Aqueous dispersions of polyester and polyesteramides cross-linked with metallic ions and casts made therefrom

This invention relates generally to cross-linking an aqueous dispersion of polyester or polyesteramide with the water soluble multivalent metallic ions. The aqueous dispersion of polyester or polyesteramides containing ether and sulfonate groups can also contain humectants and/or emollients which when cross-linked with metallic ions and poured into any desirable shaped mold form a clear or opaque cast of therapeutic functional nature. This invention also relates to the process of cross-linking the polyester or polyesteramide aqueous dispersion with metallic ions.

Many compositions used for skin treatment contain emollients of humectants in lotion, cream or gel form. Such products are applied by evenly spreading the product on the skin. Upon loss of water, the product dries providing humectants and emollients to the epidermis.

Water soluble gels that form protective films of various types are known. For example, U.S. Pat. No. 4,393,048 discloses a water soluble hydrogel of alkali metal alginate and glycerine that dries to a non-toxic, pliable protective film. U.S. Pat. No. 3,949,742 discloses a transparent medical dressing which performs as a synthetic film over skin wounds. Water soluble polyesters, for example U.S. Pat. No. 4,502,976, are used to form cross-linked bioerodible hydrogels. The hydrogels, suitable for carrying water soluble therapeutic macromolecules and for implantantion in living mammals, are produced by a complex polymerization process without using water soluble metallic ions.

U.S. Pat. No. 3,879,168 to Franklin discloses a surgical dressing made of partially soluble alginic materials in the form of gauze or wool characterized by a pH of 4 to 7 and a calcium content of 2-6% by weight comprised of a laminate of a thin layer of non-porous segmented polyurethane sewn to foam.

U.S. Pat. Nos. 3,734,874, 4,233,196, 4,335,220, 4,304,900, 4,304,901, and 4,300,580 describe water-dissipatable, meltable polyesters that are useful as adhesives, coating materials, films, packaging materials and other products that can be dissolved, dispersed or otherwise dissipated in water or aqueous solutions. These polyesters, however, are not cross-linked using metallic ions and cast into shapes to entrap water, humectants and/or emollients within the hardened cast.

As explained in a technical publication from Eastman, the water dispersability of the AQ polymer is largely attributed to the presence of ionic substituents attached to the polymer chain. A simplified representation of the polymer is shown below: ##STR1## wherein "A" is an aromatic dicarboxylic acid moiety some of which have sodiofulfo (--SO 3 -, Na+) substituents, "G" is an aliphatic or cycloaliphatic glycol residue and "OH" is a hydroxy end group.

It is the sodio sulfo group which impart the water dispersability to the polymer. To cross-link with multivalent metallic ions and obtain the moldable shapes of this invention, the multivalent metal salts must be added and mixed according to the teaching of this invention. Departing from this process results in non-compatible mixtures of non-commercial properties. Eastman technical publications teach the synthesis and preferred methods for crosslinking water dispersible polyesters and polyesteramides with other resins through high temperature curing process and subsequent drying of the cured resins, but specifically warn against the use of the heavy metal salts included in this invention as being not compatable with the polymers used in this invention.

It is therefore an object of the present invention to provide novel cross-linked polyester polymers with humectants and/or emollients by using water soluble metallic ions.

A further object of the present invention is to provide a convenient process of cross-linking the humectant and emollients with the polyester polymer in the presence of water soluble metallic ions.

A further object of this invention is to provide such casted patches containing water soluble medicaments and oil soluble medicaments. Such patches can be used as controlled release transdermal delivery patches.

It has been found that the objectives of this invention may be realized by forming a cast containing humectants and/or emollient oils, water, water dissipatable polyesters, and by cross-linking with water soluble multivalent metal ions. Such compositions when poured into a mold harden without pressure and have utility in wound treatment, skin treatment and controlled release drug and fragrance patches.

