Aqueous gelable compositions having extended gelation time and methods of preparing same

Claim 1

An aqueous gelable composition having an extended or increased time of gelation, said composition comprising water to which there has been added: a water-thickening amount of a water-dispersible polymer selected from the group consisting of (a) water-soluble cellulose ethers; (b) polyacrylamides and polymethacrylamides wherein up to about 75 percent of the carboxamide groups can be hydrolyzed to carboxyl groups; crosslinked polyacrylamides and cross-linked polymethacrylamides wherein up to about 75 percent of the carboxamide groups can be hydrolyzed to carboxyl groups; polyacrylic acid and ppolymethacrylic acid; polyacrylates; polymers of N-substituted acrylamides wherein the nitrogen atoms in the carboxamide groups can have from 1 to 2 alkyl substituents which contain from 1 to 4 carbon atoms; copolymers of acrylamide or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water, and wherein up to about 75 percent of the carboxamide groups can be hydrolyzed to carboxyl groups, and mixtures thereof; and (c) a bipolysaccharide produced by the action of bacteria of the genus Xanthomonas on carbohydrates; an amount of a water-soluble compound of a polyvalent metal selected from the group consisting of water soluble compounds of chromium and manganese wherein the metal is present in a first valence state and is capable of being reduced to metal ions having a lower polyvalent valence state, which amount is sufficient to cause gelation of said water containing said polymer when the valence of at least a portion of said metal is reduced to produce said metal ions having said lower valence state as described hereinafter; an amount of a complexing agent capable of complexing with said ions of said metal having said reduced valence state, wherein said complexing agent is selected from the group consisting of citrates, tartarates, acetates, phosphates, hydrophosphates and arsenates, wherein said amount is sufficient to complex with at least a portion of said ions and cause said extended gelation time when said ions are produced as described hereinafter; and an amount of a water-soluble reducing agent which is effective to reduce at least a portion of said metal to said metal ions having said lower valence state, with said reducing agent being added to said water after said complexing agent has been added thereto.

Claim 9

A method for preparing an aqueous gelable composition having an extended or increased time of gelation, which method comprises: mixing with water one of (1) a water-thickening amount of a water-dispersible polymer selected from the group consisting of (a) water-soluble cellulose ethers; (b) polyacrylamides and polymethacrylamides wherein up to about 75 percent of the carboxamide groups can be hydrolyzed to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides wherein up to about 75 percent of the carboxamide groups can be hydrolyzed to carboxyl groups; polyacrylic acid and polymethacrylic acid; polyacrylates; polymers of N-substituted acrylamides wherein the nitrogen atoms in the carboxamide groups can have from 1 to 2 alkyl substituents which contain from 1 to 4 carbon atoms; copolymers of acrylamide or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water, and wherein up to about 75 percent of the carboxamide groups can be hydrolyzed to carboxyl groups, and mixtures thereof; and (c) a bipolysaccharide produced by the action of bacteria of the genus Xanthomonas on carbohydrates, and (2) an amount of a water-soluble compound of a polyvalent metal selected from the group consisting of water soluble compounds of chromium and manganese wherein the metal is present in a first valence state and is capable of being reduced to metal ions having a lower polyvalent valence state, and which amount is sufficient to cause gelation of said water having said polymer dispersed therein when the valence of at least a portion of said metal is reduced to produce said metal ions having said lower valence state as described hereinafter; mixing with said water the other of said components (1) and (2) which has not been previously mixed with said water; mixing with said water an amount of a complexing agent capable of complexing with said ions of said metal having said reduced valence state, and sufficient to complex with at least a portion of said ions and cause said extended gelation time when said ions are produced as described hereinafter; wherein said complexing agent is selected from the group consisting of citrates, tartarates, acetates, phosphates, hydrophosphites, and arsenates; and thereafter mixing with said water an amount of a water-soluble reducing agent which is effective to reduce at least a portion of said metal to said metal ions having said lower valence state.

Claim 10

A method for preparing an aqueous gelable composition having an extended or increased time of gelation, which method comprises: mixing with water one of (1) a water-thickening amount of a water-dispersible polymer selected from the group consisting of (a) water-soluble cellulose ethers; (b) polyacrylamides and polymethacrylamides wherein up to about 75 percent of the carboxamide groups can be hydrolyzed to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides wherein up to about 75 percent of the carboxamide groups can be hydrolyzed to carboxyl groups; polyacrylic acid and polymethacrylic acid; polyacrylates; polymers of N-substituted acrylamides wherein the nitrogen atoms in the carboxamide groups can have from 1 to 2 alkyl substituents which contain from 1 to 4 carbon atoms; copolymers of acrylamide or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water, and wherein up to about 75 percent of the carboxamide groups can be hydrolyzed to carboxyl groups, and mixtures thereof; and (c) a bipolysaccharide produced by the action of bacteria of the genus Xanthomonas on carbohydrates, and (2) an amount of a water-soluble compound of a polyvalent metal selected from the group consisting of water soluble compounds of chromium and manganese wherein the metal is present in a first valence state and is capable of being reduced to metal ions having a lower polyvalent valence state, and which amount is sufficient to cause gelation of said water having said polymer dispersed therein when the valence of at least a portion of said metal is reduced to produce said metal ions having said lower valence state as described hereinafter; mixing with said water the other of said components (1) and (2) which has not been previously mixed with said water; mixing with said water an amount of a complexing agent capable of complexing with said ions of said metal having said reduced valence state, and sufficient to complex with at least a portion of said ions and cause said extended gelation time when said ions are produced as described hereinafter; wherein said complexing agent is selected from the group consisting of citrates, tartarates, acetates, phosphates, hydrophosphites, and arsenates; and thereafter mixing with said water an amount of a water-soluble reducing agent which is effective to reduce at least a portion of said metal to said metal ions having said lower valence state.