chamber the concentration of formaldehyde present in the outgoing air. The circulation of polluted air through the chamber is maintained for 320 hours.

[0032] FIG. 1 represents the change in the concentration of formaldehyde in the air leaving the chamber as a function of the time for the various samples tested.

[0033] As expected, the air leaving the chamber without a sample of plaster (curve represented by the triangle-shaped symbols) does not change over time: the concentration of formaldehyde remains stable (around 90 ppbv). In the chamber comprising the Weber.star 220 interior plaster without additive capable of scavenging the pollutants (curve represented by the square-shaped symbols), the concentration of formaldehyde increases regularly to reach the level of pollutant contained in the incoming air after around 180 minutes. At the start of the test, the concentration of formaldehyde is relatively low (less than 20 ppbv) which may be explained by a physical absorption of the pollutant in the pores of the plaster matrix.

[0034] On the other hand, it is noted that the concentration of formaldehyde remains stable and below 5 ppbv throughout the duration of the test in the chamber that comprises the sample according to the present invention, that is to say the sample of Weber.star 220 comprising 1% by weight of tris(hydroxy-methyl)aminomethane (curve represented by the diamond-shaped symbols). The plaster obtained from the mortar composition comprising the formaldehyde scavenging agent is consequently sufficiently reactive to eliminate all of the pollutant introduced throughout the duration of the test.

EXAMPLE 2: DETERMINATION OF THE FORMALDEHYDE SORPTION CAPACITY OF A CEMENT-BASED INTERIOR PLASTER COMPRISING 1% OF AGENT CAPABLE OF SCAVENGING FORMALDEHYDE

[0035] Tests were carried out to determine the sorption capacity of an interior plaster sold under the name Weber.star 220, to which 1% by weight of tris(hydroxymethyl)aminomethane was added, as described in the ISO 16000-23 standard.

[0036] The plaster, once hardened, was manually ground in a mortar and was screened. The fractions having a size of between 1 and 4 mm were placed in a glass tube having an internal diameter of 20 mm, in order to fill 123 mm in the tube. The amount of ground material in the glass tube is 34.99 g. A stream of air polluted by formaldehydes is sent into the tube comprising the sample and at the same time into a control tube without sample, with a flow rate of 1.6 l/min. The concentration of formaldehyde in the air entering the tubes is around 2000 ppbv. The tests are carried out at a temperature of 23 C. The concentrations of formaldehyde are measured in the stream of air leaving each of these tubes, continuously.

[0037] FIG. 2 represents the amount of formaldehyde absorbed as a function of time. The test was stopped after 240 hours (i.e. 10 days), when the maximum sorption capacity of the plaster sample tested was still not reached. At the time of stopping, the amount of plaster introduced (i.e. 34.99 g) had scavenged 28.6 mg of formaldehyde.

[0038] Consequently, 1 g of plaster according to the present invention, i.e. comprising 1% by weight of tris(hydroxymethyl)aminomethane can scavenge at least 0.82 mg of formaldehyde.

EXAMPLE 3: ESTIMATION OF THE LONG-TERM PERFORMANCE OF A PLASTER COMPRISING 1% BY WEIGHT OF TRIS(HYDROXYMETHYL)AMINOMETHANE

[0039] From tests carried out in example 2 which make it possible to deduce that the sorption capacity is at least 0.82 mg of formaldehyde per gram of plaster, owing to the fact that 3 kg of plaster is used per m.sup.2, parameters used in the AgBB control room model (the abbreviation AgBB corresponding to Ausschuss zur gesundheitlichen Bewertung von Bauprodukten which is a German committee representing the German public health authorities in charge of VOC emissions in construction materials), and by considering a concentration of formaldehyde at the equilibrium state of 50 g/m.sup.3 (which means that there is permanently 1.5 mg of formaldehyde in the room), it is possible to determine that the plaster in this room makes it possible to scavenge the total amount of formaldehydes emitted over a duration of at least 16 years.

[0040] In order to perform this calculation, the following data were used: [0041] formaldehyde sorption capacity of the plaster: at least 0.82 mg per gram of plaster [0042] surface area coated with the plaster: 43.4 m.sup.2 [0043] consumption of plaster: 3 kg/m.sup.2 [0044] amount of plaster in the room: 130.2 kg [0045] volume of the room: 30 m.sup.3 [0046] exchanged air flow rate in the room: 0.5 l/h

EXAMPLE 4: EVALUATION OF THE DISCOLORATION

[0047] An interior finishing plaster based on calcined gypsum comprising 30% by weight of hemihydrate CaSO.sub.4, 69% by weight of calcareous sand and either 1% by weight of tris(hydroxymethyl)aminomethane or 1% by weight of acetoacetamide is mixed with 25% by weight of water and is applied over a thickness of 2 mm to an asbestos-cement board. A control sample without any scavenging agent and with the same interior plaster based on calcined gypsum is also prepared in the same way. The degree of discoloration (yellowing) is evaluated by measuring the colorimetric parameters L*, a*, b* with a Konica Minolta CM-3610d spectrophotometer (illuminant D65 in the 1976 CIE Lab system) after storage indoors under ambient conditions for 1 day, 20 days and 40 days.

[0048] As can be observed in table 1 and in FIG. 3 which represents the change in the parameter b* as a function of the time for the various samples tested, the color remains stable for the control sample that does not contain scavenging agent and for the sample that contains tris(hydroxymethyl)aminomethane. On the other hand, the sample that comprises 1% by weight of acetoacetamide as scavenging agent has a tendency to yellow with time.

TABLE-US-00001 TABLE 1 L*, a*, b* L*, a*, b* L*, a*, b* After 20 After 40 After 1 day days days Control sample without 90.14 89.58 89.24 scavenging agent 0.3 0.25 0.27 3.06 2.88 2.88 Sample comprising 1 wt % of 89.23 89.06 88.37 acetoacetamide 0.23 0.06 0.19 3.68 4.77 5.87 Sample comprising 1 wt % of 89.12 89.17 89.37 tris(hydroxymethyl)aminomethane 0.33 0.29 0.26 3.37 3.27 3.2

EXAMPLE 5: AMMONIA EMISSIONS

[0049] A sample of a cement-based interior plaster that is commercially available under the name Weber.star 220 is mixed either with 1% by weight of tris(hydroxymethyl)aminomethane or with 1% by weight of acetoacetamide and with water.

[0050] 100 g of each of the fresh samples are placed in sealed desiccators. After 24 hours, the concentration of ammonia in the air inside the desiccator is measured with 5/a ammonia-detecting Draeger tubes, and with a Draeger Accuro pump. The measurements carried out showed that the air from the desiccator in which the sample comprising acetoacetamide as scavenging agent contained 40 ppm of ammonia. No trace of ammonia was detected in the air from the desiccator which contained the sample of plaster with tris(hydroxymethyl)aminomethane.