Aqueous curable molding compositions based on inorganic ingredients and process for the production of molded parts
First Claim
1. An aqueous, hardenable molding composition consisting essentially of inorganic components and water in a flowable or press-moldable distribution, said inorganic components comprising stone-forming components consisting of:
- dissolved SiO2 ;
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Abstract
Molded parts having high flexural strength, based on alkali silicates, can be produced by casting and/or press-molding and curing by heating from aqueous molding compositions which are prepared from an oxide mixture containing amorphous silicic acid and aluminum oxide, as well as, optionally, as an additional component, aqueous, amorphous, disperse-powdery silicic acid, dissolved SiO2, and alkali from alkali silicate solutions, optionally alkali hydroxide or its aqueous solutions and, if desired, fillers, by means of mixing under agitation. By addition of a blowing agent inorganic foamed products can be obtained.
82 Citations
17 Claims
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1. An aqueous, hardenable molding composition consisting essentially of inorganic components and water in a flowable or press-moldable distribution, said inorganic components comprising stone-forming components consisting of:
dissolved SiO2 ; - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 16)
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2. 3-10 parts by weight of a water-free oxide mixture containing amorphous SiO2 and aluminum oxide per part of dissolved SiO2 ;
0.7-2.5 parts by weight of K2 O or 0.55-1.5 parts by weight of Na2 O per part by weight of dissolved SiO2 or equivalent amounts of the sodium oxide being used for equivalent amounts of the potassium oxide;
wherein K2 O or Na2 O, respectively, is derived from at least one alkali hydroxide selected from the group consisting of sodium hydroxide and potassium hydroxide, an aqueous solution thereof, or an aqueous solution of at least one alkali silicate selected from the group consisting of sodium silicate and potassium silicate, and the dissolved SiO2 is derived from an aqueous solution of at least one alkali silicate selected from the group consisting of sodium silicate and potassium silicate;
said composition containing sufficient amounts of water up to attainment of flowability or press-moldability, respectively, and optionally amounts of inert fillers up to the limit of flowability.
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11. A process for the production of molded parts from molding compositions which comprises preparing a flowable or press-moldable composition containing 1.3-10 parts by weight of a water-free oxide mixture with contents of amorphous SiO2 and aluminum oxide and 0.7-2.5 parts by weight of K2 O or 0.55-1.5 parts by weight of Na2 O per 1 part by weight of dissolved SiO2 or equivalent amounts of the sodium oxide being used for equivalent amounts of the potassium oxide, as well as optionally inert fillers, by
(a) mixing the oxide mixture containing silicon dioxide and aluminum oxide into an aqueous solution of at least one alkali silicate selected from the group consisting of sodium silicate and potassium silicate which alkali silicate solution is admixed, with at least one solid or dissolved alkali hydroxide selected from the group consisting of sodium hydroxide and potassium hydroxide; - or
(b) dissolving amorphous, aqueous silicic acid in an aqueous solution of at least one alkali hydroxide selected from the group consisting of sodium hydroxide and potassium hydroxide to obtain an aqueous silicate solution thereof, and adding the oxide mixture, or (c) mixing amorphous, aqueous silicic acid with at least one alkali hydroxide selected from the group consisting of sodium hydroxide and potassium hydroxide or its aqueous solution, and reaction of the proportion of silicic acid to be dissolved to the resulting alkali silicate solution, and adding the oxide mixture, and filling this composition into molds, venting, optionally press-molding, and curing. - View Dependent Claims (17)
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15. A process according to claim wherein initial curing is effected at 50°
- -150°
C. unmolding is effected after attaining the required solidity, and thereupon final curing is effected at 80°
-200°
C.
- -150°
Specification