Process for making clear polyurethane/urea elastomers
AssigneeArco Chemical Technology, L.P.
InventorsStephen D. Seneker, Chin-Chang Shen
Life of this patent
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Abstract
A process for making clear elastomers is disclosed. First, a polyol having a narrow molecular weight distribution (Mw/Mn<1.5) reacts an aromatic diisocyanate at an NCO/OH ratio from about 1.3 to about 3.0 to give a non-viscous isocyanate-terminated prepolymer. A mixture that contains this prepolymer and an aliphatic diisocyanate is then reacted with an aromatic diamine to give a clear elastomer. The elastomers have excellent overall physical and mechanical properties, including resilience greater than 55%. The elastomers are valuable for in-line skates and other applications for which clarity is important.
Claims27
A process which comprises:
- (a) reacting an aromatic diisocyanate with a polyol having a polydispersity (Mw/Mn) less than 1.5 to produce an isocyanate-terminated prepolymer, wherein the NCO/OH mole ratio is within the range of about 1.3 to about 3.0;
- (b) mixing the prepolymer with an aliphatic diisocyanate to form a prepolymer/aliphatic diisocyanate mixture that has an NCO content within the range of about 2 to about 13 wt. %;
- and
- (c) reacting the prepolymer/aliphatic diisocyanate mixture with an aromatic diamine in an amount and manner effective to produce a clear polyurethane/urea elastomer.
A process which comprises:
- (a) reacting an aromatic diisocyanate with a polyether diol having a polydispersity (Mw/Mn) less than 1.2 and an unsaturation less than 0.007 meq/g to produce an isocyanate-terminated prepolymer, wherein the NCO/OH mole ratio is within the range of about 1.5 to about 1.8;
- (b) mixing the prepolymer with an aliphatic diisocyanate selected from the group consisting of hydrogenated MDIs, isophorone diisocyanate, tetramethylxylene diisocyanates (TMXDIs), and mixtures thereof to form a prepolymer/aliphatic diisocyanate mixture that has an NCO content within the range of about 3 to about 10 wt. %;
- and
- (c) reacting the prepolymer/aliphatic diisocyanate mixture with an aromatic diamine selected from the group consisting of diethyltoluenediamines (DETDA), dimethylthiotoluene diamines (DMTTDA), and mixtures thereof in an amount and manner effective to produce a clear polyurethane/urea elastomer.
Dependencies are inferred from the claim text.