Appeal No. 96-2810
Application 08/017,086
have been found useful in forming protective colloids for the
production of stable aqueous polymer emulsions of vinyl
monomers, i.e., latexes, for use in paints, floor polishes,
and the
like (Lo, col. 1, l. l-13 and 40-51). Lo states (Lo, col. 1,
l. 52-68):
In the emulsion polymerization of ethylenically
unsaturated monomers, the presence of an effective amount
of HEC is known to produce latexes of submicron particle
size having improved stability and performance. Although
hydroxyethylcellulose is widely used as the protective
colloid to make polymer emulsions, it does feature
certain
deficiencies. A high level of hydroxyethylcellulose
normally is needed in order to prevent agglomeration
of the emulsion during polymerization and to maintain
mechanical stability against shear force during the
mixing
of polymer emulsion with paint ingredients. Typically,
for
effective use as a protective colloid for vinyl monomers,
HEC is employed in a proportion ranging from about one
percent or more by weight of the total monomer content.
A dried film of polymer emulsion containing this high level
of hydroxyethylcellulose, however, becomes water
sensitive.
Lo states that water-soluble hydrophobically modified
hydroxyethylcellulose having an amount of hydrophobic
modification in an amount of between 0.2 to 1% have been
efficiently utilized as thickeners in aqueous paint systems
(Lo, col. 2, l. 7-30). Lo discovered that (Lo, col. 2,
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Last modified: November 3, 2007