Homogeneous low hardness polyurethane
View Patent ↗This invention employs a polyol derivative of a fatty acid that is reacted into a polyurethane formed also with a urethane prepolymer, a polydiene, and optionally, a curative for cross-linking. The fatty acid moiety becomes a relatively short side chain of the polyurethane formed. In embodiments, the polyol is an ester of the fatty acid. This achieves reduction in hardness of the polyurethane with a homogeneity that provides consistent surface characteristics over an extended period desirable for use for electrophotographic development and the like when the material is used as a developer roller.
1. A homogeneous low hardness polyurethane characterized by being the reaction product of a urethane prepolymer, a polydiene, and a polyol derivative of a fatty acid, and, optionally, a graft diol curative, the urethane prepolymer comprising from 60 to 95 parts by weight of the reaction product.
2. The polyurethane of claim 1 in which said polyol is an oleochemical ester polyol.
3. The polyurethane of claim 2 , in which said ester is glycerol monooleate.
4. The polyurethane of claim 2 , in which said ester is polyglycerol monooleate.
5. A roller comprising the reaction product of a urethane prepolymer, a polydiene, and a polyol derivative of a fatty acid and, a graft diol curative, and also comprising a metal salt, said roller having an oxidized outer layer when cured and baked at an elevated temperature of greater than 80° C.; and said urethane prepolymer comprising from 60 to 95 parts by weight of the reaction product.
6. The polyurethane of claim 5 in which said polyol is an oleochemical ester polyol.
7. The polyurethane of claim 6 in which said ester is glycerol monooleate.
8. The polyurethane of claim 7 , also comprising in said reaction product a poly(ethylhexylacrylate) graft diol.
9. The polyurethane of claim 6 in which said ester is polyglycerol monooleate.