The casts of this invention comprise water dissipatable polyester or polyesteramide in an amount from 18 to 30 percent by weight, water in an amount from .[.67.]. .Iadd.30 .Iaddend.to 80%, humectants in an amount from 0.01 to 40% by weight, and a source of multivalent metal ions for cross-linking purposes in an amount from 0.01 to 5 percent. Casts of this invention can also be formulated using emollient oils in an amount from 0.01 to 25% by weight based on the total weight of the composition, water dissipatable polyester in an amount from 18-30% by weight, water in an amount from .[.67.]..Iadd.30.Iaddend.-80% by weight based on the total weight of the composition, and a source of multivalent metallic ions in an amount from 0.01 to 5% based on the total weight of the composition. Optionally the composition also contains fragrance oils, medical agents or color.

Cross-linked clear casts of the present invention comprise (a) a water dissipatable polyester polymer in an amount from 18-30% by weight based on the total weight of the composition; (b) water in an amount from .[.67.]..Iadd.30.Iaddend.-80% by weight based on the total weight of the composition; (c) a source of multivalent metallic ions in an amount of 0.1-5% by weight based on the total weight of the composition; (d) humectant such propylene glycol, glycerine in an amount from 0.1-40% by weight based on the total weight of the composition.

The cross-linked cast of the present invention can also be in the form of an opaque emulsion system. Such emulsion cast of the present invention comprise (a) a water dissipatable polymer in an amount from 18 to 30% by weight based on the total weight of the composition; (b) water in an amount from .[.67.]..Iadd.30.Iaddend. to 80% by weight based on the total weight of the composition; (c) emollient oils in an amount from 0.1 to 25% by weight based on the total weight of the composition; (d) a source of multivalent metallic ions in an amount from 0.1 to 5% by weight based on the total weight of the composition; (e) humectants in an amount from 0.01 to 40% by weight-based on the total weight of the composition; (f) any suitable oil-in-water emulsifier in an amount from 0.01 to 5% by weight based on the total weight of the composition.

Polymers useful in the present invention must be capable of cross-linking with water soluble metal ions, and, when poured in liquid from into a mold hardening without pressure to form a cast of any desirable shape. Polymers suitable for use in this invention include the water-dissipatable polyester and polyesteramides described in U.S. Pat. No. 3,734,874 to Kibler, et al., U.S. Pat. No. 4,233,196 to Sublet and U.S. Pat. No. 4,304,901 to O'Neill, et al. A preferred water dissipatable polyester is commercially available on Eastman AQ 55S polymers.

Examples of organic and inorganic sources of the multivalent metal ions used to cross-link the polymers in this invention include magnesium chloride, zinc acetate, zinc gluconate, zinc oxide, titanium dioxide, and magnesium acetate. The preferred sources of multivalent metal ions are water soluble and include zinc gluconate and magnesium chloride.

In forming the clear cross-linked casts of this invention, water by itself or in combination with humectant such as propylene glycol and glycerine may be used.

In forming cross-linked emulsion casts of this invention any emollient oil may be used. Emollients useful in this invention include hydrocarbon oils and semi-solid hydrocarbons, lanolin and derivatives, silicone oils and esters commonly used in the cosmetic and dermatological fields.

The cross-linking of polymer containing emulsion systems by means of multivalent metallic ions can be achieved with or without the additional emulsfiers. The selection of an appropriate emulsifier for a given system is within the purview of one skilled in the art.

Optionally, a wide variety of agents may be incorporated into the compositions of this invention for a variety of purposes. For example, medicaments such as benzoyl peroxide, methyl nicolinate, salicylic acid, benzocaine and methanol can be cast into desirable shapes for therapeutic use.

The cross-linked hydrogels and emulsions can be cast into any desirable shape and used for various purposes. For example, casts in the form of face masks may be used for treating dry skin. Casts in the form of patches or pads may be used to cover burns and wounds for soothing and comforting the inflamed area, or for delivering active medicaments to the damaged skin as a controlled release, transdermal patch.

Both the clear and opaque emollient casts may also contain fragrance, insect repellents, sun screens and like chemicals.

The following examples illustrate how the cross-linked casts of this invention may be formed.