Hydrophilic polyurethanes of improved strength
First Claim
1. A substantially noncovalently crosslinked hydrophilic, substantially nonfoaming polyurethane resin having improved tear strength and a urea content of from about 13.6 to 33.7 weight percent, consisting essentially of the reaction product of a mixture of:
- A. a diol component selected from at least one of(1) a long chain poly(oxyethylene) glycol, having a molecular weight of from about 2500 to about 12000,(2) a medium chain poly(oxyethylene) glycol or polyester glycol, having a molecular weight of from about 250 to about 2500,B. at least one organic chain extender having a molecular weight of less than 250;
C. water; and
D. an organic diisocyanate;
wherein alternative mole ratios of the diol component A and water per mole of chain extender B are as follows;
(i) 0.4 to 0.5 of diol component (1), 1.5 to 10.0 of water;
(ii) 0.1 to 0.25 of diol component (2), 0.05 to 0.72 of water;
(iii) 0.25 to 0.50 of diol component (2), 0.25 to 1.00 of water;
(iv) 0.5 to 0.75 of diol component (2), 0.3 to 3.3 of water;
or(v) 0.06 to 0.07 of diol component (1), 0.1 to 0.2 of diol component (2) and 0.25 to 1.25 of water;
wherein the effective NCO;
OH ratio is in the range of 0.85;
1 to 1.1;
1 and the amount of water in the reaction mixture is in the range of about 1 to about 2.5 wt. %.
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Abstract
The strength and integrity of hydrophilic polyurethane resins prepared by reacting a diol component, an organic chain extender and an organic diisocyanate are improved by critical selection of the diol component, the amount of water in the reaction mixture and the mole rations of the reactants. The diol component is at least one of (1) a long chain poly(oxyethylene) glycol of molecular weight above 2500 and (2) a medium chain poly(oxyethylene) glycol or polyester glycol of 250-2500 molecular weight. The chain extender is a difunctional compound having a molecular weight of less than 250. The amount of water in the reaction mixture is 0.5 to 2.5 weight % and the urea content of the resins is from about 13.6 to 33.7 weight %.
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Citations
21 Claims
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1. A substantially noncovalently crosslinked hydrophilic, substantially nonfoaming polyurethane resin having improved tear strength and a urea content of from about 13.6 to 33.7 weight percent, consisting essentially of the reaction product of a mixture of:
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A. a diol component selected from at least one of (1) a long chain poly(oxyethylene) glycol, having a molecular weight of from about 2500 to about 12000, (2) a medium chain poly(oxyethylene) glycol or polyester glycol, having a molecular weight of from about 250 to about 2500, B. at least one organic chain extender having a molecular weight of less than 250; C. water; and D. an organic diisocyanate; wherein alternative mole ratios of the diol component A and water per mole of chain extender B are as follows; (i) 0.4 to 0.5 of diol component (1), 1.5 to 10.0 of water; (ii) 0.1 to 0.25 of diol component (2), 0.05 to 0.72 of water; (iii) 0.25 to 0.50 of diol component (2), 0.25 to 1.00 of water; (iv) 0.5 to 0.75 of diol component (2), 0.3 to 3.3 of water;
or(v) 0.06 to 0.07 of diol component (1), 0.1 to 0.2 of diol component (2) and 0.25 to 1.25 of water; wherein the effective NCO;
OH ratio is in the range of 0.85;
1 to 1.1;
1 and the amount of water in the reaction mixture is in the range of about 1 to about 2.5 wt. %. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification