Alkyl hydroxylamine compounds and their use for shortstopping free radical polymerizations

#This application is a U.S. National Phase Application of PCT/US2013/061108, filed Sep. 29, 2013, which claims priority to Indian Application 3054/DEL/2012, filed Sep. 28, 2012, both of which are incorporated by reference in their entireties.

#This invention relates to a method for shortstopping free radical polymerization reactions using shortstopping agents comprising combinations of primary alkyl hydroxylamines (AHAs), mixtures of at least one primary AHA and at least one secondary AHA, and salts thereof, with the proviso that N-isopropylhydroxylamine (IPHA) is substantially absent. A method for producing elastomers using the aforesaid IPHA-free AHA-based shortstopping agents is also provided.

#Free radical initiated emulsion polymerization reactions for making elastomers, such as styrene-butadiene rubber, butadiene rubber and acrylonitrile-butadiene rubber, often involve use of shortstopping agents to terminate the polymerization reaction. The polymerization reaction is stopped at a predetermined degree of monomer conversion in order to produce a rubber product with the desired characteristics.

#The terms “parts” and “phm (parts per hundred monomers),” as employed in the following examples, refers to parts by weight of shortstopping agent per 100 parts of monomer charged. The dosage and ranges of shortstopping agent are noted on active basis of the substance, not as supplied product concentration.

#The term “isopropylhydroxylamine” (IPHA) as used herein includes N-isopropylhydroxylamine, N-isopropylhydroxylamine acetate, N-isopropylhydroxylamine hydrochloride, N-isopropylhydroxylamine sulfate, and mixtures thereof. N-isopropylhydroxylamine, for example, is commercially available from ANGUS Chemical Company of Buffalo Grove, Ill. and is known for use as a primary component of short stopping agents for free radical initiated emulsion polymerization reactions for making elastomers.

#The terms “substantially absent” and “IPHA-free” are used herein to mean the absence of IPHA in the short stopping agents of the present invention and, more specifically means that IPHA may only be present in amounts less than 0.2% by weight, based on the total weight of the AHAs present in the shortstopping agents.