United States Patent:  6,066,613

Assignee:  Lever Brothers Company (New York, NY)

Filed:  November 6, 1997

The invention relates to hydrogel dispersions/particles capable of trapping water insoluble beneficial agent, yet capable of disintegrating smoothly to impart desirable in use characteristics.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to aqueous compositions containing novel hydrogel particles formed by two different water soluble polymers. The hydrogel particles "trap" water insoluble beneficial agents in a network formed by these two polymers. The polymer network which entraps the benefit agents disintegrates smoothly when rubbed on a substrate such as skin in order to impart desirable in use characteristics (e.g., smooth, rich, creamier feel) to the composition. More particularly, the aqueous composition comprises:

(1) 40 to 95% by wt. of an aqueous solution with viscosity higher than 300 centipoise (cps), preferably higher than 1,000 cps, more preferably higher than 3,000 cps, wherein said aqueous solutions contains 0% to 60%, preferably 2% to 40%, surfactant and wherein said surfactant, if present, is selected from the group consisting of anionic, nonionic, cationic, zwitterionic, amphoteric surfactant and mixtures thereof; and

(2) 5 to 60% by wt. of a hydrogel composition comprising:

(a) 0.1 to 30% by wt. of hydrogel composition, preferably 0.3-15% of at least one polymer which is soluble in water, but which is insolubilized when placed in said aqueous solution; and

(b) 0.2 to 30%, preferably 0.5-10% by wt. of hydrogel composition of at least a second polymer which is soluble in water and either soluble or dispersible in said aqueous surfactant solution; and

(c) 1.0 to 60% by wt., preferably 5 to 40% by wt. of a water insoluble beneficial agent which is entrapped in a network formed by polymers (a) and (b); wherein particles of said benefit agent have a particle size of about 0.2 to 200 micrometers;

said hydrogel having a particle size in the range of from about greater than 25 micrometers, preferably larger than 100 micrometers, more preferably greater that 200 micrometers up to about several centimeters.

In a second embodiment of the invention, the aqueous composition containing the novel hydrogel particles is prepared first by adding (e.g., injecting) a polymer solution containing the said two polymers and the water insoluble material into the said aqueous medium to form elongated (in theory, there is no limit to the size of the noodle since it can be continuously extruded), soft (i.e., rigid enough to hold benefit agent, but soft enough to be broken down initially into smaller particles and later to deliver benefit agent to skin) polymer gel noodles which are then cut into the desirable gel particle size. More specifically, the aqueous composition is prepared as follows:

(a) dissolving the first and the second polymer in water to form a polymer solution and dispersing the water insoluble material into the prepared polymer solution to form a hydrogel precursor solution;

(b) formulating the aqueous composition such that the first polymer is not soluble in said aqueous composition due to chemical or physical interaction and the second polymer is either soluble or dispersible; and

(c) injecting the hydrogel precursor solution (a) into the aqueous composition (b) to form elongated soft, hydrogel noodles and breaking the elongated soft noodles to hydrogel particles using low shear mixing device.

The second polymer or polymers (2)(b) forming the hydrogel composition is a property modifying polymer which is required (1) to help stabilize benefit agent in the polymer hydrogel system and (2) to help provide the proper gel strength of the overall hydrogel composition.

Claim 1 of 16 Claims

1. An aqueous composition comprising:

(a) 40-95% by weight aqueous solution having a viscosity greater than 300 centipoises; and

(b) 5% to 60% by wt. of a hydrogel composition comprising:

(i) 0.1 to 30% by wt. hydrogel composition of at least one polymer soluble in water which polymer is insolubilized when placed in the aqueous solution of item (a);

(ii) 0.2 to 30% by wt. hydrogel composition of a polymer soluble in water, and soluble or dispersible in the aqueous solution of item (a); and

(iii) 1.0 to 60% water insoluble benefit agent entrapped in a network formed by (i) and (ii);

wherein said particles of said benefit agent (iii) have particle size of 0.2 to 200 micrometers;

wherein said hydrogel is greater than 25 micrometers;

and wherein the size of the hydrogel (b) is greater than that of the benefit agent.

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