Self-breaking viscous aqueous solutions and the use thereof

Abstract From the Canadian patent

Viscous aqueous solutions are prepared which maintain a certain viscosity range over a predetermined period of time (i.e. induction period) and which thereafter break, i.e. decrease in viscosity over a very short period of time. The viscous aqueous solution comprises a polysaccharide having an ability to thicken water and dispersed or dissolved in the aqueous solution an effective quantity of an organic ester which at a temperature, at which it is desired to break the viscous solution hy-, drolyzes over a delayed period of time to form an acid which degrades the polysaccharide, thus causing a splitting of the polysaccharide chain and a decrease in the viscosity of the solution. r