Fire resistant glazing
AssigneePilkington plc
InventorsKarikath Sukumar Varma, John Richard Holland, David William Holden, Stephen Ian Bond
Life of this patent
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Abstract
Fire resistant glazings comprise a fire resistant interlayer based upon a silicate waterglass are characterized by the incorporation of aluminum ions. The aluminate is incorporated as a solution which has been partially neutralized using hydroxycarboxylic acid which is preferably citric acid. The incorporation of aluminum provides glazings have improved fire resistance and impact properties.
Claims21
A process for producing a clear intumescent interlayer with from 10 to 35% by weight of water:
- 1) in a first step preparing a solution comprising an alkali metal silicate;
- and
- 2) in a second step preparing a partially neutralized aluminate solution comprising:
- i) a water soluble aluminate;
- and
- ii) a hydroxy carboxylic acid, by:
- a) adding the hydroxy carboxylic acid to the water soluble aluminate in solution with mixing and stirring to partially neutralize the water soluble aluminate and until the partially neutralized aluminate solution has a pH in the range of 9.0 to 11.0;
- and
- b) maintaining the temperature of the water soluble aluminate solution below 50° C. throughout the addition of the hydroxy carboxylic acid to the water soluble aluminate and throughout the mixing thereof until a pH range of 9.0 to 11.0 is reached, and
- 3) in a third step mixing together the partially neutralized aluminate solution and the alkali metal silicate solution to provide a clear stable aqueous solution;
- and
- wherein the formation of a precipitate during addition of the partially neutralized aluminate solution to the alkali metal silicate is prevented by the addition of the hydroxy carboxylic acid to the water soluble aluminate to partially neutralize the water soluble aluminate.
A process for producing a clear intumescent interlayer including an alkali metal silicate, a partially neutralized aluminate, and a hydroxy carboxylic acid, comprising the steps of:
- i) providing a partially neutralized aluminate solution;
- and
- ii) providing an alkali metal silicate solution;
- and
- iii) mixing the alkali metal silicate solution and the partially neutralized aluminate solution together;
- and
- iv) before mixing the alkali metal silicate solution and the partially neutralized aluminate solution together, adding the hydroxy carboxylic acid to a water soluble aluminate solution with mixing until the water soluble aluminate solution is partially neutralized and has a pH in the range of 9.0 to 11.0, resulting in the partially neutralized aluminate solution;
- and
- v) maintaining the temperature of the water soluble aluminate solution both during the addition of the hydroxy carboxylic acid to the water soluble aluminate solution and throughout the mixing of the water soluble aluminate solution and the hydroxy carboxylic acid below 50° C.;
- and
- vi) only after the partially neutralized aluminate solution has a pH in the range of 9.0 to 11.0, mixing the partially neutralized aluminate solution with the alkali metal silicate waterglass to form a clear, stable aqueous solution comprising the alkali metal silicate solution, the partially neutralized aluminate, and the hydroxy carboxylic acid;
- and
- vii) drying excess water from the stable aqueous solution comprising the alkali metal silicate solution, the partially neutralized aluminate, and the hydroxy carboxylic acid to form an intumescent inorganic layer comprising from 10 to 35% by weight of water.
Dependencies are inferred from the claim text.