Curable aqueous silicate composition, uses thereof, and coatings or layers made therefrom

A two-part curable composition which is curable at room temperature when the two parts are blended together, said composition comprising:

• in a first part, an aqueous solution or dispersion of an alkali metal silicate,
• in a second part, a coreactant for said alkali metal silicate comprising a phosphate salt of a divalent metal of Group II of the Periodic Table, said phosphate salt having a water solubility ranging from 10.sup.-1 to 10.sup.-4 weight-% at room temperature;
• provided that:
• if said water solubility is greater than 10.sup.-2 weight-%, any divalent metal cation of said metal salt is less reactive with alkali metal silicates than Ca.sup.++, and
• if said water solubility is less than 10.sup.-3 weight-%, a divalent cation of said metal salt is more reactive with alkali metal silicates than -325 U.S. mesh ZnO;
• said coreactant being selected to provide a sufficiently complete curing of said alkali metal silicate to impart, to a 10 mm-thick coating of said composition after 14 days of curing at room temperature, water resistance and a Barcol hardness of at least 10 at the exposed or top surface of the coating;
• said coreactant also being selected to permit a pot life for said composition of at least 15 minutes at room temperature.

An aqueous silicate composition which is curable at room temperature and which comprises:

• (a) an aqueous solution or colloidal dispersion of an alkali metal silicate;
• (b) a combination of a divalent metal carbonate and a divalent metal phosphate or borate, wherein said metal salts are coreactants for said alkali metal silicate at room temperature, having a reactivity with alkali metal silicates at least equal to the cations of metals of Group II, A or B, of the Periodic Table, and having a water solubility ranging from about 10.sup.-1 to 10.sup.-4 weight-% at a pH of 7 and room temperature;
• provided that:
• if said water solubility is greater than 10.sup.-2 weight-%, any divalent metal cation of said metal salts is less reactive with alkali metal silicates than Ca.sup.++, and
• if said water solubility is less than 10.sup.-3 weight-%, a divalent cation of said metal salts is more reactive with alkali metal silicates than -325 U.S. mesh ZnO;
• said component (b) being selected to provide a sufficiently complete curing of said alkali metal silicate to impart, to a 10 mm-thick coating of said composition after 14 days of curing at room temperature, water resistance and a Barcol hardness of at least 10 at the exposed or top surface of the coating;
• said component (b) also being selected to permit a pot life for said composition of at least 15 minutes at room temperature.

An aqueous silicate insulation composition which is curable at room temperature and which comprises:

• (a) an aqueous solution or colloidal dispersion of an alkali metal silicate;
• (b) a combination of a divalent metal carbonate and a divalent metal phosphate or borate, wherein said metal salts are coreactants for said alkali metal silicate at room temperature, having a reactivity with alkali metal silicates at least equal to the cations of metals of Group II, A or B, of the Periodic Table, and having a water solubility ranging from about 10.sup.-1 to 10.sup.-4 weight-% at a pH of 7 and room temperature;
• provided that:
• if said water solubility is greater than 10.sup.-2 weight-%, any divalent metal cation of said metal salts is less reactive with alkali metal silicates than Ca.sup.++, and
• if said water solubility is less than 10.sup.-3 weight-%, a divalent cation of said metal salts is more reactive with alkali metal silicates than -325 U.S. mesh ZnO;
• said component (b) being selected to provide a sufficiently complete curing of said alkali metal silicate to impart, to a 10 mm-thick coating of said composition after 14 days of curing at room temperature, water resistance and a Barcol hardness of at least 10 at the exposed or top surface of the coating;
• said component (b) also being selected to permit a pot life for said composition of at least 15 minutes at room temperature, and (c) a filler comprising a particulate aggregate.

A coating composition which dries and cures to a solid, crosslinked mass at room temperature, which comprises:

• (a) an aqueous colloidal dispersion comprising about 5 to about 65% by weight of a dispersed colloidal silicate of the formula M.sub.2 O.nSiO.sub.2, wherein M represents sodium or potassium and n is a number of moles ranging from about 1.6 to about 4;
• (b) about 5 to about 25 parts by weight, per 100 parts by weight of said aqueous colloidal dispersion, of an aqueous latex comprising about 10 to about 80% by weight of elastomeric latex particles stably distributed in an aqueous medium;
• (c) about 1 to about 50 parts by weight, per 100 parts by weight of said aqueous colloidal dispersion, of trimagnesium phosphate;
• (d) about 1 to about 50 parts by weight, per 100 parts by weight of said aqueous colloidal dispersion, of magnesium carbonate;
• and
• (e) an amount of water sufficient to make said aqueous silicate composition sprayable.

A method of applying an insulative, fire-retardant coating to a substrate which comprises the steps of:

• (a) blending the composition of claim 19 or 36 with a non-flammable inorganic filler to obtain a sprayable coating composition;
• (b) spraying said sprayable coating composition onto a substrate to form a coating thereon;
• and
• (c) permitting the resulting coating to dry and cure for at least 16 hours at ambient temperatures.