Gypsum plaster-based material containing an EDTA metal complex

Abstract

A plaster-based material, in particular a plasterboard intended for the interior fitting of dwellings, contains a metal complex of EDTA. The plaster-based material is used for reducing the amount of volatile organic compounds present in the atmosphere inside dwellings, offices or public buildings.

Claims

1. A plaster-based building material, comprising a zinc complex of EDTA, wherein the zinc complex of EDTA is included in an amount selected to reduce an amount of ambient volatile organic compounds in an environment in which the building material is used.

2. The plaster-based building material according to claim 1, wherein a total amount of the zinc complex of EDTA ranges from 0.0001 to 40 parts by weight per 100 parts by weight of plaster.

3. The plaster-based building material according to claim 1, further comprising the following additives in the following weight proportions, expressed per 100 parts by weight of plaster: 0.1 to 15 parts of an adhesion agent, 0.001 to 10 parts of a setting accelerator, 0 to 10 parts of a biocide, 0.0001 to 1 part of a foaming agent, 0 to 10 parts of at least one water repellent, 0 to 20 parts of at least one fire retardant, 0 to 20 parts of at least one reinforcer, 0 to 20 parts of an agent adapted to trap formaldehyde, 0 to 20 parts of active charcoal or a zeolite.

4. The plaster-based building material according to claim 1, wherein the plaster-based material is in the form of a powder, a paste or a plaster panel.

5. The plaster-based building material according to claim 4, wherein the plaster-based material is a plasterboard.

6. The plaster-based building material according to claim 2, wherein the total amount of the metal complex of EDTA ranges from 0.001 to 10 parts by weight per 100 parts by weight of plaster.

7. The plaster-based building material according to claim 6, wherein the total amount of the metal complex of EDTA ranges from 0.05 to 5 parts by weight per 100 parts by weight of plaster.

8. The plaster-based building material according to claim 3, wherein the adhesion agent is a starch, a dextrin or a vegetable flour.

9. The plaster-based building material according to claim 3, wherein the setting accelerator is hydrated calcium sulfate or potassium sulfate.

10. The plaster-based building material according to claim 3, wherein the biocide is sodium omadine.

11. The plaster-based building material according to claim 3, wherein the foaming agent is sodium lauryl sulfate.

12. The plaster-based building material according to claim 3, wherein the at least one water repellent is a siloxane or a polysiloxane.

13. The plaster-based building material according to claim 3, wherein the at least one fire retardant is vermiculite, silica, a clay or metal fibres.

14. The plaster-based building material according to claim 3, wherein the at least one reinforcer is polymer fibres, mineral fibres, animal or vegetable fibres.

15. The plaster-based building material according to claim 3, wherein the agent adapted to trap formaldehyde is acetoacetamide, adipic acid dihydrazide or a protein.

Description

EXAMPLE 1

(1) a) Manufacture of the Plaster-Based Material

(2) 995 g of calcium sulfate hemihydrate, 5.2 g of starch, 0.1 g of ground gypsum, 1.2 g of zinc-EDTA complex (sold by the company Synthron) and 850 g of water are placed in a mixer.

(3) The mixture is stirred for 60 seconds in order to obtain a paste.

(4) The paste is poured into a grass mould (250 mm×200 mm) lined on its inner face with a sheet of paper, and a second sheet of paper cut to the sizes of the mould is then applied on the paste.

(5) After setting to a solid, the plasterboard is removed from the mould. It is then dried in an oven whose atmosphere is saturated with water, under the following conditions: at 180° C. until 80% of the water is removed, at 100° C. until 95% of the water is removed and at 40° C. for 24 hours.

(6) The board is wrapped in an airtight bag that is resistant to ultraviolet rays.

(7) For comparative purposes, a board not containing any zinc-EDTA complex (comparative example) was prepared under the same conditions.

(8) b) Capacity for Trapping Volatile Organic Compounds

(9) The measurement of the capacity for trapping volatile organic compounds (acetaldehyde, acetone and benzene) is performed in a gastight test chamber.

(10) The plasterboard (100 mm×20 mm; 125 g) is placed in the test chamber, and chamber is then hermetically closed. A continuous stream of air (relative humidity: 50%) containing 20 ppb of the volatile organic compound to be tested is circulated in the chamber at a rate of 250 ml/min.

(11) The measurement of the amount of volatile organic compound is performed in real-time using an FTICR (Fourier transform ion cyclotron resonance) mass spectrometer equipped with a 1 Tesla magnet. The measurement principle is as follows: a semi-porous flat membrane made of polydimethylsiloxane (PDMS) acting as a barrier between the pressure at the chamber outlet (atmospheric pressure) and the vacuum of the mass spectrometer is used. The pressure difference on either side of the membrane and the semi-porous nature of the membrane are such that the volatile organic compounds migrate more rapidly across the membrane than the other molecules contained in the injected air (oxygen, nitrogen, argon, carbon dioxide and water). This results in and enrichment in volatile organic compounds and hence greater sensitivity of detection by the mass spectrometer.

(12) The results given in the table below correspond to a mean value established on a series of three samples of the same plasterboard. The table indicates the percentage reduction in the content of volatile organic compounds below:

(13) TABLE-US-00001 Benzene Xylene Cyclohexanone (%) (%) (%) Ex. 1 52 52 70 Comparative Ex. 0 0 0