Films from PVA modified with nonhydrolyzable anionic comonomers

Reference Number: N 04-07

Inventors: Yang, Chihae; Kaufmann, Edward J.

USPTO Link: 4885105

Invention Summary

In one embodiment, the present invention is a film formed from a resin having a vinyl acetate monomer copolymerized with a comonomer selected from a hereinafter defined group. After such copolymerization, and a conversion step, the comonomers are characterized by the presence of an anionic species, and are hereinafter referred to as "nonhydrolyzable" comonomers. The conversion step comprises at least a base catalyzed saponification step, in an organic solvent, to convert residual acetate groups to alcohols, and to produce the anionic species characterizing the nonhydrolyzable comonomer. In some cases, the presence of adjacent alcohols and carboxylic esters causes the formation of internal lactone rings. By the additional conversion step of subsequently treating the resin with a base, the lactones can also be converted to the anionic form, resulting in an anionic resin from which a film can be made. This latter step is a hydrolysis step. It has been surprisingly found that by selecting the type and content of comonomer, the molecular weight of the PVA resin, and the degrees of hydrolysis of the vinyl acetate, lactonization and ionomer content, and depending on the type of base used to neutralize the copolymer, a film can be made which exhibits relatively temperature-independent water solubility, and is not rendered insoluble by alkaline or borate-containing detergent compositions. Further, the film is sufficiently strong to be formed into a free-standing pouch which may be used to package cleaning compositions, particularly alkaline or borate-containing cleaning compositions. The film is resistant to insolubilization caused by high humidity storage conditions, hence is stable over a typical storage shelf life. The films can be produced from a single polymer solution, without the need for making separate polymer solutions, which may be incompatible when mixed for film production. In a second aspect of the present invention, the films are formed into pouches and are used as soluble delivery means for cleaning compositions. Such cleaning compositions include, but are not limited to dry granular, liquid and mulled detergent compositions, bleaches, fabric softeners, dishwashing detergents, combinations thereof, and other compositions for improving the aesthetics, feel, sanitation or cleanliness of fabrics or wares. The invention is particularly well suited for containing detergent mulls such as those described in European published patent application No. 0,158,464, filed March 21, 1985, entitled "Low-temperature effective detergent compositions and delivery systems therefor", and 0,234,867, filed February 19, 1987, entitled "Concentrated non-phosphate detergent paste compositions", both of which are assigned to the same assignee as the present invention, the specifications of which are incorporated herein by reference. These mulls may be highly viscous gels or pastes and include relatively high concentrations of nonionic surfactants for effective removal of oily soils. The mulls are formulated to have alkaline detergent builders which aid in particulate soil removal, and are formulated to provide optimum cleaning power, not for ease of delivery. The preferred delivery method, both for convenience and accuracy, is to include a pre-measured amount of the mull within the water-soluble pouch of the present invention.