Composition comprising a phosphate binder and its preparation

A composition comprising at least:

• (a) an inorganic binder having calcium silicate sites which are connected the one with the other by alumina-silica phosphate bonds, whereby at least a portion of said alumina-silica phosphate bonds are alumina-boron-silica phosphate bonds, the calcium silicate sites acting as cross-linking sites for the alumina-silica phosphate bonds, whereby said alumina-silicate phosphate bonds have:
• a weight ratio Al2O3/SiO2, ranging from 0.3:1 to 10:1,
• a weight ratio Al2O3/P2O5 ranging from 0.0005 to 0.04, and
• a weight ratio P/B ranging from 20:1 to 100:1, and
• whereby the inorganic binder further comprises a silicon containing compound selected from the group consisting of waterproof silicon compounds, water repellent silicon compounds and mixture thereof, the weight ratio
• said silicon containing compound/P+B being comprised between 1:5000 and 1:10, and whereby at least a portion of the calcium silicate sites are at least partly provided with a layer of said silicon containing compound, and
• (b) a silicon containing filler.

A product comprising a support having at least one face at least partly coated with a composition comprising at least:

• (a) an inorganic binder having calcium silicate sites which are connected the one with the other by alumina-silica phosphate bonds, whereby at least a portion of said alumina-silica phosphate bonds are alumina-boron-silica phosphate bonds, the calcium silicate sites acting as cross-linking sites for the alumina-silica phosphate bonds, whereby said alumina-silicate phosphate bonds have:
• a weight ratio Al2O3/SiO2 ranging from 0.3:1 to 10:1,
• a weight ratio Al2O3/P2O5 ranging from 0.0005 to 0.04, and
• a weight ratio P/B ranging from 20:1 to 100:1, and
• whereby the inorganic binder further comprises a silicon containing compound selected from the group consisting of waterproof silicon compounds, water repellent silicon compounds and mixture thereof, the weight ratio
• said silicon containing compound/P+B being comprised between 1:5000 and 1:10, and whereby at least a portion of the calcium silicate sites are at least partly provided with a layer of said silicon containing compound, and
• (b) a silicon containing filler.

A process for the preparation of an inorganic binder having calcium silicate sites which are connected the one with the other by alumina-silica phosphate bonds, the calcium silicate sites acting as cross-linking sites for the alumina-silica phosphate bonds with a weight ratio Al2O3/SiO2 ranging from 0.3:1 and 10:1,

• * in which water insoluble calcium silicate particles partly coated with a layer of a silicon containing compound selected from the group consisting of waterproof silicon containing compounds, water repellent silicon containing compounds or and mixtures thereof, are mixed with an acid alumina-silica phosphate solution comprising boric acid and a silicon containing compound selected from the group consisting of waterproof silicon containing compounds, water repellent silicon containing compounds and mixtures thereof, at a temperature lower than 70° C., said acid alumina-silica phosphate solution comprising solubilized SiO2 and having a pH of less than 2, said acid alumina-silica phosphate solution having:
• a weight ratio Al2O3/SiO2 ranging from 0.3:1 and 10:1,
• a weight ratio Al2O3/P2O5 ranging from 0.0005 to 0.04, and
• a weight boron content such that the weight ration P/B is comprised from 20:1 to 100:1, and
• said acid alumina-silica phosphate comprising an amount of said silicon containing compound such that the weight ratio said waterproof and/or water repellent silicon containing compound/P+B is comprised between 1:500 and 1:75, and whereby at least a portion of the calcium silicate sites are at least partly provided with a layer of said silicon containing compound.