Inhibiting leaching of fire retardant salts from wood with cyclic sulfonium zwitterion solution impregnant
AssigneeThe Dow Chemical Company
InventorFrederick L. Brown
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Abstract
Leaching of a fire retardant salt, such as a mixture of ammonium phosphates, impregnated into a wood substrate is inhibited by a process comprising: A. impregnating the wood substrate with an aqueous solution of a cyclic sulfonium zwitterion (CSZ), exemplified by structural formula (I), and B. curing the resulting CSZ-impregnated wood substrate. ##STR1## CSZ impregnation of the wood substrate can be either concurrent with or subsequent to the fire retardant salt impregnation of same. This process provides a significant degree of leach protection to otherwise very leachable fire retardant salts.
Claims10
A process for inhibiting the leaching of a fire retardant salt from a wood substrate comprising:
- a. impregnating the wood substrate with either
- i. an aqueous solution comprising between about 5 and about 40 weight percent solids, the solids consisting of the fire retardant salt and a cyclic sulfonium zwitterion at a fire retardant salt:cyclic sulfonium zwitterion weight ratio between about 1:1 and about 20:1;
- or
- ii. subsequent to impregnating the wood substrate with the fire retardant salt, with an aqueous solution comprising between about 1 and about 40 weight percent of the cyclic sulfonium zwitterion;
- and
- b. curing the resulting cyclic sulfonium zwitterion-impregnated wood substrate.
Dependencies are inferred from the claim text.