Water-dispersible protein/polyurethane reaction product

DETAILED DESCRIPTION OF THE INVENTION In the process of our invention the isocyanate-capped liquid polyurethane prepolymer acts as: (a) a solvent to dissolve the protein which is to be bound; and (b) a reactant to react with the protein to bind it (the protein) to itself.
The solidification temperature of the isocyanate-capped liquid polyurethane prepolymer used in our process will vary depending on the molecular weight of the prepolymer and on the structure of the backbone of the prepolymer.
The thermal denaturation temperature of proteins is generally above about 35.
degree.
C.
However, some proteins are stable for relatively short periods (e.
g.
, 5-30 minutes or longer) at higher temperatures (e.
g.
at temperatures up to about 70.
degree.
C.
or somewhat higher).
The formation of the protein/prepolymer solution is conducted in the absence of water.
The solution can be formed in the presence or absence of a diluent or in the presence of a mixture of diluents.
Because of our disclosure, it will be readily apparent to those skilled in the art that a diluent which would denature the protein or prevent or substantially reduce dispersibility cannot be employed.
Diluents which are operable include but are not limited to those taught by Stanley (U.
S.
Pat.
No.
3,672,955).
The diluents can be very soluble in water, e.
g.
acetone and the like; moderately soluble in water, e.
g.
, methyl acetate, methyl ethyl ketone, and the like; or insoluble in water, e.
g.
benzene and the other diluents listed in the paragraph starting on line 45 of column 1 of Stanley's above-mentioned U.
S.
Pat.
No.
3,672,955.
Said U.
S.
Pat.
No.
3,672,955, in its entirety, is incorporated herein by reference.
Diluents serve to reduce the viscosity of: (a) the isocyanate-capped liquid polyurethane prepolymer; and (b) the resulting solution.
Where the diluent is insoluble or substantially insoluble in water, an emulsifying agent can be used during the foaming step.
Stanley (U.
S.
Pat.
No.
3,672,955) teaches the use of such emulsifying agent