Acoustic panel made of plaster

Abstract

A plaster-based board includes a plaster-based core positioned between two sheets of paper or nonwoven fabric, wherein the core contains at least one polymer selected from polyvinyl butyral (PVB), copolymers of vinyl acetate and an olefin, which copolymers have a glass transition temperature that varies from ?10? C. to +25? C., terpolymers of vinyl acetate, an olefin and a vinyl ester monomer, terpolymers of vinyl acetate, a vinyl ester monomer and a (meth)acrylate monomer, and copolymers of vinyl acetate and an acrylic monomer.

Claims

1. A plaster-based board, comprising a plaster-based core positioned between two sheets of paper or nonwoven fabric, wherein said core contains at least one polymer selected from polyvinyl butyral (PVB), copolymers of vinyl acetate and an olefin, which copolymers have a glass transition temperature that varies from ?10? C. to +25? C., terpolymers of vinyl acetate, an olefin and a vinyl ester monomer, terpolymers of vinyl acetate, a vinyl ester monomer and a (meth)acrylate monomer, and copolymers of vinyl acetate and an acrylic monomer.

2. The board as claimed in claim 1, wherein the copolymers of vinyl acetate and an olefin have a glass transition temperature that varies from ?5? C. to +20? C.

3. The board as claimed in claim 1, wherein the polymer represents 1% to 40% by weight of the mixture constituted by the plaster and the polymer.

4. The board as claimed in claim 1, wherein the polymer is in the form of particles having a mean dimension which varies from 0.01 to 1200 ?m.

5. The board as claimed in 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, 0.001 to 10 parts of a setting retarder, 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.

6. A process for manufacturing a board comprising a core positioned between two sheets of paper or nonwoven fabric, the process comprising mixing powdered calcined gypsum with water in order to form a paste, depositing the paste continuously between said sheets to form a product, pressing the product formed in order to obtain a desired thickness, cutting the board to a desired length, wherein, in order to produce the core of the board, at least one polymer selected from polyvinyl butyral (PVB), copolymers of vinyl acetate and an olefin, which copolymers have a glass transition temperature that varies from ?10? C. to +25? C., terpolymers of vinyl acetate, an olefin and a vinyl ester monomer, terpolymers of vinyl acetate, a vinyl ester monomer and a (meth)acrylate monomer, and copolymers of vinyl acetate and an acrylic monomer is added to the calcined gypsum.

7. A method comprising utilizing a polymer selected from polyvinyl butyral (PVB), copolymers of vinyl acetate and an olefin, which copolymers have a glass transition temperature that varies from ?10? C. to +25? C., terpolymers of vinyl acetate, an olefin and a vinyl ester monomer, terpolymers of vinyl acetate, a vinyl ester monomer and a (meth)acrylate monomer, and copolymers of vinyl acetate and an acrylic monomer in a composition based on calcined gypsum for the manufacture of a plaster-based board in order to improve the acoustic performance of said board.

8. A plaster-based composition, comprising calcined gypsum and at least one polymer selected from polyvinyl butyral (PVB), copolymers of vinyl acetate and an olefin, which copolymers have a glass transition temperature that varies from ?10? C. to +25? C., terpolymers of vinyl acetate, an olefin and a vinyl ester monomer, terpolymers of vinyl acetate, a vinyl ester monomer and a (meth)acrylate monomer, and copolymers of vinyl acetate and an acrylic monomer.

9. The board as claimed in claim 2, wherein the glass transition temperature varies from 0? C. to +10? C.

10. The board as claimed in claim 3, wherein the polymer represents 3% to 30% by weight of the mixture constituted by the plaster and the polymer.

11. The board as claimed in claim 10, wherein the polymer represents 5% to 20% by weight of the mixture constituted by the plaster and the polymer.

12. The board as claimed in claim 4, wherein the polymer is in the form of particles having a mean dimension which varies from 0.1 to 1000 ?m.

13. The board as claimed in claim 12, wherein the polymer is in the form of particles having a mean dimension which varies from 0.2 to 400 ?m.

14. The board as claimed in claim 5, wherein the adhesion agent is a starch.

15. The board as claimed in claim 14, wherein the starch is pretreated with an acid, a dextrin or a vegetable flour.

16. The board as claimed in claim 5, wherein the accelerator is hydrated calcium sulfate or potassium sulfate.

17. The board as claimed in claim 5, wherein the bioacide is sodium omadine.

18. The board as claimed in claim 5, wherein the foaming agent is a sodium sulfate alkyl ether or sodium lauryl sulfate.

19. The board as claimed in claim 5, wherein the at least one water repellent is a siloxane or a polysiloxane.

20. The board as claimed in claim 5, wherein the at least one fire retardant is vermiculite, silica, a clay or metal fibers.

21. The board as claimed in claim 5, wherein the at least one reinforcer is made of polymer fibers, mineral fibers or animal or vegetable fibers.

Description

EXAMPLES 1 TO 15

(1) Plaster-based boards are prepared from the compositions given in table 1.

(2) Calcium sulfate hemihydrate, the polymer and water are introduced into a mixer.

