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Zirconium (III) salts as cure co-catalysts for nonwoven binders comprising acrylamidoglycolic acid
| Details |
Inventors: Goldstein, Joel E.; Iacoviello, John G.; Hawn, Gary G.; Cook, Gerald R.;
Assignee: Air Products and Chemicals, Inc. (Allentown, PA)
Primary Examiner: McCamish; Marion C.
Assistant Examiner:
Attorney, Agent or Firm: Gourley; Keith D., Simmons; James C., Marsh; William F.
A crosslinkable anionic binder composition which comprises an emulsion copolymer containing acrylamidoglycolic acid (AGA) and a zirconium III salt of an alpha or beta hydroxycarboxylic acid, the pH of the composition being from about 1.5 to 4.5. Provided are nonwoven binder compositions which are stable for extended periods prior to application of the binder composition onto the nonwoven substrate and initiation of crosslinking by application of heat. |
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DETAILED DESCRIPTION OF THE INVENTION The present invention provides a formaldehyde-free binder composition, post-catalytically cured by addition of a zirconium III salt of an alpha or beta hydroxycarboxylic acid such as zirconium ammonium citrate and zirconium ammonium lactate.
The disclosed formaldehyde-free nonwoven binder compositions containing acrylamidoglycolic acid (AGA) as a crosslinking agent and cured with the disclosed zirconium III salts perform equivalently to formaldehyde-containing binder systems.
In a preferred embodiment, the binder composition comprises an aqueous dispersion of a vinyl acetate-ethylene copolymer at about 35 to 65 wt % solids.
The copolymer comprises from 55 to 95 wt % vinyl acetate, 1 to 30 wt % ethylene and 0.
5 to 15 wt % of AGA based upon the amount of vinyl acetate.
Whenever "AGA" is used, it is to be understood that methacrylamidoglycolic acid (MethAGA) is also contemplated.
Acrylamidoglycolic acid (AGA) and methacrylamidoglycolic acid are represented by Formula I wherein R is H and CH.
sub.
3, respectively.
##STR1## The preferred copolymer consists essentially of from about 7 to 20 wt % ethylene, vinyl acetate and 3 to about 10 wt % AGA.
Such copolymer emulsions which are useful as nonwoven binders have Brookfield viscosities ranging from 10 to 2600 cps, preferably 400-1000 cps.
The copolymers have a Tg between -20.
degree.
and 32.
degree.
C.
, preferably -5.
degree.
to 25.
degree.
C.
Other copolymers suitable for practicing the claimed invention include those known in the art, such as those discussed in U.
S.
Pat.
No.
4,289,676, which is incorporated by reference.
The zirconium III salts of alpha or beta hydroxycarboxylic acids useful to this invention, by way of example, include zirconium ammonium lactate, zirconium ammonium glycolate and zirconium ammonium trilactate.
Particularly useful is zirconium ammonium citrate which can be formed in situ by reacting citric acid and ammonium zirconium carbonate.
A more detailed discussion follows regarding how to make and use these zirconium III salts
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Manufacturing Materials 
