Union Carbide Chemicals & Plastics Technology Corporation

Kimberly S Hayson

Brian Terry Keen

Albert Ferris Joseph

William C Hoffman

Hybrid strategies generally involve treating biodegradable substrates with preservative compositions having at least two phases in which the metal biocide is distributed among at least the two phases and via equilibrium reactions moves between the two phases. Both phases are caused to contact the substrate in a manner so that the phases are in contact with each other during at least a portion of the treatment. In illustrative embodiments, the first phase is a liquid phase comprising complexed metal biocide dissolved in a liquid carrier, while the second phase comprises particles comprising the metal biocide, often precipitated and/or colloidal particles. The strategies and related compositions, processes, and treatments are hybrid in the sense that the strategies include both heterogeneous (insoluble) and homogeneous metal biocide constituents. Unlike heterogeneous strategies, hybrid strategies are less sensitive to particle size constraints and may use biocide particles with a wider range of particle sizes. Unlike homogeneous strategies, hybrid strategies are less sensitive to pH and may use a wider range of complexing agents, including mildly alkaline amines such as triethanolamine.

Hybrid strategies for reducing leaching of metal biocides from biodegradable substrates

The present invention relates to post-treatment compositions and methods useful for modifying the distribution of metal biocide(s) in biodegradable substrates such as wood, other cellulosic products, starch-based products, and the like that are vulnerable to decay due to insects, fungi, microbes, and the like. The compositions include complexing agents of moderate strength that are able to facilitate mobilization and redistribution of metal biocide(s) in substrates without undue leaching. The compositions can be used, for example, to redistribute the metal biocide(s) into depleted regions of a substrate by redistribution of metal biocide from other regions of the substrate. Post-treatment compositions that include additional metal biocide can also replenish these regions with the freshly supplied, additional biocide. Thus, the depleted regions can be restored by redistribution and/or replenishment mechanisms. Service life of substrates in the field benefits by these post-treatments as a consequence.

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Red House, WV, United States of America

Kimberly S Hayson