(3) The mixture is stirred for 15 seconds at 600 rpm and 45 seconds at 1850 rpm. The foaming agent is then added and the mixture is stirred at 250 rpm for 50 seconds in order to obtain a paste.

(4) The paste is poured into a brass mold comprising four parallelepipedal cavities (length: 300 mm; width: 30 mm; depth: 13 mm), the internal walls of which have been precoated with a layer of oil. The samples are removed from the mold after 20 minutes, then left in the open air for 40 minutes and finally dried in an oven at 40? C. until their weight remains constant.

(5) By way of comparison, prepared under the same conditions were two boards containing no polymer and having a surface density equal to 9.0 and 11.9 kg/m.sup.2 (comparative examples 10 and 11) and four boards containing a polymer not included in the invention (comparative examples 12 to 15).

(6) The acoustic performances of the boards are evaluated by measuring their mechanical impedance MIM (Measurement of Mechanical Impedance) under the conditions of the ISO 16940:2008(E) standard. From the curve of the acceleration frequency (dB) as a function of the frequency (Hz), the dynamic Young's modulus (in GN/m.sup.2) and the loss factor (in %) are calculated.

(7) The samples are bars having a length of 300 mm, a width of 30 mm and a thickness of 13 mm.

(8) The values of the Young's modulus, the loss factor and the acoustic gain calculated with respect to the reference boards from comparative examples 10 and 11 appear in table 1.

(9) TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Composition Calcined gypsum.sup.(1)(g) 800 800 1000 800 900 900 1000 1000 Water (g) 750 750 800 750 750 750 650 700 Foam.sup.(2)(g) 47 47 0 30 35 30 30 30 Polymer (g) Aqueous dispersion 200.sup.(5) 200.sup.(8) 100.sup.(8) Powder 200.sup.(3) 200.sup.(6) 100.sup.(6) 200.sup.(7) Pellets 200.sup.(4) Properties Surface density (kg/m.sup.2) 9.1 9.3 10.2 9.0 9.0 9.1 9.0 9.1 Dynamic Young's modulus (GN/m.sup.2) 1.52 1.80 1.74 1.55 1.99 1.82 1.59 2.19 Loss factor (%) 2.61 1.86 1.76 6.5 3.8 2.3 7.69 3.47 Acoustic gain (%) with respect to Ex. 10 47.9 38.3 40.4 46.9 31.8 37.7 45.5 25 with respect to Ex. 11 59.5 52.1 53.7 58.7 47.0 51.5 57.7 41.7 Comp. Comp. Comp. Comp. Comp. Comp. Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 Composition Calcined gypsum.sup.(1)(g) 1000 1000 1000 800 800 800 1000 Water (g) 650 750 750 750 750 750 650 Foam.sup.(2)(g) 30 40 13 47 47 47 30 Polymer (g) Aqueous dispersion 200.sup.(9) 200.sup.(10) 200.sup.(11) 200.sup.(12) 200.sup.(13) Powder Pellets Properties Surface density (kg/m.sup.2) 9.2 9.0 11.9 9.1 9.3 9.3 9.3 Dynamic Young's modulus (GN/m.sup.2) 2.13 2.92 3.76 2.82 2.71 2.89 2.84 Loss factor (%) 2.59 0.5 0.5 1.01 0.54 0.73 0.91 Acoustic gain (%) with respect to Ex. 10 27 3.4 7.1 1.0 2.7 with respect to Ex. 11 38.5 .sup.(1)Recycled plaster, without paper CP1 sold by the company Saint-Gobain Placo .sup.(2)Millifoam? C sold by the company Huntsman; solids content: 30% .sup.(3)Shark Powder? C2 sold by the company Shark; polyvinyl butyral; solids content: 100% .sup.(4)Shark Pellets? C3 sold by the company Shark; polyvinyl butyral; solids content: 100% .sup.(5)Shark Dispersion? C3 sold by the company Shark; polyvinyl butyral; solids content: 50% .sup.(6)Vinnapas? 5044 N sold by the company Wacker Chemie; ethylene-vinyl acetate copolymer (Tg-7? C.); solids content: 100% .sup.(7)Vinnapas? 7055 E sold by the company Wacker Chemie; vinyl acetate-ethylene-vinyl ester terpolymer; solids content: 100% .sup.(8)Emultex? VV 665 sold by the company Synthomer; vinyl acetate-VeoVa10-acrylate terpolymer; solids content: 50% .sup.(9)Emultex? VV 675 sold by the company Synthomer; vinyl acetate-VeoVa10-acrylate terpolymer; solids content: 50% .sup.(10)Plextol? DV 686 sold by the company Synthomer; styrene-acrylate copolymer; solids content: 50% .sup.(11)Synthomer? VL 10946 sold by the company Synthomer; carboxylated styrene-butadiene copolymer; solids content: 50% .sup.(12)Litex? N 5140 sold by the company Synthomer; carboxylated butadiene-acrylonitrile copolymer; solids content: 50% .sup.(13)Plextol? X 4427 sold by the company Synthomer, acrylic copolymer; solids content: 50%