Lightweight plasterboard and plaster slurry composition used for its manufacture

Abstract

A plaster slurry composition includes plaster, water and starch, the starch having a Brookfield viscosity of less than 60 cps at a temperature below 60° C. and a Brookfield viscosity greater than 10,000 cps at a temperature of 70° C.

1 . Plasterboard comprising a core obtained by setting of a plaster slurry composition comprising plaster, water and starch, said starch having a Brookfield viscosity of less than 60 cps at a temperature below 60° C. and a Brookfield viscosity greater than 10,000 cps at a temperature of 70° C., wherein the plasterboard has two facings. 
     
     
         2 . The plasterboard according to  claim 1 , having a core density varying from 540 kg/m 3  to 1100 kg/m 3 . 
     
     
         3 . The plasterboard according to  claim 1 , having a core density varying from 750 kg/m 3  to 950 kg/m 3 . 
     
     
         4 . The plasterboard according to  claim 1 , wherein the facing is paper, or a mat or nonwoven, said facing being optionally filled with a fine filler and/or a filler that has optionally received a surface treatment. 
     
     
         5 . The plasterboard according to  claim 1 , wherein the facing is a mat of glass fibres and/or of synthetic and/or cellulose fibres. 
     
     
         6 . The plasterboard according to  claim 1 , wherein the starch has a Brookfield viscosity of less than 20 cps at a temperature of 60° C. 
     
     
         7 . The plasterboard according to  claim 1 , wherein the starch has a Brookfield viscosity of greater than 20,000 cps, at a temperature of 70° C. 
     
     
         8 . The plasterboard according to  claim 1 , wherein the starch has a Brookfield viscosity of greater than 30,000 cps, at a temperature of 70° C. 
     
     
         9 . The plasterboard according to  claim 1 , wherein the starch has a Brookfield viscosity of greater than 60,000 cps at a temperature of 80° C. 
     
     
         10 . The plasterboard according to  claim 1 , wherein the starch is non-retrograding. 
     
     
         11 . The plasterboard according to  claim 1 , wherein the starch has a viscosity at 25° C., after cooling following heating of the starch solution up to 90° C., which is greater than the maximum viscosity obtained during heating of said starch solution. 
     
     
         12 . The plasterboard according to  claim 1 , wherein the starch has a viscosity at 25° C., after cooling following heating of the starch solution up to 90° C., of at least 100,000 cps. 
     
     
         13 . The plasterboard according to  claim 1 , wherein the starch has a viscosity at 25° C., after cooling following heating of the starch solution up to 90° C., of at least 300,000 cps. 
     
     
         14 . The plasterboard according to  claim 1 , wherein the plaster slurry composition comprises, relative to the weight of plaster, between 0.05 and 1% by weight of starch. 
     
     
         15 . The plasterboard according to  claim 1 , wherein the plaster slurry composition comprises, relative to the weight of plaster, between 0.1 and 0.5% by weight of starch. 
     
     
         16 . The plasterboard according to  claim 1 , wherein the plaster slurry composition has a pH between 5.5 and 8.5. 
     
     
         17 . The plasterboard according to  claim 1 , wherein the plaster slurry composition has a pH between 6 and 7.5. 
     
     
         18 . The plasterboard according to  claim 1 , wherein the plaster slurry composition comprises, in addition, a thin-boiling starch having a viscosity less than or equal to 1000 cps up to 90° C.